JP3005394B2 - microwave - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave oven.

[0002]

2. Description of the Related Art Conventionally, this kind of microwave oven has been
No. -50122. This is provided with a magnetron mounted so that an antenna protrudes into a heating chamber, and a flat plate electrode serving as a radiation antenna mounted with screws or the like to the magnetron antenna. They are attached in parallel.

However, there is a possibility that a discharge may occur between the antenna and the plate electrode depending on how the screws are attached. Therefore, a radiation antenna as described below has been considered.

This is shown in FIGS. 1, 5 and 6. 1 is an exterior of a microwave oven, 2 is a cavity for storing a food 3 to be heated from a front opening (not shown), 4 is a placing plate for placing the stored food 3 disposed in the cavity 2 and Reference numeral 5 denotes a motor for attaching the placing plate 4 to a rotating shaft 6 penetrating the bottom surface 2a of the cavity 2 and rotating the placing plate 4 during cooking. In addition, since the placing plate 4 rotates during cooking, it is generally called a turntable.

[0005] 7 is a waveguide provided on the side wall 2b of the cavity 2, 8 is a magnetron mounted on the wall surface facing the cavity 2 of the waveguide 7, that is, a magnetron mounted on the bottom surface 7a, 9 is a waveguide on the cavity side wall 2b. It is a protection plate made of a mica plate that closes the opening.

The waveguide 7 has a substantially trapezoidal cross section in which the opening area on the side of the cavity 2 is large and becomes smaller as the distance increases.
For example, it has a substantially truncated cone shape, and the wall surface facing the cavity 2, that is, the bottom surface 7a is designed to have a diameter of 80 mm or more.

The magnetron 8 includes a vacuum tube container 19 having an anode and a cathode, a radiation fin 10 fixed to the outer periphery of the vacuum tube container 19 by press-fitting or the like, a magnet 11, and both the vacuum tube container 19 and the magnet 11 in the axial direction. The yoke 12 is sandwiched between the yoke 12 and the antenna unit 13 penetrating the yoke 12 and protruding from the vacuum tube container 19.

The antenna section 13 has an antenna cap 14a covered on the tip and an antenna cap 14a.
And a ceramic insulating cylinder 14b interposed between the vacuum cylinder 19 and the vacuum tube container 19.

Reference numeral 15 denotes a radiating antenna which is disposed around the antenna cap 14a and has a substantially donut shape in a front view and is made of a circular flat metal material such as aluminum so as not to contact the antenna cap 14a.

The distance between the antenna cap 14a and the radiating antenna 15 is designed to be approximately 2 mm so that no discharge occurs and the radio wave can be efficiently coupled. In addition, a sufficient distance is provided between the waveguide 7 and the radiation antenna 15 so that no discharge occurs.

Reference numeral 16 denotes a fixing plate provided with a through hole 17 having a diameter smaller than the inner circumference of the radiation antenna 15 at a substantially central portion, and formed of a mica plate for fixing the radiation antenna 15.

The diameter of the through hole 17 of the fixing plate 16 is substantially equal to the diameter of the antenna cap 14a of the magnetron 8, and the fixing plate 16 is attached so as to be pushed into the antenna cap 14a.

[0013] This is a radiation antenna 1 for repair.
When the diameter of the through hole 17 is larger than the diameter of the antenna 13 when the antenna 5 is removed and then re-installed, the antenna can be easily installed, but the distance between the radiating antenna 15 and the antenna cap 14a changes. This is because uneven heating may occur, or electric discharge may occur between the radiation antenna 15 and the side wall of the waveguide 7.

15a, 15b and 15c are radiation antennas 1
Ribs 16c, 16 provided at approximately 120 ° intervals around
Reference numerals d and 16e denote mounting holes provided in the fixing plate 16, and each of the ribs 15a, 15b, 15c
Through the mounting holes 16c, d, and e to fix the radiation antenna 15.

