JP5467330B2 - Microwave heating device - Google Patents

Description

  The present invention relates to a microwave heating apparatus that heats an object to be heated with microwaves.

  A microwave oven, which is a typical microwave heating device, can directly heat food that is a typical object to be heated, so there is no need to prepare a pot or kettle, and it is essential for living. It has become a cooking utensil. In a microwave oven, the size of a space for storing food is generally widespread in the width and depth directions of 300 to 400 mm and in the height direction of about 200 mm.

  In recent years, a highly convenient product has been put into practical use in which the bottom of the space for storing food is flat, the width dimension is 400 mm or more, which is relatively larger than the depth dimension, and two foods can be heated side by side. It has become. However, when two products are heated simultaneously, for example, when a frozen food and a food at room temperature are heated at the same time, the food at room temperature is completed faster. Therefore, in order to finish two items at the same time, only the colder food must be heated intensively.

  In such a case, a function capable of centrally heating only the local area is required instead of heating the entire inside of the heating chamber uniformly. As what implement | achieves this, what has enabled the concentrated heating by switching a some rotating antenna and controlling a stop position is proposed (for example, refer patent document 1).

  However, since it is costly to configure a plurality of antennas, it is expected to be realized with one rotating antenna. For example, conventionally, there is one in which one antenna is disposed at the center below the bottom of the heating chamber and is rotated (see, for example, Patent Document 2). Design the antenna with the directivity as high as possible from the center of the bottom of the heating chamber, and stop the rotating antenna toward the food on the low temperature side of the two items placed on the left and right to heat it intensively. There is a possibility that you can warm up two items at the same time.

However, in this case, there is a problem that efficiency is lowered when heating a single product that is usually placed in the center of the warehouse, not at the same time. A single product placed in the center of the chamber can be heated efficiently if there is no directivity outward from the center of the bottom surface of the heating chamber. This is because if the directivity of the outward direction is high from the antenna arranged at the center part under the bottom of the heating chamber, microwaves do not directly hit the food and are first radiated to the wall surface, so the loss on the wall surface increases. . The best thing for a single product in the center of the cabinet is to increase the directivity of the antenna toward the center of the cabinet in order to directly apply microwaves to food.
Japanese Patent No. 3617224 JP 2003-17239 A

In the above-described conventional configuration, one rotating antenna is used to heat two food items intensively at the low temperature side of two items placed on the left and right at the same time. Heating was not compatible. This is because, in order to heat two items at the same time, the directivity from the center of the bottom of the heating chamber should be as high as possible, whereas for efficient heating of a single item placed in the center of the chamber This is because the directivity toward the center of the cabinet should be high and cannot be compatible.

  The present invention has been made in view of the above-described conventional circumstances. When two items are placed on the left and right in the heating chamber, the directivity outward from the center of the bottom surface of the heating chamber is increased, and one of them is heated intensively. An object of the present invention is to provide a microwave heating apparatus capable of efficiently heating a single product by increasing the directivity toward the center of the cabinet when the single product is placed in the center.

The microwave heating apparatus of the present invention is for generating microwaves from a microwave generation means, a waveguide for transmitting microwaves, a heating chamber for storing an object to be heated, and the waveguide to the heating chamber. wherein comprising a horn antenna disposed substantially at the center of the heating chamber bottom, a driving unit for driving the horn antenna, and a control unit for controlling the direction of the horn antenna by controlling the driving unit to the horn antenna Is disposed on the conductor surface forming the bottom surface of the heating chamber, and has a wide surface facing the conductor surface, three narrow surfaces from the wide surface toward the conductor surface, and further, the three narrow surfaces A short-circuit surface extending in parallel with a gap between the conductor surface and the conductor surface, and the wide surface, the conductor surface, and the three narrow surfaces form a substantially horn antenna shape, and the wide surface Has a narrow surface And the narrow surface of the end portion facing the free end and an opening formed in a configuration having a curved portion from the end portion was cut into the inside of the openings in the wide face, the said opening direction The microwave directivity toward the curved portion is made compatible .

