JP2013037795A - Microwave heating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microwave heating device which achieves efficient heating, while suppressing uneven heating by directly irradiating a wide area of an object to be heated with a microwave.SOLUTION: A microwave heating device comprises: a heating chamber 50; a magnetron 30; a waveguide 35 for transmitting a microwave; and a substantially truncated cone shaped antenna dome 44 which has a top surface providing with a guide hole 41 for connecting the waveguide 35 and guiding the microwave transmitted from the waveguide 35 and has a circumferential wall surface with a bottom being opened toward the heating chamber 50. In the antenna dome 44, there is arranged a rotary antenna 40 having a shaft element 42 provided through the guide hole 41 in the top surface of the antenna dome 44 and a substantial circular flat element 43 connected to the shaft element 42. The flat element 43 of the rotary antenna 40 is provided with a horizontal plane 43a connecting to the shaft element 42 at a position deviating from a substantially circular shape center and with an incline plane 43b curved form the horizontal plane 43a toward a side of the heating chamber 50.

Description

  The present invention relates to a microwave heating apparatus that heats an object to be heated with microwaves, and more particularly to a cooking device such as a microwave oven or an oven range for cooking food.

  Conventional microwave heating apparatuses generally include a heating chamber that accommodates an object to be heated, as represented by a microwave oven, and microwaves generated by microwave generating means such as a magnetron are supplied to the heating chamber. To subject the object to be heated to dielectric heating.

  Many inventions have been disclosed as configurations and methods for uniformly heating an object to be heated in a heating chamber using a microwave. The main ones are a method of rotating a turntable on which an object to be heated is placed, a method of stirring a microwave by rotating a stirrer provided in a heating chamber, and a method of dispersing and radiating microwaves by rotating an antenna. These methods are generally well known to those skilled in the art.

  Conventionally, many turntables that place and rotate an object to be heated have been used. Recently, however, turntables have been used in order to improve usability by increasing the effective volume of the heating chamber and downsizing the equipment. Many systems have been adopted in which the bottom surface of the heating chamber is made flat without using it and a rotating antenna is used instead of rotating the object to be heated.

  As a technology for supplying microwaves into a heating chamber using a rotating antenna, a microwave transmission waveguide is provided, and an antenna is provided in an opening penetrating from the waveguide to the heating chamber to heat the microwave. The light is derived and emitted into the room (for example, see Patent Document 1 and Patent Document 2).

  FIG. 5 shows a conventional microwave heating apparatus described in Patent Document 1. In FIG. As shown in FIG. 5, an antenna 15 and a horizontal rotation component 17 are provided in the approximate center of the coupling hole 20 between the waveguide 14 and the heating chamber 2, and generated by the magnetron 8 while the antenna 15 is rotated by a motor 19. The microwave is radiated to the heating chamber 2. A heater 10 is provided around the antenna. FIG. 6 shows a cross-sectional view of a main part of a conventional microwave oven described in Patent Document 2, and an antenna 7 is provided in a mortar-shaped diaphragm 3a on the ceiling of the heating chamber 3 to cover the diaphragm 3a. An opening cover 9 is provided. Similarly to the configuration of FIG. 5, an antenna 15 is provided in the approximate center of the coupling hole 20 between the waveguide 14 and the heating chamber 2, and microwaves generated by the magnetron 8 while rotating the antenna 15 are heated in the heating chamber 2. It is configured to radiate.

JP 58-181289 A JP 2000-164339 A

However, as shown in the above prior art, the current state is that the shape of the rotating antenna or its peripheral configuration is variously determined according to the type of the object to be heated and the dimensions of the heating chamber. Also, it is not easy to apply these conventional techniques to many other devices due to the constraints of each heating device. For example, in the case of applying the configuration of Patent Document 2 shown in FIG. 6 to the configuration of the high-frequency heating device of Patent Document 1 shown in FIG. 5, the restricting portion 3 a cannot be configured due to restrictions on the arrangement of the heaters 10 around the antenna 15. In addition, it is conceivable that a desired heating distribution cannot be obtained when the size of the throttle portion 3a is made small within a limited range. That is, there is still room for improvement in realizing an efficient heating device by suppressing uneven heating of the object to be heated.

