JP2000348858A - Microwave oven - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microwave oven capable of conducting uniform heating adapted to the material, shape and number of food, etc., by a direct radiating wave from an antenna having a strong directivity. SOLUTION: This microwave oven is provided with an antenna 8 composed of an axis element 8a disposed through a joined hole 5 to a wave guide tube 4 disposed in a ceiling wall surface 3a of a heating chamber 3 and of a plane element 8b joined to the axis element 8a. The plane element 8b is arranged at an angle θ relative to the ceiling wall surface 3a. The form of the plane element 8b is the form to be radiation characteristics having a strong radiation directivity in the direction vertical to the face of the plane element 8b by flowing a sheet-like resonant current through the plane element 8b when a microwave is supplied from the wave guide tube 4 through the axis element 8a, e.g. a length of an approximately half wavelength and a width of one to three- fourths wavelength. In accordance with the material, shape and number of a food 2, etc., the angle θis properly set and the food 2 can be heated uniformly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave oven, and more particularly to an antenna for guiding microwaves into a heating chamber and a configuration of the heating chamber.

[0002]

2. Description of the Related Art A conventional microwave oven will be described below with reference to the drawings. FIG. 15 is a longitudinal sectional view showing a configuration of a main part of an example of a conventional microwave oven.
FIG. 3A is a longitudinal sectional view showing a main configuration of the microwave oven. In FIG. 15, a magnetron 1 for generating a microwave having a frequency of 2450 mHz, a heating chamber 3 for accommodating a food 2 to be heated, a waveguide 4 for guiding the microwave to the heating chamber 3, and a heating chamber An antenna 6 provided through a coupling hole 5 between the antenna 3 and the waveguide 4 and an antenna motor 7 for rotating and driving the antenna 6 are provided in a direction perpendicular to a ceiling wall surface 3 a of the heating chamber 3. Element 6a penetrating the vertical element 6a and a horizontal element 6b horizontally connected to the vertical element 6a
It is composed of The antenna 6 is connected to the motor shaft 7
It is rotationally driven with a as a rotation axis.

In such a microwave oven, FIG.
As shown in (a), the length h of the vertical element 6a of the antenna 6 from the ceiling wall surface 3a is about 15 mm of about 1/8 wavelength, the length L of the horizontal element 6b is about 120 mm of about 1 wavelength,
The width W was generally configured in a band shape of about 1/4 wavelength and around 24 mm.

FIG. 16B is a plan view showing the structure of the antenna 6, and FIG. 16C is an equivalent circuit diagram thereof. Since the length L of the horizontal element 6b is a band-like line having substantially one wavelength,
A large resonance current I is excited in the horizontal element 6b. However, in the case of such a configuration, as shown in FIG. 16C, the image line 6c of the horizontal element 6b is formed on the opposite side of the ceiling wall surface 3a which is the ground plane, and is equivalent to a line of two parallel lines. Thus, it is known that a current having the same magnitude as the current of the horizontal element 6b and having the opposite direction is induced in the image line 6c. Therefore, the electromagnetic fields generated by the two cancel each other out, and the microwave radiated by the resonance current I flowing through the horizontal element 6b becomes smaller than the resonance current I.

On the other hand, the vertical dimension of the vertical element 6a from the ceiling wall surface 3a of the heating chamber 3 is approximately 波長 wavelength, and the length of the vertical element 6a is half the 半 分 wavelength which is generally the optimum length as a unipole antenna. It has sufficient radiation characteristics as a unipole antenna, and radiates microwaves strongly in the direction along the ceiling wall surface 3a which is a plane perpendicular to the vertical element 6a. Moreover, since the vertical element 6a is rotationally symmetric about 360 degrees around the central axis, the radiation from the vertical element 6a is basically basically uniform at 360 degrees.

Therefore, the antenna 6 does not have strong radiation directivity, and has radiation characteristics averaged in all downward directions including a vertical downward direction and a horizontal direction, that is, in a hemispherical direction.

[0007]

SUMMARY OF THE INVENTION
As described above, in the conventional microwave oven provided with the above, when viewed in the entire direction toward the hemisphere, which is the downward radiation direction of the ceiling wall surface 3a of the heating chamber 3, the direction having particularly strong radiation directivity characteristics is as follows. And has an average radiation characteristic. As a result, the rate at which microwaves are directly radiated from the antenna 6 to the food 2 to be heated is smaller than the rate at which the microwaves are once reflected by the surrounding side walls and then radiated.

