TW201633843A - Microwave heating device - Google Patents

Abstract

A waveguide structure antenna has a top surface and a side wall for limiting a waveguide structure part, and a front opening for radiating microwave to an object to be heated. The waveguide structure part has a connection part which is jointed with the top surface and couples microwave to an interior space of the waveguide structure part. The waveguide structure part has at least a microwave suction opening formed on the top surface, and emits circularly polarized waves into a heating chamber from the microwave suction opening. The microwave suction opening has a cross recess shape formed by two interlaced slit. A width of the slit near the interlaced portion is wider than a width of the slit near an end part. In accordance with this embodiment, a carrying surface provided in the heating chamber, especially an object to be heated which is supported at the central area thereof is heated uniformly.

Description

Microwave heating device Field of invention

The present disclosure relates to a microwave heating apparatus such as a microwave oven that heats a heating object such as a food by microwave.

Background of the invention

In a microwave oven which is a typical microwave heating apparatus, microwaves generated by a magnetron as a representative microwave generating unit are supplied to a inside of a heating chamber made of metal, and the object to be heated placed in the heating chamber is heated. Microwave heating is performed.

In recent years, the entire flat bottom surface in the heating chamber can be put to practical use as a microwave oven used for the mounting table. In the microwave oven, the object to be heated is uniformly heated throughout the mounting table, and a rotating antenna is provided below the mounting table (see, for example, Japanese Patent Publication No. Sho 63-53678 (hereinafter referred to as Patent Document 1)). The rotating antenna disclosed in Patent Document 1 has a waveguide structure coupled to a magnetic field coupling of a waveguide for propagating microwaves from a magnetron.

FIG. 12 is a front cross-sectional view showing the configuration of the microwave oven 100 disclosed in Patent Document 1. As shown in FIG. 12, in the microwave oven 100, the microwave generated by the magnetron 101 propagates through the waveguide 102 to reach the coupling shaft 109.

The rotating antenna 103 has a fan shape in a plan view from above, and The coupling shaft 109 is coupled to the waveguide 102, and is driven to rotate by the motor 105. The coupling shaft 109 transmits the microwave propagating inside the waveguide 102 to the rotating antenna 103 of the waveguide structure, and functions as a rotation center of the rotating antenna 103.

The rotating antenna 103 has a radiation port 107 that radiates microwaves and a low impedance portion 106. The microwave radiated from the radiation port 107 is supplied into the heating chamber 104, and the object to be heated (not shown) placed on the mounting table 108 of the heating chamber 104 is microwave-heated.

The rotating antenna 103 is rotated below the mounting table 108 to achieve uniform heating distribution in the heating chamber 104.

In addition to the function of uniformly heating the entire heating chamber (homogeneous heating), for example, in the case where the frozen food and the room temperature food are placed in the heating chamber, in order to simultaneously heat the food, it is necessary to freeze the loading. A localized and concentrated function of radiating microwaves (local heating) in the area of food.

In order to achieve local heating, a microwave oven that controls the stop position of the rotating antenna based on the temperature distribution in the heating chamber detected by the infrared sensor has been proposed (see, for example, Japanese Patent No. 2894250 (hereinafter referred to as Patent Document 2)).

FIG. 13 is a front cross-sectional view showing the configuration of the microwave oven 200 disclosed in Patent Document 2. As shown in FIG. 13, in the microwave oven 200, the microwave generated by the magnetron 201 reaches the rotating antenna 203 of the waveguide structure via the waveguide 202.

The rotating antenna 203 has a formation in a plan view from above A radiation port 207 for radiating microwaves on one side and a low impedance portion 206 formed on the other three sides. The microwave radiated from the radiation port 207 is supplied into the heating chamber 204 via the power supply chamber 209, and the object to be heated placed in the heating chamber 204 is microwave-heated.

The microwave oven disclosed in Patent Document 2 has an infrared ray sensor 210 in order to detect the temperature distribution in the heating chamber 204. The control unit 211 controls the rotation and position of the rotating antenna 203 and the orientation of the radiation port 207 based on the temperature distribution detected by the infrared sensor 210.

The rotary antenna 203 disclosed in Patent Document 2 is configured to rotate the inside of the power supply chamber 209 formed under the mounting table 208 of the heating chamber 204 by the motor 205 and to move on an arc-shaped track. According to the microwave oven 200, the radiation port 207 of the rotating antenna 203 is moved while rotating, and the low temperature portion of the object to be heated detected by the infrared sensor 210 can be collectively heated.

Summary of invention

In the microwave oven 100 disclosed in Patent Document 1, the rotating antenna 103 is configured to rotate around the coupling shaft 109 disposed below the mounting table 108. The microwave is radiated from the radiation port 107 at the front end of the rotating antenna 103.

According to this configuration, it is impossible to directly radiate the microwave to the object to be heated placed in the central portion of the mounting table 108, and it is not always possible to uniformly heat.

According to the microwave oven 200 disclosed in Patent Document 2, the object to be heated can be uniformly heated and locally heated. However, in this configuration, since the mechanism for rotating and moving the rotary antenna 203 below the mounting table 208 is required, there is a problem that the structure is complicated and the size of the device is increased.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to provide a microwave heating apparatus which can heat a mounting surface in a heating chamber, in particular, a uniform heating of a heating object placed in a central portion thereof.

A microwave heating device according to an aspect of the present disclosure includes: a heating chamber for accommodating an object to be heated; a microwave generating portion for generating a microwave; and a waveguide structure antenna having a top portion for defining a waveguide portion The surface and the side wall surface, and the front opening, and the microwaves are radiated from the front opening to the heating chamber. The waveguide structure portion has a joint portion that engages with the top surface and that couples the microwave to the inner space of the waveguide structure portion.

The waveguide structure portion has at least one microwave suction opening formed on the top surface, and the circular polarization wave is radiated from the microwave suction opening into the heating chamber. The microwave suction opening has a cross groove shape in which two slits are staggered, and the slit has a width near the staggered portion wider than the width in the vicinity of the end portion.

According to this aspect, the waveguide structure portion having higher reliability can be constructed.

