JP2018170078A - Microwave heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reliable microwave heater which enables the achievement of a small size and a low cost while keeping a high function even if it is a microwave heater in accordance with small-capacity specifications.SOLUTION: A microwave heater comprises a flat plate-shaped antenna having an antenna face arranged to rotate in one horizontal plane in a power-supplying room formed under a bottom face of a heating room. The antenna face has at least one microwave radiation aperture having an aperture shape formed by two long and narrow openings crossing each other. Two center lines of the two long and narrow openings forming the microwave radiation aperture in their longitudinal directions each have an angle with respect to a position-prescribing line connecting between a rotation center of the flat plate-shaped antenna, and a crossing point in the shape formed by the two long and narrow openings crossing each other, and extending in a horizontal direction. The microwave heater is arranged so that circularly polarized waves are radiated from the at least one microwave radiation aperture in an upright direction of the antenna face.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a microwave heating apparatus such as a microwave oven that radiates microwaves to an object to be heated and performs dielectric heating, and more particularly to a structure of an antenna that radiates microwaves.

  In a microwave oven that is a typical microwave heating device, microwaves formed by a magnetron that is a microwave generation unit are radiated into a metal heating chamber, and an object to be heated is arranged inside the heating chamber. Is dielectrically heated.

  In recent years, in a microwave oven, a product is provided in which a bottom surface of a heating chamber on which an object to be heated is placed is formed as a flat surface, and an antenna that radiates microwaves is provided below the bottom surface. In the heating chamber having a flat bottom surface as described above, it is desirable that the object to be heated be heated uniformly regardless of the region of the bottom surface. In the field of microwave ovens, various antenna structures have been proposed for the purpose of heating substantially uniformly throughout the entire heating chamber.

  For example, Patent Document 1 proposes a configuration in which an antenna having a waveguide structure is provided below the bottom surface of the heating chamber. The antenna having a waveguide structure proposed in Patent Document 1 is a rotating antenna having a waveguide structure that is connected to a waveguide that transmits microwaves from a magnetron and has a fan shape in plan view. In this antenna having a waveguide structure, a fan-shaped arc portion is opened as a microwave radiation opening, and a shield portion of a low impedance portion that reflects microwaves is provided in a portion other than the arc portion. The thus configured waveguide structure antenna rotates around an axis extending in the vertical direction below the bottom surface of the heating chamber, so that the microwave is omnidirectionally oriented in the horizontal direction below the bottom surface of the heating chamber. Is radiated.

  In the configuration of the microwave oven disclosed in Patent Document 1 configured as described above, since the rotation axis of the antenna is provided directly below the center of the bottom surface of the heating chamber, it is placed in the central region of the bottom surface of the heating chamber. In addition, microwaves cannot be directly radiated to the heated object, and it is difficult to uniformly heat the heated object placed in all the regions inside the heating chamber. .

  There exists a microwave oven disclosed by patent document 2 as a structure which radiates | emits a microwave directly with respect to the to-be-heated object mounted in the center area | region of the bottom face of a heating chamber. In the microwave oven disclosed in Patent Document 2, an antenna having a waveguide structure is provided below the central region on the bottom surface of the heating chamber. The antenna having a waveguide structure disclosed in Patent Document 2 has a substantially quadrangular shape in plan view, and is configured such that three sides of the four sides are orthogonal to each other in a straight line. The remaining one side is formed in an arc shape, and the one side of the arc shape is opened, and the microwave transmitted through the waveguide structure of the antenna is radiated in the horizontal direction. In the antenna having a waveguide structure disclosed in Patent Document 2, a side wall surface is formed on three straight side portions, and further, a low impedance extending horizontally from the respective lower ends of the side wall surfaces of the three side portions. A part is formed. In the antenna having the waveguide structure disclosed in Patent Document 2 configured as described above, leakage of microwaves transmitted through the waveguide structure from the three sides is suppressed. In addition, in the antenna having a waveguide structure disclosed in Patent Document 2, an opening that radiates circularly polarized waves is formed on the top wall of the antenna to heat the object to be heated disposed in the central region of the heating chamber. ing.

Japanese Patent Publication No. 63-53678 JP-A-2006-119251

  In the configurations of the microwave ovens disclosed in Patent Document 1 and Patent Document 2 configured as described above, an antenna having a waveguide structure disposed below the bottom surface of the heating chamber is provided so as to be uniform in the heating chamber. It is the structure which aims at heating.

  However, since the microwave ovens disclosed in Patent Document 1 and Patent Document 2 are antennas having a waveguide structure configured to transmit microwaves in a predetermined direction, the structure of the antenna is large and complicated. In addition, since the antenna is arranged below the bottom surface of the heating chamber, it is necessary to secure a space having a certain size below the bottom surface of the heating chamber.

  In the field of home appliances, due to lifestyle changes, it has a small capacity specification while maintaining high functionality so as to be compatible with a small number of households, and it has small size, low price, and high reliability A product is sought. For this reason, for example, even in the field of microwave heating devices such as microwave ovens, it has high functionality even if the capacity of the heating chamber is small, small size, low price, and reliability, corresponding to a small number of households A highly configurable structure is required.

  The antenna having a waveguide structure used in the microwave oven disclosed in Patent Document 2 can radiate microwaves in a desired direction and has a high function, but has a complicated structure. Since it is large, the manufacturing cost is high, and since the antenna has a waveguide structure, a large space is required as an antenna placement position. For this reason, the configuration disclosed in Patent Document 2 provides a microwave oven that can achieve high functionality, downsizing, and low price while having a small capacity so as to accommodate a small number of households. Was difficult.

  The present invention can uniformly heat an object to be heated in a heating chamber, and even if the specification of the apparatus is small so as to correspond to a small number of households in accordance with lifestyle changes. An object of the present invention is to provide a highly reliable microwave heating apparatus that achieves downsizing and cost reduction while maintaining high functionality.

The microwave heating apparatus of one embodiment of the present invention is
A heating chamber having a flat bottom surface on which an object to be heated is placed;
A power supply chamber formed below the bottom surface of the heating chamber;
A flat antenna having an antenna surface provided inside the feeding chamber and rotating in the same horizontal plane;
A waveguide coupled so as to be able to transmit microwaves via an antenna shaft provided at the rotation center of the planar antenna;
A microwave forming part for forming a microwave transmitted to the waveguide,
The antenna surface of the planar antenna has at least one microwave radiation opening including an opening shape in which two elongated openings intersect;
A horizontal direction in which each of the longitudinal center lines of the two elongated openings constituting the at least one microwave radiation opening connects a rotation center of the flat antenna and an intersection in a shape where the two elongated openings intersect. The circularly polarized light is radiated from the at least one microwave radiation port in a direction directly above the antenna surface with an angle with respect to a position defining line extending in the direction of the antenna.

  According to the present invention, there is provided a highly reliable microwave heating apparatus that can perform uniform heating on an object to be heated in a heating chamber and achieves downsizing and cost reduction while maintaining high functionality. can do.

