JP2007227134A - Microwave heating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently heat by matching with impedance on a side of a magnetron 2 even when impedance on a load side greatly changes depending on a loading amount. <P>SOLUTION: The microwave heating device is structured so as to include a first control pattern for controlling a position of an antenna 6 in order to match the impedance on the side of the magnetron 2 and the impedance on the load side when food 13 is a small load, and a second control pattern for controlling the position of the antenna 6 in order to match the impedance on the side of the magnetron 2 and the impedance on the load side when the food 13 is a large load. Thereby, when the food 13 is the small load, the food can be efficiently heated by the first control pattern, and when the food 13 is the large load, the food 13 can be efficiently heated by the second control pattern. Thus, the food 13 can be efficiently heated by a simple and safe structure to control the position of the antenna 6, even when an amount of the food 13 is changed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

  The microwave oven, which is a typical microwave heating device, can directly heat food, which is a typical object to be heated, and is an indispensable device in daily life with the simplicity that does not require the preparation of a pan or pot. ing. In addition, in order to uniformly heat food in a microwave oven, a turntable method in which the food itself is rotated has been the mainstream. However, in this case, the bottom of the heating chamber is used to fit a circular turntable. I had to design it in a nearly square shape. However, in recent years, a product having a heating chamber shape with a wide width has been put into practical use so that it can be heated even if a plurality of tableware are arranged in order to improve convenience. This is called a rotating antenna system rather than a turntable. The food is not moved, and is heated uniformly by rotating an antenna that can change the direction of the microwave below the food.

  In addition, the microwave oven has a characteristic that the heating efficiency varies depending on the impedance matching state, which is unique to the high frequency. The microwave radiated from the magnetron, which is a typical microwave generation means, is radiated most efficiently if the impedance on the magnetron side and the impedance on the load side match (match), whereas if the impedance of the two shifts It is known that the amount returning to the magnetron side (amount of reflection) increases, the amount radiated to the load side (incident amount) decreases, and the heating efficiency decreases. The impedance on the magnetron side may be considered constant at all times, but the impedance on the load side changes depending on the weight, shape, material, temperature, location, antenna position, etc. of the food. difficult.

  Generally, it is stipulated that the high frequency output of a microwave oven is calculated based on a temperature rise of 2 liters of water, so that the impedance in 2 liters of water (= 2 kg) is designed to best match. . As a result, when heating food (mass load) of a quantity close to 2 liters of water, it can be heated efficiently, but for example, a full glass of water (about 0.2 liters = 200 g) is a 1/10 small load. Therefore, the alignment state becomes worse. In general, it is estimated that the usage frequency of the microwave oven is much higher in the case of the small load than in the case of the large load, and about 90% of the whole is used for heating foods of 200 g or less. Therefore, it is considered that efficient heating of a small load that is frequently used leads to energy saving.

Therefore, in order to optimize the matching state for all foods, in a turntable type microwave oven, there is a directional coupler that directly detects microwaves in the waveguide, and impedance depending on the stop position in the waveguide. There is a special matching antenna that changes the frequency of the antenna, and a directional coupler determines the ratio of the amount of incident microwaves and the amount of reflection, and controls the position of the matching antenna to a position where reflection is minimized (for example, patents). Reference 1).
JP-A-7-78681

However, the conventional configuration requires a configuration in which microwaves are directly detected by a directional coupler or a dedicated matching antenna, which increases the number of parts and makes the configuration complicated or increases the price. . Further, regarding the directional coupler, a microwave is drawn out by making a hole in the wall surface of the waveguide where the electric field is strongest, and a shield configuration that does not leak to the outside and a configuration for noise reduction are also required. The matching antenna is also disposed in the waveguide, and it is necessary to ensure reliability so as not to cause a spark between the matching antenna and the adjacent waveguide wall surface at any angle. In order to improve the reliability, it is conceivable to increase the height of the waveguide. However, in this case, there is a problem that the overall configuration becomes large, and the impedance may not change much.

