JPH0757869A - Microwave oven - Google Patents

Abstract

PURPOSE:To provide a microwave oven capable of easily performing the regulation of impedance between a magnetron and a load without causing a heating unevenness. CONSTITUTION:A recessed part 7 is formed substantially in the center of the side wall part 6 of a heating chamber, a magnetron 10 is mounted on the outside of the recessed part 7 outer wall, and a radiation antenna 9 consisting of a conductor is connected to the output part 8 of the magnetron 10 protruded into the recessed part 7. The opening side of the recessed part 7 is covered with a protecting cover 4 consisting of a disc dielectric. A doughnut auxiliary radiation antenna 5 having a diameter larger than the opening area of the recessed part 7 is fixed to the heating chamber 1 side of the protecting cover 4. The radiation antenna 9 and the auxiliary radiation antenna 5 are arranged in non-contact with a distance of a degree such that they are coupled in microwave form, but cause no discharge.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave oven equipped with an antenna that radiates microwaves over a wide range.

[0002]

2. Description of the Related Art FIG. 9 is a schematic front sectional view showing the structure of a conventional microwave oven proposed in Japanese Utility Model Laid-Open No. 59-95597. Reference numeral 31 in the drawing denotes a heating chamber, and a table 35 for mounting an object to be heated is provided on the bottom surface of the heating chamber 31. A circular or polygonal recess 37 having an opening is formed substantially in the center of the side wall 36 of the heating chamber 31, a magnetron 33 is attached to the outside of the recess 37, and an output 38 of the magnetron projects into the recess 37. . The output portion 38 has a columnar shape and is set to have a dimension shorter than the depth of the recess 37. Then, in order to adjust the impedance between the magnetron 33 and the load, a radiation antenna 39 made of a disk-shaped conductor having a diameter larger than that diameter is coupled to the output portion 38.

[0003]

10 and 11 show the following.
It is a fragmentary plane sectional view showing a microwave radiation state in the above-mentioned microwave oven. FIG. 10 is a diagram showing the microwave radiation state from the radiation antenna with arrows, and FIG. 11 is a diagram showing the microwave radiation state in the heating chamber. As shown in the figure, the magnetron 3 disposed in the recess 37
Microwaves from the output section 38 of No. 3 are radiated into the heating chamber 31 through the gap between the wall surface of the recess 37 and the end edge of the radiation antenna 39. At this time, the microwave radiation range into the heating chamber 31 is determined by the maximum radiation angle α of the microwaves emitted from the radiation antenna.
Is determined by the opening area and depth of the recess 37, the angle of the wall surface of the recess 37 with respect to the side wall 36, and the like. The larger the size of the recess 37 and the larger the diameter of the radiation antenna 39 arranged in the recess 37, the larger the maximum radiation angle α. However, the size of the concave portion 37 is limited due to various structural factors of the microwave oven, so that the maximum emission angle α of the microwave is limited.

As described above, in the conventional microwave oven, there is a limit to the maximum microwave radiation angle α, and it is difficult for the microwave to be radiated to a wide area in the heating chamber 31. There was a problem that.

In order to transfer the energy from the magnetron 33 to the object to be heated with high efficiency, the magnetron 3
It is necessary to set the impedance between the antenna 3 and the radiating antenna 39 to a value at which microwaves are propagated with high efficiency. In the above-described conventional example, the radiation antenna 39 having a diameter larger than that diameter is coupled to the output portion 38, and the impedance value is set by the dimension of the radiation antenna that propagates the microwave. Thus, the impedance value is determined by the size or shape of the radiating antenna. However, as described above, the size of the recess 37 is limited, which limits the size of the radiation antenna 39 arranged in the recess 37, and the energy from the magnetron 33 to the object to be heated with high efficiency. There is a problem that it is difficult to set the impedance to be sufficient for transmission.

Further, in order to solve the above-mentioned problem, it is conceivable to dispose the radiation antenna closer to the heating chamber 31 than to the opening side of the recess 37. For this purpose, the depth of the recess 37 is changed. Or the output section 38 of the magnetron 33
However, there is a problem that the design must be changed at the standard product level.