The perspective view which shows the external appearance of the microwave oven which is the microwave heating device of Embodiment 1 which concerns on this invention Sectional drawing which looked at the main body of the microwave oven of Embodiment 1 from the front The top view which shows the flat antenna etc. which were provided under the bottom face of the heating chamber in the microwave oven of Embodiment 1 The side view which shows the microwave radiation | emission unit etc. in the microwave oven of Embodiment 1 Sectional drawing which expands and shows the coupling | bond part of the waveguide and na planar antenna in the microwave oven of Embodiment 1 FIG. 3 is a plan view showing the shape of a flat surface of the flat antenna in the first embodiment. The figure which shows the analysis result regarding the flat antenna in Embodiment 1 Plan view showing a modification of the flat antenna in the first embodiment The top view which shows the flat surface of the flat antenna in the microwave oven of Embodiment 2 which concerns on this invention The figure which shows the analysis result regarding the flat antenna in Embodiment 2 The top view which shows the flat surface of the flat antenna in the microwave oven of Embodiment 3 which concerns on this invention The figure which shows the analysis result regarding the flat antenna in Embodiment 3 The figure which shows the analysis result regarding the said flat antenna while showing the flat surface of the flat antenna in the microwave oven of Embodiment 4 which concerns on this invention The figure which shows the modified example of the flat antenna in the microwave oven of Embodiment 4, and the analysis result regarding the said modified example The figure which shows the further modification of the flat antenna in the microwave oven of Embodiment 4, and the analysis result regarding the said modification

First, various aspects in the microwave heating apparatus of the present invention will be described.
The microwave heating apparatus according to the first aspect of the present invention is
A heating chamber having a flat bottom surface on which an object to be heated is placed;
A power supply chamber formed below the bottom surface of the heating chamber,
A flat antenna having an antenna surface provided inside the feeding chamber and rotating in the same horizontal plane;
A waveguide coupled so as to be able to transmit microwaves via an antenna shaft provided at the rotation center of the planar antenna, and a microwave forming unit that forms a microwave transmitted to the waveguide,
The antenna surface of the planar antenna has at least one microwave radiation opening including an opening shape in which two elongated openings intersect;
A horizontal direction in which each of the longitudinal center lines of the two elongated openings constituting the at least one microwave radiation opening connects a rotation center of the flat antenna and an intersection in a shape where the two elongated openings intersect. The circularly polarized light is radiated from the at least one microwave radiation port in a direction directly above the antenna surface with an angle with respect to a position defining line extending in the direction of the antenna.

  The microwave heating apparatus according to the first aspect configured as described above can perform uniform heating on an object to be heated in a heating chamber and is small in size while maintaining a high function despite a simple configuration. It is possible to provide a highly reliable microwave heating apparatus that achieves reduction in cost and price.

  In the microwave heating apparatus according to the second aspect of the present invention, the antenna surface in the first aspect is divided into a plurality of areas by lines extending radially from the rotation center, and in the divided areas You may comprise the adjacent area | region by the same plane from which the shape of planar view differs.

  In the microwave heating apparatus according to the third aspect of the present invention, the at least one microwave radiation port in the second aspect may be provided in at least one region of the divided regions.

  In the microwave heating apparatus according to the fourth aspect of the present invention, in the divided area according to the second or third aspect, each of the at least one area facing each other with the rotation center therebetween. A microwave radiation port may be provided.

  In the microwave heating apparatus according to the fifth aspect of the present invention, the longitudinal center lines of the two elongated openings constituting the at least one microwave radiation port according to the first aspect are orthogonal to each other. Also good.

  In the microwave heating apparatus of the sixth aspect according to the present invention, at the intersection angle of the longitudinal center lines of the two elongated openings constituting the at least one microwave radiation port in the first aspect, The angle of the region facing the rotation center may be smaller than 90 degrees.

  In the microwave heating apparatus according to the seventh aspect of the present invention, the antenna surface in the second or third aspect is formed by two first arc regions by a line extending radially from the rotation center, Each of the first arc regions has a configuration in which the first arc region is divided into four regions, a second arc region having a smaller radius and a rectangular region, and the second arc region and the rectangular region on both sides of the first arc region. And the at least one microwave radiation port may be provided in each of the two first arc regions.

  In the microwave heating apparatus according to the eighth aspect of the present invention, a microwave radiation port having the same length in the longitudinal direction of the two elongated openings in the seventh aspect may be provided in the rectangular region. .

  In the microwave heating apparatus according to the ninth aspect of the present invention, in the first to seventh aspects, a length in a longitudinal direction of the two elongated openings constituting the at least one microwave radiation port is set. Different configurations are possible.

In the microwave heating apparatus according to the tenth aspect of the present invention, in the second and third aspects, the antenna surface is divided into an arc region and a rectangular region by a line extending radially from the rotation center. The at least one microwave radiation port is provided in the arc region;
The lengths of the two elongated openings constituting the at least one microwave radiation port may be different from each other in the longitudinal direction.

  In the microwave heating apparatus of the eleventh aspect according to the present invention, the antenna surface in the first aspect is substantially circular in a plan view, and the at least one microwave radiation port includes: An intersection may be arranged at a position decentered from the rotation center, and the two elongated openings constituting the at least one microwave radiation port may have different lengths in the longitudinal direction.

  In the microwave heating apparatus according to a twelfth aspect of the present invention, the microwave radiation port including the shape in which the two elongated openings in the first to eleventh aspects intersect each other faces the antenna axis. The configuration may be such that the edge of the opening does not have an acute angle portion.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a preferred embodiment of a microwave heating apparatus according to the invention will be described with reference to the accompanying drawings. In the microwave heating apparatus of the following embodiment, a microwave oven will be described. However, the microwave oven is an example, and the microwave heating apparatus of the present invention is not limited to the microwave oven, and uses dielectric heating. And a microwave heating device such as a garbage processing machine or a semiconductor manufacturing device. The present invention is not limited to the configuration having only the dielectric heating function of the following embodiments. For example, the heater heating function by radiant heating of the heater, the convection heating function by circulation of hot air, and steam by steam Each of the heating functions such as the heating function includes a configuration added to the dielectric heating function alone or in combination.

Embodiment 1
FIG. 1 is a perspective view showing an appearance of a microwave oven that is a microwave heating apparatus according to Embodiment 1 of the present invention. As shown in FIG. 1, the microwave oven according to the first embodiment includes a main body 1 including a heating chamber 2 having an opening (heating chamber opening 2 a) on the front surface that is the front of the microwave oven, and a door that opens and closes the heating chamber 2. 3. On the right side of the main body 1 of the microwave oven in the first embodiment, an operation unit 4 for performing various operations such as cooking setting for cooking and starting cooking is arranged.

  In the microwave oven according to the first embodiment, a flat antenna 7 made of a flat plate for radiating microwaves into a heating chamber 2 in which a heated object to be heated is accommodated and placed (see FIG. 2). ) Is provided below the flat bottom surface T of the heating chamber 2. The object to be heated placed inside the heating chamber 2 is configured to be dielectrically heated by the microwave radiated from the flat antenna 7. The wall surface of the heating chamber 2 is provided with an interior lamp that illuminates the interior of the heating chamber 2, and various temperature detection sensors for detecting the surface temperature of the object to be heated and the interior temperature (heating chamber temperature). Further, in the microwave oven of the first embodiment, a position detection sensor, for example, an infrared sensor, is provided that detects in which region inside the heating chamber 2 the object to be heated is placed.

  As shown in FIG. 1, in the microwave oven according to the first embodiment, the door 3 is provided with a rotation shaft (hinge) at a lower position with respect to the heating chamber opening 2 a. It has a structure in which the handle 3a on the upper side is gripped and pulled to the front side to open the heating chamber opening 2a. The inside of the heating chamber 2 is substantially sealed due to the closed state of the door 3, and the object to be heated disposed inside the heating chamber 2 is cooked in a substantially sealed state.

  FIG. 2 is a cross-sectional view of the main body 1 of the microwave oven according to the first embodiment when viewed from the front. In the following description, the left-right direction of the microwave oven of Embodiment 1 means the left-right direction in the heating chamber 2 shown in FIG. 2, and the front-rear direction is a direction perpendicular to the paper surface of FIG. It means the direction connecting the front side (front side) and the back side (back side) of the heating chamber 2.

