JP2008282693A - Microwave heating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microwave heating apparatus which normally performs uniform heating in the whole heating chamber, and according to a specific purpose, also performs locally concentrated heating. <P>SOLUTION: The microwave heating apparatus comprises a microwave generating means 32, a plurality of rotary antennas 38, 39 to irradiate microwaves, drive means 40, 41 to rotation-drive the rotary antennas, a temperature distribution detection means 10 to detect temperature distribution in the heating chamber, and a control means 411 to control the microwave generating means and the drive means. The control means has a center heating mode to direct a portion with the strong irradiation directionality of at least one rotary antenna out of the plurality of antennas to the center of the heating chamber and a local heating control mode to control a portion with the strong irradiation directionality to a direction determined based on the detection result of the temperature distribution detection means and heat a local part. The control means starts heating by the center heating mode at the start of heating and switches to the local heating control mode from a middle way. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

  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. Up to now, microwave ovens have a space for storing food in a heating chamber through which microwaves propagate, and the width and depth dimensions are approximately 300 to 400 mm, and the height dimension is approximately 200 mm. However, it is popular.

  In recent years, the bottom of the space for storing foods has been flattened, and the width has a width of at least 400 mm, which is relatively larger than the depth. Products with shapes have been put into practical use.

  By the way, the wavelength of the microwave used by the microwave oven is about 120 mm, a strong electric field distribution (hereinafter referred to as radio wave distribution) is generated in the heating chamber, and the influence of the shape of the object to be heated and its physical characteristics It is known that heating unevenness occurs due to synergy. In particular, in the heating chamber having a large dimension in the width direction described above, it is necessary to increase the uniformity of heating more than before in order to simultaneously heat foods placed on a plurality of tableware.

  Conventionally, this type of microwave heating apparatus is provided with one radiation antenna and rotationally drives the antenna, but it is difficult to locally heat the central portion of the heating chamber. Therefore, as a measure for improving the uniformity of heating, one provided with a plurality of radiation antennas or one provided with a plurality of high-frequency stirring means has been proposed (see Patent Document 1).

  However, even if the interior is large, it does not always heat a large amount of food. For example, when warming a full mug of milk, it is considered more efficient to concentrate only on milk without heating the entire interior uniformly. .

  Even when heating multiple foods at the same time, if there is a difference in the temperature of the food, such as when heating frozen food and food at room temperature at the same time, you may want to heat only the low-temperature food intensively. is there. In addition, if it's like a box lunch box, it contains foods (pickles, salads, desserts, etc.) that you don't want to heat in one container, and intensively heats only the foods (rice, side dishes, etc.) that should be heated. Sometimes you want to.

In such a case, the function which can carry out local concentration heating instead of the whole uniform heating is needed. For this reason, there has been proposed one that performs central heating by switching a plurality of radiation antennas and controlling the stop position (see Patent Document 2).
JP 2004-259646 A Japanese Patent No. 3617224

With reference to Patent Documents 1 and 2, first, in the case of a heating chamber having a wide width, it is likely that uniform heating of the entire heating chamber can be realized by configuring a plurality of radiation antennas on the left and right. Concentrated heating locally can be concentrated to some extent in the direction of the tip of the unipole antenna by stopping the radiation antenna, for example. However, the problem is how much it can be concentrated, and it is usually difficult to achieve local concentrated heating according to the purpose while achieving uniform heating throughout the heating chamber. there were.

  The present invention has been made in order to solve the above-described problems, and it is intended to provide a microwave heating apparatus that normally achieves uniform heating of the entire heating chamber and also achieves local concentrated heating according to the purpose. Objective.

  The microwave heating apparatus of the present invention includes a microwave generating means, a waveguide that transmits microwaves from the microwave generating means, a heating chamber that houses an object to be heated by the microwave, and the waveguide. A plurality of rotating antennas for radiating the microwave from a tube to the heating chamber; a driving means for rotating the rotating antenna; a temperature distribution detecting means for detecting a temperature distribution in the heating chamber; and the microwave generation A central heating mode in which at least one of the plurality of rotating antennas has a strong radiation directivity portion directed to the center of the heating chamber, Control at least one rotating antenna of the plurality of antennas in a direction determined based on a detection result of the temperature distribution detecting means at a portion having a strong radiation directivity A heating local control mode for heating the local Te, and the control means initially heated to start the heating at the center heating mode, in which a configuration to switch from the middle to the heating local control mode.

  With this configuration, the center of the heating chamber is generally the one that is most difficult to be heated, so the central heating mode in which the direction of the strong radiation directivity of the rotating antenna is directed toward the center of the heating chamber and the detection of the temperature distribution detection means Based on the heating local control mode that directs the strong radiation directivity part of the rotating antenna to the area that needs heating in the heating chamber, normally heating the center to achieve uniform heating of the entire heating chamber, Locally concentrated heating can be realized according to the purpose, and at the beginning of heating, the rotating antenna is controlled in the central heating mode, and when the temperature difference starts to occur, the rotating antenna is controlled in the heating local control mode from the middle of heating. The temperature distribution of food can be controlled freely.