The present invention has been made in view of the above circumstances, and by providing an auxiliary radiation antenna that is microwave-coupled with the radiation antenna, heating unevenness does not occur, and the microwave oscillating section and the load are not generated. It is an object of the present invention to provide a microwave oven capable of sufficiently setting impedance.

[0008]

In a microwave oven according to the present invention, a radiation antenna is arranged in an opening provided in a wall surface of a heating chamber for heating an object to be heated, and a microwave oscillated from a microwave oscillating unit. In a microwave oven for radiating waves from the radiating antenna into the heating chamber, an auxiliary radiating antenna is provided on the heating chamber side of the radiating antenna, and the microwave is propagated with or without contacting the auxiliary radiating antenna with the radiating antenna. It is characterized by being combined as much as possible.

[0009]

In the microwave oven of the present invention, the microwave propagated from the radiating antenna is radiated from the gap between the auxiliary antenna provided on the heating chamber side of the radiating antenna and the wall surface of the heating chamber. Can be larger than the radiation angle from the radiating antenna. This widens the microwave radiation range into the heating chamber, and the microwaves are uniformly radiated into the heating chamber. Further, since the microwave radiation range into the heating chamber is determined by the size and position of the auxiliary radiation antenna, the radiation range in the heating chamber can be optimized regardless of the size and position of the opening. . Moreover, since the auxiliary radiation antenna can be set to a desired size and shape, the impedance is set to a desired value.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings showing the embodiments. FIG. 1 is a schematic perspective view showing the structure of the microwave oven of the present invention. In the figure, 1 is a heating chamber,
An object to be heated can be loaded into the heating chamber 1 by opening an openable / closable door 2 provided in front of the heating chamber 1. FIG. 2 is a schematic cross-sectional view of the right side wall facing the front of the microwave oven as viewed from above. Heating chamber 1
A recessed portion 7 having an opening is formed at substantially the center of the side wall portion 6, a magnetron 10 is attached outside the outer wall of the recessed portion 7, and an output portion 8 of this magnetron 10 projects into the recessed portion 7. The output portion 8 has a columnar shape and is set to have a dimension shorter than the depth of the recess 7. A radiation antenna 9 made of a conductor is coupled to the output section 8 of the magnetron 10. The opening side of the concave portion 7 is covered with a protective cover 4 made of a disk-shaped dielectric for preventing discharge between the radiation antenna 9 and an auxiliary radiation antenna 5 described later.

Then, on the heating chamber 1 side of the protective cover 4,
The auxiliary radiation antenna 5 on the donut disk having a diameter larger than the opening area of the recess 7 is fixed. At this time,
The radiating antenna 9 and the auxiliary radiating antenna 5 are not in contact with each other, and are arranged with a distance such that they are microwave-coupled and discharge is not generated. Here, the condition for microwave coupling between a plurality of radiating antennas without contact is
Another radiation antenna is arranged in the microwave radiation direction from one radiation antenna, or a plurality of radiation antennas are arranged so as to have substantially parallel portions.

FIG. 3 and FIG. 4 are partial plan sectional views showing a microwave radiation state in the above-mentioned microwave oven.
FIG. 3 is a diagram showing a microwave radiation state from the radiation antenna, and FIG. 4 is a diagram showing a microwave radiation state in the heating chamber. As shown in the figure, the microwave propagated from the output part 8 of the magnetron 10 arranged in the recess 7 is radiated to the heating chamber 1 side from the gap between the edge of the radiation antenna 9 and the wall surface of the recess 7. And this microwave
The auxiliary radiation antenna 5 is radiated into the heating chamber 1 through the gap between the edge portion of the auxiliary radiation antenna 5 and the wall surface of the side wall portion 6.

In the microwave oven having the above-mentioned structure, the heating chamber 1 and the edge portion of the auxiliary radiation antenna 5 provided on the side surface of the heating chamber 1 are arranged.
Microwaves are radiated into the heating chamber 1 from the gap between the side wall portion 6 and the side wall portion 6. At this time, the maximum radiation angle β at which the microwave is radiated is determined by the size and shape of the auxiliary radiation antenna 5 and the disposition distance from the side wall portion 6. The setting of the diameter and shape of the auxiliary radiation antenna 5 and the disposition distance from the side wall portion 6 is less restricted than that of the radiation antenna 9, and the maximum radiation angle β of microwaves from the auxiliary radiation antenna 5 is It is larger than the maximum radiation angle α from the antenna 7. In this way, since the maximum radiation angle β is large, microwaves are radiated in a wide range of the heating chamber, and uneven heating hardly occurs.