  The present invention solves the above-mentioned conventional problems when microwaves are supplied into a heating chamber using a rotating antenna, and the antenna and the surrounding configuration can be miniaturized and can be applied to heating chambers having different dimensions. Heating by suppressing the strength of the standing wave generated in the heating chamber without being absorbed by the object to be heated, that is, the intensity of the electrolytic distribution, by directly radiating the microwaves and directly entering the wide area of the object to be heated An object of the present invention is to provide a microwave heating apparatus that suppresses unevenness and has high efficiency.

  In order to solve the above-described conventional problems, a microwave heating apparatus according to the present invention includes a heating chamber that houses an object to be heated, a magnetron that generates a microwave, and a waveguide that transmits the microwave generated by the magnetron. And a substantially frustoconical shape having a top surface provided with a lead-out hole for connecting the waveguide and deriving a microwave transmitted from the waveguide, and a circumferential wall having a bottom open toward the heating chamber An antenna dome, and a rotating antenna having a shaft element provided through the lead-out hole on the top surface of the antenna dome and a substantially circular flat plate element coupled to the shaft element. The flat plate element of the rotating antenna has a substantially circular outer shape center and a horizontal plane connected to the shaft element at an eccentric position, and an inclined surface bent from the horizontal plane toward the heating chamber. Ah .

  As a result, the microwave radiation to the heating chamber is appropriate for the object to be heated by the component radiated directly from the inclined surface of the flat plate element of the rotating antenna and the component radiated using the circumferential wall surface of the antenna dome. Can be directly incident on a wide area of the object to be heated, so that the influence of low standing waves that are not absorbed by the object to be heated and that are generated in the heating chamber can be reduced, so that uneven heating can be effectively suppressed. The object to be heated can be efficiently heated. Further, the flat plate element of the rotating antenna is bent toward the heating chamber, so that the rotating antenna can be reduced in size, and the rotating space of the rotating antenna can be reduced, so that the antenna dome can be made compact. This can be easily adapted to the heating chambers having different size sizes by adjusting the inclination angle.

  The microwave heating apparatus of the present invention can directly input the microwave radiated from the rotating antenna to a wide area of the object to be heated, so that the uneven heating is effectively suppressed, and the microwave is directly incident on the object to be heated. This reduces the rate of reflection to the magnetron without being consumed in the heating chamber, so that the object to be heated can be efficiently heated while maintaining high microwave generation efficiency. In addition, since the rotating antenna and the surrounding structure can be miniaturized, the magnetron that generates microwaves can be placed close to the antenna dome, reducing the transmission distance by the waveguide and reducing transmission loss. Thus, the heating efficiency can be further improved. This can easily be adapted to heating chambers of different dimensions.

Sectional schematic diagram of the microwave heating apparatus in Embodiment 1 of the present invention The enlarged schematic diagram of the rotation antenna of the microwave heating apparatus in Embodiment 1 of this invention, and its periphery structure Front cross-section block diagram of the microwave heating apparatus in Embodiment 2 of this invention Side surface cross-section block diagram of the microwave heating apparatus in Embodiment 2 of this invention Front sectional view of a conventional microwave heating device Front sectional view of a conventional microwave heating device

  1st invention connects the said waveguide to the heating chamber which accommodates to-be-heated material, the magnetron which generate | occur | produces a microwave, the waveguide which transmits the microwave which generate | occur | produced in the said magnetron, and this waveguide An antenna dome having a substantially frustoconical shape having a top surface provided with a lead-out hole for deriving microwaves transmitted from and a circumferential wall surface whose bottom is open toward the heating chamber, the antenna dome, A rotating antenna having a shaft element provided through the lead-out hole on the top surface of the antenna dome and a substantially circular flat plate element coupled to the shaft element is disposed, and the flat plate element of the rotating antenna has a substantially circular shape. A horizontal plane connected to the shaft element at a position eccentric from the center of the outer shape, and an inclined plane bent from the horizontal plane toward the heating chamber.