  ADVANTAGE OF THE INVENTION According to this invention, the microwave heating apparatus which also implement | achieves local concentrated heating according to the objective can be provided, normally implement | achieving uniform heating of the whole heating chamber.

  A microwave heating apparatus according to a first aspect of the present invention is a microwave generator, a waveguide that transmits microwaves from the microwave generator, a heating chamber that houses an object to be heated by the microwave, A plurality of rotating antennas for radiating the microwaves from the waveguide to the heating chamber, driving means for rotationally driving the rotating antennas, temperature distribution detecting means for detecting a temperature distribution in the heating chamber, and the micro A central heating mode in which a wave generating means and a control means for controlling the driving means are provided, wherein the control means directs at least one rotary antenna of the plurality of rotary antennas toward a center of the heating chamber having a strong radiation directivity. And at least one rotating antenna of the plurality of antennas in a direction determined based on a detection result of the temperature distribution detecting means with a strong radiation directivity portion A heating local control mode for heating the local and your, and said control means is initially heated to start heating in central heating mode, in which a configuration to switch from the middle to the heating local control mode.

With this configuration, the center of the heating chamber is generally the one that is most difficult to be heated, so the central heating mode in which the direction of the strong radiation directivity of the rotating antenna is directed toward the center of the heating chamber and the detection of the temperature distribution detection means Based on the heating local control mode that directs the strong radiation directivity part of the rotating antenna to the area that needs heating in the heating chamber, normally heating the center to achieve uniform heating of the entire heating chamber, Locally concentrated heating can be realized according to the purpose, and at the beginning of heating, the rotating antenna is controlled in the central heating mode, and when the temperature difference starts to occur, the rotating antenna is controlled in the heating local control mode from the middle of heating. The temperature distribution of food can be controlled freely.

  In the microwave heating apparatus according to a second aspect of the present invention, the heating local control mode stores an angle of the rotating antenna when a portion having a strong radiation directivity of the rotating antenna is directed to a specific region in the heating chamber. It has an antenna angle storage unit, and is configured to direct a portion having a strong radiation directivity of the rotating antenna to a low temperature portion of the temperature of each detection region detected by the temperature distribution detecting means, and was examined in advance by an experiment. By storing data in the antenna angle storage unit, the low temperature part can be locally heated with high accuracy.

  The microwave heating apparatus according to a third aspect of the invention is configured such that the control unit switches from the central heating mode to the local heating control mode when the maximum temperature of the temperatures detected by the temperature distribution detection unit exceeds a predetermined temperature. When the maximum temperature exceeds the specified temperature, the central heating mode is switched to the heating local control mode, so it is possible to suppress further temperature rise in the maximum temperature part and to perform local heating appropriately. Can do.

  In the microwave heating apparatus according to a fourth aspect of the invention, the control means has a predetermined maximum temperature difference among temperature differences between the temperature detected by the temperature distribution detection means and the temperature detected by the temperature distribution detection means at the beginning of heating. When the temperature difference is exceeded, the central heating mode is switched to the local heating control mode. When the maximum temperature change from the initial value is equal to or greater than a predetermined temperature change, the central heating mode is switched to the local heating control mode. Therefore, the maximum portion of the temperature change can suppress the further temperature change, and the local heating can be appropriately performed.

  In the microwave heating apparatus according to a fifth aspect of the present invention, the control means includes a timer that measures an elapsed time from the heating start time, and when the timer times a predetermined time, the central heating mode changes to the heating local control mode. When a predetermined time has elapsed from the initial stage, the central heating mode can be switched to the heating local control mode, and local heating can be appropriately performed as necessary.

  According to a sixth aspect of the present invention, the control means extracts the temperature of the food part from the temperature detected by the temperature distribution detection means, and the maximum temperature difference of the food part exceeds a predetermined temperature difference. It is configured to switch from the central heating mode to the heating local control mode.With this configuration, if the maximum temperature difference of the actual food part temperature is increased, the central heating mode is switched to the heating local control mode. A temperature difference in the food can be suppressed, and local heating can be appropriately performed.

  In the microwave heating apparatus according to a seventh aspect of the present invention, the control means switches from the heating local control mode to the minute central heating mode when the maximum temperature difference of the food part falls within a predetermined temperature difference during the heating local control mode. If the maximum temperature difference of the actual food part temperature is large, the central heating mode is switched to the heating local control mode, and if the maximum temperature difference is small, the heating local control mode is switched to the central heating. Returning to the mode, the temperature difference in the food can be suppressed, and local heating can be appropriately performed.

  Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
1 to 3 are block diagrams of a microwave oven 31 that is a typical microwave heating apparatus according to the present invention, FIG. 1 is a cross-sectional block diagram viewed from the front, and FIG. 2 is a cross-sectional block diagram of FIG. FIG. 3 and FIG. 3 are sectional views taken along the line BB ′ of FIG.

  As shown in FIG. 1, a microwave oven 31 includes a waveguide 33 that transmits a microwave radiated from a magnetron 32 that is a typical microwave generation unit, and a width dimension that is connected to the upper portion of the waveguide 33. (About 410 mm) is larger than the dimension in the depth direction (about 315 mm), and is fixed in the heating chamber 34 for placing food (not shown) as a typical object to be heated. Since it is made of a low-loss dielectric material such as glass, a mounting table 35 having a property that microwaves can be easily transmitted, an antenna space 37 formed below the mounting table 35 in the heating chamber 34, and the waveguide 33 In order to radiate microwaves into the heating chamber 34, two rotating antennas 38 and 39 that are mounted symmetrically with respect to the width direction of the heating chamber 34 from the waveguide 33 to the antenna space 37, and rotated Motors 40 and 41 as typical driving means capable of rotating the antennas 38 and 39, control means 411 for controlling the motors 40 and 41 to control the orientation of the rotating antennas 38 and 39, and the respective rotating antennas 38 and 39 A photo interrupter 36 that constitutes an origin detection mechanism for detecting the origin of rotation, and an infrared sensor 10 that is a temperature distribution detecting means for detecting a temperature distribution in the heating chamber 34.

  The microwave oven 31 includes a door 64 as shown in FIG. A setting means 63 is disposed below the door 64. The setting means 63 allows the user to select various cooking menus according to food and cooking contents. Based on the selection result, the control unit 411 can control the magnetron 32 and the motors 40 and 41.

  The rotating antennas 38 and 39 have a radiation directivity. The microwave oven 31 of the first embodiment is configured to centrally heat a specific food by controlling at least one of the rotating antennas 38 and 39 with a strong radiation directivity in a predetermined direction. The specific control method will be described later.

  The rotating antennas 38 and 39 are electrically conductive in a substantially cylindrical shape with a diameter of about 18 mm that penetrates the coupling holes 43 and 44 with a diameter of about 30 mm provided at the boundary surface between the waveguide 33 and the bottom surface 42 of the heating chamber. The coupling portions 45 and 46 made of a conductive material are integrated with the upper ends of the coupling portions 45 and 46 by caulking, welding, or the like, and are made of a conductive material having a larger area in the horizontal direction than the vertical direction. And radiating portions 47 and 48.

  The rotating antennas 38 and 39 are configured to be fitted to the shafts 49 and 50 of the motors 40 and 41 so that the centers of the coupling portions 43 and 44 are the centers of rotational driving. The radiating portions 47 and 48 have a radiation directivity because the shape is not constant with respect to the direction of rotation.

  The centers of rotation of the rotating antennas 38 and 39 are arranged at an approximately equal distance from the center in the heating chamber 34. With this configuration, it is possible to heat the vicinity of the center of the heating chamber, which is normally difficult to heat with a single antenna configuration, by directing the portions of the rotary antennas 38 and 39 having strong radiation directivity to the vicinity of the center.

  Since the waveguide 33 has a T-shape when viewed from above as shown in FIG. 3 and has a bilaterally symmetric shape, the distance from the magnetron 32 to the coupling portions 45 and 46 is equal, and the coupling portions 45 and 46 are the same. Are attached at symmetrical positions also with respect to the width direction of the heating chamber 34, so that the microwaves radiated from the magnetron 32 are almost evenly distributed in the heating chamber 34 via the waveguide 33 and the rotating antennas 38 and 39. Distributed.

The radiating portions 47 and 48 have the same shape, and the radiating portion upper surfaces 51 and 52 have a substantially quadrilateral R shape, and the radiating portion bending portion 53 bent to the heating chamber bottom surface 42 side on the opposite two sides, 54, and is configured to limit the emission of microwaves to the outside of the two sides. The distance between the heating chamber bottom surface 42 and the radiating portion upper surfaces 51 and 52 is about 10 mm, and the radiating portion bending portions 53 and 54 are pulled down to a position lower by about 5 mm.

  The remaining two sides have different horizontal lengths from the coupling portions 45 and 46 to the end portions, and the length from the center of the coupling portion is about 75 mm. Constitutes end portions 57 and 58 of about 55 mm. In addition, the dimension in the width direction of the end portion is 80 mm or more. In this configuration, the rotating antennas 38 and 39 can increase the radiation directivity in the direction from the coupling portions 45 and 46 to the end portions 57 and 58.