  As shown in FIG. 2, in the microwave oven of the first embodiment, the bottom surface T of the heating chamber 2 on which the object to be heated is placed is formed on a flat surface. Below the bottom surface T of the heating chamber 2, a microwave radiation unit 10 including a flat antenna 7 that forms and radiates microwaves is provided. In the microwave oven according to the first embodiment, a circuit component such as a power supply circuit, a control circuit, and an operation circuit, a magnetron 5 that forms a microwave, and a cooling fan are disposed in the space behind the operation unit 4 on the right side of the heating chamber 2. Such components are arranged.

  The microwave radiation unit 10 provided below the bottom surface T of the heating chamber 2 radiates the microwave to the heating chamber 2 and the waveguide 6 that transmits the microwave from the magnetron 5 that is the microwave forming unit. A flat antenna 7 and an antenna motor 8 that rotates the flat antenna 7 are included. The flat antenna 7 is provided with a metal antenna shaft 9 that is rotatable to the waveguide 6 and coupled so as to be able to transmit microwaves. The antenna shaft 9 and the drive shaft of the antenna motor 8 are made of resin. It is joined by a rotating shaft 11 made of metal.

  As shown in FIG. 2, an output end 5a of the magnetron 5 protrudes from the right end of the upper surface wall of the waveguide 6 extending in the left-right direction at a position of approximately ½ wavelength. The microwave output from the output end 5a is transmitted through the waveguide 6 that extends in a straight line from side to side. In the waveguide 6 in the first embodiment, the height H2 in the lower region (the left region of the waveguide 6) of the bottom surface T of the heating chamber 2 is the region on the output end 5a side (the right region of the waveguide 6). ) Lower than the height H1 (H2 <H1). In the configuration of the first embodiment, the height H2 of the left region of the waveguide 6 is about ½ of the height H1 of the right region of the waveguide 6.

  Since the left side region of the waveguide 6 is formed with a low height H2, a space for arranging the antenna motor 8 joined to the rotary shaft 11 penetrating the waveguide 6 is secured. Therefore, in the waveguide 6, a lower surface wall of a substantially intermediate region that connects the left region and the right region of the waveguide 6 is formed on the inclined surface 6 a. Note that the waveguide 6 has a recess in the waveguide in order to achieve impedance matching with the antenna side and to define the positions of antinodes and nodes of standing waves formed in the waveguide 6. The matching portion 6 b is formed in the left region of the waveguide 6. Further, a bulge 6c that bulges downward is formed on the lower wall facing the protruding portion of the output end 5a of the magnetron 5 in the right region of the waveguide 6, and is formed between the output end 5a and the lower wall. A desired distance is secured.

  In FIG. 2, the antenna shaft 9 of the flat antenna 7 is provided at a position of approximately ½ wavelength from the left end on the upper surface wall of the waveguide 6 extending in the left-right direction. As described above, the antenna shaft 9 is rotatably coupled to the upper wall of the waveguide 6 so as to be able to transmit microwaves. The microwave transmitted through the waveguide 6 is joined to the antenna shaft 9. Electric power is supplied to the flat antenna 7 which is a flat metal plate. A resin-made rotating shaft 11 is joined to the lower end of the antenna shaft 9, and the rotating shaft 11 is integrated with the antenna shaft 9 and penetrates the waveguide 6 up and down, and below the waveguide 6. It is joined to the antenna motor 8 provided.

  FIG. 3 is a plan view showing the flat antenna 7 and the like of the microwave radiation unit 10 provided below the bottom surface T of the heating chamber 2. In the top view of FIG. 3, the heat resistant glass used as the bottom face T of the heating chamber 2 is removed. In the space adjacent to the right side of the heating chamber 2 shown in FIG. 3 (region on the back side of the operation unit 4), the right side region of the waveguide 6 and the magnetron 5 are shown, and other components are omitted. In FIG. 3, the shaded area is an area provided with heat-resistant glass that forms the flat bottom surface T of the heating chamber 2, and the bottom surface shape of the heating chamber 2 is substantially square in the first embodiment.

  As shown in FIG. 3, a power feeding chamber 13, which is a recessed space, is provided below the bottom surface T of the heating chamber 2, and the flat antenna 7 is disposed at a substantially central position of the power feeding chamber 13. The power supply chamber 13 is made of a metal material except for its upper surface, and is configured to reflect the microwave from the flat antenna 7. The flat antenna 7 is formed of a flat metal plate, for example, an aluminum-plated steel plate having a thickness of 0.5 mm, and has a plurality of openings (microwave radiation ports 17, 18, 19) having a specific shape as described later. doing. Moreover, the flat antenna 7 in Embodiment 1 has a specific shape also in the external shape of planar view.

  As shown in FIG. 3, the planar antenna 7 in the first embodiment has a planar arc shape (antenna surface) as shown in FIG. 3. The fan-shaped arc regions (14, 15) having different radii and the rectangular region (16) having a substantially rectangular shape. And so as to form the same plane. Details of the outer shape of the flat antenna 7 will be described later. The flat antenna 7 is configured to rotate on the same plane with the center of the antenna shaft 9 as the center of rotation, and from the outer periphery of the flat antenna 7 (antenna surface) in all directions in the horizontal direction and vertically from a plurality of openings. In this configuration, microwaves are emitted.

  The feeding chamber 13 provided with the flat antenna 7 has an elongated space shape with a narrow width in the front-rear direction, and the center position of the heating chamber 2 coincides with the center position of the feeding chamber 13 (FIG. 3). reference). The center position of the feeding chamber 13 is the rotation center of the flat antenna 7. Further, the four side walls on the front, rear, left and right sides of the power supply chamber 13 are inclined so as to face upward, and the microwave radiated from the flat antenna 7 is reflected to the heating chamber 3 side (upper side). It has a function. In addition, the inclination angle of the front and rear side walls in the power supply chamber 13 is looser than the inclination angle of the left and right side walls in the power supply chamber 3, and the reflected microwaves are formed to face more upward. Yes. This is because in the power supply chamber 13 having a narrow width in the front-rear direction, the microwaves reflected by the side walls before and after the power supply chamber 13 spread widely in the regions before and after the heating chamber 2.

  FIG. 4 is a side view showing a configuration in which the magnetron 5 serving as a microwave forming unit is provided in the microwave radiation unit 10, and the feeding chamber 13, the waveguide 6, the flat antenna 7, and the like are shown in cross section. . FIG. 5 is an enlarged cross-sectional view showing a coupling portion between the waveguide 6 and the flat antenna 7.

  As shown in FIGS. 4 and 5, a part (lower end portion) of the antenna shaft 9 of the flat antenna 7 is disposed in the waveguide 6, and the rotating shaft 11 joined to the lower end portion is guided. It penetrates the lower wall of the tube 6 and is joined to the antenna motor 8. In addition, an antenna holding portion 6 d having a shape bulging upward is formed on the upper surface wall of the waveguide 6. A hole through which the antenna shaft 9 passes is formed in the antenna holding portion 6d, and an antenna receiver 12 made of wear-resistant resin is attached to the outer periphery of the hole. The antenna receiver 12 has a through hole 12 a that is penetrated by the antenna shaft 9. Further, the antenna receiver 12 is formed with a plurality of holding portions 12b protruding upward, and the upper end surfaces of at least three holding portions 12b support the flat antenna 7 so as to slide, The flat surface (antenna surface) A that is the upper surface of the flat antenna 7 is securely held at a desired position (horizontal plane). The flat antenna 7 has a flat plate shape in which the flat surface A on the upper surface functions as an antenna surface. Therefore, the flat surface A of the flat antenna 7 rotates in the same horizontal plane substantially parallel to the horizontal plane by driving the antenna motor 8.

