JP5076625B2 - Microwave heating device - Google Patents

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 only the foods that should be heated (rice, side dishes, etc.) 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, if the heating chamber has a wide width, it is likely that uniform heating of the entire heating chamber can be realized by arranging 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. In particular, it has been difficult to efficiently heat only foods placed in a heating chamber without temperature unevenness.

  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 control means for controlling the means and said drive means, said control means has a food discriminator which each detection area from the temperature detected, it is determined whether food or non-food of the temperature distribution detecting unit, said food The discriminator is configured to open the heating from a value obtained by multiplying the maximum temperature difference by a predetermined ratio among the temperature difference between the temperature detected by the temperature distribution detecting means and the temperature detected by the temperature distribution detecting means at the beginning of heating. An area having a large temperature difference from the initially detected temperature is identified as food, and the control means directs the rotating antenna having a strong radiation directivity toward a specific area in the heating chamber. An antenna angle storage unit for storing the angle of the rotation antenna, and the radiation direction of the rotating antenna at a low temperature portion of each detection region determined by the food discrimination unit as food among the temperature of each detection region detected by the temperature distribution detection means The angle of the rotating antenna is selected from the antenna angle storage unit so that a strong part is directed, and the rotating antenna is controlled to stop at the selected angle of the rotating antenna .

  With this configuration, a portion where the temperature rise from the beginning of heating is large, that is, a portion where the temperature rises easily is identified as food, and a portion where the temperature rise from the beginning of heating is small, that is, the microwave is difficult to absorb. The parts that are difficult to rise in temperature are identified as non-food such as the bottom of the cabinet or tableware, so that the food can be properly identified and the rotating antenna can be controlled based on the temperature distribution of the food that you want to heat. Centralized heating can be realized, and the temperature distribution of food can be controlled freely.

  In the microwave heating apparatus of the present invention, the food discrimination unit is configured to determine the food discrimination when the maximum temperature exceeds a predetermined temperature among the temperatures detected by the temperature distribution detecting means.

  In general, as food rises in temperature and approaches the boiling temperature of water, the rise in temperature stops.However, with this configuration, food discrimination is determined when the maximum temperature exceeds a predetermined temperature. The food discrimination can be confirmed before the temperature rise stops, the wrong food discrimination can be prevented, the food can be properly discriminated, and the rotating antenna is set based on the temperature distribution of the food to be actually heated. Since it can be controlled, local concentrated heating can be realized according to the purpose, and the temperature distribution of food can be controlled freely.

  In the microwave heating apparatus of the present invention, the food discriminating unit has a timer for measuring an elapsed time from the start of heating, and determines the food discrimination when the timer counts a predetermined time. is there.

With this configuration, since the food discrimination is confirmed when a predetermined time has elapsed from the start of heating, the food discrimination can be confirmed before the temperature rise of the food stops, and an incorrect food discrimination is made. Since the rotating antenna can be controlled based on the temperature distribution of the food that is actually desired to be heated, local concentrated heating can be realized according to the purpose, and the temperature distribution of the food can be freely controlled.

  According to the present invention, since the rotating antenna can be controlled based on the temperature distribution of the food that is actually desired to be heated, a microwave heating apparatus that can realize local concentrated heating according to the purpose and can freely control the temperature distribution of the food is provided. can do.

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 control unit that controls the wave generation unit and the driving unit, the control unit includes a food determination unit that determines whether each detection region is food or non-food from each temperature detected by the temperature distribution detection unit, The food discriminating unit adds a maximum temperature difference from a value detected by the temperature distribution detecting unit and a temperature detected by the temperature distribution detecting unit at the beginning of heating to a value obtained by multiplying a predetermined ratio. A region having a large temperature difference from the temperature detected at the beginning of the start is determined as food, and the control means rotates the rotation antenna when directing a portion having a strong radiation directivity of the rotating antenna to a specific region in the heating chamber. An antenna angle storage unit that stores the angle of the antenna, and the radiation of the rotating antenna is radiated to a low temperature portion of each detection region that the food determination unit determines as food out of the temperature of each detection region detected by the temperature distribution detection unit The angle of the rotating antenna is selected from the antenna angle storage unit so as to direct a highly directional part, and the rotating antenna is controlled to stop at the selected angle of the rotating antenna .

With this configuration, a portion where the temperature rise from the beginning of heating is large, that is, a portion where the temperature rises easily is identified as food, and a portion where the temperature rise from the beginning of heating is small, that is, the microwave is difficult to absorb. The parts that are difficult to rise in temperature are identified as non-food such as the bottom of the cabinet or tableware, so that the food can be properly identified and the rotating antenna can be controlled based on the temperature distribution of the food that you want to heat. Centralized heating can be realized, and the temperature distribution of food can be controlled freely.