Reference numerals 16a and 16b denote ribs provided around the fixing plate 16, which penetrate through slits (not shown) provided at appropriate positions on the side wall of the waveguide 7 to fix the fixing plate 16 in the waveguide. , The radiation antenna 15 is arranged in the waveguide 7.

Numeral 18 denotes a plurality of vents provided on the side wall of the waveguide 7, and the inside of the waveguide becomes high in temperature during the heating operation. The vent 18 is provided so as to be parallel to the radiation antenna 15, and the vent 18 is not provided on the side wall of the waveguide 7 facing the radiation antenna 15.

That is, when the radiation antenna 15 is attached to the antenna cap 14a of the magnetron 8 and the vent 18 is viewed from outside the waveguide 7, the radiation antenna 1 is positioned at a predetermined position.
5 is not visible if it is mounted, and becomes visible if it is mounted at a shifted position, so that the mounting state can be easily confirmed.

In such a configuration, during the heating operation, the antenna cap 14a of the magnetron 8 and the radiation antenna 15
An electric field is generated between them, and microwaves are emitted in a direction perpendicular to the electric field. Also, an electric field is generated between the radiation antenna 15 and the wall surface of the waveguide 7, and the microwave is radiated similarly.

The radiation antenna 15 floats in space without contacting anywhere, whereas the wall surface of the waveguide 7 is grounded, so that the electric field between the antenna cap 14a and the radiation antenna 15 causes The microwave between the radiation antenna 15 and the wall of the waveguide 7 is more radiated because the electric field between the antenna and the wall of the waveguide 7 is much stronger.

Therefore, microwaves are radiated only between the antenna cap 14a and the wall of the waveguide 7 in the related art. Therefore, the radiation area from which the microwaves are radiated becomes very large, the microwaves can be radiated in the cavity 2 in a shower shape, and the heating unevenness can be improved accordingly.

[0021]

However, since the above-mentioned radiating antenna 15 is fixed parallel to the side wall 2b of the cavity 2, the micro-wave radiated from the entire circumference of the radiating antenna 15 in the waveguide 7. The waves are similarly reflected in the waveguide and diffused into the cavity 2.

Accordingly, the heating unevenness in the vertical direction may not be improved only by moving the mounting position of the radiating antenna back and forth, because the position at which the heating unevenness occurs is changed and the like.

In particular, when the amount of food to be heated is large, microwaves absorbed by the food increase, so that it is inconspicuous. However, when heating a small amount of food, for example, when heating alcohol or milk, the cavity is not absorbed by the food. Since there are many microwaves propagating in 2, heat unevenness is conspicuous.

The present invention solves such a problem.

[0025]

The object of the present invention is to provide a cavity for accommodating an object to be heated and a cross section having a large opening area on the cavity side for transmitting and supplying microwaves into the cavity. A trapezoidal waveguide, a magnetron having an antenna protruding into the waveguide from the bottom surface of the waveguide facing the cavity, and no discharge around the antenna and to the antenna and the waveguide. A radiating antenna having a flat plate shape attached at a position separated by a distance, wherein the radiating antenna is configured to be inclined and fixed to a wall surface of the cavity.

[0026]

That is, since the microwave radiated from the radiation antenna into the cavity is inclined with respect to the wall surface of the cavity, the direction of the microwave radiated therefrom is radiated from other parts. Since the direction is different from the direction of the object, the direction of the microwave incident into the cavity from the waveguide is also different, and the microwave is diffused substantially uniformly in the cavity.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 2 and 3. Components having the same reference numerals as those already described have the same functions and will not be described.

Numeral 20 denotes a fixing plate formed of a mica plate having a through hole 21 at a substantially central portion, and is inclined by approximately 30 ° with respect to the side wall 2b of the cavity 2 toward the cavity 2 (FIG. 2).
(Tilted in the x direction inside) and fixed to the waveguide 7.
The surface 20a faces the cavity 2 and the surface 20b faces the magnetron 8.