  FIG. 6 is a plan view showing a planar view shape of the flat surface A of the flat antenna 7 in the first embodiment. As shown in FIG. 6, in the microwave oven according to the first embodiment, three openings (17, 18, 19) are formed. Since these openings (17, 18, 19) are formed in the flat surface A of the flat antenna 7, a plurality of circularly polarized waves and linearly polarized waves are directed directly upward from the flat surface A of the rotating flat antenna 7. It is a radiated configuration.

  As shown in FIG. 6, the planar antenna 7 has a plan view shape in which the first arc regions 14 and 14 are two fan-shaped shapes located opposite to each other with the rotation center P of the antenna shaft 9 therebetween, The sector-shaped second arc region 15 formed in one region in the region sandwiched between the two first arc regions 14 and 14 and the other region sandwiched between the two first arc regions 14 and 14. The same plane is formed by the rectangular region 16 formed in the above. That is, the upper surfaces of the two first arc regions 14, 14 are at opposite positions with the rotation center P of the antenna shaft 9 in between, and are included in the same plane. In addition, the upper surfaces of the second arc region 15 and the rectangular region 16 are at opposite positions with the rotation center P of the antenna shaft 9 in between, and are included in the same plane. As is clear from FIG. 6, the sector shapes of the first arc regions 14 and 14 are sector shapes having a larger radius than the sector shape of the second arc region 15. As described above, the flat surface (antenna surface) A of the flat antenna 7 is divided into four regions by lines extending radially from the rotation center P, and adjacent regions in the divided regions are planarly viewed. The shape is different.

  As described above, the planar antenna 7 according to the first embodiment has a planar shape of four regions including the two first arc regions 14, 14, the second arc region 15, and the rectangular region 16 in the same plane. It is comprised by. In the first embodiment, for example, the center angle of the first arc region 14 is about 80 degrees, the center angle of the second arc region 15 is about 100 degrees, and the center angle of the rectangular area 16 is about 100 degrees. In addition, as a radial dimension of the flat antenna 7 in Embodiment 1, the radius of the 1st circular arc area | region 14 is 60 mm, and the radius of the 2nd circular arc area | region 15 is 45 mm, for example. Further, the outer side of the rectangular region 16 (the right end side in FIG. 6) is formed at a position 70 mm from the rotation center P, and the substantially rectangular projecting region in the rectangular region 16 (substantially projecting on the right side in FIG. 6). The width of the (rectangular region) was 50 mm. The radius of the first arc region 14 is set to 60 mm in consideration of the length of about one wavelength of the frequency (2.45 GHz) used in the microwave oven.

  As described above, the planar view shape of the flat antenna 7 in the first embodiment has been described with specific dimensions, but this specific example is a configuration example, and is appropriately changed according to the specification of the microwave oven. However, the present invention is not limited to this configuration example.

  Regarding the three openings (17, 18, 19) formed in the flat antenna 7 in the first embodiment, the first microwave radiation port 17, the second microwave radiation port 18, and the third microwave radiation port 19 are provided. Will be described later.

  The first microwave radiation port 17 and the second microwave radiation port 18 in the first embodiment have the same opening shape, and the longitudinal center line (J of the elongated openings (20, 21) having the same length) , K) is a cross opening shape having a shape orthogonal to each other. That is, the first microwave radiation port 17 and the second microwave radiation port 18 have the same X shape.

  The cross opening shape (X shape) of the first microwave radiation port 17 is such that the longitudinal center line (J or K) of each of the two elongated openings (20, 21) is the rotation center P of the antenna shaft 9. An angle of 45 degrees is formed with respect to a straight line (first position defining line E) connecting the intersection B of the cross opening shape. Similarly, the cross opening shape of the second microwave radiation port 18 is such that the longitudinal center line (J or K) of each of the two elongated openings (20, 21) crosses the rotation center P of the antenna shaft 9. An angle of 45 degrees is formed with respect to a straight line (first position defining line E) connecting the intersection C of the opening shape. That is, in the cross opening shape (substantially X shape) of the first microwave radiation port 17, the center line J extending in the longitudinal direction of the first opening 20 is the intersection B of the rotation center P of the antenna shaft 9 and the cross opening shape. Is formed at an angle of 45 degrees with respect to the first position defining line E. Similarly, a center line K extending in the longitudinal direction of the second opening 21 forms an angle of 45 degrees with respect to the first position defining line E.

  In the cross opening shape of the first microwave radiating port 17 and the second microwave radiating port 18, the end portion and the bent portion are all formed by curved surfaces in order to prevent discharge. Note that the first opening 20 and the second opening 21 in the cross opening shape of the first embodiment are elongated openings formed from the left back side to the right front side when viewed from the rotation center P of the flat antenna 7. The elongated opening formed from the right back side to the left front side is referred to as a second opening portion 21. In the description of each embodiment below, the positional relationship between the first opening and the second opening in the (substantially) cross opening shape is the same.

  The first microwave radiating port 17 and the second microwave radiating port 18 are arranged to face each other with the rotation center P of the antenna shaft 9 therebetween, and are respectively disposed in the first arc regions 14 and 14 having a large radius. Is formed. A straight line (first position defining line E) connecting the intersections (B, C) of the respective cross opening shapes of the first microwave radiation port 17 and the second microwave radiation port 18 passes through the rotation center P of the antenna shaft 9. The first position defining line E is a center line that bisects the first arc regions 14 and 14 into substantially the same area.

  The specific cross opening shape of the first microwave radiating port 17 and the second microwave radiating port 18 in the first embodiment is such that the longitudinal length of the elongated opening is, for example, 35 mm, and the width of the elongated opening. Is, for example, 10 mm. These numerical values are examples, and the present invention is not limited to these numerical values.

  The third microwave radiation port 19 in the first embodiment has a larger opening shape than the first microwave radiation port 17 and the second microwave radiation port 18 described above. The third microwave radiation port 19 is formed in the rectangular region 16. The third microwave radiation port 19 has a substantially cross opening shape including a cross opening shape in which elongated openings of the same length intersect at right angles. Further, as shown in FIG. 6, the substantially microwave-opening shape of the third microwave radiation port 19 is such that one region G of the outer region divided into four regions by the cross-opening shape is opened in a substantially triangular shape. And includes the triangular opening. Further, in the substantially cross-opening shape of the third microwave radiation port 19, the center line in the longitudinal direction of each of the two elongated openings connects the rotation center P of the antenna shaft 9 and the intersection D of the substantially cross-opening shape. It has an angle of 45 degrees with respect to the straight line (second position defining line F).

  As shown in FIG. 6, the substantially cross-opening shape of the third microwave radiating port 19 includes a cross-opening shape (X-shape) in which elongated openings of the same length are orthogonal, and an antenna axis in the outer region of the cross-opening shape. A region G facing the rotation center P of 9 is formed by a substantially triangular opening shape. This is because the third microwave radiation port 19 has a larger opening shape than the first microwave radiation port 17 and the second microwave radiation port 18, and the electric field becomes stronger at the third microwave radiation port 19. If there is a bent portion in the region close to the antenna axis 9, there is a risk of electric discharge. Therefore, a region G having a substantially triangular opening shape is formed in the region close to the antenna axis 9 to eliminate the acute angle portion.

  The third microwave radiation port 19 is formed at a position where a straight line (second position defining line F) connecting the rotation center P of the antenna shaft 9 and the intersection D having a substantially cross opening shape is the rectangular region 16 and the second arc. This is a position that becomes a center line that bisects the region 15 into substantially the same area. In the substantially cross-opening shape of the third microwave radiating port 19, in order to prevent discharge, the end portion and the bent portion are all formed of a curved surface. The specific opening shape of the third microwave radiation port 19 in the first embodiment is, for example, that the length of the elongated opening in the longitudinal direction is 45 mm, and the width of the elongated opening is 10 mm. These numerical values are examples, and the present invention is not limited to these numerical values.