[0008] Therefore, the food 2 is heated mainly by the microwaves that are reflected on the side wall of the surrounding heating chamber and propagate from the periphery toward the center. Generally, an object to be heated such as the food 2 contains a large amount of water and has a large attenuation rate with respect to microwaves. Therefore, microwaves entering from the surroundings attenuate toward the center and attenuate. It changes according to the shape, number, placement, and, of course, the shape and dimensions of the heating chamber 3.

However, in the case of the antenna 6 of the conventional example, since the radiation directivity is originally not so large in the direction toward the hemisphere, it is impossible to increase the radiation intensity at the center or to change the radiation distribution. Was. Further, even when the antenna 6 is rotated, there is no significant change in the radiation intensity for 360 degrees in the rotation direction, and therefore, there is little effect of stirring the electric field in the heating chamber 3 to make the heating distribution uniform.

The present invention solves the above-mentioned problems, and provides a microwave oven having an antenna having a strong radiation directivity in a downward direction as viewed from a ceiling wall surface of a heating chamber and capable of achieving uniform heating distribution of food. The purpose is to:

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a shaft element provided through a coupling hole provided in a wall surface of a heating chamber, and a planar surface formed by microwaves supplied through the shaft element. And a flat plate element that emits microwaves with strong directivity in a direction perpendicular to the plane by passing a resonance current of the flat plate element, and the flat plate element is arranged at an angle to the wall surface. .

According to the present invention, microwaves having strong directivity are radiated in a direction perpendicular to the plane of the flat plate element, and the flat plate element is disposed at an angle to the wall surface of the heating chamber provided with the antenna. Thus, the central axis of the radiation beam has an angle with respect to the central axis of the axial element corresponding to said angle. Therefore, the pattern of the radiation intensity distribution can be optimized by setting the angle in accordance with the target food, the size of the heating chamber, and the like.

[0013]

In the present invention according to the first aspect, the antenna is connected to a shaft element provided through a coupling hole for supplying microwaves provided on a wall surface of the heating chamber and to the shaft element. A flat plate element, and the flat plate element has a shape in which a planar resonance current flows by the microwave supplied through the shaft element, so that microwaves are strong in a direction perpendicular to the plane of the flat plate element. The flat plate element is arranged at an angle with respect to the wall surface of the heating chamber so as to have radiation directivity. This antenna has strong radiation directivity in the direction perpendicular to the plane of the flat element, and the direction of the central axis of the strong radiation is determined by the angle of the flat element with respect to the wall surface. The radiation intensity distribution can be optimized so as to irradiate strongly with microwaves.

In the present invention according to claim 2, the antenna comprises a shaft element provided through a coupling hole provided in a wall surface of the heating chamber, and a flat plate element joined to the shaft element. The shape of the element is such that a planar resonance current flows by the microwave supplied through the axis element, thereby giving a strong radiation directivity of the microwave in a direction perpendicular to the plane of the flat element. The element is bent at the joint with the shaft element, and the bending places the flat element at an angle to the wall surface of the heating chamber. With this configuration, the mechanical joining structure between the shaft element and the flat plate element can be as simple as that of the conventional example, and substantially the same effect as that of the present invention can be obtained.

In the present invention according to claim 3, the flat plate element is disposed at an angle in a direction away from the wall surface of the heating chamber in which the antenna is disposed. With this configuration, it is possible to secure a sufficient distance between the tip of the flat plate element and the wall surface irrespective of the dimension of the shaft element protruding from the wall surface of the heating chamber, and to set the angle of the flat plate element relatively freely.

According to a fourth aspect of the present invention, it is assumed that an end of the flat plate element in a direction farthest from a joint with the shaft element is bent in parallel with a wall surface of the heating chamber. In this configuration, since the distance of the flat plate element in the axial element direction can be reduced, the space occupied by the antenna in the axial element direction can be reduced.

According to the fifth aspect of the present invention, when the flat plate element is developed on a plane parallel to the wall surface on which the antenna is disposed and passing through the junction between the flat plate element and the axis element, the axis of symmetry passing through the center of the axis element is formed. And the maximum width in the symmetric axis direction is approximately 1/2
The flat plate has a wavelength and a maximum width in a direction perpendicular to the axis of symmetry of approximately １ ／ to ／ wavelength. With these settings, strong radiation directivity is realized.

According to the sixth aspect of the present invention, when the flat plate element is developed on a plane parallel to the wall surface on which the antenna is arranged and passing through the junction of the flat plate element and the axis element, the axis of symmetry passing through the center of the axis element is formed. And the width in the direction of the symmetry axis is approximately 波長 wavelength, and the width in the direction perpendicular to the symmetry axis is approximately ４ wavelength to 3 /
It is a rectangular flat plate with four wavelengths, preferably a square flat plate with one side of approximately 53 mm. With these settings, a flat plate element suitable for microwave wavelengths for microwave ovens is realized.