In the microwave heating apparatus of the second invention, the food discrimination unit is configured to determine the food discrimination when the maximum temperature exceeds a predetermined temperature among the temperatures detected by the temperature distribution detecting means. In general, as food rises in temperature and approaches the boiling temperature of water, the rise in temperature stops.However, with this configuration, food discrimination is determined when the maximum temperature exceeds a predetermined temperature. The food discrimination can be confirmed before the temperature rise stops, the wrong food discrimination can be prevented, the food can be properly discriminated, and the rotating antenna is set based on the temperature distribution of the food to be actually heated. Since it can be controlled, local concentrated heating can be realized according to the purpose, and the temperature distribution of food can be controlled freely.

The microwave heating apparatus according to a third aspect of the present invention is such that the food discrimination unit has a timer that counts an elapsed time from the start of heating, and determines the food discrimination when the timer counts a predetermined time. Because the food discrimination is confirmed when the predetermined time has elapsed from the start of heating, the food discrimination can be confirmed before the temperature rise of the food stops, preventing erroneous food discrimination Since the rotating antenna can be controlled based on the temperature distribution of the food that is actually desired to be heated, local concentrated heating can be realized according to the purpose, and the temperature distribution of the food can be freely controlled.

  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 the case of heating a general food uniformly in this configuration, it is not necessary to pay particular attention to the place of placement as in the case of a conventional microwave oven, and the rotating antennas 38 and 39 may be rotated at a constant speed as in the conventional case. On the other hand, in the case of central heating, when the vicinity of the center in the heating chamber 34 is heated, the control means 411 sets the end portions 57 and 58 of the rotating antennas 38 and 39 to the width of the heating chamber 34 as shown in FIG. Control is performed so as to be directed in a predetermined direction, that is, approximately the center of the direction and approximately the center of 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.

  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. 8, 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 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 according to the first embodiment controls the direction of the rotating antenna in accordance with the place where it is desired to locally heat. In order to orient the rotating antennas 38 and 39 in a predetermined direction, a stepping motor is used as the motors 40 and 41, or even if the motor rotates at a constant speed, the reference position is detected and the energization time is controlled. Conceivable.

  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 unit 411 includes an antenna control unit 101 that controls the operation of the rotating antennas 38 and 39, a food discrimination unit 102 that determines whether or not an object to be heated placed in the heating chamber 34 is food, a heating unit It is the structure which has the heating completion determination part 103 which determines the completion | finish of a process.

  The food discrimination unit 102 includes a food A point determination unit 104 that determines that the food is frozen food, and a food B point determination unit 105 that determines that the food is normal temperature food. In addition, an initial temperature distribution storage unit 106 that stores a temperature distribution at the beginning of heating is provided. The food A point determination unit 104 that determines whether the food is frozen or not detects the temperature distribution at the beginning of heating, and determines a portion that is lower than a predetermined frozen determination temperature (for example, 0 ° C.) as food. The food B point determination unit 105 that determines that the food is normal temperature food calculates a difference between the detected temperature distribution and the initial temperature distribution stored in the initial temperature distribution storage unit 106, and determines whether the food is a food based on the difference. Is determined. 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 103 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 101 includes a low temperature part extraction unit 107 and an antenna angle storage unit 108. In the antenna angle storage unit 108, for example, the angle of the antenna for concentrating the microwave on a part as shown in FIGS. 4 to 8 and causing a partial temperature rise is stored in advance. Temperature distribution information is input from the infrared sensor 10, and a low temperature portion is extracted from the temperature detection portions of the portion determined as food by the food discrimination unit 102. The antenna control unit 101 selects an antenna angle capable of centrally heating the low temperature portion of the food extracted by the low temperature portion extraction unit 107 from the antenna angle storage unit 108, and performs control such as stopping the antenna at that angle.