  As described above, the flat antenna 7 according to the first embodiment forms a flat surface (antenna surface) A that radiates microwaves from a substantially flat plate material, and the rotation center P (flat surface A). The antenna shaft 9 is provided on the back surface of the antenna. Therefore, the flat antenna 7 according to the first embodiment does not have a waveguide structure, and has a configuration different from the configuration in which microwaves are transmitted and radiated in a predetermined direction by the waveguide structure. For this reason, the flat antenna 7 radiates microwaves in the horizontal direction from the outer peripheral portion of the flat antenna 7 while rotating, and also has a plurality of openings (first microwave radiation openings) formed on the flat surface A. 17, the second microwave radiation port 18 and the third microwave radiation port 19) radiate circularly polarized waves and linearly polarized waves.

  FIG. 7 shows the results obtained by analysis by the inventors regarding the flat antenna 7 having the configuration of the first embodiment. FIG. 7A shows the locus of the electric field vector of the microwaves radiated from the first microwave radiating port 17, the second microwave radiating port 18, and the third microwave radiating port 19 in the flat antenna 7. FIG. FIG. 7B shows the electric field strength in the flat antenna 7 in a contour diagram. In the contour diagram of FIG. 7B, the dark region in the central region indicates a region where the electric field strength is strong. The contour diagram used here is a color diagram, where the dark region in the central region is red, the dark region in the outer region is blue, and the electric field strength is low. Also in the contour diagrams described below, similarly, a dark region in the central region indicates a region having a high electric field strength.

  As shown in FIG. 7A, the first microwave radiation port 17 and the second microwave radiation port 18 emit elliptically polarized microwaves in which the locus of the electric field vector is an elliptical circularly polarized wave. ing. On the other hand, a linearly polarized microwave is emitted from the third microwave radiation port 19. The linearly polarized wave radiated from the third microwave radiation port 19 is on a substantially line connecting the rotation center P and the intersection D of the substantially microwave opening shape of the third microwave radiation port 19 on the flat surface A of the flat antenna 7. Is the linearly polarized wave that becomes the locus of the electric field vector.

  The reason why circularly polarized waves are radiated from the first microwave radiating port 17 and the second microwave radiating port 18 is that the direction of the current flowing through the flat surface (antenna surface) A of the flat antenna 7 is that of the microwave radiating port. This is probably because the flow does not flow symmetrically on both sides of the opening. That is, the intersection (B or C) of the first microwave radiation port 17 or the second microwave radiation port 18 is connected to the rotation center P of the antenna shaft 9 coupled to the waveguide 6 so as to be able to transmit microwaves. This is probably because the outer region divided by the line (first position defining line E) does not have a symmetric shape. As for the third microwave radiation port 19, the outer region divided by the line (second position defining line F) connecting the intersection D of the opening shape and the rotation center P of the antenna shaft 9 is symmetric.

  As shown in the contour diagram of FIG. 7B, the first microwave radiating port 17, the second microwave radiating port 18, and the third microwave radiating port 19 have high electric field strength, and the flat antenna 7 The electric field strength is also strong at the outer peripheral portion of the, and microwaves with a large output are radiated.

  FIG. 8 is a plan view showing a modification of the flat antenna 7 in the first embodiment. The difference between the flat antenna 7A shown in FIG. 8 and the flat antenna 7 shown in FIG. 6 is the opening shape of the third microwave radiation port 19A, and the other configurations are the same. As shown in FIG. 8, the third microwave radiation port 19 </ b> A has a cross opening shape in which elongated openings having the same length are orthogonal to each other. That is, the cross opening shape of the third microwave radiation port 19A shown in FIG. 8 is a cross opening shape that does not include the substantially triangular opening shape (G) as shown in FIG. Thus, as shown in the flat antennas (7, 7A), the microwave radiation opening has a cross opening shape or a substantially triangular opening shape (opening of the region G) according to the specifications of the microwave oven. ) Including a substantially cross-opening shape. That is, in an apparatus with a large heating output and heating capacity, in order to prevent discharge more reliably, the edge of the microwave radiation port in the region near the antenna shaft 9 does not have an acute angle part. A configuration that includes a substantially triangular aperture shape (aperture in the region G) is an aperture shape that removes sharp corners. Conversely, in a device with a small heating output and heating capacity, it can be configured as a simple cross aperture shape. is there.

  As described above, in the microwave oven that is the microwave heating apparatus according to the first embodiment, a flat plate shape including a flat antenna surface (A) that radiates circularly polarized waves and linearly polarized microwaves. Even if the heating chamber has a small capacity and the heating output is small, the antenna retains a high function capable of substantially uniformly heating an object to be heated in the heating chamber. Since it is simple and small, it is possible to reduce the size of the entire apparatus and to reduce the price. In the microwave oven of Embodiment 1, since the antenna structure is simplified, a highly reliable microwave heating apparatus with few failures can be provided.

<< Embodiment 2 >>
Hereinafter, the microwave heating apparatus according to the second embodiment will be described focusing on differences from the first embodiment. In the description of the second embodiment, components having the same functions as those of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. In addition, the contents having the same operations as those of the first embodiment described above may be omitted in order to avoid redundant description.

  The microwave oven that is the microwave heating apparatus according to the second embodiment is different from the microwave oven according to the first embodiment in the shape of the flat antenna, and particularly in the opening shape. FIG. 9 is a plan view showing a flat surface (antenna surface) A of the flat antenna 7B in the microwave oven of the second embodiment.

  The first microwave radiating port 17B and the second microwave radiating port 18B in the second embodiment are the second positions connecting the intersection D of the opening shape of the third microwave radiating port 19B and the rotation center P of the antenna shaft 9. With respect to the prescribed line F, they are arranged in line symmetry and have the same opening shape. Each of the first microwave radiation port 17B and the second microwave radiation port 18B has a cross opening shape (substantially X-shaped) in which elongated openings (first opening 20B and second opening 21B) having different lengths intersect each other. It is. The positions of the intersections (B, C) of each cross opening shape are the same as the positions of the intersections (B, C) on the flat surface (antenna surface) A of the flat antenna 7 in the first embodiment.

  In the cross opening shape (substantially X shape) of the first microwave radiating port 17B, the center line J extending in the longitudinal direction of the first opening 20B has the rotation center P of the antenna shaft 9 and the intersection B of the cross opening shape. An angle of 45 degrees is formed with respect to the connecting first position defining line E. On the other hand, the center line K extending in the longitudinal direction of the second opening 21B forms an angle of 25 degrees with respect to the first position defining line E. That is, at the intersection angle of the longitudinal center lines (J, K) of the two elongated openings constituting the first microwave radiation port 17B, the angle of the region facing the center of rotation is narrower than 90 degrees (70 Degree).

  Similarly, in the cross opening shape of the second microwave radiation port 18B, the center line J extending in the longitudinal direction of the first opening 20B forms an angle of 45 degrees with respect to the first position defining line E. On the other hand, the center line K extending in the longitudinal direction of the second opening 21B in the second microwave radiation port 18B forms an angle of 25 degrees with respect to the first position defining line E. The cross opening shape of the first microwave radiating port 17B and the second microwave radiating port 18B has a curved surface configuration at all ends and bent portions in order to prevent discharge.

  The first microwave radiation port 17B and the second microwave radiation port 18B are formed in each of the first arc regions 14 and 14 as in the configuration of the first embodiment. The intersections (B, C) of the cross opening shapes of the first microwave radiation port 17B and the second microwave radiation port 18B exist on the first position defining line E, and the first position defining line E Is a center line that bisects the first arc regions 14, 14 into substantially the same area.