  The normal horn antenna has a smooth shape at the end that forms the opening and high directivity only in the direction of the opening, but this time, by having a bending part at the end of the opening of the horn antenna, The directivity in the opening direction and the directivity in the direction of the curved portion can be made compatible by the configuration of the present invention.

  Therefore, when two products are placed on the left and right (that is, when there is no food in the center), the directivity toward the opening direction of the horn antenna is dominant, and the directivity outward from the center of the bottom surface of the heating chamber. As a result, only one of the two products targeted can be heated intensively. On the other hand, when the single item is placed in the center (ie, when there is no food on the left and right), the directivity toward the curved portion of the horn antenna is dominant and the directivity toward the center of the chamber is increased. The single product can be heated efficiently.

  A normal horn antenna has a smooth shape at the end forming the opening and high directivity only in the direction of the opening, but this time, by having a bending part at the end of the opening of the horn antenna, Since it has been found that the directivity increases to some extent, the configuration of the present invention makes it possible to achieve both directivity in the opening direction and directivity in the bending portion direction. Therefore, when two items are placed on the left and right (that is, when there is no food in the center), the directivity toward the opening direction of the horn antenna is dominant, and the directivity is directed outward from the center of the bottom of the heating chamber. As a result, only one of the two products targeted can be heated intensively. On the other hand, when the single item is placed in the center (that is, when there is no food on the left and right), the directivity of the horn antenna toward the curved portion is dominant, and the directivity toward the center of the cabinet is high. Thus, a single product can be efficiently heated.

The microwave heating apparatus of the present invention is for generating microwaves from a microwave generation means, a waveguide for transmitting microwaves, a heating chamber for storing an object to be heated, and the waveguide to the heating chamber. wherein comprising a horn antenna disposed substantially at the center of the heating chamber bottom, a driving unit for driving the horn antenna, and a control unit for controlling the direction of the horn antenna by controlling the driving unit to the horn antenna Is disposed on the conductor surface forming the bottom surface of the heating chamber, and has a wide surface facing the conductor surface, three narrow surfaces from the wide surface toward the conductor surface, and further, the three narrow surfaces A short-circuit surface extending in parallel with a gap between the conductor surface and the conductor surface, and the wide surface, the conductor surface, and the three narrow surfaces form a substantially horn antenna shape, and the wide surface Has a narrow surface And the narrow surface of the end portion facing the free end and an opening formed in a configuration having a curved portion from the end portion was cut into the inside of the openings in the wide face, the said opening direction The microwave directivity toward the curved portion is made compatible .

  A normal horn antenna has a smooth shape at the end that forms the opening and high directivity only in the direction of the opening, but this time, by having a bending part at the end of the opening of the horn antenna, the directivity in the direction of the bending part Therefore, the configuration of the present invention makes it possible to achieve both directivity in the opening direction and directivity in the bending portion direction. Therefore, when two items are placed on the left and right (that is, when there is no food in the center), the directivity toward the opening direction of the horn antenna is dominant, and the directivity outward from the center of the bottom surface of the heating chamber is obtained. It becomes so high that only one of the two items can be heated intensively. On the other hand, when the single item is placed in the center (ie, when there is no food on the left and right), the directivity toward the curved portion of the horn antenna is dominant and the directivity toward the center of the chamber is increased. The single product can be heated efficiently.

In addition, this configuration makes it difficult for microwaves to pass between the conductor surface and the short-circuit surface, so it may be considered that the conductor surface and the short-circuit surface are generally conductive, and thus the wide surface, the conductor surface, and the three narrow surfaces. Thus, a substantially box shape and a direction without a narrow surface are formed as an opening, and it is possible to act as a horn antenna having directivity in the direction of the opening. Accordingly, it is possible to realize a horn antenna that can be driven independently of the bottom surface of the heating chamber with a simple configuration, and it is also possible to easily form a curved portion at an end portion that forms an opening.

Moreover, the directivity to a wide surface can be improved by this structure.

  In addition, as an aspect of the present invention, the microwave heating device described above includes a configuration in which a curved portion is provided at an end of a narrow surface that forms an opening.

  With this configuration, directivity to a narrow surface can be enhanced.