  In addition, the conventional configuration is a turntable method, and no specific method has been found as to how it should be realized by a recent rotating antenna method.

  The present invention solves the above-described conventional problems, and an object thereof is to provide a microwave heating apparatus that can efficiently heat even if the amount of an object to be heated is changed with a simple and safe configuration of a rotating antenna system. To do.

  In order to solve the above-described conventional problems, a microwave heating apparatus according to the present invention includes a heating chamber that accommodates an object to be heated, a microwave generation unit that generates a microwave, and a microwave generated by the microwave generation unit. A waveguide that guides the heating chamber to the heating chamber, an antenna that can change the direction of the microwave radiated from the waveguide into the heating chamber, and a control that controls the direction of the microwave by controlling the position of the antenna And a first control pattern for controlling the position of the antenna so as to match the impedance on the microwave generating means side and the impedance on the load side when the object to be heated is a small load. When the object to be heated is a large load, the position of the antenna is controlled so that the impedance on the microwave generating means side and the impedance on the load side are matched. It is configured to have a second control pattern.

  This allows efficient heating with the first control pattern when the object to be heated has a small load, and efficient heating with the second control pattern when the object to be heated has a large load. Therefore, it is possible to efficiently heat even if the amount of the object to be heated is changed with a simple and safe configuration of controlling the position of the antenna.

  According to the microwave heating apparatus of the present invention, when the object to be heated is a small load, the first control pattern can be efficiently heated, and when the object to be heated is a large load, the second control is performed. Since the pattern can be efficiently heated, the simple and safe configuration of controlling the position of the antenna enables efficient heating even when the amount of the object to be heated is changed.

  A microwave heating apparatus according to a first aspect of the present invention includes a heating chamber that houses an object to be heated, a microwave generating unit that generates a microwave, and a waveguide that guides the microwave generated by the microwave generating unit to the heating chamber. A control unit for controlling the direction of the microwave by controlling the position of the antenna, and an antenna capable of changing the direction of the microwave radiated from the waveguide into the heating chamber. Is a first control pattern for controlling the position of the antenna so that the impedance on the microwave generating means side and the impedance on the load side are matched when the object to be heated is a small load, and the object to be heated is a large load A second control pattern for controlling the position of the antenna so that the impedance on the microwave generating means side and the impedance on the load side are matched. It is set to.

  This allows efficient heating with the first control pattern when the object to be heated has a small load, and efficient heating with the second control pattern when the object to be heated has a large load. Therefore, it is possible to efficiently heat even if the amount of the object to be heated is changed with a simple and safe configuration of controlling the position of the antenna.

  The microwave heating apparatus according to the second invention, in the first invention, in particular, is configured such that the control means controls so as to heat with the second control pattern after heating with the first control pattern.

  As a result, the heating time of the small load is shorter than that of the large load, so even if you do not know whether the object to be heated is a small load or a large load, the heating is first started with the first control pattern that efficiently heats the small load. In this case, it is possible to reliably and efficiently heat a small load that is frequently used. On the other hand, if the object to be heated has a large load, it will start with inefficient heating at first, but the second control pattern will efficiently heat the large load from the timing when the heating of the small load ends. By switching, since the subsequent time can be efficiently heated, the heating can obviously be performed more efficiently than in the case of heating with the first control pattern until the end.

  A microwave heating apparatus according to a third aspect of the invention has weight detection means for detecting the weight of the object to be heated, particularly in the first or second invention, and the control means is for the object to be heated detected by the weight detection means. The control pattern is switched according to the weight.

  As a result, when the weight of the object to be heated is light, it can be seen that the load is small, so it can be surely heated efficiently with the first control pattern. The pattern can be heated efficiently.

  A microwave heating apparatus according to a fourth aspect of the invention includes the shape detection means for detecting the shape of the object to be heated, particularly in the first or second aspect of the invention, and the control means The control pattern is switched according to the shape.