  As a result, the microwave radiation to the heating chamber is appropriate for the object to be heated by the component radiated directly from the inclined surface of the flat plate element of the rotating antenna and the component radiated using the circumferential wall surface of the antenna dome. Can be directly incident on a wide area of the object to be heated, so that the influence of low standing waves that are not absorbed by the object to be heated and that are generated in the heating chamber can be reduced, so that uneven heating can be effectively suppressed. The object to be heated can be efficiently heated. Further, as a result of bending the flat element of the rotating antenna toward the heating chamber, the rotating antenna can be reduced in size, and the rotating space of the rotating antenna can be reduced, so that the antenna dome can be made compact. Furthermore, the heating chamber volume can be increased without reducing the size of the device itself or the size of the device, thereby improving usability.

  The second invention is particularly determined by the relationship with the height dimension of the heating chamber so that the inclined surface of the flat plate element of the rotating antenna according to the first invention faces substantially the center of the bottom surface of the heating chamber. .

  Thereby, the microwave radiated from the inclined surface of the flat plate element of the rotating antenna can be set to an angle at which the microwave can be radiated toward the vicinity of the center of the object to be heated corresponding to the height dimension of the heating chamber. This makes it possible to directly enter the wide area of the object to be heated together with the component radiated using the circumferential wall surface of the antenna dome, so that the low standing wave generated in the heating chamber without being absorbed by the object to be heated Therefore, unevenness in heating can be effectively suppressed and the object to be heated can be efficiently heated. This can be easily adapted to the heating chambers having different size sizes by adjusting the inclination angle. Furthermore, since the flat element of the rotating antenna is bent toward the heating chamber, the space for rotating the rotating antenna is reduced, so that the antenna dome can be made compact.

  In the third invention, in particular, the inclination of the circumferential wall surface of the antenna dome of the first or second invention is such that the outer diameter dimension of the downward extension line of the circumferential wall surface intersects the bottom surface of the heating chamber. It is determined in the bottom dimension of the heating chamber so as to be substantially the same as the width dimension or depth dimension of the chamber bottom face.

  In other words, the antenna dome circle is formed by making the outer diameter dimension of the downward extension line of the circumferential wall crossing the heating chamber bottom surface substantially the same as the vertical, horizontal, or vertical and horizontal dimensions of the heating chamber bottom surface. Since the component radiated using the peripheral wall can be directly incident on a wide area of the object to be heated, it is effective because it can reduce the influence of low standing waves generated in the heating chamber without being absorbed by the object to be heated. The heating unevenness can be suppressed and the object to be heated can be efficiently heated. This can be easily adapted to the heating chambers having different size sizes by adjusting the inclination angle.

In the fourth aspect of the invention, in particular, the circumferential wall surface of the antenna dome in any one of the first to third aspects of the invention is set so as to intersect with the downward extension line of the inclined surface of the flat plate element of the rotating antenna. It is a thing.

  That is, the radiation direction of the component radiated from the flat element toward the circumferential wall surface of the antenna dome can be reliably regulated by the circumferential wall surface of the antenna dome. Thus, while realizing a compact antedome, the component radiated using the circumferential wall surface of the antenna dome and the component radiated directly from the flat plate element can be set to be optimum. In other words, the microwave radiation to the heating chamber is emitted directly from the inclined surface of the flat plate element of the rotating antenna and incident near the center of the object to be heated and the circumferential wall surface of the antenna dome to be heated. Since it can be properly dispersed in the components that mainly enter the surroundings of the object and directly incident on a wide area of the object to be heated, it is not absorbed by the object to be heated. Therefore, unevenness in heating can be effectively suppressed and the object to be heated can be efficiently heated.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a schematic cross-sectional view showing a configuration of a microwave oven that is a microwave heating apparatus according to a first embodiment of the present invention. In FIG. 1, a frustoconical antenna dome 44 is disposed at the approximate center of the upper wall surface of the heating chamber 50 that houses the food 200 that is to be heated. A waveguide 35 is connected to the top surface of the antenna dome 44 by providing a lead-out hole 41 for supplying microwaves to the heating chamber. Inside the antenna dome 44, there is provided a rotating antenna 40 constituted by a shaft element 42 made of a metal rod provided through the lead-out hole 41 and a flat plate element 43 made of a metal plate connected to the shaft element 42. ing.