100‧‧‧ microwave oven

101‧‧‧Magnetron

102‧‧‧guide tube

103‧‧‧Rotating antenna

105‧‧‧Motor

106‧‧‧low group resistance

107‧‧‧radiation

108‧‧‧mounting table

109‧‧‧ Combined shaft

200‧‧‧ microwave oven

201‧‧‧Magnetron

202‧‧‧guide tube

203‧‧‧Rotating antenna

204‧‧‧heating room

206‧‧‧Low Impedance Department

207‧‧‧radiation

208‧‧‧mounting table

209‧‧‧Power supply room

210‧‧‧Infrared sensor

211‧‧‧Control Department

300‧‧‧guide tube

301‧‧‧ Wide breadth

302‧‧‧width narrow face

303‧‧‧section

400‧‧‧guide tube

401‧‧‧ openings

500‧‧‧guide tube

501‧‧‧ openings

600‧‧‧guide tube structure department

614a‧‧‧ first opening

614b‧‧‧2nd opening

700‧‧‧guide tube structure department

714a‧‧‧ first opening

714b‧‧‧2nd opening

800‧‧‧guide tube structure department

814a‧‧‧ first opening

814b‧‧‧2nd opening

900A‧‧‧guide tube structure department

900B‧‧‧guide tube structure department

909a‧‧‧ recess

914a‧‧‧ first opening

914b‧‧‧2nd opening

1‧‧‧ microwave oven

2a‧‧‧heating room

2b‧‧‧Power supply room

2c‧‧‧ sidewall surface

3‧‧‧Magnetron

4‧‧‧guide tube

5‧‧‧Rotating antenna

6‧‧‧ mounting table

6a‧‧‧Loading surface

7‧‧‧Combination Department

7a‧‧‧ Combined shaft

7b‧‧‧Flange

8‧‧‧guide tube structure department

9‧‧‧ top surface

9a‧‧‧ recess

10a, 10b, 10c‧‧‧ side wall

11‧‧‧ bottom

12‧‧‧Low Impedance Department

12a‧‧‧Slit

13‧‧‧ openings

14‧‧‧Microwave suction opening

14a‧‧‧1st opening

14b‧‧‧2nd opening

15‧‧‧Motor

16‧‧‧Infrared sensor

17‧‧‧Control Department

18, 18a, 18b‧‧‧ convex

19‧‧‧ Keeping Department

20a, 20b, 20c, 20d‧‧‧ slits

22‧‧‧heated objects

24‧‧‧Microwave suction opening

24a‧‧‧ first opening

28‧‧‧guide tube structure department

29‧‧‧ top surface

A‧‧‧width

B‧‧‧ Height

A‧‧‧1st length

B‧‧‧2nd length

C‧‧‧3rd length

D‧‧‧4th length/distance

C1, C2, C3, C4‧‧ corner

D1, D2, D3, D4‧‧‧ distance

G‧‧‧ Rotation Center

J‧‧‧ center line

P1, P2‧‧‧ Center Point

V‧‧‧ tube axis

W‧‧‧Width direction

X, Y‧‧‧ distance

Z‧‧‧Transfer direction

Fig. 1 is a cross-sectional view showing a schematic configuration of a microwave heating apparatus according to an embodiment of the present disclosure.

Fig. 2A is a perspective view showing a power supply chamber of the microwave heating apparatus of the embodiment.

Fig. 2B is a plan view showing a power supply chamber of the microwave heating apparatus of the embodiment.

Figure 3 is a view showing the division of the rotating antenna of the microwave heating apparatus of the embodiment. Solve the stereogram.

Fig. 4 is a perspective view showing a general square waveguide.

Fig. 5A is a plan view showing a H-face of a waveguide having an opening of a rectangular groove shape for radiating a linearly polarized wave.

Fig. 5B is a plan view showing a H-face of a waveguide having an opening for radiating a circularly polarized wave.

Fig. 5C is a front elevational view showing the positional relationship between the waveguide and the object to be heated.

Fig. 6A is a characteristic diagram showing experimental results of the aspect of the waveguide shown in Fig. 5A.

Fig. 6B is a characteristic diagram showing the experimental results of the aspect of the waveguide shown in Fig. 5B.

Fig. 7 is a characteristic diagram showing the experimental results when "loaded".

Fig. 8A is a schematic cross-sectional view showing the suction effect of the embodiment.

Fig. 8B is a schematic cross-sectional view showing the suction effect of the embodiment.

Fig. 9A is a schematic view showing a planar shape of an example of a rotating antenna used in an experiment.

Fig. 9B is a schematic view showing a planar shape of an example of a rotating antenna used in an experiment.

Fig. 9C is a schematic view showing a planar shape of an example of a rotating antenna used in an experiment.

Fig. 10A is a schematic view showing a planar shape of an example of a rotating antenna used in an experiment.

Fig. 10B is a schematic view showing a planar shape of an example of a rotating antenna used in an experiment.

Fig. 11A is a plan view showing a waveguide structure portion of the embodiment.

Fig. 11B is a plan view showing a modification of the waveguide structure portion of the embodiment.

Fig. 12 is a front sectional view showing the microwave oven disclosed in Patent Document 1.

Fig. 13 is a front sectional view showing the microwave oven disclosed in Patent Document 2.

Detailed description of the preferred embodiment

A microwave heating apparatus according to a first aspect of the present disclosure includes: a heating chamber for accommodating an object to be heated; a microwave generating unit for generating microwaves; and a waveguide structure antenna having a structure for defining a waveguide structure The top surface and the side wall surface, and the front opening, and the microwaves are radiated from the front opening to the heating chamber. The waveguide structure portion has a joint portion that engages with the top surface and that couples the microwave to the inner space of the waveguide structure portion.

The waveguide structure portion has at least one microwave suction opening formed on the top surface, and the circular polarization wave is radiated from the microwave suction opening into the heating chamber. The microwave suction opening has a cross groove shape in which two slits are staggered, and the slit has a width near the staggered portion which is wider than the width in the vicinity of the end portion. According to this aspect, the waveguide structure portion having higher reliability can be constructed.

According to the microwave heating apparatus of the second aspect, in addition to the first aspect, the micro microwave suction opening has an angle of a curved shape in the aforementioned interlaced portion. According to this aspect, the waveguide structure portion having higher reliability can be constructed.

According to the microwave heating apparatus of the third aspect, in addition to the second aspect, the microwave suction opening has an angle of a curved shape having the smallest curvature from the joint portion having the smallest curvature. According to this aspect, the waveguide structure portion having higher reliability can be constructed.

According to the microwave heating apparatus of the fourth aspect, in addition to the third aspect, the waveguide structure portion has a plurality of microwave suction openings arranged along the tube axis of the waveguide structure, and has the farthest distance from the joint portion. The microwave suction opening of the corner of the curved shape having the smallest curvature is disposed closest to the joint. According to this aspect, the waveguide structure portion having higher reliability can be constructed.

According to the microwave heating apparatus of the fifth aspect, in addition to any of the first to fourth aspects, the microwave suction opening is provided at a position shifted from the tube axis of the waveguide structure portion. According to this aspect, the circularly polarized wave can be more reliably radiated from the microwave suction opening.

According to the microwave heating apparatus of the sixth aspect, in addition to any one of the first to fifth aspects, the at least one microwave suction opening includes two microwave suctions symmetrical with respect to the tube axis of the waveguide structure portion. Opening. According to this aspect, the object to be heated placed in the central portion of the mounting surface can be more uniformly heated.

Hereinafter, preferred embodiments of the microwave heating apparatus of the present disclosure will be described with reference to the accompanying drawings.

In the following embodiments, one example of the microwave heating apparatus disclosed in the present invention is a microwave oven. However, the present invention is not limited thereto, and includes a heating device using microwave heating, a kitchen processor, or a semiconductor manufacturing device. The present disclosure is not limited to the specific configurations shown in the following embodiments, and includes configurations according to the same technical idea.

In the following drawings, the same reference numerals are given to the same or equivalent parts, and the repeated description is omitted.