  The specific cross opening shape of the first microwave radiating port 17B and the second microwave radiating port 18B in the second embodiment is such that the length in the longitudinal direction of the first opening 20B is 50 mm, for example. The length in the longitudinal direction of the two openings 21A is, for example, 35 mm. That is, the length in the longitudinal direction of the first opening 20B is 32.5 mm in the direction in which the second position defining line F exists from each intersection (B or C) of the cross opening shape. The length is 17.5 mm in the opposite direction from (B or C). The width of the first opening 20B and the second opening 21B is, for example, 10 mm.

  The third microwave radiation port 19B in the second embodiment has the same shape as the third microwave radiation port 19 in the above-described first embodiment, and is formed in the rectangular region 16 of the flat antenna 7B. In addition, the specific opening shape of the 3rd microwave radiation opening 19B in Embodiment 2 is 45 mm in the length of the longitudinal direction of an elongate opening, for example, and the width | variety of an elongate opening is 10 mm. The above specific numerical values are examples, and the present invention is not limited to these numerical values.

  As described above, the flat antenna 7B according to the second embodiment forms a flat surface (antenna surface) A that radiates microwaves from a substantially flat plate material, and the antenna shaft 9 is provided at the center of rotation. This is a configuration provided. Therefore, the flat antenna 7B according to the second embodiment does not have a waveguide structure, and has a configuration different from a configuration in which microwaves are transmitted and radiated in a predetermined direction by the waveguide structure. For this reason, the flat antenna 7B according to the second embodiment radiates microwaves from the outer peripheral portion of the flat antenna 7A in the horizontal direction while rotating and also has a plurality of openings (first apertures) formed in the flat surface A. The first microwave radiation port 17B, the second microwave radiation port 18B, and the third microwave radiation port 19B) radiate circularly polarized waves and linearly polarized waves.

  FIG. 10 shows the results obtained by analysis by the inventors regarding the flat antenna 7B having the configuration of the second embodiment. (A) of FIG. 10 shows the locus of the electric field vector of the microwave radiated from the first microwave radiating port 17B, the second microwave radiating port 18B, and the third microwave radiating port 19B in the flat antenna 7B by a broken line. FIG. FIG. 10B shows the electric field intensity radiated from the flat antenna 7B in a contour diagram.

  As shown in FIG. 10A, microwaves whose electric field vectors are elliptically polarized are emitted from the first microwave radiation port 17B and the second microwave radiation port 18B. The electric field vector locus is elliptically polarized with a larger diameter than the elliptically polarized waves radiated from the first microwave radiating port 17 and the second microwave radiating port 18 in the first embodiment. A linearly polarized microwave is emitted from the third microwave radiation port 19A. Since the microwave radiated from the third microwave radiation port 19A is linearly polarized, the locus of the electric field vector is substantially linear.

  As shown in the contour diagram of FIG. 10B, the first microwave radiation port 17B, the second microwave radiation port 18B, and the third microwave radiation port 19B have a high electric field strength, and the flat antenna 7B. A microwave with a strong electric field strength is also radiated from the outer peripheral portion of.

  As described above, in the microwave oven that is the microwave heating apparatus according to the second embodiment, a heating chamber is provided by a flat antenna having a flat antenna surface (A) that radiates circularly polarized waves and linearly polarized microwaves. Even if the capacity is small and the heating output is small, it retains the high function that can heat the object to be heated in the heating chamber substantially uniformly, and the antenna structure is simple and small. The entire apparatus can be reduced in size and can be reduced in price. In the microwave oven of Embodiment 2, since the antenna structure is simplified, a highly reliable microwave heating apparatus with few failures can be provided.

<< Embodiment 3 >>
Hereinafter, the microwave heating apparatus according to the third embodiment will be described focusing on differences from the first embodiment and the second embodiment. In the description of the third embodiment, components having the same functions as those of the first embodiment and the second embodiment described above are denoted by the same reference numerals, and description thereof is omitted. In addition, contents having the same operations as those of the first embodiment and the second embodiment described above may be omitted in order to avoid redundant description.

  The microwave oven that is the microwave heating apparatus of the third embodiment is different from the microwave ovens of the first and second embodiments in the shape of the flat antenna, and in particular, the outer shape and the opening shape are different. FIG. 11 is a plan view showing a flat surface (antenna surface) A of the flat antenna 7B in the microwave oven of the third embodiment.

  The first microwave radiating port 17C and the second microwave radiating port 18C in the third embodiment are the second positions connecting the intersection D of the opening shape of the third microwave radiating port 19C and the rotation center P of the antenna shaft 9. With respect to the prescribed line F, they are arranged in line symmetry and have the same opening shape. Each of the first microwave radiation port 17C and the second microwave radiation port 18C has a cross opening shape (substantially X-shaped) in which elongated openings having different lengths (first opening 20C and second opening 21C) are orthogonal to each other. It is. The positions of the intersections (B, C) of each cross opening shape are the same as the positions of the intersections (B, C) on the flat surface (antenna surface) A of the flat antenna 7 in the first embodiment.

  In the cross opening shape (substantially X shape) of the first microwave radiation port 17C, the center line J extending in the longitudinal direction of the first opening 20C forms an angle of 45 degrees with respect to the first position defining line E. ing. A center line K extending in the longitudinal direction of the second opening 21C forms an angle of 45 degrees with respect to the first position defining line E.

  Similarly, in the cross opening shape of the second microwave radiation opening 18C, the center line J extending in the longitudinal direction of the first opening 20C forms an angle of 45 degrees with respect to the first position defining line E. A center line K extending in the longitudinal direction of the second opening 21C in the second microwave radiation port 18C forms an angle of 45 degrees with respect to the first position defining line E.

  Although the opening shapes of the first microwave radiation port 17C and the second microwave radiation port 18C in the third embodiment are the same, the center position in the longitudinal direction of each of the first opening 20C and the second opening 21C. There is no intersection (B, C). That is, in the first opening 20C, the opening region extending from the intersection B in the direction of the second position defining line F is formed longer than the opening region extending from the intersection B in the opposite direction. Similarly, in the second opening 21C, an opening region extending from the intersection B in the direction of the second position defining line F is formed longer than an opening region extending from the intersection B in the opposite direction.

  The specific cross opening shape of the first microwave radiation port 17C and the second microwave radiation port 18C in the third embodiment is such that the length in the longitudinal direction of the first opening 20C is, for example, 50.0 mm. The length in the longitudinal direction of the two openings 21C is, for example, 42.5 mm. That is, the length of the first opening 20C in the longitudinal direction is 32.5 mm in the direction of the second position defining line F from each intersection (B or C) of the cross opening shape, and each intersection (B Or the length is 17.5 mm in the opposite direction from C). On the other hand, the length in the longitudinal direction of the second opening 21C is 25.0 mm in the direction of the second position defining line F from each intersection (B or C) of the cross opening shape, and each intersection (B Or the length is 17.5 mm in the opposite direction from C). The width of the first opening 20C and the second opening 21C is, for example, 10 mm. These numerical values are examples, and the present invention is not limited to these numerical values. In addition, the cross opening shape of the first microwave radiation port 17C and the second microwave radiation port 18C has a curved surface configuration at all ends and bent portions in order to prevent discharge.

  The third microwave radiation port 19C in the third embodiment has the same shape as the third microwave radiation port 19 (FIG. 5) in the first embodiment, and is formed in the rectangular region 16C of the flat antenna 7C. Yes. The specific opening shape of the third microwave radiation port 19C in Embodiment 3 is, for example, that the length of the elongated opening in the longitudinal direction is 45 mm, and the width of the elongated opening is 10 mm. These numerical values are examples, and the present invention is not limited to these numerical values. In the first microwave radiation port 17C, the second microwave radiation port 18C, and / or the third microwave radiation port 19C in the third embodiment, the third microwave radiation port of FIG. As in 19A, in the region close to the antenna axis 9, for example, an opening having a substantially triangular shape (opening of the region G) may be formed so as to eliminate an acute angle portion and further prevent the risk of occurrence of discharge. .

