JP3005393B2 - 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 is disclosed in
No. -135040. In this device, a microwave transmission path composed of a band-shaped conductor is arranged between an antenna of a magnetron and a cavity wall surface in a state of non-contact with the antenna and in parallel with the antenna, and a reflection plate is provided at a position sandwiching the antenna with the band-shaped conductor. , Receiving microwaves radiated from the antenna, and radiating the microwaves from the radiation antenna via the microwave transmission path.

[0003]

In the above conventional example,
A reflector is placed on the opposite side of the strip conductor plate so that as much microwaves as possible can be received by the strip conductor, but there is no direction other than the strip conductor or reflector when viewed from the magnetron antenna. Since the microwave leaks therefrom, the radio wave coupling between the band-shaped conductor and the antenna is weakened.

[0004] The present invention solves such a problem.

[0005]

Means for solving the problems of the present invention include a cavity for accommodating an object to be heated, a waveguide for propagating and supplying microwaves into the cavity, A magnetron having an antenna projecting therefrom, and a radiation antenna which penetrates through the antenna and is fixed at a distance not causing discharge to the waveguide, and which is radio-coupled to the antenna to radiate microwaves. The antenna has a through hole of a size that can secure a distance that does not discharge to the antenna, for fixing the antenna through the antenna,
A configuration is provided in which a rib extending substantially parallel to the antenna is provided around the entire periphery of the through hole.

[0006]

The microwave radiated from the magnetron antenna is received by the radiating antenna. In particular, the rib of the radiating antenna, which is substantially parallel to the antenna and extends all around, is close to the antenna and has a large facing area. Therefore, the leaked microwaves are small and the microwaves are received well, and the radio coupling between the magnetron antenna and the radiating antenna is correspondingly increased, so that the microwaves can be efficiently radiated from the radiating antenna.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 1 denotes an exterior of a microwave oven, 2 denotes a cavity for accommodating a food 3 to be heated from a front opening (not shown), and 4 denotes a food 3 disposed in the cavity 2 and accommodated. Is a motor that mounts the plate 4 on a rotating shaft 6 that penetrates the bottom surface 2a of the cavity 2 and rotates the plate 4 during cooking. In addition, since the placing plate 4 rotates during cooking, it is generally called a turntable.

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 cavity 2 side is large and becomes smaller as the waveguide 2 is further away.
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.

FIG. 2 is an enlarged view of a portion A in FIG. 19
Is a vacuum tube container having an anode and a cathode, 10 is a radiation fin fixed to the outer periphery of the vacuum tube container by press-fitting or the like, 11 is a magnet, 12 is a yoke which holds the vacuum tube container 19 and the magnet 11 in both axial directions. , 13 are antenna portions penetrating the yoke 12 and projecting from the vacuum tube container 19.

The antenna section 13 is provided with an antenna cap 14a serving as a radio wave radiating section covered at a tip end thereof, and a ceramic insulating cylinder 14b interposed between the cap 14a and the vacuum tube container 19. I have.

Reference numeral 15 denotes a circular plate-shaped radiation antenna made of a metal material such as aluminum. As shown in FIG.
A substantially donut shape in front view having a through hole 20 in the center,
When the magnetron 8 is fixed to the antenna section 13, a rib 21 extending in the cavity direction and substantially parallel to the antenna cap 14 a extends all around the through hole 20.

Reference numeral 16 denotes a fixed plate formed of a dielectric material having a low dielectric constant such as ceramics.
Through hole 17 substantially equal to the diameter of the antenna cap 14a of FIG.
Are provided, and ribs 16a and 16b are provided on the periphery.

The fixing plate 16 penetrates the antenna cap 14 a while pushing it into the through hole 17.
It is mounted on the antenna cap 14a by the frictional force between the portion and the antenna cap 14a, and is fixed in the waveguide 7 by penetrating ribs 16a and 16b through slits (not shown) provided at appropriate positions on the side wall of the waveguide 7. are doing.

The reason why the diameter of the antenna cap 14a and the diameter of the through hole 17 of the fixing plate 16 are substantially equal is that the diameter of the through hole 17 is changed when the radiating antenna 15 is detached for repair and then mounted again. Antenna cap 1
If the diameter is larger than the diameter of the radiation antenna 4a, it is easy to mount, but the distance between the radiating antenna 15 and the antenna cap 14a changes, and the radio wave mode in the cavity 2 changes to cause uneven heating. This is because there is a possibility that discharge occurs between the side wall and the side wall.