  In addition, as an embodiment of the present invention, the microwave heating device described above includes a configuration in which a curved portion is provided at the ends of two narrow surfaces that form an opening.

  With this configuration, directivity to two narrow surfaces can be increased.

  Further, as one embodiment of the present invention, in the above microwave heating apparatus, the curved portion is formed by having an inward cut at an end portion of a smooth shape typified by a straight line or an arc. Also included.

  With this configuration, the bending portion can be easily formed, the characteristics as the horn antenna can be changed, and as a result, the directivity toward the bending portion can be increased.

  In addition, as an aspect of the present invention, in the above microwave heating apparatus, the incision includes a shape in which the notch is cut inward from both ends of the end portion and the center of the end portion is extended outward from the notch.

  With this configuration, it is possible to increase the directivity toward the center side of the end portion of the bending portion.

  In addition, as one embodiment of the present invention, the above microwave heating device includes a configuration in which the center of the end portion has a substantially arc shape.

  With this configuration, it is possible to improve the directivity toward the arcuate side of the center of the curved portion, particularly the end portion.

  Further, an aspect of the present invention includes an aspect in which the radius R of the arc at the center of the end is set to 1/4 of the wavelength of the microwave.

  With this configuration, the directivity toward the center arc side of the end portion of the bending portion can be enhanced most.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited by this embodiment.

(Embodiment 1)
1 to 3 are diagrams showing a schematic configuration of a microwave oven that is a microwave heating apparatus according to an embodiment of the present invention. FIG. 1 is a cross-sectional view viewed from the right, and FIG. 2 is a flat cross-section viewed from above. 3 and 3 are configuration diagrams of the antenna.

  The microwave oven according to the present embodiment includes a magnetron 1 that is a typical microwave generation means, a waveguide 2 having a square cross-sectional shape for propagating microwaves radiated from the magnetron 1, and an upper portion of the waveguide 2. The connected heating chamber 3, the mounting table 4 that is fixed in the heating chamber 3 and places an object to be heated, the antenna space 5 that is formed below the mounting table 4 on the bottom surface of the heating chamber, and the heating chamber 3 A coupling hole 6 provided on the bottom surface at an approximately equal distance from the center of the antenna, an antenna 7 arranged on the mounting table 4 and rotatable about the coupling hole 6 are arranged, and further, as a drive unit for driving the antenna 7 The motor 8 and a control unit 9 that controls the rotation and stop of the motor 8 are provided.

  Moreover, the microwave oven of this embodiment is provided with the setting means 10 in the front of the heating chamber 4, and a user can select a cooking menu according to food or cooking content. Based on the selection result, the control unit 9 controls the magnetron 1 to generate and stop the microwave, and also controls the motor 8 to control the rotation and stop of the antenna 7. Thereby, the food mounted on the mounting table 4 can be heated and cooked.

  FIG. 3 shows a configuration diagram of the antenna. 3A is a plan view seen from above, FIG. 3B is a sectional view seen from the front, and FIG. 3C is a front view seen from the front.

  The antenna 7 is disposed on a conductor surface 11 that forms the bottom surface of the heating chamber 3, and has a wide surface 12 that faces the conductor surface 11, and three narrow surfaces that are bent from the wide surface 12 toward the conductor surface 11 side. 13, 14, 15, and the short-circuit surfaces 16, 17, which extend from the narrow surfaces 13, 14, 15 and extend in parallel through a slight gap (about 5 mm), though not contacting the conductor surface 11. 18 The space surrounded by the wide surface 12, the conductor surface 11, and the three narrow surfaces 13, 14, 15 constitutes a substantially horn antenna shape, and in FIGS. 2 and 3, toward the opening opened on the right side of the horn antenna. It is thought that microwaves are emitted.

In the conventional microwave oven, the horn antenna is also called a rotating waveguide, and has a configuration in which only one end of the waveguide is opened to radiate microwaves in the open direction. However, although the normally open portion, that is, the end portion forming the opening is straight or has a smooth shape such as an arc, the antenna 7 according to the present embodiment has a curved portion 19, 20, 21 at the end portion. It is. The curved portion 19 is configured at the end of the wide surface 12, and the curved portions 20 and 21 are configured at the respective end portions of the two narrow surfaces. By deliberately bending, unlike a normal horn antenna, it has a configuration having microwave directivity not only in the direction of the opening but also in the direction of the curved portion.