Reference numeral 22 denotes a flat radiating antenna fixed to the surface 20b of the fixing plate 20 on the magnetron 8 side.
A substantially oval opening 23 larger than the through hole 21 in the center
Is provided.

The shape of the opening 23 is such that the shape of the radiating antenna 15 of the conventional example described above, that is, the shape of the inner circle corresponding to the opening 23 is true when the antenna 23 is attached to the antenna section 13 of the magnetron 8 with the fixing plate 20 inclined. If it is a circle, the distance between the antenna unit 13 and the radiation antenna 15 will not be uniform,
For example, if the distance between the antenna unit 13 and the radiating antenna 15 is set to a distance of 2 mm for efficient coupling, other parts may come too close to each other to cause a discharge. 13 and radiation antenna 1
If the closest distance to 5 is 2 mm, the other parts are too far apart to be able to efficiently couple in terms of radio waves, so that they should be substantially oblong and the distance between the antenna section 13 and the radiation antenna 22 should be constant. This is because

In such a configuration, the microwave is applied to the antenna cap 14 a of the magnetron 8 and the radiation antenna 22.
And an electric field is generated between the radiating antenna 22 and the waveguide 7 and radiated in the direction of the cavity 2, but since the radiating antenna 22 is inclined and fixed, the side wall 2b of the cavity 2 The distance to the outer circumference of the radiation antenna 22 is different over the entire circumference.

Therefore, the portion of the radiating antenna 22 close to the cavity 2 is radiated and propagates as it is in the cavity 2, while the portion distant from the cavity 2 is reflected on the wall surface of the waveguide 7 and is reflected by the microwave. Then, the propagation direction changes and the light propagates into the cavity 2.

Therefore, in the cavity 2, the microwave propagates in a complicated manner so that the unevenness in propagation is eliminated, and the unevenness in heating is improved.

FIG. 4 shows another embodiment. The embodiment differs from the embodiment of FIG. 2 in the shape of the waveguide 7 and the manner in which the radiation antenna 22 is attached.

First, the waveguide 7 has the same point that the cross-sectional area increases as the side wall approaches the cavity 2 from the bottom surface 7a, that is, the waveguide 7 is formed in a truncated cone shape. About 30 °.

The radiating antenna 22 is fixed such that the antenna cap 14a and the radiating antenna 22 are perpendicular to each other, as in the above-described conventional technique.

Therefore, as in the embodiment shown in FIG. 2, the radiation antenna 22 is inclined with respect to the side wall 2b of the cavity 2, so that the same action improves the uneven heating.

[0038]

According to the present invention, the radiation antenna is tilted and fixed, thereby changing the microwave radiation direction from the radiation antenna, thereby improving the uneven propagation of the microwave in the cavity and improving the uneven heating. Is what you do.

[Brief description of the drawings]

FIG. 1 is a sectional view of a microwave oven according to the present invention.

FIG. 2 is a partially enlarged view of a portion A in FIG.

FIG. 3 is a front view of a radiation antenna according to the present invention.

FIG. 4 is a diagram showing another embodiment.

FIG. 5 is an enlarged sectional view showing a conventional structure of a portion A in FIG.

FIG. 6 is a front view of a conventional radiation antenna.

[Explanation of symbols]

 2 Cavity 7 Waveguide 8 Magnetron 13 Antenna 14a Antenna cap 20 Fixing plate 22 Radiation antenna

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H05B 6/72

Claims (1)

(57) [Claims] 1. A cavity accommodating an object to be heated, a waveguide having a substantially trapezoidal cross section having a large opening area on the cavity side for propagating and supplying microwaves into the cavity, and the waveguide facing the cavity. A magnetron having an antenna projecting from the bottom surface of the waveguide into the waveguide, and a flat radiating antenna mounted around the antenna and at a distance away from the antenna and the waveguide so as not to discharge. Wherein the radiating antenna is fixed at an angle to the wall surface of the cavity.