  As a result, when the shape of the object to be heated is small, it can be understood that the load is almost a small amount, so that the first control pattern can be efficiently heated, and when the shape is large, the load is almost a large amount. It can be heated efficiently.

  A microwave heating apparatus according to a fifth aspect of the invention includes a temperature detection means for detecting the temperature of the object to be heated, particularly in the first or second aspect of the invention, and the control means is for the object to be heated detected by the temperature detection means. The control pattern is switched according to the temperature.

  As a result, when the temperature rise of the object to be heated is fast, it can be seen that the load is almost small, so it can be heated efficiently with the first control pattern. The pattern can be heated efficiently.

  The microwave heating apparatus according to a sixth aspect of the present invention is the microwave heater according to the first aspect of the invention, in which the first control pattern is compared with the second control pattern and the microwave is placed at the center of the mounting table on which the object to be heated is placed. It is configured to concentrate.

  As a result, the small load has a small shape and is likely to be placed near the center of the mounting table, and can be efficiently heated by concentrating the microwave on the center of the mounting table using the first control pattern. By the way, the large load has a large shape and can be placed not only near the center of the mounting table but also across the end, so in the second control pattern the microwave is as central as the first control pattern. There is no need to concentrate.

  In the microwave heating apparatus of the seventh invention, particularly in the sixth invention, the first control pattern is configured to bring the antenna closer to the center of the mounting table as compared to the second control pattern.

  As a result, microwaves radiated from the vicinity of the antenna generally try to spread around, but the first control pattern ensures that the antenna is brought closer to the center of the mounting table before the microwave diffuses. Microwaves can be concentrated on. As a result, a small amount of load placed in the center of the mounting table is directly irradiated and absorbed before the microwaves are diffused, and can be efficiently heated.

  The microwave heating apparatus according to an eighth invention is the microwave heater according to the sixth invention, in particular, in the sixth invention, the at least two antennas are arranged substantially symmetrically when viewed from the center of the bottom surface of the heating chamber, and the first control pattern and the second control pattern In comparison, the antennas having strong directivity face each other.

  Thus, the microwaves radiated from the respective antennas by the first control pattern are directed toward the center of the bottom surface of the heating chamber, and the microwaves can be concentrated at the center of the mounting table.

  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 block diagrams of a microwave oven as a typical microwave heating apparatus according to the present invention. FIG. 1 is a cross-sectional view seen from the right, FIG. 2 is a cross-sectional view seen from the top, and FIG. It is sectional drawing of a part.

  This embodiment is a microwave oven using a rotating antenna system, and is generated from a magnetron 2 which is a typical microwave generating means for supplying microwaves from below the mounting table 1 on which food is placed. A waveguide 5 that guides microwaves into the heating chamber 3 through a coupling hole 4 provided on the bottom surface of the heating chamber 3, and an antenna 6 that is disposed on the coupling hole 4 and is rotatable about the coupling hole 4 are provided. The antenna 6 mainly has a radiation directivity in the direction from the coupling hole 4 to the opening 7 because the amount of microwaves radiated from the opening 7 increases.

  Then, the driving shaft 9 of the motor 8 is engaged with the coupling shaft 10 of the antenna 6, and the antenna 6 is rotated to change the radiation direction of the microwave so as to make the heating uniform. The vertical driving means 11 moves the antenna 6 up and down, and the protruding length of the coupling shaft 10 protruding into the waveguide 5 changes depending on the position of the antenna 6, so that the impedance on the magnetron side and the impedance on the load side are matched. Can be adjusted.

  The weight detection means 12 detects the weight of the food table 13 which is a typical heated object placed on the mounting table 1 and the mounting table 1, and detects the difference from the known weight of the mounting table 1 in advance. By calculating, the weight of the food 13 can be calculated.