  In FIG. 3, as an image of a conventional end portion for reference, an end portion of the arc is indicated by a one-dot chain line 22 and a straight end portion is indicated by a two-dot chain line 23. In the antenna 7 of the present embodiment, the curved portion 19 is formed by a notch that is largely cut inwardly from the end portion (the left side in FIGS. 2 and 3). In addition, the notch is cut inwardly from both ends 24 and 25 of the end portion of the wide surface 12, and the center 26 of the end portion extends outwardly from the notch to form an arc shape, and the radius R of the arc is changed to the microwave. The wavelength is about 1/4 of the wavelength (about 120 mm in the case of a microwave oven), that is, the radius R is approximately 30 mm.

  The results of actual heating experiments using this configuration are shown below.

  First, as shown in FIG. 4, using two foods with different initial temperatures, the hamburger 27 (8 ° C., 100 g) that had been refrigerated was on the left, and the frozen rice 28 (−20 ° C., 150 g) was on the right. In order to be able to radiate microwaves to the right most, the antenna 7 can be heated very well when heated at 800 W output for 3 minutes with the opening side of the antenna 7 facing right (with the same orientation as in FIGS. 2 and 3). . At the end of heating, both the hamburger and the rice were sufficiently warmed, and the temperature was 60 ° C. or higher even at the warmest part of the rice. This is because the characteristics of the horn antenna are utilized, because it has high directivity from the center of the bottom of the heating chamber to the right, and one of the two items (frozen rice with a low initial temperature) can be heated intensively. it is conceivable that.

  Next, as shown in FIG. 5, the water 29 was arranged in the center, and the heating efficiency was evaluated. In 2008, an energy-saving top runner was also introduced into the microwave oven, and the evaluation scale is to conduct experiments with several representative water quantities and calculate the annual power consumption. Therefore, the annual power consumption was calculated according to this method. At this time, since the water 19 is in the center and the antenna 7 is also in the center, it is considered that the way the microwave hits the water 19 is not so close to the direction of the antenna 7. Therefore, this time, when the antenna 7 was always rotated and heated at an output of 800 W, the annual power consumption by the microwave was 52.5 kWh / year, equivalent to the energy-saving top at that time. This is considered to be because the directivity toward the center of the cabinet can be increased by suppressing the characteristics of the horn antenna, and the center single item can be heated efficiently.

  Here, the results of FIG. 4 and FIG. 5 seem to contradict each other from the conventional viewpoint. With a conventional horn antenna, it is possible to aim at one of the two products with a high directivity outward from the center of the bottom surface of the heating chamber as shown in FIG. 4, but as shown in FIG. The single product cannot be efficiently heated, resulting in poor energy saving performance. On the other hand, when considering an antenna having high directivity upward from the center of the bottom of the heating chamber (for example, a slot antenna), the energy saving performance of the single product at the center is improved, but the center of the heating chamber is outward from the center. Directivity disappears and one of the two items cannot be aimed at.

  However, in the present embodiment, both directivity from the center of the bottom surface of the heating chamber to the outward direction with two products and efficient heating with a single product at the center can be achieved. The reason for this is considered to be largely due to the configuration of the antenna 7 and the position of the object to be heated (two foods in FIG. 4 and water in FIG. 5). The configuration of the antenna 7 is a configuration having a curved portion at an end portion that forms the opening of the horn antenna, and having a microwave directivity not only in the direction of the opening but also in the direction of the curved portion.

A normal horn antenna has a smooth shape at the end forming the opening and high directivity only in the direction of the opening, but this time, it has curved portions 19, 20, 21 at the end of the opening of the horn antenna. Thus, since it has been found that the directivity in the direction of the curved portion is increased to some extent, the configuration of the present invention makes it possible to achieve both the directivity in the opening direction and the directivity in the direction of the curved portion. Rather than always having both directivities, this is a state where the balance is delicately maintained, and the balance is broken by the distribution of the dielectric constant in the vicinity of the antenna, so that either directivity changes to be dominant. That is. The dielectric constant of air is small (about 1), and the dielectric constant of water contained in water or food is large (about 80), and the dielectric constant distribution near the antenna depends on where the heated object is placed. Changes.