  In the microwave heating apparatus configured as described above, the operation and action of microwave radiation will be described below.

  First, the 2450 MHz microwave generated in the magnetron 30 is transmitted through the waveguide 35 and supplied from the outlet hole 41 to the heating chamber 50 side with the shaft element 42 as the central conductor. Here, the shaft element 42 is made of a highly conductive metal rod such as aluminum and has a cylindrical shape with a diameter of 15 mm. It penetrates and protrudes into the antenna dome 44 by 15 mm. Thus, the microwave transmitted from the waveguide 35 is supplied to the heating chamber 50 side. A rotating antenna 40 is formed by the shaft element 42 and a flat plate element 43 mechanically and electrically connected to one end of the shaft element 42 protruding into the antenna dome 44.

  A motor 45 serving as an antenna driving means is provided on an upper portion of a shaft element 42 protruding into the waveguide 35, and the rotating antenna 40 rotates inside the antenna dome 44 by the rotation of the rotor 45 a of the motor 45.

  Here, the flat element 43 of the rotating antenna 40 is a circle having a diameter of 62 mm and is made of a highly conductive metal plate such as aluminum having a thickness of 0.8 mm, and is connected to the shaft element 42 at a position deviated by 12 mm from the center of the circle. The resonance is set so that both the resonance with respect to the used frequency and the impedance matching with the microwave generator can be obtained satisfactorily.

In the circular flat plate element 43, the microwave has a directivity characteristic of a patch antenna mainly radiating in a direction perpendicular to the plane. However, the flat plate element 43 is bent to provide the inclined surface 43b to change the radiation direction. It can be set so as to be directly incident near the center of the object to be heated accommodated in the heating chamber, and at the same time, the radiation direction acts so as to spread to the circumferential wall surface side of the antenna dome 44. Microwaves can be radiated appropriately.

  Therefore, the microwave radiated from the rotating antenna 40 can spread in the radiation directions A and B in the figure and can be directly incident on a wide area of the object to be heated. Further, the total length from the joint of the shaft element 42 to the antenna dome 44 side and the joint between the flat element 43 and the shaft element 42 to the outer shape is about ½ of the operating wavelength λ.

  That is, since the microwave radiation amount is set to be the maximum at the outer end where the distance from the shaft element 42 is farthest, the radiation characteristic is the electric field standing on the inner surface of the flat element 43 and the antenna dome 44 serving as the ground plane. The component radiated in the vertical direction is born.

  Therefore, it is possible to appropriately radiate microwaves using the antenna dome 44. Therefore, since the microwave radiated from the rotating antenna 40 is radiated in the B direction in the figure, it is directly incident on a wide area of the object to be heated together with the radiation in the A direction in the figure from the inclined surface 43b toward the vicinity of the center of the food 200. be able to.

  Further, the ratio of the component radiated from the outer peripheral surface of the projecting portion of the shaft element 42 toward the antenna dome 44 can be adjusted according to the dimension of the projecting dimension, and the radiated microwave can be horizontally distributed to the circumferential wall surface of the antenna dome 44. Although it spreads, it is radiated between A and B in the figure by being reflected by the circumferential wall surface and can be directly incident on the object to be heated.

  As described above, the microwave radiated from the rotating antenna 40 can be directly incident on a wide area of the object to be heated appropriately by setting the inclined surface 43 b of the flat plate element 43 and the circumferential wall surface of the antenna dome 44.

  A frustoconical antenna dome 44 is disposed at the approximate center of the upper wall surface of the heating chamber 50, and the rotating antenna 40 can radiate microwaves while rotating to effectively suppress uneven heating.

  Furthermore, direct incidence of microwaves on the object to be heated reduces the rate of reflection to the magnetron without being consumed in the heating chamber, so that the object to be heated is efficiently heated while maintaining high microwave generation efficiency. be able to.

  Further, it is possible to reduce the size of the rotating antenna and the surrounding structure. Here, the same radiation directivity can be obtained even if the flat plate element 43 has a square shape other than the circular shape. The theoretical value of the effective dimension in this case is a square with a side of 53 mm, the diagonal dimension is about 75 mm, and the dimension required for rotation is determined by the diagonal dimension. Therefore, size reduction can be achieved by making the flat plate element 43 circular.