1 is a view showing a microwave heating apparatus according to an embodiment of the present disclosure. A front cross-sectional view of a schematic configuration of a microwave oven. In the following description, the left-right direction of the microwave oven is shown in the left-right direction of FIG. 1, and the front-back direction is the depth direction of FIG.

As shown in Fig. 1, the microwave oven 1 of the present embodiment includes a heating chamber 2a, a power supply chamber 2b, a magnetron 3, a waveguide 4, a rotating antenna 5, and a mounting table 6. The mounting table 6 has a flat upper surface on which an object to be heated (not shown) such as food is placed. The heating chamber 2a is an upper space of the mounting table 6, and the power supply chamber 2b is a lower space of the mounting table 6.

The mounting table 6 covers the power supply chamber 2b provided with the rotating antenna 5, and divides the heating chamber 2a and the power supply chamber 2b, and constitutes the bottom surface of the heating chamber 2a. Since the upper surface (mounting surface 6a) of the mounting table 6 is flat, it is easy to enter and exit the object to be heated, and dirt or the like adhering to the mounting surface 6a is easily wiped.

Since the mounting table 6 uses a material that is easily penetrated by microwaves such as glass or ceramics, the microwave radiated from the rotating antenna 5 passes through the mounting table 6 and is supplied to the heating chamber 2a.

The magnetron 3 is an example of a microwave generating unit that generates microwaves. The waveguide 4 is an example of a propagation portion that is disposed below the power supply chamber 2b and that transmits the microwave generated by the magnetron 3 to the junction portion 7. The rotating antenna 5 is disposed in the internal space of the power supply chamber 2b, and radiates microwaves transmitted by the waveguide 4 and the joint portion from the front opening 13 into the power supply chamber 2b.

The rotating antenna 5 is a waveguide structure portion 8 having a box-shaped waveguide structure that propagates microwaves in its internal space, and a joint portion that combines the microwaves in the waveguide 4 with the internal space of the waveguide structure portion 8. The waveguide of 7 is constructed with an antenna. The joint portion 7 has a coupling shaft 7a that is coupled to the motor 15 as a drive portion, And joining the waveguide structure portion 8 and the flange 7b of the joint portion 7.

The motor 15 is driven in response to a control signal from the control unit 17, and the rotating antenna 5 is rotated about the coupling shaft 7a of the joint portion 7 and stopped in a desired direction. Thereby, the radiation direction of the microwave from the rotating antenna 5 is changed. The joint portion 7 is made of a metal such as an aluminum-plated steel sheet, and a connecting portion of the motor 15 connected to the joint portion 7 is made of, for example, a fluororesin.

The coupling shaft 7a of the joint portion 7 penetrates through the opening of the waveguide 4 and the power supply chamber 2b, and the coupling shaft 7a has a predetermined pitch (for example, 5 mm or more) between the through-holes. By combining the shaft 7a, the waveguide 4 is coupled to the internal space of the waveguide structure portion 8 of the rotating antenna 5, and the microwaves are efficiently propagated from the waveguide 4 to the waveguide structure portion 8.

An infrared sensor 16 is provided on the upper side of the side of the heating chamber 2a. The infrared sensor 16 is an example of a state detecting portion for detecting the temperature in the heating chamber 2a, that is, the surface temperature of the object to be heated placed on the mounting table 6 as the object to be heated. The infrared sensor 16 detects a temperature that is supposed to be divided into regions of the plurality of heating chambers 2a, and transmits the detection signals to the control unit 17.

The control unit 17 performs the oscillation control of the magnetron 3 and the drive control of the motor 15 based on the detection signal of the infrared sensor 16.

In the present embodiment, the infrared sensor 16 is provided as an example of the state detecting portion, but the state detecting portion is not limited thereto. For example, a weight sensor for detecting the weight of the object to be heated, or an image sensor or the like for capturing an image of the object to be heated may be used as the state detecting portion. In the configuration without setting up the status checkout section, it is also possible to respond to pre-memorized programs and users. The control unit 17 performs the vibration control of the magnetron 3 and the drive control of the motor 15 in accordance with the selection.

Fig. 2A is a perspective view showing the power supply chamber 2b in a state where the mounting table 6 is removed. Fig. 2B is a plan view showing the power supply chamber 2b in the same state as Fig. 2A.

As shown in FIG. 2A and FIG. 2B, the rotating antenna 5 is provided in the power supply chamber 2b which is disposed below the heating chamber 2a and which is separated from the heating chamber 2a by the mounting table 6. The rotation center G of the coupling shaft 7a of the rotary antenna 5 is located at the center in the front-rear direction and the left-right direction of the power supply chamber 2b, that is, below the center in the front-rear direction and the left-right direction of the mounting table 6.

The power supply chamber 2b has an internal space formed by the bottom surface 11 and the lower surface of the mounting table 6. The internal space of the power supply chamber 2b includes the rotation center G of the joint portion 7, and has a shape symmetrical with respect to the center line J (see FIG. 2B) in the left-right direction of the power supply chamber 2b. On the side wall surface of the internal space of the power supply chamber 2b, a convex portion 18 that protrudes inward is formed. The convex portion 18 includes a convex portion 18a provided on the left side wall surface and a convex portion 18b provided on the right side wall surface.

A magnetron 3 is disposed below the convex portion 18b. The microwave radiated from the antenna 3a of the magnetron 3 propagates in the waveguide 4 disposed below the power supply chamber 2b, and is transmitted to the waveguide structure portion 8 by the joint portion 7.

The side wall surface 2c of the power supply chamber 2b has an inclination for reflecting the microwave radiated from the rotating antenna 5 in the horizontal direction toward the upper heating chamber 2a.

FIG. 3 is an exploded perspective view showing a specific example of the rotating antenna 5. As shown in Fig. 3, the waveguide structure portion 8 has a top surface 9 and side wall surfaces 10a, 10b, 10c for defining an internal space thereof.

The top surface 9 includes three linear edge portions, one arcuate edge portion, and a concave portion 9a that joins the joint portion 7, and is disposed to face the mounting table 6 (see FIG. 1). The side wall surfaces 10a, 10b, and 10c are bent downward from the three linear edges of the top surface 9, respectively.

The arcuate edge portion is not provided with a side wall surface, but an opening is formed below it. This opening has a function as a front opening 13 for radiating microwaves that propagate in the internal space of the waveguide structure portion 8. That is, the side wall surface 10b is opposed to the front opening 13, and the side wall surfaces 10a and 10c are opposed to each other.

A low-impedance portion 12 that extends in the vertical direction with respect to the outside of the waveguide structure portion 8 and the side wall surface 10a is provided at the lower edge portion of the side wall surface 10a. The low-impedance portion 12 is formed in parallel with the bottom surface 11 of the power supply chamber 2b with a slight gap therebetween. The microwave leaking in the direction perpendicular to the side wall surface 10a is suppressed by the low-impedance portion 12.

In order to ensure a constant gap between the power supply chamber 2b and the bottom surface 11, a holding portion 19 for mounting an insulating resin spacer (not shown) on the lower surface of the low-impedance portion 12 may be formed.