Further, around the radiation antenna 15,
Ribs 15a, 15b, and 15c are provided at approximately 120 ° intervals, and mounting holes are formed in the fixing plate 16 so that the center of the through hole 17 of the fixing plate 16 and the center of the through hole 20 of the radiation antenna 15 can be fixed. 16c, 16d, and 16e are provided at appropriate places, and the radiation antenna 15 is bent there and fixed through the ribs 15a, 15b, and 15c.

At the fixed position, the distance between the antenna cap 14a and the rib 21 of the radiating antenna 15 is designed to be approximately 2 mm so that electric discharge does not occur and radio waves can be efficiently transmitted. In addition, a sufficient distance is provided between the waveguide 7 and the radiation antenna 15 so that no discharge occurs.

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, the waveguide 7
When the ventilator 18 is viewed from the outside, it is invisible if the radiating antenna 15 is mounted at a predetermined position, and becomes visible if the radiating antenna 15 is mounted at a shifted position, so that the mounting state can be easily checked. It is.

In this configuration, during the heating operation, the antenna cap 14a of the magnetron 8 and the radiation antenna 1
An electric field is generated between the ribs 21 and the microwaves, 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 is in a state of floating in space without contacting anywhere, whereas the wall surface of the waveguide 7 is grounded, so that the radiation is radiated from the electric field between the antenna cap 14a and the radiation antenna 15. Antenna 15 and waveguide 7
The electric field between the wall surfaces is much stronger, and microwaves are more often radiated from between the radiation antenna 15 and the wall surface of the waveguide 7.

Therefore, microwaves are radiated only between the antenna cap 14a and the wall of the waveguide 7 in the related art. The radiation area from which the microwaves are radiated becomes very large, and the microwaves can be radiated into the cavity 2 like a shower using the radiation antenna 15, thereby improving the uneven heating. it can.

Incidentally, in order to exhibit the function of the radiation antenna 15, the outer diameter of the radiation antenna 15 is designed to be half or more of the wavelength of the microwave used.

Table 1 below shows the relationship between the ratio of the length of the antenna cap 14a of the magnetron 8 to the length of the rib 21 of the radiating antenna 15, input / output, and uneven heating.

[0025]

[Table 1]

According to Table 1, by setting each dimension so that the ratio of the length of the antenna cap 14a of the magnetron 8 to the length of the rib 21 of the radiating antenna 15 is larger than 1/10, the heating unevenness can be improved efficiently. Can be improved.

In the remarks column in Table 1, A is rib 2
1 shows a case where the antenna 1 extends from the radiation antenna 15 in the direction of the cavity 2, B shows a case where the antenna extends in the direction of the magnetron 8,
It can be seen that the type A has improved efficiency and uneven heating.

The method for measuring the unevenness in the plane shown in Table 1 is 10
Place beaker with 0cc of water on turntable 1/4
After placing two at a wavelength interval and heating at 200 W for 3 minutes and 30 seconds, the temperature rise of each beaker was measured, and the value was obtained by subtracting the minimum value from the maximum value.

[0029]

According to the present invention, the radiating antenna is provided with ribs substantially parallel to the magnetron antenna and on the entire periphery, so that there is no leakage of microwaves and the radio coupling between the antenna and the radiating antenna is strong. Thus, microwave radiation can be performed more efficiently from the radiation antenna.

[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.

[Explanation of symbols]

 2 Cavity 7 Waveguide 8 Magnetron 13 Antenna part 14a Antenna cap 15 Radiation antenna 16 Fixing plate

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

Claims (1)

(57) [Claims] 1. A cavity for accommodating an object to be heated, a waveguide for propagating and supplying microwaves into the cavity,
A magnetron having an antenna protruding into the waveguide, and a radiation antenna which penetrates the antenna and is fixed at a distance that does not discharge to the waveguide, and which is radio-coupled to the antenna to radiate microwaves; The radiating antenna includes a through hole having a size for securing a distance that does not discharge to the antenna for penetrating and fixing the antenna, and extending substantially in parallel with the antenna around the entire periphery of the through hole. A microwave oven comprising a set rib.