  For example, in FIG. 4, since there are hamburger 27 and rice 28, the dielectric constant on the peripheral side is high, and in the center where there is only air, the dielectric constant is low. On the other hand, in FIG. 5, the dielectric constant on the peripheral side where there is only air is low, and the dielectric constant is high in the center where the water 29 is present. For this reason, with respect to the directivity in the opening direction and the directivity in the direction of the curved portion, which is balanced when the dielectric constant distribution is uniform, in FIG. 4, the directivity in the opening direction (rightward in the figure) is dominant. In FIG. 5, directivity in the direction of the bending portion 19 (upward in the figure) is dominant. That is, when the dielectric constant is not uniform, the directivity characteristic located closest to the place where the dielectric constant is high is considered to be dominant.

  4 and 5 show this as an image. In FIG. 4, the directivity in the opening direction is high and the directivity in the direction of the curved portion 19 is low, that is, the microwave (arrow line 30) radiated outward from the center is strong and radiated upward from the curved portion 19. The microwave (arrow line 31) is weakened. On the other hand, in FIG. 5, the directivity in the opening direction is low and the directivity in the direction of the curved portion 19 is high, that is, the microwave (arrow line 32) radiated outward from the center is weak and radiates upward from the curved portion 19. The microwave (arrow line 33) is strengthened.

  The effects in the embodiment of the microwave heating apparatus of the present invention will be summarized.

  Magnetron 1 (microwave generating means), a waveguide 2 for transmitting microwaves, a heating chamber 3 for storing an object to be heated, and a heating chamber for radiating microwaves from the waveguide 2 to the heating chamber 3 A horn antenna 7 disposed substantially at the center of the bottom surface, a drive unit 8 that drives the horn antenna 7, and a control unit 9 that controls the drive unit 8 to control the orientation of the horn antenna 7. It is configured to have the curved portions 19, 20, and 21 at the end portion that forms the opening, and has a microwave directivity in the direction of the curved portion as well as the direction of the opening.

  A normal horn antenna has a smooth shape at the end forming the opening and high directivity only in the direction of the opening, but this time, by having the curved portions 19, 20, 21 at the end of the opening of the horn antenna, Since it has been found that the directivity in the part direction increases to some extent, the configuration of the present invention makes it possible to achieve both the directivity in the opening direction and the directivity in the bending part direction.

  In particular, when the dielectric constant in the vicinity of the antenna 7 is non-uniform, it can be seen that the directivity characteristic located closest to the place where the dielectric constant is high is dominant. When there is no food in the center), the directivity in the opening direction of the horn antenna 7 is dominant, and the directivity outward from the center of the bottom of the heating chamber is increased, and one of the two products aimed Can only be heated intensively. On the other hand, when the single item is placed in the center (ie, when there is no food on the left and right), the directivity toward the curved portion of the horn antenna is dominant and the directivity toward the center of the chamber is increased. The single product can be heated efficiently.

  The antenna 7 is disposed on the conductor surface 11 that forms the bottom surface of the heating chamber, and has a wide surface 12 that faces the conductor surface 11, and at least three narrow surfaces 13 and 14 that extend from the wide surface 12 toward the conductor surface 11. , 15 and short-circuit surfaces 16, 17, 18 extending in parallel with a gap between the narrow surfaces 13, 14, 15 and the conductor surface 11, and the wide surface 12, the conductor surface 11, The narrow surfaces 13, 14, and 15 form a substantially horn antenna shape, and have curved portions 19, 20, and 21 at the end portions that form the openings of the horn antenna.

  This configuration makes it difficult for microwaves to pass between the conductor surface 11 and the short-circuit surfaces 16, 17, 18. Therefore, it may be considered that the conductor surface 11 and the short-circuit surfaces 16, 17, 18 are generally conducted. The wide surface 12, the conductor surface 11, and the three narrow surfaces 13, 14, 15 are substantially box-shaped and the shape without the narrow surfaces 13, 14, 15 (FIGS. 2 and 3) is open as an opening. Therefore, it becomes possible to act as a horn antenna having directivity in the direction of the opening. Therefore, a horn antenna that can be driven independently of the bottom surface of the heating chamber can be realized with a simple configuration, and the curved portions 19, 20, and 21 can be easily formed at the end portion that forms the opening.