In the present invention according to claim 7, when the flat element is developed on a plane parallel to the wall surface on which the antenna is arranged and passing through a joint point between the flat element and the axis element, the axis of symmetry passing through the center of the axis element is formed. And the width in the direction of the symmetry axis is approximately 波長 wavelength, and the width in the direction perpendicular to the symmetry axis is approximately ４ wavelength to 3 /
An elliptical flat plate of four wavelengths, preferably with a diameter of approximately 62 mm
And a substantially circular flat plate. With these settings, a flat plate element suitable for microwave wavelengths for microwave ovens is realized.

According to the present invention, the dimension of the axial element of the antenna protruding from the wall surface of the heating chamber is set to 1/10 to 1/100 wavelength. In the present invention, by setting the length of a vertical element of an antenna with a horizontal element, which has been widely used, to be shorter than 1/8 wavelength (about 15 mm) of a vertical element, the micro-radiation mainly emitted in the horizontal direction from the axis element is achieved. The intensity of the wave can be significantly reduced as compared with the conventional configuration, and the directivity due to the radiation from the flat plate element is further increased.

According to the ninth aspect of the present invention, the antenna is configured to rotate about the central axis of the axis element. This rotation enables the object to be heated to be uniformly heated at the center and the periphery, and even on the circumference. The antenna is driven to rotate by an antenna motor coupled to the shaft element.

According to the tenth aspect of the present invention, the coupling hole is provided on the ceiling wall surface of the heating chamber, and the food mounting table on which the food is mounted is rotated. In this case, the reflected wave from the wall surface of the heating chamber together with the direct radiated wave from the antenna acts so as to be uniformly applied 360 degrees on the circumference.

According to the eleventh aspect of the present invention, the antenna is configured to rotate around the axis element, and a predetermined distance is provided between the rotation center of the food table and the rotation center of the antenna. In this case, since the center of the rotation circle in the direction in which the radiation beam from the antenna is directed is offset from the center of rotation of the food mounting table, the direction in which the radiation beam is directed is changed in the radial direction of the rotation center of the food mounting table. Act on.

In the twelfth aspect of the present invention, the stop angle of rotation of the antenna or the range of the rotation angle is selected.
Or it can be changed. In this case, it is possible to optimize the direction of the radiation beam in the direction of the radius of rotation of the food placing table by selecting the stop angle or the rotation angle of the antenna according to the type, shape, number, etc. of the food.

Hereinafter, embodiments of the present invention will be described.

[0026]

(Embodiment 1) Hereinafter, Embodiment 1 of a microwave oven according to the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view showing a configuration of a main part of the present embodiment, FIG. 2 is a longitudinal sectional view showing a configuration near an antenna in the present embodiment, and FIG. 3 is a development showing a configuration of a flat element of the antenna in the present embodiment. It is a top view.

1 to 3, reference numeral 1 denotes a magnetron that generates microwaves, 2 denotes a food heated by the microwave, 3 denotes a heating chamber for storing the food 2, and 4 denotes a microwave generated by the magnetron 1. A waveguide 5 leading to the heating chamber 3, a coupling hole 5 provided through the waveguide 4 and the ceiling wall 3 a of the heating chamber 3, an antenna 8 in the present embodiment, and a coupling hole 5.
And a flat plate element 8b joined to the shaft element 8a. Further, the antenna 8 is driven to rotate about the shaft element 8a by the antenna motor 7 and the motor shaft 7a made of a dielectric having a small dielectric loss. The dimension h of the shaft element 8a from the ceiling wall 3a is 1/1.
The wavelength is set to 0 wavelength to 1/100 wavelength, and is set to 6 mm in this embodiment.

The flat plate element 8b is provided on the ceiling wall 3a of the heating chamber 3.
Are arranged at an angle θ with respect to. Now, assuming that an xy plane is a plane passing through the junction between the flat element 8b and the axis element 8a and parallel to the flat element 8b, the flat element 8b has a symmetric axis passing through the center of the axis element 8a. Can be the x-axis. The flat element 8b is made of a square metal plate having a side of about 53 mm and made of an electric conductor such as aluminum, for example. The axis element 8a is joined on the x-axis at about 19 mm from the center of the flat element 8b. The direction perpendicular to the xy plane passing through the junction between the axis element 8a and the flat plate element 8b on the x axis is defined as the z axis.