  FIG. 2 is an enlarged schematic diagram showing the rotating antenna 40 and its peripheral configuration of the microwave heating apparatus according to the first embodiment of the present invention. In FIG. 2, since the bearing portion 47 that supports the rotor 45a of the motor 45 vertically and rotatably is provided, the flat plate element 43 is provided with a predetermined space between the antenna dome 44 and without contacting each other. The microwave can be rotated stably without sparking when radiating.

  In FIG. 2, a two-dot chain line 143 indicates a flat plate element when the inclined surface is not provided with the same external dimensions as the flat plate element 43. On the other hand, the antenna dome 44 can be further downsized in the configuration of the flat element of the present invention in which the inclined surface 43b is bent.

Since the waveguide 35 is formed in an inverted L shape and the antenna for radiating microwaves of the magnetron 30 is horizontally arranged, the height direction is kept low in addition to the plane direction, so that a more compact configuration can be realized.

  This increases the degree of freedom of arrangement of peripheral components such as a power supply and a control board, thereby enabling downsizing of the apparatus and expansion of the heating chamber volume. As shown in FIG. 1, the magnetron 30 that generates microwaves can be disposed close to the antenna dome 44, and the transmission distance by the waveguide 35 can be shortened to reduce transmission loss, thereby further increasing the heating efficiency. Can be improved. This can easily be adapted to heating chambers of different dimensions.

  Effectively, the microwave radiated from the inclined surface 43b of the flat plate element 43 of the rotating antenna 40 is directed toward the vicinity of the center of the food 200 stored corresponding to the height dimension of the heating chamber 50 (h in FIG. 1). The angle C can be set to be radiated.

  For example, the angle C may be set smaller as the height of the heating chamber 50 increases. Conversely, when the height of the heating chamber is low, the angle C may be increased. Here, the meaning of bending the flat element 43 is that the joint surface with the shaft element 42 can be made horizontal, so that mechanical fixing is good and easy, and the bending angle of the flat element 43 is changed, for example, the volume of the heating chamber is reduced. It has the effect of being easily adaptable to other different microwave heating devices.

  Further, the inclination D of the circumferential wall surface of the antenna dome 44 is determined in relation to the bottom surface dimension and the height dimension of the heating chamber 50 (h in FIG. 1). In other words, the outer diameter dimension at which the downward extending line of the circumferential wall intersects the bottom surface of the heating chamber 50 is made to be substantially the same as the width dimension (w in FIG. 1) or the depth dimension of the heating chamber bottom surface. Thus, the component radiated using the circumferential wall surface of the antenna dome 44 can be directly incident on a wide area of the object to be heated.

  For example, as the slope D becomes smaller, the radiated range becomes wider. Conversely, as the slope D becomes larger, the radiated range becomes narrower and narrower. Further, when the bottom surface of the heating chamber is rectangular, the antenna dome 44 is shaped so that the range radiated to the bottom surface of the heating chamber along the circumferential wall surface of the antenna dome 44 is elliptical according to both the width and the depth. May have an elliptical truncated cone shape or a long truncated cone shape.

  The meaning of making the antenna dome 44 substantially frustoconical is to provide a circumferential wall surface close to the periphery of the rotating antenna 40, but the area of the surrounding wall surface can be made smaller than the rectangular trapezoidal shape and no unnecessary electric field is generated. Therefore, even if the radiation direction from the rotating antenna 40 is regulated, the microwave loss due to the wall surface can be suppressed to an extremely small value.

  More effectively, the circumferential wall surface of the antenna dome 44 is set so as to intersect the downward extension of the inclined surface of the flat plate element of the rotating antenna. Thus, while realizing a compact antedome, the component radiated using the circumferential wall surface of the antenna dome 44 and the component radiated directly from the flat plate element 43 can be set to be optimum. .