The plurality of slits 12a are provided in the low-impedance portion 12 at a predetermined interval and periodically extending from the side wall surface 10a in the vertical direction. The leakage of the microwave parallel to the direction of the side wall surface 10a can be suppressed by the plurality of slits 12a. The interval between the slits 12a is appropriately determined in accordance with the wavelength at which the waveguide structure portion 8 propagates.

Similarly to the side wall surface 10b and the side wall surface 10c, the low-impedance portion 12 having a plurality of slits 12a is provided in the lower edge portion.

The rotating antenna 5 of the present embodiment has a circular arc shape The opening 13 is not limited to this shape, and may have a straight or curved front opening 13.

As shown in FIG. 3, the top surface 9 includes a plurality of microwave suction openings 14, that is, a first opening 14a, and a second opening 14b having an opening smaller than the first opening 14a. The microwave propagating in the internal space of the waveguide structure portion 8 is radiated from the front opening 13 and the plurality of microwave suction openings 14.

The flange 7b formed on the joint portion 7 is joined to the lower surface of the top surface 9 of the waveguide structure portion 8 by, for example, ablation, spot welding, screwing, or welding, and the rotary antenna 5 is fixedly joined to the joint portion 7.

In the present embodiment, the rotating antenna 5 has a waveguide structure portion 8 to be described later, so that the object to be heated placed on the mounting table 6 can be uniformly heated. In particular, in the central region of the mounting surface 6a located above the rotation center G (see FIGS. 2A and 2B) of the rotating antenna 5, it is possible to efficiently and uniformly heat. Hereinafter, the waveguide structure of the present embodiment will be described in detail.

[guide tube structure]

First, in order to understand the characteristics of the waveguide structure portion 8, a general waveguide 300 will be described using FIG. As shown in FIG. 4, the most simple and general waveguide 300 is a square waveguide, and has a rectangular section 303 having a width a and a height b, and a depth along the tube axis V of the waveguide 300. The tube axis V is the center line of the waveguide 300 which extends through the center of the section 303 and extends in the direction of propagation of the microwaves Z.

If the wavelength of the microwave in the free space is λ ₀ , when the width a and the height b are selected from the range of λ ₀ > a > λ ₀ / 2, and b < λ ₀ /2, the microwave is in the TE10 mode in the waveguide Spread within 300.

The TE10 mode is a transmission mode for guiding an H-wave (TE wave; Transverse Electric Wave) in which the magnetic field component exists in the microwave transmission direction Z and there is no electric field component in the waveguide 300.

The wavelength λ ₀ of the microwave in the free space can be obtained by the formula (1).

[Formula 1] λ _O = c / f‧‧‧(1)

In the formula (1), the light velocity c is about 2.998 × 10 ⁸ [m/s], and the oscillation frequency f is 2.4 to 2.5 [GHz] (ISM band) in the case of a microwave oven. The oscillation frequency f fluctuates due to the unevenness of the magnetron or the load condition, so the wavelength λ ₀ in the free space varies between a minimum of 120 [mm] (2.5 GHz) and a maximum of 125 [mm] (at 2.4 GHz). .

In the waveguide 300 for use in a microwave oven, the width a of the waveguide 300 is preferably 80 to 100 mm and the height b is 15 to 40 mm in consideration of the range of the wavelength λ ₀ in the free space.

In general, in the waveguide 300 shown in FIG. 4, the wide and wide faces 301 above and below the upper surface thereof indicate the plane in which the magnetic field vortexes in parallel, which is called the H plane, and the width of the left and right sides of the narrow surface 302 represents the electric field. Parallel faces are called E faces. For the sake of simplicity, in the plan view shown below, a straight line projecting the tube axis V onto the H plane on the H surface is referred to as a tube axis V.

The wavelength of the microwave from the magnetron is defined as the wavelength λ ₀ , and when the wavelength of the microwave when propagating in the waveguide is defined as the wavelength λg in the tube, λg can be obtained by the equation (2).

Therefore, the in-tube wavelength λg varies depending on the width a of the waveguide 300, but is independent of the height b. In the TE10 mode, the electric field is 0 at both ends (E surface) of the width direction W of the waveguide 300, that is, at the width narrow surface 302, and the electric field is maximum at the center of the width direction W.

In the present embodiment, the same principle as that of the waveguide 300 shown in Fig. 4 is applied to the rotating antenna 5 shown in Figs. 1 and 3 . In the rotary antenna 5, the top surface 9 and the bottom surface 11 of the power supply chamber 2b are H faces, and the side wall surfaces 10a and 10c are E faces.

The side wall surface 10b serves as a reflection end for totally reflecting the microwaves in the rotating antenna 5 toward the front opening 13. In the present embodiment, specifically, the width a of the waveguide 300 is 106.5 mm.

A plurality of microwave aspiration openings 14 are formed in the top surface 9. The microwave suction opening 14 includes two first openings 14a and two second openings 14b. The two first openings 14a are symmetrical with respect to the tube axis V of the waveguide structure portion 8 of the rotating antenna 5. Similarly, the two second openings 14b are symmetrical with respect to the tube axis V. The first opening 14a and the second opening 14b are formed so as not to straddle the tube axis V.

The first opening 14a and the second opening 14b are disposed at a position shifted from the position of the tube axis V of the waveguide structure portion 8 (correctly, the line on which the tube axis V is projected on the top surface 9 of the top surface 9). The circularly polarized wave can be more reliably radiated from the microwave suction opening 14. By radiating a circularly polarized wave of microwaves, it can be loaded The central area of the face 6a is uniformly heated.

Further, by providing the first opening 14a and the second opening 14b in any one of the left and right regions of the tube axis V, it is possible to determine the direction of rotation of the electric field, that is, a right-handed polarized wave (CW: Clockwise) or a left-handed polarized wave ( CCW: Counterclockwise).

In the present embodiment, each of the microwave suction openings 14 is disposed so as not to straddle the tube axis V. However, the present disclosure is not limited thereto, and a circularly polarized wave may be released in a configuration in which one of the openings spans the tube axis V. In this case, a twisted circularly polarized wave is generated.

[circular polarized wave]

Next, a circularly polarized wave will be described. Circularly polarized waves are widely used in the field of mobile communications and satellite communications. As an example of use around, for example, an ETC (Electronic Toll Collection System), that is, an automatic toll collection system is not interrupted.

The circularly polarized wave is a microwave in which the polarized wave of the electric field rotates in response to the traveling direction in response to the time, and the direction in which the electric field changes continuously in response to time, and the magnitude of the electric field strength does not change.

When the circularly polarized wave is applied to a microwave heating apparatus, it is expected that the object to be heated is uniformly heated in comparison with the microwave heating of a conventional linearly polarized wave, particularly with respect to the circumferential direction of the circularly polarized wave. Furthermore, even the right-handed polarized wave and the left-handed polarized wave can achieve the same effect.

The circularly polarized wave is originally mainly used in the field of communication, and is directed to radiation in an open space, and therefore is generally based on a non-reflected wave, which is a so-called traveling wave. On the other hand, in the present embodiment, it has a dense A reflected wave is generated in the heating chamber 2a of the closed space, and the generated reflected wave is combined with the traveling wave to generate a constant wave.