  The control unit 14 controls the magnetron 2 based on the setting information from the setting unit 15 for setting the menu and the heating time by the user, the weight information from the weight detection unit 12, and the like, thereby generating and stopping the microwave. Control, control of the motor 8 to control the rotation and stop of the antenna 6, and control of the vertical drive means 11 to control the vertical movement and stop of the antenna 6.

  Next, the control pattern will be described.

  For example, when auto is set by the setting means 15, the control means calculates the weight of the food 13 based on the weight information from the weight detection means 12 when the food 13 is arranged, and in accordance with the food weight in advance. The magnetron 2, the motor 8, and the vertical drive means 11 are controlled by a predetermined control pattern.

  First, when the food 13 has a small load (for example, 300 g or less), even if the antenna 6 is in the lower position (position A in FIG. 3), the vertical drive means 11 moves the antenna 6 to the upper position (position B in FIG. 3). ) To control and heat. (First control pattern). This is ensured by designing the antenna 6 so that the impedance on the magnetron 2 side matches the impedance on the load side with a small load of 300 g or less when the antenna 6 is in the upper position (position B in FIG. 3). Can be matched.

  Here, impedance matching will be described with reference to FIG. The characteristics of the magnetron 2 are generally given by a characteristic diagram of a polar coordinate system as shown in FIG. This indicates the reflection characteristics of the magnetron 2 (generally called S11), indicating that the impedance is matched toward the center of the circle and is not reflected toward the magnetron 2, and the impedance is matched toward the circumference of the circle. This indicates that there are many reflections on the magnetron 2.

  If there is little reflection, it will be easy to be supplied to a load, and if there is much reflection, it will be difficult to be supplied to a load. Eventually, the output supplied from the magnetron 2 to the load changes depending on the impedance on the load side. If this is expressed as an iso-output line, the iso-output lines C, D, E, F, G... It is expressed in Therefore, in the present embodiment, when a small load (for example, 300 g or less) is arranged and the antenna 6 is set to the upper position (position B in FIG. 3), it is designed to enter the hatched area H in the equal output line C. By doing so, it is possible to maximize the output that enters the small load, so that heating can be performed most efficiently. At this time, if the position of the antenna 6 is lowered to the lower position (position A in FIG. 3) with the same small amount of load, the alignment state is lost and the area changes to, for example, the hatched area I.

  Next, when the food 13 has a large load (for example, 1000 g or more), the vertical driving means 11 controls the antenna 6 to a lower position (position A in FIG. 3) to heat it. (Second control pattern). This is achieved by designing the antenna 6 so that the impedance on the magnetron 2 side matches the impedance on the load side due to a large load of 1000 g or more when the antenna 6 is in the lower position (position A in FIG. 3). Can be matched.

  Incidentally, when the food 13 has a medium load (for example, 200 g to 1000 g), it is conceivable that the vertical driving means 11 controls the antenna 6 to a position between the lower side and the upper side. Or you may make it reciprocate between a lower position and an upper position.

  As described above, in the present embodiment, when the food 13 is in a small load, the first control pattern for controlling the position of the antenna 6 so that the impedance on the magnetron 2 side and the impedance on the load side are matched, and the food 13 has a large load. In this case, the second control pattern is used to control the position of the antenna 6 so that the impedance on the magnetron 2 side and the impedance on the load side are matched.

  Thereby, when the food 13 is a small load, it can be heated efficiently with the first control pattern, and when the food 13 is a large load, it can be efficiently heated with the second control pattern. Therefore, with the simple and safe configuration of controlling the position of the antenna 6, even if the amount of the food 13 is changed, it can be efficiently heated.

  Moreover, it has the weight detection means 12 which detects the weight of the foodstuff 13, and the control means 15 is set as the structure which switches a control pattern with the weight of the foodstuff 13 which the weight detection means 15 detected.

As a result, when the weight of the food 13 is light, it is known that the load is small, so that it can be surely efficiently heated by the first control pattern. Can be efficiently heated.

