JP2846795B2 - 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.

[0003]

In the above conventional example,
There is a possibility that a discharge may occur between the antenna and the flat electrode depending on how the screws are attached. Therefore, a radiation antenna as described below has been considered.

This is shown in FIGS. 1, 4 and 5. 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] Reference numeral 7 denotes a waveguide provided on the side wall 2b of the cavity 2, 8 denotes a wall facing the cavity 2 of the waveguide 7, that is, a magnetron mounted on the bottom surface, and 9 denotes a waveguide opening on the cavity wall 2b. Is a protective plate made of a mica plate that closes off.

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 diameter of the surface facing the cavity 2 is designed to be 80 mm or more.

[0007] 19 is a vacuum tube container having an anode and a cathode,
Reference numeral 10 denotes a radiation fin fixed to the outer periphery of the vacuum tube container 19 by press fitting or the like, 11 denotes a magnet, 12 denotes a yoke holding the vacuum tube container 19 and the magnet 11 in both axial directions, 1
Reference numeral 3 denotes an antenna portion that penetrates the yoke 12 and protrudes from the vacuum tube container 19.

The antenna section 13 is composed of an antenna cap 14a covered at the tip and a ceramic insulating cylinder 14b interposed between the antenna cap 14a 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. Further, 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 this configuration, during the heating operation, the antenna cap 14a of the magnetron 8 and the radiation antenna 1
5, an electric field is generated, 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, the microwave was radiated only between the antenna cap 14a and the wall surface of the waveguide 7 in the related art.
Radiation from the space between the radiation antenna 15 and the wall surface of the waveguide 7, the radiation area from which the microwave is radiated becomes very large, and the microwave can be radiated in the cavity 2 like a shower, Heat unevenness can be improved by that amount.

However, the aforementioned radiation antenna 15
Is fixed to the surface of the fixing plate 16 on the cavity 2 side, so that dirt of the food such as oil evaporating when the food 5 is heated is removed from the gap between the cavity 2 and the protection plate 9 by the waveguide 7.
Radiating antenna 15 and its surrounding fixed plate 16
May adhere to the This dirt is the radiation antenna 15
If it adheres to the fixing plate 16, the surface resistance of the fixing plate 16 decreases, and therefore, a discharge occurs between the antenna cap 14 a of the magnetron and the radiation antenna 15 and between the radiation antenna 15 and the waveguide 7. There is fear.

The present invention solves such a problem.

[0023]

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 a bottom surface of the waveguide facing the cavity, and a waveguide provided substantially at a center for penetrating the antenna; A fixed plate of a dielectric material that is fixed to the antenna, and a radiation antenna attached to the magnetron side surface of the fixed plate, around the through hole, and at a distance that does not discharge the antenna and the waveguide. It is a configuration provided.

[0024]

In other words, by fixing the radiation antenna to the surface of the fixing plate on the magnetron side, even if food dirt enters the waveguide, it adheres to the surface of the cavity where the radiation antenna is not fixed. There is a sufficient distance between the magnetron antenna cap and the waveguide, and no discharge occurs between them. Further, on the magnetron side of the fixing plate, there is no contamination of food, so there is no decrease in surface resistance, and no discharge occurs on this surface.

[0025]

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

Reference numeral 20 denotes a fixing plate formed of a mica plate having a through hole at a substantially central portion similarly to the fixing plate 16 described above.
The side 20b faces the side. The mounting method of the waveguide 7 and the magnetron 8 to the antenna unit 13 is the same as that of the fixing plate 16 described above.

A radiating antenna 21 is fixed to the surface of the fixed plate 20 on the magnetron 8 side. The radiating antenna 21 is fixed in the same manner as the radiating antenna 15 described above.

In such a configuration, when the food 3 is stored in the cavity 2 and heating by microwaves is started, moisture evaporates from the food 5 with the progress of heating, and floats in the cavity 2 as steam. . If the food 5 is a food using, for example, meat or the like, the generated steam contains oil, so that the floating steam is
When only water is dried after adhering to the wall surface, only oil remains and becomes dirty.

This water vapor enters the waveguide 7 from the gap between the wall surface 2 b of the cavity 2 and the protection plate 9,
Will adhere to.

The atmospheric pressure in the cavity 2 is increased by the heat radiated from the food 5 by heating, so that the room temperature becomes higher.
Since the airtightness inside is high, it is higher than the atmospheric pressure in the waveguide 7. Therefore, the air flow in the waveguide 7 flows from the cavity 2 toward the magnetron 8 and the water vapor also flows from the cavity 2 to the magnetron 8, so that the water vapor adheres to the surface 20a of the fixed plate 20 on the cavity 2 side. Even if there is, there is rarely a case where it goes around and adheres to the surface 20b on the magnetron 8 side.

Accordingly, food stains floating with the water vapor on the radiating antenna 21 and on the fixing plate 20 around the radiating antenna 21 do not adhere to the radiating antenna 21, thereby causing a discharge due to a decrease in the surface resistance of the fixing plate 20. Can also be prevented.

In order to perform grill cooking by providing a heater in the cavity 2, the inside of the waveguide 7 is partitioned by a fixing plate 20 as shown in FIG. A room partitioned by the fixed plate 20, the fixed plate 20 and the waveguide 7
It is also conceivable that by providing two air layers with the room separated by the bottom plate, the heat retaining effect is enhanced and heat is hardly released. This structure also prevents the food 5 from being stained on the surface 20b of the fixing plate 20 on the magnetron 8 side, further improving the effect of the above-described embodiment.

[0033]

According to the present invention, since the radiating antenna is fixed to the surface of the fixing plate on the magnetron side, dirt on the food such as oil which evaporates when the food is heated is reduced. Therefore, the discharge between the antenna cap of the magnetron and the radiation antenna or between the radiation antenna and the waveguide can be prevented.

[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 diagram showing another embodiment of the present invention.

FIG. 4 is an enlarged sectional view showing a conventional structure of a portion A in FIG.

FIG. 5 is a front view of the radiation antenna.

[Explanation of symbols]

 2 Cavity 7 Waveguide 8 Magnetron 13 Antenna part 14a Antenna cap 20 Fixing plate 21 Radiation antenna

Continued on the front page (58) Fields surveyed (Int.Cl. ⁶ , DB name) H05B 6/46 H05B ⁶ /52-6/64 H05B ⁶ /70-6/80

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 protruding into the waveguide from the bottom surface of the waveguide, a fixing plate of a dielectric material provided with a through hole at substantially the center and penetrating the antenna, and fixed to the waveguide; and And a radiation antenna attached to the magnetron-side surface around the through-hole and at a distance from the antenna and the waveguide so as not to discharge.