  In this configuration, when the central area in the heating chamber 34 is centrally heated, the control means 411 causes the end portions 57 and 58 of the rotating antennas 38 and 39 to be substantially in the width direction of the heating chamber 34 as shown in FIG. Control is performed so as to be directed in a predetermined direction at the center and substantially the center in the depth direction. When the end portions 57 and 58 of the rotating antennas 38 and 39 are directed to the approximate center in the width direction of the heating chamber 34 and the approximate center in the depth direction, the radiation directivity in the direction of the end portions 57 and 58 is strong. Microwaves are radiated from the directions 57 and 58, and the food located in that direction can be intensively heated.

  Foods are generally easy to be heated from the periphery or end, and the center of the food is the least heated. Since food is generally placed in the center of the heating chamber 34, the food can be uniformly heated by centrally heating the center of the heating chamber 34. The center heating mode, which will be described later, is based on stopping in the direction of the antenna shown in FIG. 4, and the center may be overheated only by this stop, and there is a safety problem. Thus, for example, the rotation antennas 38 and 39 are controlled by a method of rotating for 10 seconds after stopping for 10 seconds.

  Further, when heating the vicinity of the left side in the heating chamber 34, as shown in FIG. 5, the control means 411 faces the ends 57 and 58 of the rotating antennas 38 and 39 to the left (the heating chamber 34 is viewed from the door 64 side). To the left).

  When the end portions 57 and 58 of the rotating antennas 38 and 39 both face the left side when the heating chamber 34 is viewed from the door 64 side, each antenna has a strong radiation directivity in the direction of the end portions 57 and 58. In particular, microwaves are emitted from the direction of the end portions 57 and 58, and the food located in that direction can be intensively heated.

  Similarly, when the vicinity of the right side in the heating chamber 34 is heated, as shown in FIG. 6, the control means 411 turns the end portions 57 and 58 of the rotating antennas 38 and 39 to the right (the heating chamber 34 from the door 64 side). Control to turn to the right).

  When both ends 57 and 58 of the rotating antennas 38 and 39 face the right side when the heating chamber 34 is viewed from the door 64 side, each antenna has a strong radiation directivity in the direction of the ends 57 and 58. Microwaves are emitted from the direction of the ends 57 and 58, and the food located in that direction can be intensively heated.

  In addition, when the vicinity of the front center in the heating chamber 34 is heated, as shown in FIG. 7, the control means 411 connects the end portions 57 and 58 of the rotating antennas 38 and 39 to the substantially center in the width direction of the heating chamber 34. Control is made so as to be directed forward in the depth direction (near the center front in the heating chamber 34).

  As shown in FIG. 7, when the end portions 57 and 58 of the rotating antennas 38 and 39 are directed near the center front in the heating chamber 34, each antenna has a strong radiation directivity in the direction of the end portions 57 and 58. Particularly, microwaves are radiated from the direction of the end portions 57 and 58, and the food located in that direction can be heated intensively.

  In addition, when the vicinity of the rear center in the heating chamber 34 is heated, as shown in FIG. Control is performed so as to be directed rearward in the depth direction (near the central rear in the heating chamber 34).

  As shown in FIG. 8, when the end portions 57 and 58 of the rotating antennas 38 and 39 face the vicinity of the center rear in the heating chamber 34, each antenna has a strong radiation directivity in the direction of the end portions 57 and 58. Particularly, microwaves are radiated from the direction of the end portions 57 and 58, and the food located in that direction can be heated intensively.

  As described above, the microwave oven 31 of the first embodiment controls the direction of the rotating antenna in accordance with the location where it is desired to locally heat, and in order to point the rotating antennas 38 and 39 in a predetermined direction. Further, a stepping motor may be used as the motors 40 and 41, or a means for detecting the reference position and controlling the energization time even with a constant rotation motor can be considered.

  In the microwave oven 31 of the first embodiment, stepping motors are used as the motors 40 and 41, and origin detection mechanisms are provided on the shafts 40 and 41 of the respective motors. FIG. 9 is a cross-sectional view taken along the line D-D ′ of FIG. 1, and this origin detection mechanism includes a disc 36 a having a shaft as a central axis and a photo interrupter 36 as shown in FIG. 9. The circular plate 36a is provided with a rectangular slit 36b.

  The disc 36a is commonly attached to the shafts of the motor shafts 49 and 50 for rotating the rotary antennas 38 and 39, and rotates so as to block the optical path of the photo interrupter 36 including a light emitting element and a light receiving element. Is.

  With this configuration, when the slit 36b passes through the optical path of the photointerrupter 36, there is nothing to block the optical path, so that the passage time of the slit can be detected. Therefore, by setting the position of the slit 36b as the origin of the rotating antennas 38 and 39, the origin of the rotating antenna can be detected by the photo interrupter 36 attached to each motor.

  Further, the control means 411 uses the origin that can be detected by the origin detection mechanism as a reference, and determines the angle (stop position) of the rotating antennas 38 and 39 when the highly directional portions of the rotating antennas 38 and 39 are concentrated on the local heating location. An antenna angle storage unit is stored in advance. When local heating is performed by controlling the operation of the rotating antennas 38 and 39, information in the antenna angle storage unit is referred to.