Further, since the diameter of the auxiliary radiation antenna 5 is less restricted, it is easy to set the impedance value for efficiently transmitting the energy from the output section 8 of the magnetron 10 to the object to be heated. As a result, even when the size of the recess 7 is limited and the diameter of the radiation antenna 9 is small,
A desired impedance value can be adjusted depending on the size and shape of the auxiliary radiation antenna 5. Further, since the protective cover 4 is arranged between the radiation antenna 9 and the auxiliary radiation antenna 5, the discharge between them is prevented.

Although the auxiliary radiation antenna has a donut shape in the above-mentioned embodiment, the invention is not limited to this.
It may be disk-shaped or rectangular.

Next, a second embodiment of the present invention will be specifically described with reference to the drawings showing the same. FIG. 5 is a schematic sectional view of the structure of the microwave oven according to the second embodiment of the present invention as seen from above. Reference numeral 11 in the drawing is a heating chamber, and a recess 17 is formed in the rear side of the side wall 16 rather than in the center thereof. And
A protective cover 14 made of a disk-shaped dielectric material having a diameter larger than the opening area of the recess 7 is disposed substantially in the center of the side wall portion 16. The protective cover 14 is provided on the heating chamber 11 side of the protective cover 14. An auxiliary radiating antenna 5 on a donut disk having substantially the same diameter is fixed at a position substantially eccentric to the center of the side wall 16 and eccentric to the center of the recess 7. The other points are the same as those in the above-described embodiment, and the description thereof will be omitted.

As described above, the output section 1 of the magnetron 20
The recess 17 for housing 8 may not be provided in the central portion of the side wall portion 16. For example, when a control circuit or control component for cooking control is provided in the side wall portion of the microwave oven,
As described above, the recess 17 must be provided from the rear rear surface. The microwave radiation from the radiation antenna 19 arranged in the recess 17 is biased to the back side in the heating chamber 11 and uneven heating is likely to occur, but as in the second embodiment, the auxiliary By fixing the radiation antenna 15 substantially at the center of the side wall portion 16, the microwave is generated by the auxiliary radiation antenna 15.
Is uniformly radiated into the heating chamber 11. Thus, even when the position where the recess 17 is provided is limited, the microwave can be uniformly radiated into the heating chamber 11.

In the above embodiment, one auxiliary radiation antenna is provided on the side wall surface, but a plurality of auxiliary radiation antennas may be provided. FIG. 6 is a schematic side view of the side wall surface of the microwave oven according to the third embodiment of the present invention as viewed from the inside of the heating chamber. In the figure, reference numeral 26 denotes a side wall surface, and the side wall surface 26 is provided with a recessed portion that projects to the outside of the heating chamber. A protective cover 24 made of a disk-shaped dielectric is disposed so as to cover the opening side of the recess, and eight rectangular radiation antennas 25, 25 ... Are provided on the surface of the protective cover 24 from the side wall surface 26 for a predetermined length. The protective cover 24 is spaced apart and fixed radially around the center of the protective cover 24. The other points are the same as those in the above-described first embodiment, and the description thereof will be omitted.

In such a microwave oven, microwaves are radiated from the outer edge portions of the radiation antennas 25, 25 ... Arranged radially, and the maximum radiation angle of the microwaves into the heating chamber is large, causing uneven heating. hard.

Although the radiating antenna and the auxiliary radiating antenna are arranged in non-contact with each other in the above-mentioned embodiment, the present invention is not limited to this. Wave coupling may be performed.