  Moreover, it is set as the structure which has the curved part 19 in the edge part of the wide surface 12 which forms opening. The wide surface 12 is the surface closest to the object to be heated. Therefore, the wide surface 12 is easily affected by the dielectric constant distribution of the object to be heated, and is the position where microwaves can be radiated from the shortest distance. Depending on the design of the bending portion 19, the directivity can be affected most effectively.

  Moreover, it is set as the structure which has the curved parts 20 and 21 in the edge part of the narrow surfaces 13 and 14 which form opening. The directivity to the narrow surfaces 13 and 14 can be enhanced. The bending portions 20 and 21 are slightly separated from the object to be heated compared to the bending portion 19, so the influence on directivity is small. However, the bending portions 20 and 21 have a certain effect compared to the state where the bending portions 20 and 21 are not provided. is there.

  Moreover, it is set as the structure which has the curved parts 20 and 21 in the edge part of both the two narrow surfaces 13 and 14 which form opening. The effect on directivity can be increased compared to the case where only one is provided. In particular, when configured in a target positional relationship as in the present embodiment, uneven unevenness hardly occurs and the heating distribution in the object to be heated is good.

  Moreover, it is set as the structure which has a curved part in both the edge part of the wide surface which forms an opening, and the edge part of a narrow surface. This can also increase the influence on directivity as compared with the case where the wide surface or the narrow surface is used alone.

  In addition, the curved portions 19, 20, and 21 are provided at the ends of the wide surface 12 and the two narrow surfaces 13 and 14 that form the opening. As a result, the curved portion is formed on all workable surfaces except the conductor surface among the four surfaces forming the opening, so that the influence on directivity can be enhanced most.

  In addition, the curved portion 19 has a cut from the end portion (one-dot chain line 22 or two-dot chain line 23) of a smooth shape typified by a straight line or an arc to the inside (left side in FIGS. 2 and 3). The structure is formed. With this configuration, the bending portion 19 can be easily formed, and the characteristics of the horn antenna can be changed. As a result, the directivity toward the bending portion 19 can be enhanced.

  In addition, this cut is cut inward from both ends 24 and 25 of the end portion of the wide surface 12, and the center 26 of the end portion has a shape that extends outward from the cut. With this configuration, it is possible to improve the directivity of the bending portion 19 toward the center 26 side of the end portion.

  Further, the center 26 of the end portion has a substantially arc shape. With this configuration, it is possible to increase the directivity of the bending portion 19 toward the arc side of the center 26 of the end portion in particular.

  Further, the radius R of the circular arc is set to ¼ of the wavelength of the microwave (about 120 mm in the case of a microwave oven), that is, approximately the radius R = 30 mm. With this configuration, directivity toward the arc side of the center 26 at the end of the bending portion 19 can be enhanced most. In this case, the arc at the center 26 at the end has a high effect of concentrating microwaves particularly in the vertically upward direction, and thus may function as a patch antenna.

(Embodiment 2)
FIG. 6 shows a configuration diagram of the antenna. FIG. 6 (a) is a plan view seen from above, FIG. 6 (b) is a sectional view seen from the front, and FIG. 6 (c) is a front view seen from the front. is there.

  The antenna 34 has a wide surface 35, three narrow surfaces 36, 37, 38 that are bent from the wide surface 35, and short-circuit surfaces 39, 40, 41 that extend from the narrow surfaces 36, 37, 38. A space surrounded by the wide surface 35, a conductor surface (not shown), and the three narrow surfaces 36, 37, and 38 forms a substantially horn antenna shape. In FIG. It is thought that waves are emitted.