However, it is considered that in addition to the absorption of microwaves by the food, the reflected waves are also reduced. At the moment when the microwaves are radiated from the microwave suction opening 14, the balance of the fixed waves is destroyed until a traveling wave is generated between the fixed waves again. Therefore, according to the present embodiment, the inside of the heating chamber 2a can be uniformly heated by the above-described characteristics of the circularly polarized wave.

Here, the difference between the communication field of the open space and the dielectric heating of the closed space will be described.

In the field of communication, in order to surely transmit and receive information, either a right-handed polarized wave or a left-handed polarized wave is used, and a receiving antenna having directivity suitable for reception is used on the receiving side.

On the other hand, in the field of microwave heating, since the object to be heated which does not have directivity such as food receives microwaves, instead of the receiving antenna having directivity, it is important that the microwaves are irradiated to the entire object to be heated. Therefore, in the field of microwave heating, it is not important whether a right-handed polarized wave or a left-handed polarized wave is present, and even if, for example, a right-handed polarized wave and a left-handed polarized wave are mixed, there is no problem.

[Microwave suction effect]

Here, the suction effect of the microwave from the rotating antenna, which is a feature of the present embodiment, will be described. In the present embodiment, the microwave suction effect is such that when the object to be heated such as food is in the vicinity, the microwave in the waveguide structure is sucked from the microwave suction opening 14.

Figure 5A is an opening having an aperture for generating a linearly polarized wave A plan view of the waveguide 400 of the H plane. Fig. 5B is a plan view of a waveguide 500 having a H-face provided with an opening for generating a circularly polarized wave. Fig. 5C is a front elevational view showing the positional relationship between the waveguide 400 or 500 and the object 22 to be heated.

As shown in FIG. 5A, the opening 401 is a rectangular slit which is disposed to be interlaced with the tube axis V of the waveguide 400. The opening 401 is a microwave that radiates a linearly polarized wave. As shown in FIG. 5B, the two openings 501 are openings of a cross slot shape formed by two rectangular slits which are staggered at right angles. The two openings 501 are symmetrical with respect to the tube axis V of the waveguide 500.

Either opening is also symmetrical with respect to the tube axis V of the waveguide, and has a width of 10 mm and a length of Lmm. In the above configuration, the "no load" of the object 22 to be heated and the "load" of the object 22 to be heated are not analyzed, and CAE is used for analysis.

In the case of "loading", as shown in Fig. 5C, the height of the object 22 to be heated is 30 mm, the bottom area of the two types of the object 22 to be heated (the area of the side of 100 mm, the area of the side of 200 mm), and In the material of the object to be heated 22 (frozen beef, chilled beef, water), the distance D between the waveguides 400 and 500 to the bottom surface of the object 22 to be heated was measured as a parameter.

In order to use the radiation power from the opening in the case of "no load" as a reference, the relationship between the length of the opening in the case of "no load" and the radiation power is shown in FIGS. 6A and 6B.

Fig. 6A shows the characteristics of the aspect of the opening 401 shown in Fig. 5A, and Fig. 6B shows the characteristics of the opening 501 shown in Fig. 5B. In FIGS. 6A and 6B, the horizontal axis represents the length L [mm] of the opening, and the vertical axis represents the electric power [W] of the microwaves radiated from the openings 401 and 501 when the electric power propagating in the waveguide is 1.0 W.

In order to compare with the "loaded" aspect, in the "no load" mode, the radiated power is 0.1 W in length L, that is, in the graph shown in Fig. 6A, the length L is selected as 45.5 mm. In the chart shown in 6B, the length L is selected to be 46.5 mm.

Figure 7 contains six graphs showing that in the case where the length L is the above length (45.5 mm, 46.5 mm) and "loaded", there are two kinds of bottom areas (area of 100 mm side and area of 200 mm side). The results of analysis of three kinds of foods (frozen beef, chilled beef, and water).

In each of the graphs included in Fig. 7, the horizontal axis represents the distance D [mm] from the object 22 to the waveguide, and the vertical axis represents the relative radiation power when the radiation power at the time of "no load" is 1.0. That is, compared with the "no load" aspect, the "loaded" aspect is a view showing how much the microwaves are sucked from the waveguides 400, 500 by the object 22 to be heated.

In each of the graphs shown in Fig. 7, the broken line shows the characteristic of the opening 401 which is a straight line shape (I-shape) (indicated by "I" in the figure), and the solid line shows the shape of two cross grooves ( The characteristic of the opening 501 of the X-shaped shape (indicated by "2X" in the figure).

In any of the six charts, it can be recognized that the opening 501 has more radiation power than the opening 401, especially when the distance D is 20 mm or less, which is twice the same distance as the actual microwave oven. Poor. Therefore, it is understood that the opening of the circularly polarized wave is higher than the opening of the linearly polarized wave regardless of the type or the bottom area of the object 22 to be heated, and the microwave suction effect is high.

In the case of the detailed review, it is special in the type of the object to be heated 22 When the distance D is 10 mm or less, the effect of sucking out the frozen beef having a small dielectric constant and dielectric loss is large, and the effect of sucking out water having a large dielectric constant and dielectric loss is small.

In the case of chilled beef or water, when the distance D becomes large, especially in a linearly polarized wave, the radiation power falls below 1. This is considered to be because the radiation power is offset by the reflected power from the object 22 to be heated. The area of the bottom surface of the object to be heated 22 is almost the same as the area of the area of 100 mm on the side and the area of 200 mm on the side. Therefore, it is considered that the effect on the suction effect of the microwave is small.

The inventors reviewed the conditions for the opening of a circularly polarized wave by using experiments of various opening shapes. The result is as follows. An ideal condition for generating a circularly polarized wave is to dispose the opening and the tube axis V of the waveguide, and the opening shape includes an opening having a cross-shaped groove shape. The microwave of the circularly polarized wave is radiated most efficiently - that is, the effect of having a high suction effect is an opening having a cross groove shape.

8A and 8B are schematic cross-sectional views showing the suction effect of the embodiment. The front opening 13 of the rotating antenna 5 is in the left direction in the drawing in both of Figs. 8A and 8B. The object to be heated 22 is disposed above the joint portion 7 in Fig. 8A, and is placed on the left corner of the mounting surface 6a in Fig. 8B. That is, in the two states shown in FIGS. 8A and 8B, the distance from the joint portion 7 to the object 22 to be heated is different.

In the state shown in Fig. 8A, the object 22 to be heated is close to the microwave suction opening 14, and particularly close to the first opening 14a, and the suction effect from the first opening 14a occurs. As a result, the micro travels from the joint portion 7 toward the front opening 13 Most of the wave is a microwave of a circularly polarized wave from the first opening 14a, and is radiated to the object 22 to be heated, and the object 22 is heated.

On the other hand, in the state shown in FIG. 8B, since the object to be heated 22 is spaced apart from the microwave suction opening 14, the suction effect from the microwave suction opening 14 does not occur much. As a result, most of the microwaves that travel from the joint portion 7 toward the front opening 13 are radiated from the front opening 13 to the object 22 by the microwave of the linearly polarized wave, and the object 22 is heated.