The operation and operation of the above configuration will be described. First, before describing the operation and operation of the present embodiment, a configuration serving as a basis of the operation and operation of the present invention, that is, a case where the flat plate element 8b is disposed parallel to the ceiling wall surface 3a (positioned at an angle θ) ) Will be described with reference to FIG. FIG.
As described above, it is assumed that an antenna 9 is provided for distinction from the antenna 8 of the present embodiment, and a flat plate element 9b coupled to a vertical element 9a is set in parallel with the ceiling wall surface 3a. The other configuration is completely the same as the configuration of the present embodiment.

The vertical element 9a of the antenna 9 is 6 mm from the ceiling wall 3a of the heating chamber, which corresponds to the ground plane, and is approximately 1/2 in wavelength.
The length corresponding to 0 wavelength is provided so as to protrude into the heating chamber 3, and this length is set sufficiently shorter than the length of about 15 mm of the vertical element of the antenna with the horizontal element which has been widely used conventionally. The intensity of the microwave radiated from the vertical element 9a is much smaller than that of the conventional configuration.

On the other hand, the microwave guided from the waveguide 4 is guided to the plate element 9b via the vertical element 9a, and a planar resonance current of a mode generally called Tm100 wave is excited. FIG. 5 is a schematic diagram showing magnetic lines of force generated by a current flowing when Tm100 waves are excited in the flat plate element 9b. The distance h between the ceiling wall surface 3a and the flat plate element 9b is
For example, if it is as close as possible to 1 mm or less and is close to zero, Tm100 waves are excited by resonance at a half-wavelength 60 mm square. However, in the case of this example, since the distance h is set to 6 mm, it is estimated that the resonance Q is greatly reduced, and a current component is generated in the y-axis direction, so that the resonance frequency is reduced. Therefore, resonance occurs at the square plate element 9b with a shorter side of 53 mm, which is slightly shorter than the half wavelength, and a strong unidirectional radiation pattern having a maximum value in the z-axis direction is generated by the resonance current.

This is because, unlike the conventional band-shaped horizontal element 6b, since a planar resonance current flows through the flat element 9b, a magnetic current which is not canceled by the image current is generated.
It is the teaching of microwave engineering that this occurs at the end of b in the y-axis direction.

FIGS. 6A, 6B and 6C are characteristic diagrams comparing the radiation pattern of the antenna 9 with the radiation pattern of the antenna 6 of the conventional example. FIG. 6C shows the relationship between the antennas 6 and 9 and the coordinate axes. FIG. 6A shows the radiation pattern of the antenna 6, and FIG. 6B shows the radiation pattern of the antenna 9. 5 shows a radiation pattern in a well-known xy section. The ceiling wall surface 3a is used as a ground plane, and an electric wave horizontal thereto is referred to as a horizontal wave, and a vertical wave is referred to as a vertical wave. The radiation intensity in the z-axis direction of the antenna 9 shown in FIG. 6B is 8 compared with the radiation intensity in the z-axis direction of the conventional antenna 6 shown in FIG.
dB, that is, 6 times or more, the radiation intensity in the peripheral direction is correspondingly reduced.

Next, based on the basic technology described above, FIG.
Returning to FIG. 3, the present embodiment will be described. In FIG. 2 showing a cross section of a main part in this embodiment, the flat plate element 8b of the antenna 8 is arranged at an angle θ with respect to the ceiling wall surface 3a of the heating chamber 3. As described above, the planar element 8b is excited by a planar resonance current and has a strong radiation directivity in the direction perpendicular to the planar element 8b.
The direction of the central axis of the radiation beam is determined according to the angle θ of b. As a result, the central axis of the radiation beam is aligned with the arrow (z
As shown by (axis), it passes through the center of the junction between the flat plate element 8b and the shaft element 8a, and faces in the z-axis direction which is a coordinate axis perpendicular to the xy plane where the flat plate element 8b is located. Heading away from the center of the

Therefore, by setting the angle θ of the flat plate element 8b in accordance with the type of the food 2 and the shape of the heating chamber 3, it is possible to select and optimize the distribution in which the food 2 receives radiation directly from the antenna 8. Can be. As a result, in the conventional configuration, it was possible to uniformly heat only the limited food 2 and the limited shape of the heating chamber 3, but in the configuration of the present embodiment, it was possible to heat the food 2 and the heating chamber 3 according to the shape. Flat plate element 8 of antenna 8
By setting the angle θ of b, optimization of the heating distribution can be realized.

In the case of a rectangular flat plate element 8b in which Tm100 waves are excited, a square is the most common, but the flat plate element 8b basically has a different horizontal width, that is, a different width W in the y-axis direction. Only the resonance frequency changes slightly. Therefore, it is possible to configure the flat plate element 8b that sufficiently realizes the characteristics of the present invention when the width W is in the range of about 1/4 wavelength to about 3/4 wavelength.