  That is, the radiation direction of the component radiated from the flat element 43 toward the circumferential wall surface of the antenna dome 44 can be reliably regulated by the circumferential wall surface of the antenna dome 44. Specifically, in the present embodiment, the inclined surface 43 b is set to be inclined by about 10 ° with respect to the horizontal, and when extended, the inclined surface 43 b intersects the circumferential wall surface of the antenna dome 44. The antenna dome 44 has a truncated cone shape whose bottom surface is open toward the heating chamber, and the circumferential wall surface is inclined at about 57.5 ° with respect to the horizontal. Thereby, it can enter directly into the wide area | region of a flat to-be-heated object like the foodstuff 200 shown in FIG.

(Embodiment 2)
FIG. 3 is a front cross-sectional configuration diagram of the microwave heating apparatus according to the second embodiment of the present invention, and FIG. 4 is a side cross-sectional configuration diagram of the microwave heating apparatus according to the second embodiment of the present invention. The schematic structure of the microwave oven which is the microwave heating device of embodiment which concerns on is shown. The difference from the first embodiment is that an oven heater or the like is arranged around the rotating antenna, and a plurality of shelves are provided so that the height on which the food can be placed is selected. In addition, the thing of the same code | symbol as Embodiment 1 has the same structure, and abbreviate | omits description.

  3 and 4, the food item 200 that is an object to be heated is placed on a net 80 placed on a shelf 58 provided in the heating chamber 50. The shelves 58 are provided in a plurality of stages on the side surfaces on both sides so that the user can select the height on which the food is placed according to the form of the food and cooking. A heater 55 is provided in the upper part of the heating chamber 50, and the food can be directly heated by the radiant heat of the heater 55 in addition to the heating by the microwave, corresponding to a plurality of cooking menus. In addition, a lower heater 62 is provided below the bottom surface of the heating chamber 50. A convection heater 61 for cooking hot air and a fan 60 are provided on the rear side, and hot air is sent to the heating chamber 50. Further, the temperature of the heating chamber 50 is detected by the thermistor 75 during heating.

  The food is put into the heating chamber by opening the heating chamber door 110. An operation / display unit 100 is arranged above the heating chamber door 110, and an operation switch (not shown) and an operation setting button (not shown) are provided.

  Also, the heating time (heating temperature) can be arbitrarily set by the user with the operation knob 101 and is instructed to the control means 90. The illumination 70 is provided, and the heating condition of the food can be visually observed by the user by illuminating the inside of the heating chamber 50 during the heating operation. An illumination cover 71 is provided on the front surface of the illumination 70. The heating chamber door 110 is provided with an open / close door detection switch (not shown), and is not operated unless the heating chamber door 110 is completely closed.

  Also, it functions as a safety device so that if the door is opened during operation, the operation is immediately stopped.

  On the upper surface of the heating chamber 50, an exhaust fan 65 for exhausting odors and smoke generated by heating food is provided. A ventilation fan 66 is provided to ventilate around the heating chamber 50 inside the microwave heating apparatus. The ventilation fan 66 is configured with a ventilation passage 67 so as to simultaneously cool the magnetron 30, the waveguide 35, and a power source (not shown).

  In the microwave heating apparatus configured as described above, the control means 90 controls the energization of the magnetron and each heater and supplies the microwave and at least one of the radiant heat and convection heat of the heater to heat the food. Can be done. Hereinafter, the operation and action will be described focusing on the heating (operation) by the microwave.

  First, the microwave generated in the magnetron 30 is transmitted through the waveguide 35 and led out from the waveguide 35 to the heating chamber 50 side in a coaxial configuration with the microwave lead-out hole (coupling hole) 41 and the shaft element 42. Further, the microwave is radiated to the heating chamber 50 directly from the rotating antenna 40 composed of the shaft element 42 and the flat plate element 43 and through the peripheral wall of the antenna dome. Specifically, the light is also emitted from the surface of the flat plate element 43, the outer end face, and the outer peripheral surface of the shaft element 42.

  Here, as an effect by providing the antenna dome 44, even if the heater 55 and the thermistor 75 are arranged around the antenna plate, the microwave is not directly radiated there but the electric field is concentrated. It is in a place where it is possible to prevent heat loss and loss.