  For example, if the low temperature portion is any one of B2, B3, C2, and C3 in FIG. 12, the rotating antennas 38 and 39 are placed in the direction in which the rotating antennas 38 and 39 heat the center, that is, in the stop position shown in FIG. Stop. If the low temperature portion is any one of B1 and C1 in FIG. 12, the rotating antennas 38 and 39 are stopped in the direction in which the rotating antennas 38 and 39 heat the left direction, that is, in the stop position shown in FIG. . Further, if the lowest temperature point is any of B4 and C4 in FIG. 12, the rotating antennas 38 and 39 are stopped in the direction in which the rotating antennas 38 and 39 heat in the right direction, that is, in the stop position shown in FIG. Let If the low temperature portion is any one of A2 and A3 in FIG. 12, the rotating antennas 38 and 39 are stopped in the direction in which the rotating antennas 38 and 39 heat the front, that is, in the stop position shown in FIG. If the low temperature portion is either D2 or D3 in FIG. 12, the rotating antennas 38 and 39 are stopped in the direction in which the rotating antennas 38 and 39 heat the rear, that is, in the direction shown in FIG. By doing so, the temperature of a low temperature part rises and the whole temperature becomes uniform.

  However, if microwaves are continuously radiated into the heating chamber while the rotating antenna is stopped at a predetermined position, the rotating antenna itself may be excessively heated and melt. In view of this point, the antenna control unit 101 reciprocally swings the rotating antenna about a predetermined angle (for example, ± 5 degrees) around the target angle (stop position). Thereby, deterioration of the rotating antenna can be prevented without affecting the local heating effect. In addition, since the rotating antenna continues to stop during the microwave radiation, the microwave is prevented from being excessively concentrated on a part of the rotating antenna to prevent overheating.

  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 infrared sensor 10 detects the initial temperature distribution, that is, the initial temperature T0 at each temperature detection location (S201). Next, the food point A determination part 104 determines whether it is frozen food by determining whether the initial temperature T0 of each detection location is lower than the predetermined temperature TA (S202). That is, the portion lower than the freezing determination temperature (for example, 0 ° C.) is determined to be the food point A by determining that the frozen food is placed instead of the storage table.

  Next, the infrared sensor 10 detects the temperature distribution, that is, the temperature at each temperature detection location (S203). At this time, a predetermined time (for example, 3 minutes) has not yet elapsed from the start of heating (S204-No), and the detected maximum temperature Tmax is a predetermined temperature TC (for example, 60 ° C.). If not higher (S205-No), the food point B determination is performed (S206). The food point B determination is performed by the food point B determination unit 105 to determine the food at normal temperature. The difference between the temperature T detected in S203 and the initial temperature T0 detected in S201 is calculated and further divided by the elapsed time t. Thus, the rate of temperature increase per unit time is calculated. If this calculated value is greater than a preset temperature increase rate ΔTB, it is determined that the temperature detection location is a normal temperature food.

If the predetermined time has already passed (S204-Yes), or if the maximum temperature Tmax is higher than the predetermined temperature TC (S205-Yes), the antenna control is performed without performing the food point B determination (S207). Then, the heating end determination unit 103 determines whether or not the heating is finished. If the heating is not finished yet, the process returns to S203 to repeat the processing from the temperature distribution detection. If the heating is finished, the magnetron 32 is stopped and the heating is finished. Exit.

  Here, since the food point B determination is repeatedly performed, the point of the room temperature food continues to change. It has the effect of being corrected next even if a wrong food point is judged due to noise or the like. Then, when the maximum temperature exceeds the predetermined temperature or the predetermined time has elapsed, the food point B determination is not performed at the last point where the food point B determination has been made. That is, as the temperature of the food becomes higher, the rate of temperature increase becomes gentler, and the rate of temperature increase per unit time gradually becomes smaller. When it becomes small, it will be judged as non-food by the food point B judgment. In other words, this is to prevent food points from decreasing and eventually disappearing.

  Next, the antenna control S207 of FIG. 14 will be described using the flowchart of FIG. The location of the lowest temperature is extracted from the temperature detection locations determined as food point A or food point B 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 (No in S306), the antenna control unit 101 continuously rotates the rotating antennas 38 and 39 so as to stir the radio wave in the heating chamber 34. (S307).

  The antenna control unit 101 executes one of steps S307 and S308 to S312. Since this antenna control process is repeatedly performed until the heating is completed as shown in FIG. 14, the control works so as to always heat the low temperature portion, and the low temperature portion is eliminated and the entire temperature distribution is uniform.

(Embodiment 2)
Next, a second embodiment of the operation of the microwave heating apparatus of the present invention will be described with reference to the flowchart of FIG.

  When heating is started, first, the infrared sensor 10 detects the initial temperature T0 of each temperature detection location (S401), and then the food point A determination unit 104 determines whether the initial temperature T0 of each detection location is lower than a predetermined temperature TA. It is determined whether it is frozen food by determining (S402). Next, the temperature of each temperature detection location is detected by the infrared sensor 10 (S403). The steps so far are the same as those in the first embodiment.