FIG. 7 is a schematic side view of the side wall surface of the microwave oven of the fourth embodiment of the present invention in which a part of the auxiliary radiation antenna is in contact with the radiation antenna, as seen from the heating chamber side, and FIG. It is a typical sectional view which looked at this side wall surface from the upper part. 4 in the figure
Reference numeral 6 denotes a side wall surface, and the side wall surface 46 is provided with a recess 47 protruding to the outside of the heating chamber. A protective cover 44 made of a disk-shaped dielectric is provided so as to cover the opening side of the recess 47, and the protective cover 44 is provided with a hole at a position symmetrical with the center. The magnetron 40 is attached to the outside of the outer wall of the recess 47, and the output unit 4 of the magnetron 40 is attached.
8 projects into the recess 47. The output portion 48 has a cylindrical shape and is set to have a dimension shorter than the depth of the recess 47. A radiation antenna 49 made of a conductor is coupled to the output section 48 of the magnetron 40.

The rectangular auxiliary radiation antenna 4
5, 45 have one end fixed to a substantially central portion of the radiating antenna 49, and the other end penetrating a hole provided in the protective cover 44 so as to extend in a radial direction from the center of the protective cover 44 and the side wall surface 46. They are spaced apart from each other and extend substantially in parallel. The other points are the same as those in the above-described first embodiment, and the description thereof will be omitted.

In such a microwave oven, microwaves are radiated from the outer edge ends of the auxiliary radiation antennas 45, 45 extending from the recess 47 into the heating chamber, and the maximum radiation angle of microwaves into the heating chamber is large. , Heating unevenness hardly occurs.
Further, since the radiating antenna and the auxiliary radiating antenna are in contact with each other, it is not necessary to consider the discharge, and the distance between the microwave radiations of the two is less limited as compared with the case of non-contact.

In the fourth embodiment described above, two auxiliary radiation antennas are arranged. However, the number of auxiliary radiation antennas is not limited to this, and a large number of auxiliary radiation antennas are arranged radially as in the third embodiment. May be. Further, the auxiliary radiation antenna 45 is not limited to the rectangular shape, and one auxiliary radiation antenna having a trumpet shape, for example, may be provided.

[0025]

As described above, according to the present invention, since the radiation antenna provided in the opening is provided with the auxiliary radiation antenna microwave-coupled to the heating chamber side, the auxiliary radiation antenna is removed from the heating chamber. The maximum radiating angle of the microwave radiated to the chamber is large, and the microwave is uniformly radiated into the heating chamber, so that heating unevenness does not occur. Further, since there are few restrictions on the size, shape and arrangement position of the auxiliary radiation antenna, the present invention has excellent effects such as easy impedance adjustment.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing a structure of a microwave oven of the present invention.

FIG. 2 is a schematic cross-sectional view of a wall surface of a microwave oven as viewed from above.

FIG. 3 is a partial plan cross-sectional view showing a microwave radiation state of a microwave oven.

FIG. 4 is a partial plan sectional view showing a microwave radiation state of a microwave oven.

FIG. 5 is a schematic sectional view of the structure of the microwave oven according to the second embodiment of the present invention as seen from above.

FIG. 6 is a schematic side view of a side wall surface of a microwave oven according to a third embodiment of the present invention.

FIG. 7 is a schematic side view of the side wall surface of the microwave oven according to the fourth embodiment as viewed from the heating chamber side.

FIG. 8 is a schematic cross-sectional view of a side wall surface of a microwave oven according to a fourth embodiment as viewed from above.

FIG. 9 is a schematic front sectional view showing the structure of a conventional microwave oven.

FIG. 10 is a partial plan sectional view showing a microwave radiation state of a conventional microwave oven.

FIG. 11 is a partial plan cross-sectional view showing a microwave radiation state of a conventional microwave oven.

[Explanation of symbols]

 1,11,21 Heating chamber 4,14,24,44 Protective cover 5,15,25,45 Auxiliary radiation antenna 6,16,26,46 Side wall part 7,17,47 Recessed part 8,18,48 Output part 9, 19,49 Radiant antenna 10,20,40 Magnetron

Claims (1)

[Claims] 1. A radiation antenna is disposed in an opening provided in a wall surface of a heating chamber for heating an object to be heated, and a microwave oscillated from a microwave oscillator is radiated from the radiation antenna into the heating chamber. In the microwave oven, an auxiliary radiating antenna is provided on the heating chamber side of the radiating antenna, and the auxiliary radiating antenna is coupled to the radiating antenna in a contactable or non-contact manner so that microwaves can propagate therein. range.