  In addition, although the case where there are two rotating antennas has been described so far, the number of rotating antennas is not limited to this, and may be two or more. For example, as illustrated in FIG. It is good also as a structure. In the state shown in FIG. 10, the end portions of the respective rotating antennas face the vicinity of the center in the heating chamber, and the food located near the center can be intensively heated.

  Next, with reference to FIG. 11, the temperature detection means with which the microwave oven 31 of this Embodiment 1 is provided is demonstrated. This temperature detection means includes a plurality of infrared detection elements 13 arranged in a line on the substrate 19, a case 18 that houses the entire substrate 19, and a case 18 that is perpendicular to the direction in which the infrared detection elements 13 are aligned. And a stepping motor 11 that moves in the intersecting direction.

On the substrate 19, a metal can 15 enclosing the infrared detection element 13 and an electronic circuit 20 for processing the operation of the infrared detection element are provided. The can 15 is provided with a lens 14 through which infrared rays pass. Further, the case 18 is provided with an infrared passage hole 16 through which infrared light passes and a hole 17 through which a lead wire from the electronic circuit 20 passes.

  With this configuration, when the stepping motor 11 rotates, the case 18 can be moved in a direction perpendicular to the direction in which the infrared detection elements 13 are aligned.

  FIG. 12 is a diagram for explaining infrared temperature detection spots in the C-C ′ cross section in FIG. 1. As shown in the figure, the microwave oven 31 of the first embodiment can detect the temperature distribution in almost all regions in the heating chamber 34 by the reciprocating rotation of the stepping motor 11 of the temperature detecting means. Is.

  Specifically, for example, first, the temperature detection elements 13 (for example, infrared sensors) arranged in a line of the temperature detection means simultaneously detect the temperature distribution in the areas A1 to A4 in FIG. Next, when the stepping motor 11 rotates and the case 18 moves, the temperature detection element 13 detects the temperature distribution in the region of B1 to B4. Furthermore, when the stepping motor 11 rotates and the case 18 moves, the temperature detection element 13 detects the temperature distribution in the region C1 to C4, and similarly detects the temperature distribution in the region D1 to D4.

  In addition, the temperature distribution is detected in the order of C1 to C4, B1 to B4, and A1 to A4 from the region side of D1 to D4 by the reverse rotation of the stepping motor 11 following the above operation. The temperature distribution detecting means can detect the entire temperature distribution in the heating chamber 34 by repeating the above operation.

  Next, a schematic configuration of the control unit 411 will be described with reference to FIG. The control means 411 includes a food determination unit 101 that determines whether the object to be heated placed in the heating chamber 34 is food, a heating end determination unit 102 that determines the end of the heating process, and the rotating antenna 38. , 39, and an antenna control unit 103 that controls the operation of 39.

  The food determination unit 101 includes an initial temperature distribution storage unit 104 that stores a temperature distribution at the beginning of heating. The food determination unit 101 calculates a difference between the detected temperature distribution and the initial temperature distribution stored in the initial temperature distribution storage unit 104, and determines whether the food is food based on the difference. This is to determine whether the region where the temperature is detected is a mounting table on which an object to be heated is placed or a food to be heated, but the mounting table transmits microwaves and hardly rises in temperature. Foods are susceptible to temperature rise by absorbing microwaves, and are distinguished by their characteristic differences.

  The heating end determination unit 102 determines, for example, a determination condition for determining that the heating process is to be ended when the maximum temperature in the temperature distribution of the object to be heated exceeds a preset set temperature, or the average temperature of the portion determined to be food. Measure conditions for ending the heat treatment when the set temperature is exceeded, and the time required for the highest temperature of the object to be heated to reach a predetermined temperature, and a certain percentage of the time required (for example, 50%) Is heated as the additional heating time, and when the additional heating time ends, the heating process is ended, or the end of the heating process is determined based on the combination of these.

  The antenna control unit 103 includes a central heating mode control unit 105, a heating local control mode control unit 106, a mode determination unit 107 that determines which mode control unit is used to control the antenna, and a mode determination unit This is a configuration having a switching unit 108 for switching the mode by determination.

  The central heating mode control unit 105 basically stops the two rotating antennas 38 and 39 in the direction shown in FIG. 4, but strongly heats the center in the heating chamber 34 by periodically rotating the antenna. Thus, the motors 40 and 41 are controlled so that the whole can be heated uniformly.

  The heating local control mode control unit 106 stops the two rotating antennas 38 and 39 at a predetermined angle, fixes the position of a portion having a strong radiation directivity, and concentrates the microwave locally to perform heating control. When the two rotating antennas 38 and 39 are stopped in the directions as shown in FIGS. 4 to 8, a specific portion can be locally heated. The angle of the rotating antenna is stored in the antenna angle storage unit 109 in advance. ing.