  In the microwave oven of the third embodiment, the shape of the planar antenna 7C in plan view (the shape of the antenna surface) is different from the shape of the planar antenna 7 in plan view in the first embodiment. As shown in FIG. 11, in the flat antenna 7C according to the third embodiment, the first arc region 14 and the second arc region 15 have the same radius, and one arc region 22 is formed. . That is, in the configuration of the third embodiment, the flat surface (antenna surface) of the flat antenna 7C is composed of the arc region 22 and the rectangular region 16, and the center angle of the arc region 22 is about 260 degrees. Yes.

  The first microwave radiation port 17C and the second microwave radiation port 18C in the third embodiment are formed to face each other in the arc region 22 with the rotation center P therebetween. The intersections (B, C) of the respective cross opening shapes of the first microwave radiation port 17C and the second microwave radiation port 18C exist on the first position defining line E.

  As described above, the flat antenna 7C according to the third embodiment forms a flat surface (antenna surface) A that radiates microwaves from a substantially flat plate material, and the antenna shaft 9 is formed at the rotation center P thereof. Is provided. Therefore, the flat antenna 7C according to the third embodiment does not have a waveguide structure, and has a configuration different from the configuration in which microwaves are transmitted and radiated in a predetermined direction by the waveguide structure. For this reason, the flat antenna 7C according to the third embodiment radiates microwaves from the outer peripheral portion of the flat antenna 7C in the horizontal direction while rotating, and also has a plurality of openings (first apertures) formed in the flat surface A. The first microwave radiation port 17C, the second microwave radiation port 18C, and the third microwave radiation port 19C) radiate circularly polarized waves and linearly polarized waves.

  FIG. 12 shows the results obtained by analysis by the inventors regarding the flat antenna 7C having the configuration of the third embodiment. (A) of FIG. 12 shows the locus of the electric field vector of the microwave radiated from the first microwave radiating port 17C, the second microwave radiating port 18C, and the third microwave radiating port 19C in the flat antenna 7C by a broken line. FIG. (B) of FIG. 12 shows the electric field strength in the flat antenna 7C in a contour diagram.

  As shown in FIG. 12 (a), microwaves whose electric field vectors are elliptically polarized are emitted from the first microwave radiation port 17C and the second microwave radiation port 18C. The locus of the electric field vector is an elliptically polarized wave closer to a perfect circle than the elliptically polarized wave radiated from the first microwave radiating port 17 and the second microwave radiating port 18 in the first embodiment. A linearly polarized microwave is radiated from the third microwave radiation port 19C.

  As shown in the contour diagram of FIG. 12B, the first microwave radiation port 17C, the second microwave radiation port 18C, and the third microwave radiation port 19C have high electric field strength, and the flat antenna 7C. The electric field strength is also strong at the outer peripheral portion of the, and microwaves with a large output are radiated.

  As described above, in the microwave oven that is the microwave heating apparatus according to the third embodiment, the flat chamber antenna (A) that radiates circularly polarized waves and linearly polarized microwaves is used as the heating chamber. Even if the capacity is small and the heating output is small, it retains the high function that can heat the object to be heated in the heating chamber substantially uniformly, and the antenna structure is simple and small. The entire apparatus can be reduced in size and can be reduced in price. In the microwave oven of Embodiment 3, since the antenna structure is simplified, a highly reliable microwave heating apparatus with few failures can be provided.

<< Embodiment 4 >>
Hereinafter, the microwave heating apparatus according to the fourth embodiment will be described focusing on differences from the first to third embodiments. In the description of the fourth embodiment, components having the same functions as those in the first to third embodiments are denoted by the same reference numerals, and the description thereof is omitted. In addition, contents having the same operations as those of the first to third embodiments described above may be omitted in order to avoid redundant description.

  The microwave oven that is the microwave heating apparatus according to the fourth embodiment is different from the microwave ovens according to the first to third embodiments in the shape of the flat antenna, and in particular, the outer shape and the opening shape are different. FIG. 13 shows a flat surface (antenna surface) A of the flat antenna 7D in the microwave oven according to the fourth embodiment, and also shows an analysis result related to the flat antenna 7D. FIG. 13A is a diagram showing the shape of the flat antenna 7D and the locus of the electric field vector of the microwave radiated from the microwave radiation port 23 in the flat antenna 7D by a broken line. (B) of FIG. 13 shows the electric field strength in the flat antenna 7D in a contour diagram.

  As shown to (a) of FIG. 13, the planar view (antenna surface) shape of the flat antenna 7D in Embodiment 4 is a disk shape. In the configuration of the fourth embodiment, one microwave radiation port 23 is formed on the antenna surface (A). As shown in the first to third embodiments, the microwave radiation opening 23 is a cross opening in which two elongated openings (first opening 20D and second opening 21D) having different lengths are orthogonal to each other. The shape (substantially X shape).

  In the cross opening shape (substantially X shape) of the microwave radiating port 23, the center line J extending in the longitudinal direction of the first opening 20D connects the rotation center P of the antenna shaft 9 and the crossing point M of the cross opening shape. An angle of 45 degrees is formed with respect to one position defining line E. Similarly, the center line K extending in the longitudinal direction of the second opening 21D forms an angle of 45 degrees with respect to the first position defining line E.

  Further, the length of the first opening 20D in the longitudinal direction is longer than the length of the second opening 21D in the longitudinal direction. Specifically, in the configuration of the fourth embodiment, the length of the first opening 20D in the longitudinal direction is 110.78 mm, and the length of the second opening 21D in the longitudinal direction is 51.55 mm. The ratio of the length of the second opening 21D / first opening 20D was about 46.5%.

  The microwave radiating port 23 is formed at a position eccentric from the rotation center P of the antenna surface (A) of the flat antenna 7D, and the intersection M is located at a position of 1/3 of the radius of the circular antenna surface (A). Is set. Note that the outer diameter of the flat antenna 7D in the fourth embodiment is 120 mm, which is a length of about one wavelength of the frequency (2.45 GHz) used in the microwave oven.

  As shown in FIG. 13A, a circularly polarized microwave having a substantially circular locus of the electric field vector is radiated from the microwave radiation port 23 of the flat antenna 7D according to the fourth embodiment. As shown in the contour diagram of FIG. 13B, the electric field strength is strong in the vicinity of the microwave radiation port 23 and in the outer peripheral portion of the flat antenna 7D, and a microwave with a large output is radiated. .

  14 and 15 show a modification of the configuration of the disk-shaped flat antenna (7E, 7F) in the fourth embodiment. FIG. 14 shows a flat surface (antenna surface) A of the flat antenna 7E and an analysis result related to the flat antenna 7E. FIG. 15 shows a flat surface (antenna surface) A of the flat antenna 7F and an analysis result related to the flat antenna 7F.

  In a plan view (antenna surface) of the disk-shaped flat antenna 7E shown in FIG. 14A, one microwave radiation port 24 is formed on the antenna surface. The cross opening shape (substantially X shape) of the microwave radiation port 24 is different from the microwave radiation port 23 shown in FIG. 13 in that each of the first opening 20E and the second opening 21E in the longitudinal direction. Length. The specific length of the microwave radiation port 24 in the flat antenna 7E is 98.37 mm in the longitudinal direction of the first opening 20E, and 57.37 mm in the longitudinal direction of the second opening 21E. 9 mm. The ratio of the length of the second opening 21E / first opening 20E was about 58.9%.

