Cooking appliance

Abstract

To achieve both prevention of early cut-off and securement of safety of a cooker.SOLUTION: A cooking device 1 includes a heat generating member 10 on which a cooked object C can be placed and which is attachable to and detachable from a heating chamber 5 and generates heat when microwaves are radiated, an infrared sensor 16 capable of measuring a temperature of an object present in a detection area 17 set in the heating chamber 5 in a non-contact manner, and a controller 20 that executes a microwave heating process of heating the cooked object C with microwaves output from a microwave generator 13. The controller 20 determines whether or not the heat generating member 10 is mounted at the predetermined position in the heating chamber 5 based on the detection value of the infrared sensor 16 during the execution of the microwave heating treatment, determines whether or not the carbonized product B is present in the heating chamber 5 based on the detection value of the infrared sensor 16 during the subsequent execution of the microwave heating treatment when it is determined that the heat generating member 10 is not mounted at the predetermined position, and reduces or stops the output of the microwave generators 13 when it is determined that the carbonized product B is present.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a cooking appliance. [Background technology]

[0002] Patent Document 1 discloses, as an example of a cooking appliance, a high-frequency heating device that includes a high-frequency generating means for heating food in a heating chamber with high-frequency waves, a surface temperature detecting means for detecting the surface temperature of the food in the heating chamber without contact, and an internal temperature detecting means for detecting the ambient temperature in the heating chamber. In order to prevent premature burnout when using a heat-generating sheet that absorbs microwaves, the control unit of the high-frequency heating device is configured to reduce the output level of the high-frequency generating means when the surface temperature is above a predetermined value and the ambient temperature is above a predetermined value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-127924 Summary of the Invention [Problem to be solved by the invention]

[0004] However, if carbonized matter, such as food residue, is present in the heating chamber, sparks may be generated from the carbonized matter during high-frequency heating (microwave heating). The above configuration cannot detect such carbonized matter, and therefore safety cannot be fully ensured.

[0005] An object of the present invention is to prevent premature burnout of a heat-generating member that absorbs microwaves and generates heat while in use, while ensuring the safety of the cooker. [Means for solving the problem]

[0006] One aspect of the present invention provides a cooker comprising: a heating chamber in which an item to be cooked is accommodated; a microwave generator that outputs microwaves to the heating chamber; a heat-generating element that can be placed with the item to be cooked and is detachable from the heating chamber and generates heat when the microwaves are radiated; a radiation thermometer that has a detection area set within the heating chamber and can measure the temperature of an object present within the detection area in a non-contact manner; and a controller that performs a microwave heating process to heat the item to be cooked with the microwaves output from the microwave generator, wherein the controller performs a heat-generating element detection process during the microwave heating process to determine whether the heat-generating element is attached to a predetermined position in the heating chamber based on the detection value of the radiation thermometer, and if it determines that the heat-generating element is not attached to the predetermined position, then performs a carbide detection process during the microwave heating process to determine whether carbides are present in the heating chamber based on the detection value of the radiation thermometer, and if it determines that carbides are present, reduces or stops the output of the microwave generator.

[0007] According to the above configuration, the controller first determines whether a heat-generating element is attached to a predetermined position based on the detection value of the radiation thermometer. During microwave heating, the surface temperature of the heat-generating element rises rapidly to a high temperature, making it possible to determine the presence or absence of a heat-generating element using the detection value of the radiation thermometer. When a heat-generating element is not attached, the controller determines whether carbonized matter is present in the heating chamber based on the detection value of the radiation thermometer. When there are signs of sparks being generated from the carbonized matter, the carbonized matter becomes hot, making it possible to determine the presence or absence of carbonized matter using the detection value of the radiation thermometer. When carbonized matter is detected, the output of the microwave generator is reduced or stopped. This prevents damage to the heating chamber due to sparks and improves the safety of the cooker. Furthermore, the carbonized matter detection process is performed based on the detection value of the radiation thermometer after it has been determined that a heat-generating element is not attached to a predetermined position. This prevents premature shutdown due to erroneous detection (a situation in which the output is reduced or stopped because the food being cooked is not sufficiently heated).