  In addition, the first control pattern is configured to concentrate microwaves at the center of the mounting table on which the food 13 is mounted, as compared with the second control pattern. The point is the direction of the microwave indicated by the arrows 16, 17, and 18 in FIGS. Microwaves are radiated from the coupling hole 4 into the heating chamber 3, and among them, a large proportion of radiation is radiated through the opening 7, so that the antenna 6 is moved to the upper position (in FIG. 3) as in the first control pattern. When arranged at the position B), the microwave is radiated in the direction as indicated by the arrow 17, and when the antenna 6 is arranged at the lower position (position A in FIG. 3) as in the second control pattern, the arrow 18. It is considered that microwaves are radiated in such a direction. Therefore, generally, when the coupling shaft 10 is disposed at the center of the bottom surface of the heating chamber 3, the arrow line 17 is closer to the center of the mounting table 1 than the arrow line 18, that is, the first control pattern is more. Microwaves can be concentrated in the center of the mounting table.

  As a result, the small load has a small shape and thus is likely to be placed near the center of the mounting table 1, and the microwave can be efficiently heated by concentrating the microwave on the center of the mounting table 1 with the first control pattern. it can. By the way, the large load has a large shape and may be placed not only near the center of the mounting table 1 but also across the end. Therefore, in the second control pattern, the first control pattern is as small as the center. There is no need to concentrate the waves.

  In addition, the first control pattern is configured to bring the antenna 6 closer to the center of the mounting table 1 than the second control pattern.

  As a result, in general, microwaves radiated from the vicinity of the antenna 6 tend to diffuse to the surroundings, but by placing the antenna 6 close to the center of the mounting table 1 with the first control pattern, the microwaves are reliably mounted before spreading. Microwaves can be concentrated in the center of the table 1. As a result, a small amount of load placed in the center of the mounting table 1 is directly irradiated and absorbed before the microwaves are diffused, and can be efficiently heated.

(Embodiment 2)
5 to 7 are configuration diagrams of the microwave oven, FIG. 5 is a cross-sectional view seen from the right, and FIGS. 6 and 7 are cross-sectional views seen from the top. In the present embodiment, an example in which a rotating waveguide type antenna is used as the two antennas 19 in the horizontal direction of the horizontally long heating chamber 3 has been described. However, one magnetron 2 is provided, the waveguide 5 is branched in a T shape, and the antennas 19 are arranged symmetrically on both sides.

  The antenna 19 has bent portions 20 and 21 which are bent on two sides facing each other with the coupling shaft 10 and a bent portion 22 which is bent on the other side, and an open portion is formed only on the tip 23 side which is not bent. Thus, microwaves with strong directivity can be radiated mainly to the tip 23 side. The two antennas 19 may be provided with one motor 8 individually, but the two antennas 19 may be rotated by one motor 8 and a gear.

  In any case, by appropriately controlling whether the antenna 19 is rotated or stopped at a specific position, it is possible to change the radiation direction of the microwave and make the heating uniform. Further, since the antenna 19 is a rotating waveguide, the directivity in the horizontal direction is relatively strong unlike the antenna 6 of the first embodiment, and the rotation center is not in the center of the heating chamber. The impedance is considered to change greatly depending on the direction of 19. Therefore, it is considered that impedance matching according to the load amount can be easily performed by controlling the direction of the antenna 19.

The shape detecting means 24 detects the shape of the food. Based on the setting information from the setting means 15 and the shape information from the shape detection means 24, the control means 14 controls the magnetron 2 to control the generation and stoppage of the microwave, or the motor 8 to The rotation and stop of the antenna 19 are controlled.

  Next, the control pattern will be described.