Embodiment 2 Hereinafter, a microwave oven according to Embodiment 2 of the present invention will be described with reference to the drawings. FIG. 7 is a longitudinal sectional view showing the configuration of the main part of the present embodiment, and FIG. 8 is a developed plan view showing the configuration of the antenna 8 in the present embodiment. This embodiment is different from the first embodiment in that the flat element 8
b is bent at the joint with the shaft element 8a, and the flat plate element 8b is arranged at an angle θ with respect to the ceiling wall surface 3a of the heating chamber 3 by this bending. Other configurations are the same as those of the first embodiment, and a detailed description will be omitted.

The operation and operation of the above configuration will be described. In the case of the configuration of the present invention, as shown in FIGS. 7 and 8, the joint between the flat element 8b and the shaft element 8a is located at the end of the flat element 8b, so that microwaves can be efficiently transmitted to the flat element 8b. Propagated and excited. Therefore, the bent portion occupies most of the area of the flat plate element 8b, and exhibits substantially the same characteristics and functions as those of the first embodiment.

In the structure described in the first embodiment, the flat plate element 8
The joint between b and the shaft element 8a has a configuration having an angle θ, and the structure for coupling is unexpectedly restricted. That is, as in the case of the antenna 6 in the conventional example, it is not possible to use a simple coupling means that penetrates a screw portion provided at the tip of the shaft element 8a into a hole provided in the flat plate element 8b and fastens with a nut. On the other hand, in the configuration of the present embodiment, it is possible to realize a simple method of simply bending the flat plate element 8b while keeping the coupling portion the same as that of the conventional example.

(Embodiment 3) A microwave oven according to Embodiment 3 of the present invention will be described below with reference to the drawings. FIG. 9 is a longitudinal sectional view showing the configuration of a main part of the present embodiment, and FIG. 10 is a developed plan view showing the configuration of the antenna 8 in the present embodiment. This embodiment is different from the second embodiment in that the bent portion of the flat plate element 8b is disposed at an angle θ in a direction approaching the ceiling wall surface 3a of the heating chamber 3, and the bent portion in the direction farthest from the axial element 8a. The configuration is such that the end is bent in parallel with the ceiling wall surface 3a. The other configuration is the same as that of the second embodiment, and the detailed description is omitted.

The operation and operation of the above configuration will be described. The state of the lines of magnetic force generated by the current flowing when the Tm 100 wave is excited in the flat plate element 8b is the same as that shown in FIG. Therefore, it can be seen that the density of the lines of magnetic force is small at both ends in the x-axis direction, and the proportion of the entire flat plate element 8b that contributes to microwave radiation is small compared to its area. As a result, the distance of the flat plate element 8b in the axial element 8a direction can be reduced while minimizing the influence on the radiation characteristics, so that the ceiling wall 3a of the heating chamber 3 and the ceiling wall 3a in the limited axial space of the axial element 8a are reduced. A sufficient gap g that does not cause troubles such as electric discharge can be secured.

(Embodiment 4) Hereinafter, a microwave oven according to a fourth embodiment of the present invention will be described with reference to the drawings. FIG.
FIG. 3 is a developed plan view showing the configuration of the flat plate element 8b of the antenna 8 in the present embodiment. The fourth embodiment differs from the first embodiment in that the flat plate element 8b of the antenna 8 has a substantially circular shape with a diameter of approximately 62 mm. The shaft element 8a is joined at a position approximately 19 mm from the center of the flat plate element 8b. The other configuration is the same as that of the first embodiment, and the detailed description is omitted.

The operation and operation of the above configuration will be described. The circular flat plate element 8b in the present embodiment resonates to generate a Tm110 mode. In the case of a circular flat plate element 8b, it is known that the resonance frequency at which the fundamental mode is excited can be obtained at c = 0.58 wavelength, where c is the diameter. Also in this embodiment, as in the case of the first embodiment, the dimension of the shaft element 8a protruding from the ground plane is set to 6 mm, so that the resonance Q is greatly reduced. Therefore, the radius is approximately 62mm
Resonates in the circular flat plate element 8b, and generates a unidirectional radiation pattern having the center axis of the beam in the z-axis direction perpendicular to the flat plate element 8b by the resonance current.

However, since the resonance frequency including the shaft element 8a varies depending on the length and diameter of the shaft element 8a, the position on the flat plate element 8b to which the shaft element 8a is joined, the exact dimensions include these dimensions and shapes. This is the same as the case of the rectangle in the case of the circle.