  In addition, the heating local control mode control unit 106 includes a low temperature part extraction unit 110, and the low temperature part extraction unit 110 has a low temperature detected by the temperature distribution detection unit 10 among the portions determined to be food by the food determination unit 101. Extract the part. Then, the heating local control mode control unit 106 extracts the angles of the two antennas 38 and 39 for locally heating the location of the low temperature portion from the antenna angle storage unit 109, and stops the two motors 40 so as to stop at the angle. , 41 are controlled.

  The mode determination unit 107 determines whether the central heating mode control unit 105 or the heating local control mode control unit 106 controls the rotation of the two rotating antennas 38 and 39. Since the whole food has the same temperature at the beginning of the heating, it is not necessary to heat the local portion, and the switching unit 108 is controlled so as to select the central heating mode control unit 105 in order to uniformly heat the whole food. When the central heating mode control unit 105 performs uniform heating while centrally heating the center of the heating chamber 34, a difference in temperature between the high temperature portion and the low temperature portion often starts to occur in the food, so the mode determination unit 107 Operates the switching unit 108 to switch to the local overheating mode control unit 106, and controls to raise the temperature by locally heating the low temperature part and reduce the temperature difference.

  The switching control is performed as follows. That is, the mode determination unit 107 includes a timer 111 and switches from the central heating mode control unit 105 to the heating local control mode control unit 106 when a predetermined time has elapsed since the start of heating. Alternatively, control is performed by the central heating mode control unit 105 until the maximum temperature detected by the input from the temperature distribution detection means 10 exceeds a predetermined temperature, and when it exceeds the predetermined temperature, switching to the heating local control mode control unit 106 is performed. The central heating mode control unit 105 controls until the maximum value of the temperature change from the initial temperature exceeds the predetermined temperature change, and switches to the heating local control mode control unit 106 when the temperature exceeds the predetermined temperature. In addition, if the difference between the highest and lowest temperatures at the location determined as food by the food determination unit 101 is not more than a predetermined value, the control is performed by the central heating mode control unit 105. In this case, when the temperature difference becomes equal to or greater than a predetermined value and the low temperature portion is locally heated by the heating local control mode control unit 106, if the temperature difference decreases and becomes equal to or less than the predetermined value, the control is returned to the central heating mode control unit 105.

  These switching controls are performed by any one of the above or a combination thereof, and an example adopted in the present embodiment will be described later.

  Next, the operation of the microwave oven 31 of the first embodiment will be described with reference to the flowchart of FIG. When heating is started, first, the temperature distribution detecting means 10 detects the initial temperature distribution, that is, the initial temperature T0 at each temperature detection location (S201).

Next, the temperature distribution detecting means 10 detects the temperature distribution, that is, the temperature at each temperature detection location (S202). And food point determination is performed (S203). The food point determination is performed by the food determination unit 101. The temperature per unit time is calculated by calculating the difference between the temperature T detected in S202 and the initial temperature T0 detected in S201 and further dividing by the elapsed time t. Calculate the rate of increase. If this calculated value is larger than a preset temperature increase rate ΔTa, it is determined that the temperature detection location is food.

  Next, the maximum temperature Tfmax and the minimum temperature Tfmin are extracted from the temperatures Tf determined as food in S203, the temperature difference (Tfmax−Tfmin) is calculated, and this is calculated from a predetermined temperature difference Tb. It is determined whether it is larger (S204). If the temperature difference is larger than the predetermined value (S204-Yes), the heating local control mode control unit 106 controls the two antennas 38 and 39 to perform local heating (S205). If the temperature difference is not greater than the predetermined value (S204-No), the central heating mode control unit 105 controls the two antennas 38 and 39 to perform central heating.

  Then, the heating end determination unit 102 determines whether or not to end the heating (S207). If the heating has not ended yet (S207-No), the process returns from S202 to repeat the processing from the temperature distribution detection to end the heating. If it is (S207-Yes), the magnetron 32 is stopped and heating is completed.

  Next, another control example including switching between central heating / local heating according to the present invention will be described with reference to the flowchart of FIG. When heating is started, first, the temperature distribution detection means 10 detects the initial temperature T0 of each temperature detection location (S401), then the temperature distribution detection means 10 detects the temperature of each temperature detection location (S402), and in S402 If the difference between the detected temperature T and the initial temperature T0 detected in S401 is calculated and the temperature increase rate per unit time divided by the elapsed time t is greater than a preset temperature increase rate ΔTa, the temperature detection location is the food (S403). The steps so far are the same as those in the first embodiment.