  However, the antenna 34 according to the present embodiment has a curved portion 42 at the end of the wide surface 35, and the ends of the narrow surfaces 36 and 37 are not curved. Unlike the normal horn antenna, the curved portion 42 is configured to have a microwave directivity in the direction of the curved portion as well as the direction of the opening. In FIG. 6, as an image of the conventional end portion for reference, the end portion of the arc is indicated by a one-dot chain line 43.

(Embodiment 3)
FIG. 7 shows a configuration diagram of the antenna. FIG. 7A is a view seen from above, FIG. 7B is a sectional view seen from the front, and FIG. 7C is a front view seen from the front. .

The antenna 44 includes a wide surface 45, three narrow surfaces 46, 47, 48 bent from the wide surface 45, and short-circuit surfaces 49, 50, 51 extending from the narrow surfaces 46, 47, 48. A space surrounded by the wide surface 45, a conductor surface (not shown), and the three narrow surfaces 46, 47, and 48 constitutes a substantially horn antenna shape . In FIG. It is thought that waves are emitted. However, the antenna 44 of the present embodiment has a curved portion 52 in which the end of the narrow surface 46 is cut, and the end portions of the wide surface 45 and the narrow surface 47 are not curved. Unlike the normal horn antenna, the bending portion 52 has a configuration having microwave directivity in the direction of the bending portion as well as the direction of the opening.

  The embodiment of the present invention has been described above. Finally, the performance is compared with that of the prior art. A hole is formed in the first embodiment, a conventional horn type antenna (also referred to as a rotating waveguide, see FIG. 8), another conventional slot antenna (see FIG. 9), and a horn type antenna. And an antenna (see FIG. 10) that is fused with a slot antenna. As described above, the evaluated performance was as follows. First, two items of refrigerated hamburger and frozen rice were heated at the same time, and the lowest temperature of rice immediately after the end of heating was measured. Second, the annual power consumption by microwave was measured. As described above, it is desirable that the minimum temperature of rice is as high as possible, and that the annual power consumption is as small as possible.

  First, as a result of the first embodiment, the minimum temperature of rice was good at 60 ° C., and the annual power consumption was good at 52.5 kWh / year.

  Next, as a result of the conventional horn type antenna (rotating waveguide), the minimum temperature of rice was as good as 60 ° C., but the annual power consumption was quite bad as 59 kWh / year. The reason why the annual power consumption is bad will be described with reference to the drawings. 8A is a view of the horn antenna 53 as viewed from above, and FIG. 8B is a cross-sectional view as viewed from the front. Since it is a horn type antenna, the microwave (arrow 54) radiated rightward from the center is strong, and there is no microwave radiated upward. Therefore, most of the microwaves (arrow line 55) first hit the wall surface 56 before hitting the water 29 and cause wall surface loss, so it is considered that the heating efficiency is inevitably deteriorated.

  Next, the results of other prior art slot antennas show that the minimum temperature of rice is quite low at 5 ° C (though hamburger is carbonized by overheating), while the annual power consumption is good at 52.5 kWh / year Met. The reason why the temperature of the rice is low will be described with reference to the drawings. 9A is a plan view of the slot antenna 57 as viewed from above, and FIG. 9B is a cross-sectional view as viewed from the front. Since it is a slot antenna, the microwave radiated upward from the hole 58 (arrow line 59) is strong, and there is no microwave radiated rightward. Accordingly, it is considered that a considerable amount of microwaves (arrow line 60) hits the hamburger 27 that is not desired to be hit and is absorbed, and the soldering iron cannot be heated in a concentrated manner.

  Furthermore, the result of the antenna 61 (see FIG. 10) in which a hole is formed in the conventional horn type antenna and fused with the slot antenna, the characteristics seem to change extremely depending on the size of the hole 62, and the hole 62 is small. And the performance of the conventional horn type antenna, and if the hole 62 is large, the performance is the same as that of the conventional slot antenna, the two cannot be balanced well, the minimum temperature of rice and the annual power consumption Could not satisfy both.

  Therefore, it has been found that the embodiment of the present invention can realize extremely superior performance that cannot be achieved by the combination of the prior art and the prior art.

  Although various embodiments of the present invention have been described above, the present invention is not limited to the matters shown in the above-described embodiments, and those skilled in the art can make modifications and applications based on the description and well-known techniques. This is also the scope of the present invention, and is included in the scope for which protection is sought.