In this embodiment, the case where the flat plate element 8b excited by the Tm110 wave is circular is shown. However, the circle is a kind of ellipse, and even if the flat plate element 8b is elliptical, the axial length c in the x-axis direction is small. If the wavelength is approximately １ ／, even if the axis length d in the y-axis direction is slightly different, excitation is performed in a similar resonance mode, and the resonance frequency only slightly changes. Therefore, the axial length d in the y-axis direction is 1
In the range of about す る wavelength to about ／ wavelength, it is possible to configure the flat plate element 8 b that realizes the characteristics exhibiting the function of the present invention sufficiently. FIG. 12 is a developed plan view showing a configuration in the case where the flat plate element 8b is elliptical.

Although the flat plate element 8b described in the first to fourth embodiments has a rectangular or elliptical shape only, the flat plate element 8b does not need to be a perfect rectangular or elliptical shape to be in a resonance state. Needless to say, for example, various shapes such as a rectangle whose corners are largely cut or rounded and an intermediate shape thereof can be considered. That is, basically, the maximum width of the flat plate element 8b in the x-axis direction is approximately １ ／ wavelength, and y
It is sufficient if the maximum width in the axial direction is approximately １ ／ to ３ wavelength.

Further, when a resonance current flows through the flat horizontal element so that the generated electromagnetic field is not canceled by the image line as in the case of the linear antenna, even in the higher-order mode, the resonance current is perpendicular to the flat element 8b. Since strong directivity is produced in any direction, the same effect is produced even when the width in the x-axis direction is ２ wavelength or more and excitation is performed in a higher-order mode.

(Embodiment 5) Hereinafter, Embodiment 5 of the microwave oven of the present invention will be described with reference to the drawings. FIG.
FIG. 3 is a longitudinal sectional view showing a configuration of a main part of the present embodiment. This embodiment is different from the first embodiment in that first, the antenna 8 is not rotated, and the food mounting table 10 on which the food 2 is mounted.
Is rotated by the turntable motor 11. Other configurations are the same as those of the first embodiment, and detailed description is omitted.

The operation and action of the above configuration will be described. In this embodiment, the antenna 8 is fixed and the food 2
Is rotated, so that not only uniform heating in the circumferential direction due to the direct radiation wave is realized as in the case of rotating the antenna 8, but also heating due to the reflected wave from the ceiling wall surface 3 a is 360 ° average with the rotation. Therefore, more uniform heating can be realized than in the case of the configuration in which the antenna 8 is rotated.

Further, since the coupling portion formed by the axis element 8a of the antenna 8 and the waveguide 4 does not have an electric field distribution symmetrical with respect to the center axis of the axis element 8a in the direction of propagation of the microwave in the waveguide 4, Although a completely circularly symmetric electric field pattern cannot be realized by rotating the antenna 8, the configuration of the present embodiment naturally solves the problem.

In this embodiment, the configuration in which the antenna 8 is not rotated has been described. However, if the antenna 8 is also rotated, it goes without saying that both effects are added.

Embodiment 6 Hereinafter, a microwave oven according to Embodiment 6 of the present invention will be described with reference to the drawings. FIG.
FIG. 3 is a longitudinal sectional view showing a configuration of a main part of the present embodiment. This embodiment is different from the fifth embodiment in that the antenna 8 is
It is configured to rotate around the center a, and a fixed distance d is provided between the rotation center of the food table 10 and the rotation center of the antenna 8. Another feature is that the range of the rotation stop angle or the rotation angle of the antenna 8 can be selected or changed. FIG. 14 illustrates a case where the antenna 8 is at a rotation angle where the x-axis and the z-axis are on the plane of the paper.
The x axis, which is the symmetry axis of b, and the z axis, which indicates the direction of the radiation beam at that position, and the symmetry axis of the plate element 8b and the direction of the radiation beam, at which the antenna 8 is rotated 180 degrees, are x1 axes, respectively. Indicated by the z1 axis. The other configuration is the same as that of the fifth embodiment, and the detailed description is omitted.

The operation and operation of the above configuration will be described. In the case of the present embodiment, there is a distance d between the center of the rotation circle drawn by the direction of the radiation beam from the antenna 8 due to the rotation of the antenna 8 and the rotation center of the rotation of the food table 10, The direction of the beam changes in the radial direction around the center of rotation of the food table 10 with the rotation of the antenna 8. Therefore, if the cycle of rotating the antenna 8 and the cycle of rotating the food table 10 are different, the direction of the radiation beam changes in the radial direction of the rotation center of the food table 10 with the rotation of the antenna 8. The direct microwave radiation to a wide range corresponding to the variation width is uniformly performed by 360 degrees.