[0008] When the controller determines that the heat-generating member is attached to the predetermined position, the controller may continue the microwave heating process without executing the carbide detection process.

[0009] According to the above configuration, when the heat-generating element is attached in the predetermined position, the carbide detection process is not executed, so that even if the heat-generating element becomes hot, it is possible to prevent a false detection of the presence of carbides. Therefore, it is possible to prevent a decrease or stop of output due to a false detection, and cooking can be continued appropriately when using the heat-generating element.

[0010] In the heat-generating member detection process, the controller may determine that the heat-generating member is attached to the predetermined position if the rate of increase in the detection value is equal to or greater than a predetermined heat-generating member detection threshold value.

[0011] According to the above configuration, in view of the fact that the surface temperature of the heat-generating component rises rapidly during microwave heating, the presence or absence of the heat-generating component can be accurately determined using the detection value of the radiation thermometer.

[0012] The controller may execute the heat-generating member detection process at a determination point when a predetermined determination time has elapsed since the start of the microwave heating process.

[0013] According to the above configuration, when the microwave heating process starts, the surface temperature of the heat-generating component rises rapidly to a high temperature, and therefore the presence or absence of the heat-generating component can be accurately and quickly determined using the detection value of the radiation thermometer.

[0014] The controller may execute the heat-generating component detection process at a determination point when a predetermined determination time has elapsed since the start of the microwave heating process, and in the heat-generating component detection process, determine whether the heat-generating component is attached to the predetermined position by comparing the rate of increase of the detection value with a predetermined heat-generating component detection threshold, and the rate of increase may be calculated based on the amount of increase in the detection value from the calculation start point when a predetermined waiting time has elapsed since the start of the microwave heating process.

[0015] Immediately after the start of microwave heating, the temperature rise of the food or heat-generating component is unstable due to the influence of the temperatures inside and outside the heating chamber. With the above configuration, the temperature rise rate is calculated excluding the values ​​detected by the radiation thermometer during the period from the start of microwave heating to the start of calculation. This increases the reliability of the calculated temperature rise rate, enabling accurate determination of the presence or absence of a heat-generating component.

[0016] When the heat-generating element is attached to the predetermined position, the heat-generating element may be located within the detection area, and when the heat-generating element is removed from the heating chamber, at least a portion of the bottom surface of the heating chamber may be located within the detection area.

[0017] According to the above configuration, when the heat-generating member is attached to a predetermined position, the presence or absence of the heat-generating member can be determined with high accuracy. When the heat-generating member is removed, the presence or absence of carbides on the bottom surface can be determined with high accuracy. [Effects of the Invention]

[0018] According to the present invention, it is possible to prevent premature burnout when using a heat-generating member that absorbs microwaves and generates heat, while also ensuring the safety of the cooker. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a front view of a cooking appliance according to an embodiment. [Figure 2] FIG. 2 is a perspective view of the cooking device with the heating chamber open. [Figure 3] Cross-sectional view of a cooker. [Figure 4] Block diagram of the cooker. [Figure 5] 10 is a flowchart showing an example of a cooking process executed by a controller. [Figure 6] 10 is a flowchart showing an example of a cooking process executed by a controller. [Figure 7] 10 is a flowchart showing an example of a cooking process executed by a controller. [Figure 8]8 is a graph showing the transition of the detected value of a radiation thermometer during the execution of the cooking process shown in FIGS. 5 to 7. [Figure 9] A partial enlarged view of Figure 8. [Figure 10] FIG. 10 is a cross-sectional view of a cooking device according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, embodiments will be described with reference to the drawings. Note that the same or corresponding elements are designated by the same reference numerals throughout the drawings, and detailed descriptions thereof will be omitted.

[0021] Hereinafter, a cooking appliance 1 according to an embodiment will be described with reference to the drawings, taking a microwave oven as an example. Note that the same or corresponding elements are denoted by the same reference numerals throughout the drawings, and detailed descriptions thereof will be omitted.