  Next, it is determined whether the elapsed time from the start of heating counted by the timer 111 exceeds a predetermined time (S404). If the predetermined time has passed (S404-Yes), the local heating control is performed by the heating local control mode control unit 106 (S408). If the predetermined time has not elapsed (S404-No), it is next determined whether or not the maximum temperature detected by the temperature distribution detecting means exceeds a predetermined temperature Tc (S405). If the predetermined temperature is exceeded (S405-Yes), the local heating control is performed by the heating local control mode control unit 106 (S408). If the temperature does not exceed the predetermined temperature (S405-No), then the temperature change between the temperature detected by the temperature distribution detection means and the initial temperature is calculated, and the maximum temperature change exceeds a predetermined temperature change ΔTd. It is determined whether or not (S406). If the predetermined temperature change is exceeded (S406-Yes), local heating control is performed by the heating local control mode control unit 106 (S408). If the predetermined temperature change is not exceeded (S406-No), central heating control is performed by the central heating mode control unit 105.

  Then, the heating end determination unit 102 determines whether or not to end the heating (S409). If the heating has not ended yet (S409-No), the process returns from S402 to repeat the process from the temperature distribution detection to end the heating. If it is (S409-Yes), the magnetron 32 is stopped and the heating is finished. The heating local control mode S408 will be described later with reference to FIG.

  Next, local heating mode control S205 in FIG. 14 and local heating mode control S408 in FIG. 15 will be described using the flowchart in FIG. The location of the lowest temperature is extracted from the temperature detection locations determined as food points in the above description (S301).

It is determined whether or not the minimum temperature location is any one of B2, B3, C2, and C3 in FIG. 12 (S302). When the lowest temperature location is any one of B2, B3, C2, and C3 (S302-Yes), the antenna control unit 101 causes the rotating antennas 38 and 39 to heat the center in the heating three chamber 34. That is, the stop position shown in FIG. 4 is selected from the antenna angle storage unit 108, and operation control is executed so that the rotating antennas 38 and 39 are stopped there (S308).

  If the lowest temperature location is not any of B2, B3, C2, and C3 (S302-No), then it is determined whether the lowest temperature location of the food location is any of B1 or C1. (S303).

  When the lowest temperature location is one of B1 and C1 (S303-Yes), the antenna control unit 101 determines the direction in which the rotating antennas 38 and 39 heat the left direction in the heating chamber 34, that is, FIG. Is selected from the antenna angle storage unit 108, and operation control is executed so that the rotating antennas 38 and 39 are stopped there (S309).

  If the lowest temperature location is neither B1 nor C1 (S303-No), then it is determined whether the lowest temperature location of the food location is B4 or C4 (S304). .

  When the lowest temperature location is one of the regions B4 and C4 (S304-Yes), the antenna control unit 101 causes the rotating antennas 38 and 39 to heat the right direction in the heating chamber 34, that is, FIG. Is selected from the antenna angle storage unit 108, and operation control is executed so that the rotating antennas 38 and 39 are stopped there (S310).

  If the lowest temperature location is not in any of B4 and C4 regions (S304-No), it is then determined whether the lowest temperature location of the food location is either A2 or A3 (S305). .

  When the lowest temperature location is one of the areas A2 and A3 (S305-Yes), the antenna control unit 101 causes the rotating antennas 38 and 39 to heat the front direction in the heating chamber 34, that is, FIG. Is selected from the antenna angle storage unit 108, and operation control is executed so that the rotating antennas 38 and 39 are stopped there (S311).

  If the lowest temperature location is not in any of the areas A2 and A3 (S305-No), it is subsequently determined whether the lowest temperature location is D2 or D3 among the food locations (S306). .

  When the lowest temperature location is one of the areas D2 and D3 (S306-Yes), the antenna control unit 101 causes the rotating antennas 38 and 39 to heat the rearward direction in the heating chamber 34, that is, FIG. Is selected from the antenna angle storage unit 108, and operation control is executed to stop the rotating antennas 38 and 39 there (S312).

  If the lowest temperature location is neither D2 nor D3 (S306-No), the antenna control unit 101 continuously rotates the rotating antennas 38 and 39 so as to disperse the microwaves in the heating chamber 34. (S307).

  The antenna control unit 101 executes one of steps S307 and S308 to S312. This heating local control mode control process is repeated until there is a food temperature difference as shown in FIG. 14 until the heating is completed. Therefore, the control always works so as to heat the low temperature portion, and the temperature difference is reduced. The entire temperature distribution is uniform.

  As described above, the microwave oven 31 according to the first embodiment can intensively heat a specific portion in the heating chamber 34 by two rotating antennas. Stopping the two rotating antennas at an angle at which the food can be heated intensively is an effective method for heating the center where the food is difficult to be heated, and as a result, the food can be heated uniformly. However, the center may be heated too much, or another part may be heated too much, resulting in a high temperature. The temperature distribution is based on the temperature detected by the temperature distribution detecting means 10, and the two rotating antennas are heated in the heating local control mode. By controlling the temperature, the low temperature part can be heated intensively to raise the temperature and make the temperature of the whole food uniform. In particular, the food can be appropriately heat-treated by performing central heating at the initial stage of heating without temperature difference and acting so as to reduce the temperature difference by locally overheating if the temperature difference is applied.