Further, a stepping motor or the like is used as the antenna motor 7 and a control panel (not shown) for controlling the stepping motor is provided. If the angle can be selected, the position of the radiation beam and the width of change thereof can be optimized in the radial direction of rotation of the food table 10 according to the food 2.

[0055]

According to the first aspect of the present invention, a planar resonance current flows through a flat plate element by microwaves supplied through a shaft element provided through a ceiling wall of a heating chamber. By using a microwave oven arranged at an angle with respect to the ceiling wall surface of the heating room, it is possible to obtain a radiation characteristic having a strong directivity corresponding to this angle, and if only the vicinity of the center of the food is strongly illuminated The radiation intensity distribution can be optimized.

According to a second aspect of the present invention, the antenna is formed by bending a flat plate element at a joint with the axis element, and by bending the flat plate element at an angle with respect to the ceiling wall surface of the heating chamber. The same effect as that of the microwave oven according to the first aspect can be obtained while the joint structure between the shaft element and the flat element remains the same as the conventional simple structure.

According to a third aspect of the present invention, there is provided the microwave oven according to any one of the first and second aspects, wherein the flat plate element has an angle in a direction away from the ceiling wall surface of the heating chamber in which the antenna is arranged. Thereby, the distance from the wall surface of the tip of the flat plate element can be sufficiently ensured irrespective of the dimension of the shaft element from the ceiling wall surface of the heating chamber.

According to a fourth aspect of the present invention, the end of the flat plate element in the direction farthest from the junction with the axis element is bent in parallel with the wall surface of the heating chamber. By using any of the microwave ovens, the space occupied by the antenna in the axial element direction can be reduced.

According to a fifth aspect of the present invention, the maximum width of the flat plate element in the direction of the target axis is approximately 波長 wavelength, and the maximum width in the direction perpendicular to the target axis is approximately １ ／ wavelength to 3 times. / 4
A flat plate element having a rectangular or substantially circular wavelength, preferably a square or substantially circular plate element having a wavelength of about 53 mm.
By using the microwave oven according to any one of the fourth to fourth aspects, a flat plate element having an appropriate size with respect to microwaves for a microwave oven can be formed.

The present invention according to claim 8 is the microwave oven according to any one of claims 1 to 7, wherein the length of the axis element is set shorter than the conventional 1/8 wavelength (about 15 mm). Thereby, the radiation directivity of the flat plate element can be further enhanced.

According to a ninth aspect of the present invention, there is provided the microwave oven according to any one of the first to eighth aspects, wherein the antenna is configured to rotate about the central axis of the axis element, thereby providing an object to be heated. The heating can be made uniform around the circumference.

According to a tenth aspect of the present invention, there is provided the microwave oven according to any one of the first to ninth aspects, wherein a coupling hole is provided on a ceiling wall surface of the heating chamber, and the food mounting table on which the food is mounted is rotated. By doing so, the reflected wave from the wall surface of the heating chamber can be uniformly applied 360 degrees on the circumference simultaneously with the radiation wave from the antenna.

According to the eleventh aspect of the present invention, the antenna is configured to rotate around the axis element, and a fixed distance is provided between the rotation center of the food table and the rotation center of the antenna.
By setting the microwave oven to 0, the direction of the radiation beam can be changed in the radial direction of the rotation center of the food table.

According to a twelfth aspect of the present invention, there is provided a microwave oven according to the eleventh aspect, in which the stop angle or the range of the rotation angle of the antenna can be selected or changed, so that the radiation beam can be changed according to the food. The direction can be optimized on the rotational direction of the food table.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a configuration of a main part of a microwave oven according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing a configuration near an antenna in the embodiment.

FIG. 3 is a developed plan view showing the configuration of the flat plate element of the antenna according to the embodiment.

FIG. 4 is a longitudinal sectional view showing a main part configuration of a microwave oven on which the operation principle of the embodiment is based.

FIG. 5 is a schematic diagram showing lines of magnetic force generated in a flat element of the antenna corresponding to the operation principle.

FIG. 6A is a radiation pattern diagram showing a radiation characteristic of a conventional microwave oven antenna. FIG. 6B is a radiation pattern diagram showing a radiation characteristic of a microwave oven antenna based on the operation principle of the first embodiment of the present invention. c) Layout diagram showing the relationship between antenna and coordinate axes

FIG. 7 is a longitudinal sectional view showing a main part configuration of a microwave oven according to a second embodiment of the present invention.

FIG. 8 is a developed plan view showing the configuration of the flat plate element of the antenna in the embodiment.

FIG. 9 is a longitudinal sectional view showing a main part configuration of a microwave oven according to a third embodiment of the present invention.

FIG. 10 is a developed plan view showing the configuration of the flat plate element of the antenna according to the embodiment.