For example, when the setting means 15 sets warming auto, the control means calculates the volume of the food based on the information from the shape detection means 24 when the food is placed, and is determined in advance according to the volume of the food. The magnetron 2 and the motor 8 are controlled by the control pattern. (Of course, as the volume generally increases, the weight tends to be heavier, so it may be converted into the weight.)
First, when the food is in a small load (for example, 200 cubic centimeters or less), it is heated by controlling so that the tips 23 of the antennas 19 face each other as shown in FIG. 6 (first control pattern). This is achieved by matching the impedance on the magnetron 2 side with the impedance on the load side with a small load of 200 cubic centimeters or less when the tips 23 of the antennas 19 face each other in advance. (Of course, it may be allowed to have a certain allowable width without strictly facing each other, or may be reciprocated within a narrow range without stopping completely).

  Next, when the food is in a large load (for example, 1000 cubic centimeters or more), heating is performed by controlling so that the tips 23 of the antennas 19 do not face each other as shown in FIG. 7 (second control pattern). This is because the impedance on the magnetron 2 side and the load due to a large load of 1000 cubic centimeters or more when the antenna 23 is reciprocated in the range in which the tips 23 of the antenna 19 do not face each other as shown in FIG. By matching the impedance on the side, matching can be ensured.

  By the way, when the food 13 has a medium load (for example, 200 to 1000 cubic centimeters), the antenna 19 may be switched alternately between the case where it faces each other and the case where it does not face each other. good.

  As described above, in the present embodiment, the shape detection unit 24 that detects the shape of the food is provided, and the control unit 14 is configured to switch the control pattern according to the shape of the food detected by the shape detection unit 24.

  As a result, when the shape of the food is small, it can be seen that the load is generally small, so it can be heated efficiently with the first control pattern, and when the shape is large, it is found that the load is generally large, so it is efficient with the second control pattern. Can be heated.

  Moreover, the 1st control pattern is set as the structure which concentrates a microwave on the center of the mounting base which mounts the foodstuff 13 compared with a 2nd control pattern. The point of this is the direction of the microwave indicated by the arrows 27, 28, 29, and 30 in FIGS.

  Since microwaves are radiated in the heating chamber 3 from the tip 23 of the rotating waveguide type antenna 19 in a large amount, the antennas 19 are arranged inward (FIG. 6) as in the first control pattern. Is radiated in the direction of arrows 27 and 28, and when the antennas 19 are arranged outward (FIG. 7) as in the second control pattern, the directions of arrows 29 and 30 are used. Microwaves are considered to be emitted.

  Therefore, in general, when the two antennas 19 are arranged symmetrically with respect to the center of the bottom surface of the heating chamber 3, the arrow lines 27 and 28 are closer to the center of the mounting table 1 than the arrow lines 29 and 30, that is, The first control pattern can concentrate the microwaves at the center of the mounting table.

  As a result, the small load has a small shape and thus is likely to be placed near the center of the mounting table 1, and the microwave can be efficiently heated by concentrating the microwave on the center of the mounting table 1 with the first control pattern. it can. By the way, the large load has a large shape and may be placed not only near the center of the mounting table 1 but also across the end. Therefore, in the second control pattern, the first control pattern is as small as the center. There is no need to concentrate the waves.

(Embodiment 3)
8 to 9 are configuration diagrams of the microwave oven, FIG. 8 is a cross-sectional view seen from the right, and FIG. 9 is a cross-sectional view seen from the top. In this Embodiment, the example which has the three antennas 31a, 31b, and 31c in the left-right direction of the horizontally long heating chamber 3 was shown. However, there are three magnetrons 2a, 2b and 2c and three waveguides 5, and in particular, the magnetrons 2a, 2b and 2c can be individually controlled. The antennas 31a, 31b, and 31c have bent portions 32 and 33 that are bent on opposite sides of the coupling shaft 10, and a wide front end 34 and a narrow rear end 35 are formed in a portion without the bend. By forming the open portions at two locations, it is possible to radiate microwaves with strong directivity mainly on the tip 34 side. The three antennas 31a, 31b, and 31c may be provided with one motor 8 individually, but the three antennas 31a, 31b, and 31c may be rotated by one motor 8 and a gear. In any case, by appropriately controlling which of the three magnetrons 2a, 2b, and 2c radiates the microwave, rotating the antennas 31a, 31b, and 31c, or stopping at a specific position, the microwave The heating direction can be made uniform by changing the radiation direction.