  It should be noted that the present invention is not limited to the matters shown in the above-described embodiments, and those skilled in the art also intend to change or apply the present invention based on the description in the specification and well-known techniques, It is included in the range to calculate.

  For example, the operation of the antenna control described with reference to FIG. 16 is not limited to the order in which the lowest temperature portion of the food is searched, and may be executed in another order as long as the entire food is searched as a result.

  As described above, the present invention detects the temperature distribution in the heating chamber and, based on the temperature detection result, concentrates the strong radiation directivity portion of the rotating antenna disposed in the heating chamber in the center, Since the control is made so as to concentrate on the place, it can be applied to various dielectrics represented by food such as heating, thawing, ceramics heating, drying, sintering, or biochemical reaction. is there.

1 is a cross-sectional configuration diagram of a microwave heating apparatus according to a first embodiment of the present invention viewed from the front. Cross-sectional configuration view of the microwave heating device viewed from the side (A-A 'cross-sectional view in FIG. 1) FIG. 1 is a cross-sectional configuration view of the microwave heating apparatus as viewed from above (a cross-sectional view taken along line B-B ′ in FIG. 1) The figure explaining the direction of the rotating antenna when locally heating around the center of the heating chamber The figure explaining the direction of the rotating antenna when locally heating the left side of the heating chamber The figure explaining the direction of the rotating antenna when locally heating the right side of the heating chamber The figure explaining the direction of the rotating antenna when locally heating the front of the heating chamber The figure explaining the direction of a rotation antenna when heating the back of a heating chamber locally The figure explaining the origin detection mechanism of a rotating antenna (D-D 'sectional view in Drawing 1) Plane cross-sectional view of a microwave heating device having three rotating antennas Schematic cross-sectional configuration diagram of temperature distribution detection means The figure explaining the infrared temperature detection spot in the C-C 'cross section in FIG. Schematic configuration diagram of the control means 411 Flow chart for explaining the operation of the control means 411 Flowchart for explaining operation of distributed heating / local heating of control means 411 A flowchart for explaining the operation of the antenna control unit 101

Explanation of symbols

10 Infrared sensor (temperature distribution detection means)
31 Microwave oven (microwave heating device)
32 Magnetron (microwave generation means)
33 Waveguide 34 Heating chamber 38, 39 Rotating antenna 40, 41 Motor (driving means)
105 Central heating mode control unit 106 Heating local control mode control unit 109 Antenna angle storage unit 111 Timer

Claims (7)

A microwave generating means; a waveguide for transmitting microwaves from the microwave generating means; a heating chamber for storing an object to be heated by the microwave; and the microwave from the waveguide to the heating chamber. A plurality of rotating antennas for radiating light, driving means for rotationally driving the rotating antennas, temperature distribution detecting means for detecting a temperature distribution in the heating chamber, control for controlling the microwave generating means and the driving means A central heating mode in which a strong radiation directivity portion of at least one of the plurality of rotating antennas is directed toward the center of the heating chamber; and at least one of the plurality of antennas. Heating local control that heats the local area by controlling the part with strong radiation directivity of the rotating antenna in the direction determined based on the detection result of the temperature distribution detecting means Has over de, and the control means initially heated to start the heating at the center heating mode, the microwave heating apparatus in which switching from the middle to the heating local control mode. The heating local control mode has an antenna angle storage unit for storing the angle of the rotating antenna when a portion having a strong radiation directivity of the rotating antenna is directed to a specific region in the heating chamber, and is detected by the temperature distribution detecting means. The microwave heating device according to claim 1, wherein a portion having a strong radiation directivity of the rotating antenna is directed to a low temperature portion of the temperature of each detection region. The microwave heating apparatus according to claim 1, wherein the control means switches from the central heating mode to the local heating control mode when the maximum temperature among the temperatures detected by the temperature distribution detection means exceeds a predetermined temperature. The control means performs local heating control from the central heating mode when the maximum temperature difference exceeds a predetermined temperature difference between the temperature detected by the temperature distribution detection means and the temperature detected by the temperature distribution detection means at the beginning of heating. The microwave heating device according to claim 1, wherein the microwave heating device is switched to a mode. The microwave heating apparatus according to claim 1, wherein the control means includes a timer for measuring an elapsed time from the heating start time, and switches from the central heating mode to the heating local control mode when the timer measures a predetermined time. The control means extracts the temperature of the food part from the temperature detected by the temperature distribution detection means, and switches from the central heating mode to the heating local control mode when the maximum temperature difference of the food part exceeds a predetermined temperature difference. Microwave heating device. The microwave heating apparatus according to claim 6, wherein the control means returns from the heating local control mode to the central heating mode if the maximum temperature difference of the food part falls within a predetermined temperature difference during the heating local control mode.

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