FIG. 11 is a developed plan view showing a configuration of an antenna according to a fourth embodiment of the microwave oven of the present invention.

FIG. 12 is an exploded plan view showing a configuration in the case where the flat plate element of the antenna in the embodiment is elliptical.

FIG. 13 is a longitudinal sectional view showing a configuration of a main part of a microwave oven according to a fifth embodiment of the present invention.

FIG. 14 is a longitudinal sectional view showing a configuration of a main part of a microwave oven according to a sixth embodiment of the present invention.

FIG. 15 is a longitudinal sectional view showing a configuration of a main part of an example of a conventional microwave oven.

16A is a longitudinal sectional view of a main part of the microwave oven, FIG. 16B is a plan view of a horizontal element of the antenna of the microwave oven, and FIG. 16C is an equivalent circuit diagram of the antenna of the microwave oven.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnetron 2 Food 3 Heating room 3a Ceiling wall surface (wall surface) 4 Waveguide 5 Coupling hole 6 Antenna 6a Vertical element 6b Horizontal element 6c Image line 7 Antenna motor 7a Motor axis 8 Antenna 8a Axis element 8b Flat element 9 Antenna 9a Vertical element 9b Flat plate element 10 Food table 11 Turntable motor

Claims (12)

[Claims] 1. An antenna comprising: a shaft element provided through a coupling hole for supplying microwaves provided on a wall surface of a heating chamber; and a flat plate element joined to the shaft element. Is arranged at an angle with respect to the wall surface, and by making the shape of the flat plate element into a shape in which a planar resonance current flows by microwaves supplied through the axial element, in a direction perpendicular to the plane of the flat plate element. A microwave oven with a strong radiation directivity for microwaves. 2. An antenna comprising: a shaft element provided through a coupling hole for supplying microwaves provided on a wall surface of a heating chamber; and a flat plate element joined to the shaft element. Bending at the junction with the element, disposing the flat element at an angle with respect to the wall surface by the bending, and changing the shape of the flat element to a shape in which a planar resonance current flows by microwaves supplied through the shaft element. A microwave oven having a strong radiation directivity of microwaves in a direction perpendicular to the plane of the flat plate element. 3. The microwave oven according to claim 1, wherein an angle of the flat plate element is set in a direction away from a wall surface of the heating chamber. 4. The microwave oven according to claim 1, wherein an end of the flat plate element in a direction farthest from a junction with the shaft element is bent in parallel with a wall surface of the heating chamber. . 5. The flat element has a symmetry axis passing through the center of the axis element when developed on a plane parallel to the wall surface on which the antenna is arranged and passing through a junction with the axis element, and the direction of the axis of symmetry. 5. The flat plate according to claim 1, wherein the maximum width of the flat plate is approximately １ ／ wavelength, and the maximum width in the direction perpendicular to the axis of symmetry is approximately １ ／ wavelength to ／ wavelength. 6. microwave. 6. The flat element has a symmetric axis passing through the center of the axis element when developed on a plane parallel to the wall surface on which the antenna is arranged and passing through a junction with the axis element, and the direction of the symmetric axis. Has a width of about 波長 wavelength and a width of about 1 in a direction perpendicular to the axis of symmetry.
The microwave oven according to any one of claims 1 to 4, wherein the microwave oven is a rectangular flat plate having a wavelength of ／ to ／ wavelength, preferably a square flat plate having a side of approximately 53 mm. 7. The flat element has a symmetry axis passing through the center of the axis element when developed on a plane parallel to the wall surface on which the antenna is arranged and passing through a contact point with the axis element, and has a width in the direction of the symmetry axis. 2. An elliptical flat plate having a wavelength of about 1/2 wavelength and a width in a direction perpendicular to the axis of symmetry of about 1/4 wavelength to 3/4 wavelength, preferably a substantially circular flat plate having a diameter of about 62 mm. The microwave oven according to claim 4. 8. The microwave oven according to claim 1, wherein a dimension of a shaft element of the antenna from a wall surface of the heating chamber is 1/10 to 1/100 wavelength. 9. The microwave oven according to claim 1, wherein the antenna is configured to rotate about an axis element. 10. The microwave oven according to claim 1, wherein a coupling hole is provided on a ceiling wall surface of the heating chamber, and the food mounting table on which the food is mounted is rotated. 11. The microwave oven according to claim 10, wherein the antenna is configured to rotate about the axis element, and a predetermined distance is provided between the rotation center of the food table and the rotation center of the antenna. 12. The antenna according to claim 11, wherein the rotation stop angle or the rotation angle range is selected or changed.
The microwave oven as described.