As described above, the microwave suction opening 14 of the present embodiment causes a special phenomenon in which the radiation power is increased when the food is placed close to the microwave suction opening 14, and the radiation power is distributed when the food is disposed away from the microwave suction opening 14. Will become less.

[Uniform heating by the waveguide structure section]

Hereinafter, uniform heating by the waveguide structure portion of the present embodiment will be described. The inventors conducted experiments using a rotating antenna having a waveguide structure of various shapes, and found that the waveguide structure is most suitable for uniform heating.

9A, 9B, and 9C are model diagrams showing planar shapes of three examples of the rotating antenna used in the experiment, respectively.

As shown in FIG. 9A, the waveguide structure portion 600 has two first openings 614a and two second openings 614b. The first opening 614a has a cross groove shape, and each of the rectangular slits is provided in the vicinity of the joint portion 7 at an angle of 45 degrees with respect to the tube axis V of the waveguide structure portion 600. The second opening 614b is smaller than the first opening 614a and is provided away from the joint portion 7.

As shown in FIG. 9B, the waveguide structure portion 700 and the waveguide structure portion Unlike 600, there is one first opening 714a, and the first opening 714a has a cross groove shape similar to that of the first opening 614a.

As shown in FIG. 9C, the waveguide structure portion 800 has two T-shaped first openings 814a, unlike the waveguide structure portion 600. That is, the first opening 814a is different from the first opening 614a in that one of the two rectangular slits does not have a portion extending from the staggered portion toward the joint portion 7.

In common with the waveguide structure shown in FIG. 9A to FIG. 9C, a microwave suction opening having a plurality of cross-shaped groove shapes and a first opening having the same size are provided in the same place, and the second opening of the same size is provided. In the same place. In particular, the second opening 614b and the second opening 714b are the same as the second opening 814b.

A rotating antenna having a waveguide structure as shown in Figs. 9A to 9C was used, and an experiment was conducted under the same heating conditions using a frozen Osaka-fired ceramic placed in the central portion of the mounting surface 6a, which was verified by CAE. The Osaka-style roast is a pancake-shaped dish that is fried with a batter containing various materials.

As is apparent from the aspect of the waveguide structure portion 600 shown in FIG. 9A, the circularly polarized waves outputted from the openings interfere with each other, causing the object to be heated located in the central portion of the mounting surface 6a above the joint portion 7. The temperature of some of the portions is abnormally not increased as compared with the surrounding portion thereof (hereinafter, referred to as a temperature drop in the vicinity of the joint portion 7).

The waveguide structure portion 700 shown in Fig. 9B is capable of suppressing a temperature drop in the vicinity of the joint portion 7. Also in the aspect of the waveguide structure portion 800 shown in Fig. 9C, the temperature drop in the vicinity of the joint portion 7 can be suppressed in the same manner.

As described above, it can be confirmed that by not in the vicinity of the joint portion 7 The opening is provided, or only one open waveguide tube structure is provided in the vicinity of the joint portion 7, and the temperature drop in the vicinity of the joint portion 7 is suppressed, and the heating chamber 2a can be uniformly heated.

Further, the inventors conducted an experiment on the shape of the microwave suction opening, and found a waveguide structure in which the heating distribution can be further uniformized.

According to the first opening 814a of the waveguide structure portion 800 shown in FIG. 9C, the circular circularly polarized wave which is different from the circular circularly polarized wave formed by the opening of the shape of the cross groove, that is, the twisted circularly polarized wave Therefore, good results cannot be obtained from the viewpoint of uniform heating in the heating chamber 2a.

Therefore, in order to suppress the dryness of the two circularly polarized waves and form a circularly polarized wave having a shape as close as possible to the circle, the first opening 914a having the shape shown in Figs. 10A and 10B is examined.

Hereinafter, the waveguide structure portion having the first opening 914a will be described in detail using the drawings.

10A and FIG. 10B are model diagrams each showing a planar shape of the waveguide structure portion 900A and the waveguide structure portion 900B in which the above-described first opening 914a is provided.

As shown in FIGS. 10A and 10B, the waveguide structure portions 900A and 900B have the same first opening 914a and second opening 914b.

The first opening 914a has a cross groove shape in one of the two rectangular slits extending from the staggered portion toward the joint portion 7, and has a shorter portion extending from the staggered portion toward the opposite direction of the joint portion 7. length. As a result of the review, it was confirmed that the first opening 914a suppresses the drying of the two circularly polarized waves and can be uniformly heated. The aforementioned suction effect is higher than the first opening 814a shown in FIG. 9C.

In the first opening 914a, the length of the portion extending from the staggered portion in the direction of the joint portion 7 can be appropriately set in accordance with the specifications so that the drying of the two circularly polarized waves does not occur.

The waveguide structure portion 900A has a flat top surface as a whole. On the other hand, the waveguide structure portion 900B is formed with a concave joint portion (a concave portion 909a as a step region) which is recessed downward when the flange 7b is joined to the joint portion of the top surface (see, for example, FIG. 3). Therefore, in the top surface of the waveguide structure portion 900B, the distance between the joint region and the mounting table is longer than the other portions.

Using a rotating antenna having the above-described waveguide structure, the same was used for the frozen Osaka-fired ceramic placed on the central portion of the mounting surface 6a, and the experiment was carried out under the same heating conditions, and verified by CAE.

As a result, since the first opening 914a has a substantially cross-shaped groove shape, the waveguide structure portion 900A suppresses the drying of the two circularly polarized waves and generates a circularly polarized wave that is close to the shape of a circle.

Moreover, the suction effect is increased by the first opening 914a, and the temperature drop in the vicinity of the joint portion 7 can be suppressed. In addition, it is understood that the temperature drop in the vicinity of the joint portion 7 can be suppressed by the concave joint region formed on the top surface of the waveguide structure portion 900B.

A specific configuration example of the rotating antenna of the present embodiment will be described below based on the recognition from various experiments as described above. According to the above findings, various modifications can be utilized depending on the specifications of the microwave heating apparatus and the like.

Fig. 11A is a plan view showing a rotary antenna having the waveguide structure portion 8 of the embodiment.

As shown in FIG. 11A, the waveguide structure portion 8 has a plurality of microwave suction openings 14 provided on the top surface 9. The plurality of microwave suction openings 14 include a first opening 14a and a second opening 14b having an opening smaller than the first opening 14a. The first opening 14a and the second opening 14b have substantially a cross groove shape.

The center point P1 of the first opening 14a and the center point P2 of the second opening 14b are disposed at a position shifted from the tube axis V of the waveguide structure portion 8, whereby the microwave suction opening 14 can emit circular polarization. wave. Here, the center point P1 of the first opening 14a and the center point P2 of the second opening 14b are the center points of the interlaced regions in which the two slits of the first opening 14a and the second opening 14b are formed, respectively.

In the present embodiment, the first opening 14a and the second opening 14b are disposed so as not to straddle the tube axis V of the waveguide structure portion 8. The longitudinal direction of each of the rectangular slits of the first opening 14a and the second opening 14b has a substantially 45° C. inclination with respect to the tube axis V.