  The temperature detection means 36 detects the temperature in the heating chamber 3. The control means 14 controls the magnetrons 2a, 2b and 2c based on the setting information from the setting means 15 and the temperature information from the temperature detecting means 36 to control the generation and stop of the microwaves, or the motor 8 To control the rotation and stop of the antennas 31a, 31b, 31c.

  Next, an example of a control pattern in the case where the three antennas 31a, 31b, and 31c are provided with one motor 8 individually will be described.

  For example, when the setting unit 15 is set to 500 W3 minutes by manual setting, the control unit needs to perform appropriate control for 3 minutes. When food is placed, the temperature detection means 24 detects the temperature in the heating chamber 3, but the control means calculates the rate of temperature rise especially after the start of heating, and is determined in advance according to the speed of temperature rise. The magnetrons 2a, 2b, 2c and the motor 8 are controlled by the control pattern. In general, the faster the temperature rises, the lighter the weight tends to be. Therefore, it is possible to control the rate of temperature rise in terms of weight.

  In the present embodiment, there are a great many possible combinations of the combinations of the magnetrons 2a, 2b, and 2c and the control of the motor 8 depending on the load, but a simple example is shown here.

  First, when the food is loaded in a small amount, only the magnetron 2b is heated by generating microwaves. The antenna 31b is rotated at a constant speed, and the antennas 31a and 31c are stopped (first control pattern). This is designed so that the impedance on the magnetron 2b side is matched with the impedance on the load side due to a small load when microwaves are radiated only from the antenna 31b arranged in the center in advance. be able to. At this time, since the microwaves are not radiated from the antennas 31a and 31c, the antennas 31a and 31c may be stopped without being bothered to rotate.

Next, when the food is in a large load, microwaves are generated from the magnetrons 2a and 2c and heated. The antennas 31a and 31c are rotated at a constant speed, and the antenna 31b is stopped (second control pattern). This is because the impedance on the magnetron 2a and magnetron 2b side is matched with the impedance on the load side by a large load when microwaves are radiated from the antennas 31a and 31c arranged at both ends in advance. It can be surely aligned. At this time, since the microwave is not radiated from the antenna 31b, it is preferable to stop the antenna 31b without rotating it.

  Incidentally, when the food 13 has a medium load, the first control pattern and the second control pattern may be switched in the middle, or microwaves are generated from all of the magnetrons 2a, 2b, 2c, and the antenna 31a, Both 31b and 31c may be rotated.

  As described above, in the present embodiment, the temperature detection unit 36 that detects the temperature of the food is provided, and the control unit 14 is configured to switch the control pattern according to the temperature of the heated object detected by the temperature detection unit 36.

  As a result, when the temperature rise of the food is fast, it can be seen that the load is generally small, so it can be heated efficiently with the first control pattern. It can be heated efficiently.

  However, as in the present embodiment, when the load amount is estimated by calculating the rate of temperature rise after the start of heating based on the temperature information from the temperature detecting means 36, it is appropriate that the temperature rise does not occur. It will not be possible to shift to a simple control pattern. Therefore, the control means is preferably configured to start heating with the first control pattern and control to heat with the second control pattern only when it is determined that the temperature rise is slow.

  As a result, the heating time of the small load is shorter than that of the large load, so even if you do not know whether the object to be heated is a small load or a large load, the heating is first started with the first control pattern that efficiently heats the small load. In this case, it is possible to reliably and efficiently heat a small load that is frequently used.

  On the other hand, if the object to be heated has a large load, it will start with inefficient heating at first.However, since the large load originally takes a long time, the large load is efficiently removed after determining that the temperature rise is slow. By switching to the second control pattern to be heated, it is possible to increase the efficiency in the subsequent time, and it is possible to heat clearly more efficiently than in the case of heating to the last control pattern.