[0022] (heating chamber) Referring to FIG. 3, the main body 2 of the cooking appliance 1 has a double structure consisting of an inner shell portion 3 and an outer shell portion 4 surrounding the inner shell portion 3. Both the inner shell portion 3 and the outer shell portion 4 are rectangular box-shaped. The main body 2 forms a heating chamber 5 inside the inner shell portion 3, and an outer space 6 outside the inner shell portion 3 and inside the outer shell portion 4. The heating chamber 5 is defined by an inner bottom wall 3a, an inner upper wall 3b, an inner rear wall 3c, and a pair of inner walls 3d of the inner shell portion 3, and is open to the front. In the following description, the surface of the inner bottom wall 3a that faces the heating chamber 5 will be referred to as the "bottom surface 5a" of the heating chamber 5.

[0023] 1 and 2, heating chamber 5 is opened and closed by a door 7 swingably attached to the front of main body 2. On the front surface of door 7, an operation panel 8 is provided which is operated by the user.

[0024] (Trays and heat-generating components) 2 and 3, the main body 2 is provided with a plurality of support parts 11 that detachably support the tray 9 and the heat-generating member 10 housed therein within the heating chamber 5. Each support part 11 is composed of a pair of rails that protrude from each of the pair of inner walls 3d so as to approach each other and extend in the front-to-rear direction. The pair of rails are arranged at the same height.

[0025] The multiple support portions 11 support the tray 9 at different support positions in the height direction. Each support position is set between the inner bottom wall 3a and the inner top wall 3b. In this embodiment, the cooker 1 has two support portions 11, including an upper support portion 11a that supports the tray 9 at an upper support position and a lower support portion 11b that supports the tray 9 at a lower support position that is lower than the upper support position.

[0026] The tray 9 is a square plate-like shape of a size that can be stored horizontally in the heating chamber 5. The tray 9 is made of a material (such as ceramics or glass) that is microwave-transparent.

[0027] The heat-generating member 10 is composed of a plate-shaped upper member 10a made of a material with high thermal conductivity (e.g., steel), and a lower member 10b attached to the bottom surface of the upper member 10a. Although detailed illustration is omitted, ribs and grooves are arranged alternately on the upper surface of the upper member 10a. The upper member 10a is the part that receives heat from the lower member 10b through solid-state heat transfer and becomes hot. The lower member 10b is plate- or sheet-shaped and is made of a material (e.g., ferrite) that has the property of generating heat when microwaves are radiated, i.e., microwave-absorbing properties. The lower member 10b is a heat-generating part (heat-generating member in the narrow sense) that generates heat by itself when microwaves are radiated.

[0028] The user opens the door 7 and places the food in the heating chamber 5. At this time, the user can select the method of placing the food from the following patterns A to C, depending on the food and the desired cooking method.

[0029] Pattern A: The tray 9 is removed from the heating chamber 5, and the food to be cooked is placed on the bottom surface 5a. Pattern B: The heat generating member 10 is removed from the tray 9, the food to be cooked is placed on the tray 9, and the tray 9 is placed in the heating chamber 5 without the heat generating member 10. Pattern C: The heat generating member 10 is placed in the tray 9, the food to be cooked is placed on the heat generating member 10, and the tray 9 with the heat generating member 10 attached is placed in the heating chamber 5.

[0030] Pattern B is further divided into pattern B1, in which the tray 9 is accommodated in the upper support position, and pattern B2, in which the tray 9 is accommodated in the lower support position. Similarly, pattern C is further divided into pattern C1, in which the upper support portion 11a is used, as shown by the solid line in Fig. 3, and pattern C2, in which the lower support portion 11b is used, as shown by the two-dot chain line in Fig. 3.

[0031] The user closes the door 7 and inputs a command for the cooking method and a command to start cooking on the operation panel 8 (see Figure 1). In response to the command, the cooker 1 performs a "cooking process" to heat and cook the food in the heating chamber 5. The "cooking process" refers to a series of processes from the start to the end of cooking.