  Similarly to the microwave radiation port 23 shown in FIG. 13, the microwave radiation port 24 is also formed at a position eccentric from the rotation center P of the antenna surface (A) of the flat antenna 7E, and has a circular antenna surface. An intersection M is set at a position of 1/3 of the radius in (A). In addition, a specific outer diameter of the flat antenna 7E was 120 mm.

  As shown in FIG. 14 (a), the microwave radiation port 24 of the flat antenna 7E emits microwaves whose elliptical polarization is an electric field vector locus. As shown in the contour diagram of FIG. 14B, the electric field strength is strong in the vicinity of the microwave radiation port 24 and in the outer peripheral portion of the flat antenna 7E, and a microwave with a large output is radiated. .

  In a plan view (antenna surface) of the disk-shaped flat antenna 7F shown in FIG. 15A, one microwave radiation port 25 is formed on the antenna surface. In the cross opening shape (substantially X shape) of the microwave radiation port 25, the length in the longitudinal direction of the first opening 20F is 84.04 mm, and the length in the longitudinal direction of the second opening 21F is 67.04 mm. 2 mm. The ratio of the length of the second opening 21F / first opening 20F was about 80%.

  Similarly to the microwave radiation port 23 shown in FIG. 13, the microwave radiation port 25 is also formed at a position eccentric from the rotation center P of the antenna surface (A) in the flat antenna 7E, and has a circular antenna surface. An intersection M is set at a position of 1/3 of the radius in (A). In addition, a specific outer diameter of the flat antenna 7F is 120 mm.

  As shown in FIG. 15A, microwaves whose elliptical polarization is an electric field vector locus are radiated from the microwave radiation opening 25 of the flat antenna 7F. As shown in the contour diagram of FIG. 15B, the electric field strength is strong in the vicinity of the microwave radiation opening 25 and the outer peripheral portion of the flat antenna 7F, and microwaves with a large output are radiated. .

  As described above, in the configuration of the microwave oven of the fourth embodiment, the antenna surface (A) is a flat plate antenna (7D, 7E, 7F) having a circular flat plate, and a specific position of the antenna surface (A) is used. By forming a substantially cross-opening microwave radiating aperture that intersects two elongated apertures with different lengths, the electric field distribution on the antenna surface (A) becomes unbalanced, and circularly polarized waves are generated from the microwave radiating aperture. The structure is radiated.

  As a result of the analysis by the inventors, when the disk-shaped antenna surface (A) is used, the ratio of the length in the longitudinal direction between the first opening and the second opening having a substantially cross-opening shape (first It can be understood that a desired circularly polarized wave is formed by setting (2 openings / first opening) in the range of 50 to 80%, and contributes to uniform heating in the heating chamber.

  As described above, in the microwave oven that is the microwave heating apparatus according to the fourth embodiment, the disk-shaped flat antenna having the flat antenna surface (A) that radiates the circularly polarized microwaves is used. Even if the capacity is small and the heating output is small, it retains the high function that can heat the object to be heated in the heating chamber substantially uniformly, and the antenna structure is simple and small. As a whole, downsizing can be achieved and cost reduction can be achieved. In the microwave oven of Embodiment 4, since the antenna structure is simplified, a highly reliable microwave heating apparatus with few failures can be provided.

  As described above, in the microwave heating apparatus of the present invention, as specifically described by using each embodiment and modification, a small change is made so as to correspond to a small number of households due to lifestyle changes. Although it is a capacity specification, it is possible to provide a highly reliable product that is small in size, low in price, and highly reliable while maintaining high functionality, and can provide a microwave heating device with a highly reliable configuration. Become.

  The present invention is to provide a small-sized, low-cost, and highly reliable microwave heating apparatus to the market while maintaining high functionality while supporting a small number of households. This is a useful invention.

DESCRIPTION OF SYMBOLS 1 Microwave oven body 2 Heating chamber 3 Door 3a Handle 4 Operation part 5 Magnetron (microwave formation part)
6 Waveguide 6d Antenna holding portion 7 Flat antenna 8 Antenna motor 9 Antenna shaft 10 Microwave radiation unit 11 Rotating shaft 12 Antenna receiver 13 Feeding chamber 14 First arc region 15 Second arc region 16 Rectangular region 17 First microwave Radiation port 18 Second microwave radiation port 19 Third microwave radiation port 20 First opening 21 Second opening 22 Arc region 23 Microwave radiation port 24 Microwave radiation port 25 Microwave radiation port A Flat surface B First Microwave Radiation Exit Intersection C Second Microwave Radiation Exit Intersection D Third Microwave Radiation Exit Intersection E First Position Regulating Line F Second Position Regulating Line

Claims (12)

A heating chamber having a flat bottom surface on which an object to be heated is placed;
A power supply chamber formed below the bottom surface of the heating chamber,
A flat antenna having an antenna surface provided inside the feeding chamber and rotating in the same horizontal plane;
A waveguide coupled so as to be able to transmit microwaves via an antenna shaft provided at the rotation center of the planar antenna, and a microwave forming unit that forms a microwave transmitted to the waveguide A microwave heating device,
The antenna surface of the planar antenna has at least one microwave radiation opening including an opening shape in which two elongated openings intersect;
A horizontal direction in which each of the longitudinal center lines of the two elongated openings constituting the at least one microwave radiation opening connects a rotation center of the flat antenna and an intersection in a shape where the two elongated openings intersect. A microwave heating apparatus configured to radiate circularly polarized waves from the at least one microwave radiation port in a direction immediately above the antenna surface with an angle with respect to a position defining line extending in a straight line.   2. The antenna surface according to claim 1, wherein the antenna surface is divided into a plurality of regions by lines extending radially from the rotation center, and adjacent regions in the divided regions are configured by the same plane having different shapes in plan view. Microwave heating device.   The microwave heating device according to claim 2, wherein the at least one microwave radiation port is provided in at least one region of the divided regions.   4. The microwave heating apparatus according to claim 2, wherein, in the divided area, the at least one microwave radiation port is provided in each of the areas facing each other with the rotation center therebetween.   The microwave heating apparatus according to claim 1, wherein longitudinal centerlines of the two elongated openings constituting the at least one microwave radiation port are orthogonal to each other.   The crossing angle of the longitudinal center line of the two elongated openings constituting the at least one microwave radiation port is configured such that the angle of the region facing the rotation center is smaller than 90 degrees. The microwave heating apparatus according to claim 1.   The antenna surface is divided into four regions: two first arc regions, a second arc region having a smaller radius than each of the first arc regions, and a rectangular region by a line extending radially from the rotation center. The second arc region and the rectangular region are disposed on both sides of the first arc region, and the at least one microwave radiation port is provided in each of the two first arc regions. The microwave heating device according to claim 2 or 3.   The microwave heating apparatus according to claim 7, wherein a microwave radiation port in which two elongated openings have the same length in the longitudinal direction is provided in the rectangular region.   The microwave heating device according to any one of claims 1 to 7, wherein lengths in the longitudinal direction of the two elongated openings constituting the at least one microwave radiation port are different from each other. The antenna surface is divided into a circular arc region and a rectangular region by a line extending radially from the center of rotation, and the at least one microwave radiation port is provided in the circular arc region,
The microwave heating apparatus according to claim 2 or 3, wherein lengths in the longitudinal direction of the two elongated openings constituting the at least one microwave radiation port are different from each other.   The antenna surface has a substantially circular shape in plan view, and the at least one microwave radiating port is disposed at a position deviated from the rotation center to constitute the at least one microwave radiating port. The microwave heating apparatus according to claim 1, wherein the two elongated openings are configured to have different lengths in the longitudinal direction.   12. The microwave radiating port including a shape in which the two elongated openings intersect with each other, wherein the edge of the opening facing the antenna axis does not have an acute angle portion. The microwave heating device according to item.

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