  Next, the food discrimination unit 102 calculates the temperature difference between the detected temperature at each temperature detection location and the initial temperature, and extracts the maximum temperature difference, that is, the temperature rise value ΔTmax at the maximum temperature rise location (S404). . If this maximum temperature rise value ΔTmax is not larger than a preset value ΔTC (for example, 50K) (S405—No), the food point B determination is performed (S406). The food point B determination is performed by the food point B determination unit 105 to determine a normal temperature food. The temperature difference between the detected temperature at each temperature detection location calculated in S404 and the initial temperature is a predetermined ratio to the maximum temperature rise value ΔTmax. If it is larger than a value obtained by multiplying α (for example, 0.5), it is determined that the temperature detection location is a food at normal temperature.

  If the maximum temperature rise value ΔTmax is larger than the preset value ΔTC (S405—Yes), the antenna control is performed without performing the food point B determination (S407). Then, the heating end determination unit 103 determines whether or not the heating is finished. If the heating is not finished yet, the process returns to S403 to repeat the processing from the temperature distribution detection. If the heating is finished, the magnetron 32 is stopped and the heating is finished. Exit. The antenna control S407 is as shown in FIG.

Here, as in the first embodiment, since the food point B determination is repeatedly performed, the point of the room temperature food continues to change. If the maximum temperature increase value ΔTmax is larger than the predetermined set value ΔTC, the food point B determination is not performed at the last point where the food point B determination has been made. That is, as the food becomes hot, the temperature rises gradually, and ΔTmax no longer changes. However, since the temperature rises little by little even in a portion that is not food, such as a mounting table, if ΔTmax does not change, the mounting table will eventually be determined as a food point. In order to prevent this, the food point is determined when the maximum temperature rise value ΔTmax is larger than a predetermined set value ΔTC.

  As described above, the microwave oven 31 according to the first and second embodiments can intensively heat a specific portion in the heating chamber 34 by two rotating antennas. Can be detected and the temperature distribution of the food can be detected, and a spot can be applied to the lowest temperature portion, which is the low temperature portion of the food, to be heated locally.

  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 in FIG. 15 is not limited to the order of searching for the minimum temperature portion of the food, and as a result, the order of searching for the whole food may be performed in another order.

  As described above, the present invention detects the temperature distribution in the heating chamber, discriminates the food from the detected temperature, and determines the portion having the strong radiation directivity of the rotating antenna disposed in the heating chamber as the food. Since it can be controlled in a predetermined direction from the detected temperature and can be centrally heated, it can also be used for various dielectrics such as food, such as heating, thawing, ceramic heating, drying, sintering, or biochemical reaction. It is something that can be done.

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) Cross-sectional configuration view of the microwave heating apparatus viewed from above (B-B ′ cross-sectional view 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 A flowchart for explaining the operation of the antenna control unit 101 A flowchart for explaining the operation of the control unit 411 according to the second embodiment.

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)
102 food discrimination unit 108 antenna angle storage unit 411 control means

Claims (3)

Microwave generation means;
A waveguide for transmitting microwaves from the microwave generating means;
A heating chamber for storing an object to be heated by the microwave;
A plurality of rotating antennas for radiating the microwave from the waveguide to the heating chamber;
Drive means for rotationally driving the rotating antenna;
Temperature distribution detecting means for detecting a temperature distribution in the heating chamber;
Control means for controlling the microwave generating means and the driving means;
The control means has a food discrimination unit for discriminating whether each detection region is food or non-food from each temperature detected by the temperature distribution detection means,
The food discriminating unit is configured to start heating earlier than a value obtained by multiplying a maximum temperature difference by a predetermined ratio among temperature differences between the temperature detected by the temperature distribution detecting unit and the temperature detected by the temperature distribution detecting unit at the beginning of heating. An area with a large temperature difference from the detected temperature is identified as food,
The control unit includes an antenna angle storage unit that 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, and the temperature distribution detecting unit The angle of the rotating antenna is stored in the antenna angle so that a portion having a strong radiation directivity of the rotating antenna is directed to a low temperature portion of each of the detection regions determined by the food discrimination unit as food in the temperature of each detection region detected by A microwave heating apparatus configured to stop and control the rotating antenna at an angle of the selected rotating antenna . The microwave heating apparatus according to claim 1 , wherein the food discrimination unit determines the food discrimination when the maximum temperature of the temperatures detected by the temperature distribution detection means exceeds a predetermined temperature. The microwave heating apparatus according to claim 1 , wherein the food discrimination unit determines the food discrimination when a predetermined time has elapsed since the start of heating.

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