  Since the microwave heating device of the present invention has been found to have a certain degree of directivity in the direction of the curved portion by having the curved portion at the end of the opening of the horn antenna, the directivity in the direction of the opening and the direction of the curved portion Of microwave ovens, microwave ovens, heating of various dielectrics, defrosters, semiconductor devices using microwaves, drying devices, etc. It is useful for heating devices in industrial fields, ceramics heating, sintering, biochemical reactions, and the like.

Cross-sectional block diagram which looked at the microwave heating apparatus in Embodiment 1 of this invention from the right Cross-sectional configuration view of the microwave heating device viewed from above (A) Plan view of antenna viewed from above (b) Cross section of antenna viewed from front (c) Front view of antenna viewed from front Cross-sectional configuration view of the microwave heating device when there are two items to be heated from the front Cross-sectional configuration view of the microwave heating device from the front when the object to be heated is a single item (A) The top view which looked at the antenna in Embodiment 2 of this invention from the top (b) The sectional view which looked at the antenna from the front (c) The front view which looked at the antenna from the front (A) The top view which looked at the antenna in Embodiment 3 of this invention from the top (b) The sectional view which looked at the antenna from the front (c) The front view which looked at the antenna from the front (A) The top view which looked at the horn type | mold antenna of the conventional microwave heating apparatus from the top (b) The cross-sectional block diagram which looked at the microwave heating apparatus in case a to-be-heated object is a single item from the front (A) The top view which looked at the slot antenna of the conventional microwave heating apparatus from the top (b) The cross-sectional block diagram which looked at the microwave heating apparatus in case the to-be-heated object is two goods from the front Top view of an antenna that combines a conventional horn type antenna and slot antenna from above

1 Magnetron (microwave generation means)
2 Waveguide 3 Heating chamber 7, 34, 44 Antenna (horn antenna)
8 Motor (drive unit)
9 Control section 11 Conductor surface 12, 35, 45 Wide surface 13, 14, 15, 36, 37, 38, 46, 47, 48 Narrow surface 16, 17, 18, 39, 40, 41, 49, 50, 51 Short-circuit surface 19, 20, 21, 42, 52 Curved portion 24, 25 Both ends of end portion 26 Center of end portion 27 Hamburger (object to be heated)
28 Rice (to be heated)
29 Water (object to be heated)

Claims (7)

A microwave generating means, a waveguide for transmitting microwaves, a heating chamber for storing an object to be heated, and approximately at the center of the bottom of the heating chamber for radiating microwaves from the waveguide to the heating chamber A horn antenna disposed; a drive unit that drives the horn antenna; and a control unit that controls the drive unit to control the direction of the horn antenna,
The horn antenna is disposed on a conductor surface forming the bottom surface of the heating chamber, and has a wide surface facing the conductor surface, three narrow surfaces from the wide surface toward the conductor surface, and the three A short-circuit surface extending in parallel with a gap between the narrow surface and the conductor surface is provided, and the wide surface, the conductor surface, and the three narrow surfaces form a substantially horn antenna shape. An opening formed by an end portion of the wide surface that does not have a narrow surface and an end portion of the narrow surface facing the wide surface, and a curved portion cut inwardly from an end portion of the wide surface in the opening. A microwave heating apparatus configured to have both microwave directivity in the opening direction and the bending portion direction. Microwave heating apparatus according to claim 1, wherein where the structure has a curved portion at an end portion of the narrow surfaces forming the opening. The microwave heating device according to claim 1 , wherein the microwave heating device has a curved portion at the ends of two narrow surfaces forming the opening. Curved part, the microwave heating device according to claim 1, wherein the configuration and which is formed by having the notch in the inward end of the smooth shape typified line or an arc. The microwave heating device according to claim 4 , wherein the notch is cut inward from both ends of the end portion and the center of the end portion extends outward from the notch. The microwave heating device according to claim 5 , wherein the center of the end portion has a substantially arc shape. The microwave heating apparatus according to claim 6 , wherein R of the arc at the center of the end portion is set to ¼ of the wavelength of the microwave.