As shown in FIG. 11A, the first opening 14a is formed close to the concave portion 9a of the top surface 9. The recessed portion 9a is a stepped region that is provided to protrude from the top surface 9 in a direction (downward direction) opposite to the traveling direction of the microwave radiated from the first opening 14a (see FIG. 3). The two first openings 14a are symmetrical with respect to the tube axis V.

The second opening 14b is formed farther from the joint portion 7 than the first opening 14a, and is formed in the vicinity of the front opening 13. Similarly to the first opening 14a, the two second openings 14b are symmetrical with respect to the tube axis V.

The first opening 14a is characterized in that the length of the portion extending from the center point P1 toward the tube axis V in the two grooves is shorter than the length of the portion extending from the center point P1 toward the side wall surface 10a.

As shown in FIG. 3, the flange 7b provided on the joint portion 7 has a microwave transmission. The length of the feed direction Z is shorter than the length of the waveguide structure portion 8 in the width direction W. That is, the length of the joint portion 7 in the microwave transfer direction Z is shorter than the length in the direction orthogonal to the transport direction Z. According to the flange 7b, the front end of the slit extending from the center point P1 toward the joint portion 7 can be formed in the vicinity of the joint portion 7.

In the present embodiment, since the flange 7b is joined to the inside of the recessed portion 9a, the recessed portion 9a is configured to be in the recessed portion 9a in engagement with the flange 7b such as the protrusion of the TOX, the weld mark, the screw, and the head of the nut. The height of the protrusion generated on the surface side is also deep. According to this embodiment, there is no problem that the projections come into contact with the lower surface of the mounting table 6.

The waveguide structure portion 8 shown in Fig. 11A has a concave portion 9a provided on the top surface 9 above the joint portion 7, and has the same configuration as the waveguide structure portion 900B shown in Fig. 10B. According to the waveguide structure portion 8 shown in Fig. 11A, the temperature drop in the vicinity of the joint portion 7 can be suppressed similarly to the waveguide structure portion 900B. The reason is that the following two things can be considered.

The first one is that when the object to be heated is placed above the first opening 14a, a part of the microwave that is radiated from the first opening 14a and becomes a circularly polarized wave is reflected by the object to be heated. The reflected microwaves are repeatedly reflected in the space formed between the upper surface of the concave portion 9a and the lower surface of the mounting table 6, and as a result, the object to be heated is heated more strongly.

The second is that in the present embodiment, the inner space of the waveguide structure portion 8 in which the concave portion 9a is formed is narrower than the other portions. When most of the microwaves that have propagated from the coupling shaft 7a into the waveguide structure portion 8 travel from the narrow space in the vicinity of the concave portion 9a toward the wider space away from the concave portion 9a, the suction effect is radiated from the first opening 14a, and is strongly enhanced. Heating is placed in the mounting surface 6a The heated object in the central area.

Hereinafter, the shape of the first opening 14a of the present embodiment will be described in detail.

As shown in FIG. 11A, the first opening 14a includes slits 20a, 20b having a cross groove shape which is staggered at the center point P1. The major axis of each slit of the first opening 14a has an angle of 45 degrees with respect to the tube axis V.

The slit 20a extends from the lower right to the upper left of the center point P1, and has a first length A from the center point P1 to the lower right front end, and a third length C from the center point P1 to the upper left front end. The front end on the lower right side of the slit 20a faces the joint portion 7 and approaches the recess portion 9a.

The slit 20b extends from the lower left to the upper right of the center point P1, and has a second length B from the center point P1 to the lower left front end and a fourth length D from the center point P1 to the upper right front end. That is, the first length A is the length from the center point P1 to the front end of the slits 20a, 20b up to the length of the front end closest to the joint portion 7.

The third length C is the same as the fourth length D, which corresponds to 1/4 of the wavelength of the microwave propagating in the waveguide structure portion 8. The second length B is shorter than the third length C and the fourth length D, and the first length A is the shortest among the others.

Further, the distance X between the slit 20a and the tube axis V is longer than the distance Y between the slit 20b and the tube axis V. That is, the top surface 9 is a region in the vicinity of the concave portion 9a between the two first openings 14a wider than a region away from the concave portion 9a.

When the area between the two first openings 14a is not flat, a turbulent electromagnetic field is generated in the waveguide structure portion 8, and the circular polarization wave is adversely affected. Therefore, it is preferable that the two first openings 14a are formed. Set a wider flat area between them. According to this embodiment, it is provided in the two first openings 14a. The wider flat area creates a circularly polarized wave with less turbulence and a higher suction effect.

In the present embodiment, the distance between the two first openings 14a is 1/8 or more of the wavelength of the microwave propagating in the waveguide structure portion 8. According to experiments by the inventors, better results were obtained when the two first openings 14a had substantially the same distance from the axial diameter (18 mm) of the coupling shaft 7a.

On the other hand, the second opening 14b is a slit having two slits of the same length and having a cross groove shape orthogonal to the center of each. The major axis of each slit of the second opening 14b has an angle of 45 degrees with respect to the tube axis V. In the present embodiment, the length of the major axis of each slit of the second opening 14b is the same length as the third length C and the fourth length D of the first opening 14a.

The joint portion 7 of the present embodiment has the flange 7b having the above-described shape. However, the shape of the flange 7b is not limited thereto, and may be appropriately changed depending on specifications and the like.

For example, when the portion of the flange 7b in the direction of the tube axis V is made shorter, the first opening 14a can be brought close to each other by the joint portion 7. A flange 7b having a notch between the first opening 14a and the like may be used, and the first opening 14a may be brought close to each other by the joint portion 7 by the shape of the flange 7b.

When the shape of the flange 7b is made, the area of the joint portion can be reduced, and the joint between the joint portion 7 and the waveguide structure portion 8 can be strengthened, and the quality unevenness of the product can be suppressed.

When the coupling shaft 7a has a cross section such as a semicircle, a circle, or a rectangle, or when the coupling shaft 7a having such a cross-sectional shape is directly joined to the waveguide structure portion 8, the same effect as in the embodiment can be obtained. . If the configuration of the flange 7b is not provided, the space for forming the first opening 14a can be further expanded.

According to this embodiment, a high suction effect can be obtained, whereby the temperature drop in the vicinity of the joint portion 7 can be suppressed, and the central region of the mounting surface 6a can be uniformly heated.

In the present embodiment, the microwave suction opening has a cross groove shape, but the microwave suction opening of the present disclosure is not limited thereto. The microwave suction opening may have a shape in which a circularly polarized wave can be generated in addition to the cross groove shape.

As a result of the experiment, it is presumed that the necessary condition for generating a circularly polarized wave from the waveguide structure portion is to arrange the two elongated openings in combination at a position shifted from the tube axis.

The slits constituting the microwave suction opening 14 are not limited to the rectangular shape. For example, a circularly polarized wave can occur even in the case where the corner has a circular opening or a circular opening.