  Even when there is no means for estimating the amount of food, such as the weight detection means, shape detection means, temperature detection means, etc. described in this embodiment, the general time for heating a small amount of load is 2 minutes, for example. By pre-determining and heating with the first control pattern that efficiently heats a small load for 2 minutes from the start of heating, and switching to the second control pattern that efficiently heats a large load after 2 minutes, Since the subsequent time can be efficiently heated, the heating can be obviously performed more efficiently than when the first control pattern is used until the end.

  As described above, according to the present invention, since the antenna position control pattern can be switched and matched according to the amount of the object to be heated, it can be efficiently heated, so the microwave oven as a cooking utensil using microwaves It can be applied to microwave ovens, various dielectric heating and thawing devices, semiconductor devices using microwaves, heating devices in industrial fields such as drying devices, ceramics heating, sintering or biochemical reactions. .

1 is a cross-sectional configuration diagram of a microwave heating apparatus according to a first embodiment of the present invention viewed from the side. Cross-sectional configuration view of the microwave heating device viewed from above The figure explaining the image of the up-and-down movement of an antenna with the section lineblock diagram of the principal part of the microwave heating device Characteristic diagram showing impedance matching state of the microwave heating device The cross-sectional block diagram which looked at the microwave heating apparatus of Embodiment 2 of this invention from the side A cross-sectional view of the microwave heating device from above, with the antennas facing each other A cross-sectional configuration view of the microwave heating apparatus from above, with the antennas facing each other The cross-sectional block diagram which looked at the microwave heating apparatus of Embodiment 3 of this invention from the side Cross-sectional configuration view of the microwave heating device viewed from above

Explanation of symbols

1 Mounting table 2, 2a, 2b, 2c Magnetron (microwave generating means)
3 Heating chamber 5 Waveguide 6, 19, 31a, 31b, 31c Antenna 12 Weight detection means 13 Food (object to be heated)
14 Control means 48 Second opening 24 Shape detection means 36 Temperature detection means

Claims (8)

A heating chamber for storing an object to be heated; microwave generation means for generating microwaves; a waveguide for guiding the microwave generated by the microwave generation means to the heating chamber; and from the waveguide to the heating chamber. And an antenna capable of changing the direction of the microwave radiated to the antenna, and a control means for controlling the direction of the microwave by controlling the position of the antenna. A first control pattern for controlling the position of the antenna so as to match the impedance on the microwave generating means side with the impedance on the load side; and when the object to be heated is a large load, the impedance on the microwave generating means side A microwave heating apparatus having a second control pattern for controlling the position of the antenna so as to match impedance on a load side. The microwave heating apparatus according to claim 1, wherein the control unit is configured to control to heat with the second control pattern after heating with the first control pattern. 3. The microwave heating apparatus according to claim 1, further comprising weight detection means for detecting the weight of the object to be heated, wherein the control means switches the control pattern according to the weight of the object to be heated detected by the weight detection means. . The microwave heating apparatus according to claim 1 or 2, further comprising a shape detection unit that detects a shape of the object to be heated, wherein the control unit switches the control pattern according to the shape of the object to be heated detected by the shape detection unit. . The microwave heating apparatus according to claim 1 or 2, further comprising a temperature detection unit that detects a temperature of the object to be heated, wherein the control unit switches a control pattern according to the temperature of the object to be heated detected by the temperature detection unit. . The microwave heating device according to claim 1, wherein the first control pattern is configured to concentrate microwaves at a center of a mounting table on which an object to be heated is mounted, as compared with the second control pattern. The microwave heating device according to claim 6, wherein the first control pattern is configured to bring the antenna closer to the center of the mounting table than the second control pattern. Claims wherein at least two antennas are arranged substantially symmetrically when viewed from the center of the bottom surface of the heating chamber, and the first control pattern is configured so that the strong antenna directivity portions face each other compared to the second control pattern. Item 7. A microwave heating apparatus according to Item 6.

Images