That is, it has the same meaning as that directly radiated microwaves are directly incident on the food to be heated. In the present embodiment, the antenna dome 44 that reflects the microwave radiation is configured around the rotating antenna 40, so that the microwave radiation in the heating chamber 50 can be detected by the presence or absence of members around the rotating antenna 40, It becomes difficult to be affected by the shape and arrangement of members, and the emitted microwaves are supplied to the object to be heated with little loss and high efficiency. In the present embodiment, a trapezoidal cone-shaped dome surface is formed at an angle of about 45 degrees with respect to the axis of the shaft element 42. This angle is optimum for microwaves depending on the height from the power supply unit to the object to be heated. You just have to decide to be a good radiation.

  Depending on the size of the object to be heated, the object to be heated having a large area is heated by the lower shelf, and the object having a small area is more effectively selected by selecting the upper shelf close to the antenna dome 44. The food can be heated. Further, as another effect of reducing the size of the antenna dome 44, the area occupied by the antenna dome 44 on the upper wall surface of the heating chamber 50 is reduced. Therefore, the heater 55 can be arranged favorably, and is good even when food is heated by radiant heat. Heating can be realized. Here, the antenna dome 44 does not need to be provided separately, and can be easily molded (drawing or the like) integrally with the wall surface of the heating chamber. The planar shape of the antenna dome 44 is not limited to a circle as long as it does not interfere with the rotation of the flat plate element 43, and may be an ellipse, a polygon, or a combination thereof.

  As described above, in the microwave heating apparatus according to the present invention, the microwave radiation in the heating chamber is radiated directly from the inclined surface of the flat element of the rotating antenna and the component radiated using the circumferential wall surface of the antenna dome. Therefore, it is possible to appropriately disperse the object to be heated and directly enter a wide area of the object to be heated, thereby reducing the influence of the standing wave generated in the heating chamber without being absorbed by the object to be heated. Therefore, uneven heating can be effectively suppressed and the object to be heated can be efficiently heated. Furthermore, it becomes difficult to be affected by members (for example, a heater) around the rotating antenna that radiates microwaves, and the radiated microwaves are supplied to the object to be heated with little loss and high efficiency. Further, the flat plate element of the rotating antenna is bent toward the heating chamber, so that the rotating antenna can be reduced in size, and the rotating space of the rotating antenna can be reduced, so that the antenna dome can be made compact. Therefore, the length of the waveguide for transmitting the microwave can be shortened, and the loss due to transmission can be reduced. Therefore, it can be easily adapted to the heating chambers having different size sizes by adjusting the inclination angle, and can be widely applied to microwave ovens and microwave ovens.

DESCRIPTION OF SYMBOLS 30 Magnetron 35 Waveguide 40 Rotating antenna 41 Derivation hole 42 Axial element 43 Flat plate element 43a Horizontal surface 43b Inclined surface 44 Antenna dome 90 Control means 200 Food

Claims (4)

A heating chamber for storing an object to be heated;
A magnetron that generates microwaves;
A waveguide for transmitting microwaves generated by the magnetron;
A substantially frustoconical antenna dome having a top surface having a lead-out hole for connecting the waveguide and leading out a microwave transmitted from the waveguide, and a circumferential wall whose bottom is open toward the heating chamber And comprising
The antenna dome is provided with a rotating antenna having a shaft element provided through a lead-out hole on the top surface of the antenna dome and a substantially circular flat plate element coupled to the shaft element,
The flat plate element of the rotating antenna includes a horizontal plane connected to the shaft element at a position eccentric with a substantially circular outer shape center, an inclined surface bent from the horizontal plane toward the heating chamber,
A microwave heating apparatus. The microwave heating device according to claim 1, wherein the inclined surface of the flat plate element of the rotating antenna is determined by the relationship with the height dimension of the heating chamber so as to face the substantially center of the bottom surface of the heating chamber. The inclination of the circumferential wall surface of the antenna dome is heated so that the outer diameter dimension where the downward extension of the circumferential wall surface intersects the heating chamber bottom surface is substantially the same as the width or depth dimension of the heating chamber bottom surface. The microwave heating apparatus according to claim 1 or 2, wherein the microwave heating apparatus is determined by a bottom dimension of the chamber. The microwave heating device according to any one of claims 1 to 3, wherein a circumferential wall surface of the antenna dome is set to intersect with a downward extension line of the inclined surface of the flat plate element of the rotating antenna.