Instead, in order to suppress the concentration of the electric field, the corner portion of the opening should preferably have a circular shape. In the present embodiment, as shown in FIGS. 3, 9A to 9C, 10A, 10B, and 11A, the slits included in the first opening 14a and the second opening 14b have a circle at the end portion and the staggered portion. The corner of the shape. That is, the two slits included in the microwave suction opening 14 have a width in the vicinity of the staggered portion wider than the width in the vicinity of the end portion.

In the present embodiment, the concave portion 9a is formed above the joint portion 7 of the top surface 9, but the waveguide structure portion 8 of the present disclosure is not limited thereto.

For example, the propagation state of the microwave radiated from the opening or the like may be considered, and between the microwave suction opening 14 and the rotation center of the waveguide structure portion 8. A recess 9a is provided. A convex portion that protrudes toward the inner space of the waveguide structure portion 8 may be provided on the top surface 9 of the center of rotation of the waveguide structure portion 8 closer to the microwave suction opening 14.

That is, the waveguide structure portion 8 is provided closer to a portion of the top surface 9 of the joint portion 7 than the microwave suction opening 14, and only has a step region having a height lower than that of the other portions of the top surface 9.

[slit shape]

The inventors of the present invention have focused on the angular shape of the interlaced portion of the two slits in the first opening 14a, thereby developing a waveguide structure portion having higher reliability. This waveguide structure portion will be described with reference to Fig. 11B.

As shown in FIG. 11B, the waveguide structure portion 28 of the present modification has a microwave suction opening 24 provided on the top surface 29. The microwave suction opening 24 includes a first opening 24a and a second opening 14b. As will be described below, the first opening 24a differs only in the angular shape of the interlaced portions of the two slits of the first opening 24a shown in Fig. 11A.

As shown in Fig. 11B, the first opening 24a has four corners C1, C2, C3, and C4 at the staggered portion of the slit 20c and the slit 20d.

The angle C1 is located farthest from the tube axis V. The angle C2 is set on the most upstream side in the transport direction Z of the microwave, and is located closest to the joint portion 7. The angle C3 is located closest to the tube axis V. The angle C4 is disposed on the most downstream side in the transport direction Z of the microwave, and is located farthest from the joint portion 7.

In the angles C1 to C4, the angles C1 to C3 have curved shapes having equal curvature, and on the other hand, the angle C4 has a curved shape having a smaller curvature than the angles C1 to C3. In the configuration shown in Fig. 11B, the angle C4 has a portion as indicated by a broken line in Fig. 11B. The shape is almost cut in a straight line.

Let the distance D1 be the distance from the center point P1 to the angle C1, and let the distance D2 be the distance from the center point P1 to the angle C2. When the distance D3 is the distance from the center point P1 to the angle C3, the distances D1 to D3 are the same, and the center point P1 is The distance D4 of the angle C4 is larger than the distances D1 to D3. That is, the two slits included in the first opening 24a have a width in the vicinity of the staggered portion which is wider than the width in the vicinity of the end portion.

The electric field of the slit is the largest at the center and 0 at the end. In the first opening 24a of the cross groove shape, since the two electric fields are combined in the interlaced portion, the electric field of the interlaced portion becomes strong.

The inventors have found that in the configuration shown in Fig. 11B, the waveguide structure portion 28 has the first opening 24a having the above-described shape, and it is possible to suppress excessive electric field concentration in the interlaced portion.

In particular, the inventors have found that in the corners C1 to C4 of the staggered portion of the first opening 24a, the corner C4 located at the most downstream side in the transport direction Z of the microwave, that is, at the position farthest from the joint portion 7, has the smallest curvature. When the shape is curved, the effect of suppressing electric field concentration is remarkable. According to this configuration, the waveguide structure portion having higher reliability can be constructed.

The reason why such a phenomenon occurs is that the electric field generated around the second opening 14b is generated around the corner C4 of the first opening 24a, particularly around the corner C4 of the first opening 24a closest to the second opening 14b. The electric field has a slight effect.

Further, the shape of the corner of the staggered portion of the first opening 24a is not limited to the curved shape as shown in Fig. 11B. The first opening 24a is formed by a slit having a width in the vicinity of the staggered portion which is wider than the width of the vicinity of the end portion. The shape of the cross groove can be. Alternatively, a corner of a substantially curved shape formed by a plurality of straight lines may be formed in the interlaced portion of the cross groove shape. The angle C1 to the angle C3 may have the same shape as the angle C4.

The angle of the staggered portion of the second opening 14b, particularly in the most upstream side of the microwave transport direction Z, that is, at the closest angle to the joint portion 7, has the same shape as the angle C4 of the first opening 24a shown in Fig. 11B. The same effect can be obtained.

In addition to the microwave oven, the microwave heating device for various industrial applications such as a drying device, a ceramics heating device, a kitchen processor, and a semiconductor manufacturing device can be used.

5‧‧‧Rotating antenna

9a‧‧‧ recess

10a, 10b, 10c‧‧‧ side wall

12‧‧‧Low Impedance Department

13‧‧‧ openings

14b‧‧‧2nd opening

19‧‧‧ Keeping Department

20c, 20d‧‧‧ slit

24‧‧‧Microwave suction opening

24a‧‧‧ first opening

28‧‧‧guide tube structure department

29‧‧‧ top surface

C1, C2, C3, C4‧‧ corner

D1, D2, D3, D4‧‧‧ distance

G‧‧‧ Rotation Center

P1, P2‧‧‧ Center Point

X, Y‧‧‧ distance

W‧‧‧Width direction

Z‧‧‧Transfer direction

V‧‧‧ tube axis

Claims (6)

A microwave heating device includes: a heating chamber for accommodating an object to be heated; a microwave generating portion for generating microwaves; and a waveguide structure antenna having a top surface and a side wall surface for defining a waveguide structure portion, And a front opening, and the microwave is radiated from the front opening to the heating chamber, and the waveguide structure portion has a joint portion that is joined to the top surface, and the microwave and the waveguide structure portion are In combination with the internal space, the waveguide structure has at least one microwave suction opening formed on the top surface, and the circular polarization wave is radiated from the microwave suction opening into the heating chamber, and the microwave suction opening has two slits The cross-shaped groove shape, and the slit has a width near the staggered portion wider than the width near the end portion. A microwave heating apparatus according to claim 1, wherein said microwave aspirating opening has an angle of a curved shape in said interlaced portion. A microwave heating apparatus according to claim 2, wherein said microwave suction opening has an angle of said curved shape which is the farthest from the aforementioned joint portion. The microwave heating device of claim 3, wherein the waveguide structure portion has a plurality of microwave suction openings disposed along a tube axis of the waveguide structure. The aforementioned microwave suction opening having the corner of the aforementioned curved shape having the smallest curvature at the farthest from the aforementioned joint portion is disposed closest to the joint portion. A microwave heating apparatus according to claim 1, wherein said microwave suction opening is provided at a position shifted from a tube axis of said waveguide structure. The microwave heating apparatus of claim 1, wherein the waveguide structure is such that the at least one microwave suction opening comprises two microwave suction openings that are symmetrical with respect to a tube axis of the waveguide structure.