[0032] (heating means / sensor) 3, cooking appliance 1 includes microwave generator 13, heater 14, temperature sensor 15, and infrared sensor 16. These are provided in main body 2.

[0033] The microwave generator 13 is configured, for example, by a magnetron and generates microwaves. The microwave generator 13 is disposed at the end of a waveguide 12 installed below the inner bottom wall 3a. The microwaves are guided by the waveguide 12, pass through the inner bottom wall 3a, and are output from below into the heating chamber 5.

[0034] The heater 14 is, for example, a resistance heater, and generates heat when electricity is applied. The heater 14 is disposed close to the inner upper wall 3b. When the heater 14 generates heat, radiant heat is emitted from above into the heating chamber 5, heating the heating chamber 5. The heater 14 may also be a heater used to heat the heating chamber 5 and the food contained therein by heat transfer other than radiant heat, such as a convection type or steam heating type.

[0035] Temperature sensor 15 is, for example, a thermistor, and detects the temperature inside heating chamber 5 (hereinafter also referred to as "internal temperature"). Temperature sensor 15 is attached to inner upper wall 3b so that its temperature measuring part is exposed inside heating chamber 5.

[0036] Infrared sensor 16 is a type of radiation thermometer. Infrared sensor 16 has a detection area 17 set within heating chamber 5, and detects the amount of infrared radiation emitted from an object present within detection area 17. Based on the detected amount of infrared radiation, the temperature of the object can be measured without contact. Infrared sensor 16 may output either the amount of infrared radiation or the temperature as its detection value.

[0037] The infrared sensor 16 is attached to one of the inner walls 3d (for example, the right inner wall 3d) and is disposed above the upper support part 11a. The detection area 17 is conical, with its apex at the attachment position of the infrared sensor 16, and its central axis is directed obliquely downward from the attachment position.

[0038] In the case of pattern A, the food C placed on the bottom surface 5a is located within the detection area 17. In the case of pattern B2, the food C placed on the tray 9 is located within the detection area 17. In the case of pattern C2, the food C placed on the heat-generating member 10 is located within the detection area 17. In the case of pattern B1, the food C is often not located within the detection area 17, in which case the tray 9 is located within the detection area 17.

[0039] In the case of pattern C1, the food C is often not located within the detection area 17, in which case the heat-generating member 10 is located within the detection area 17. When the tray 9 and the heat-generating member 10 are removed from the heating chamber 5 and the food C is not placed on the bottom surface 5a (so-called "empty baking"), the bottom surface 5a is located within the detection area 17. If carbonized material B is present on the bottom surface 5a, the carbonized material B may enter the detection area 17.

[0040] (Controller) 4, the cooking appliance 1 includes a controller 20. Although not shown in detail, the controller 20 may be disposed in the exterior space 6 (see FIG. 3). The controller 20 is connected to the operation panel 8, the microwave generator 13, the heater 14, the temperature sensor 15, and the infrared sensor 16.

[0041] The controller 20 includes, for example, a central processing unit (CPU) or a micro processing unit (MPU) that cooperates with software to realize predetermined functions. The controller 20 may be configured with hardware circuits such as dedicated electronic circuits or reconfigurable electronic circuits designed to realize predetermined functions, or may be configured with various semiconductor integrated circuits. Examples of various semiconductor integrated circuits include, in addition to CPUs and MPUs, microcomputers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), and application specific integrated circuits (ASICs).

[0042] The controller 20 may include a memory 21 such as a RAM (Random Access Memory) and a ROM (Read Only Memory). The memory 21 stores a program for executing the cooking process and information used by the program. The controller 20 may also include a timer 22 for measuring time.

[0043] The controller 20 starts the cooking process when a command to start cooking is input via the operation panel 8. During the cooking process, the controller 20 controls the operation of the microwave generator 13 and the heater 14 according to the detection values ​​successively output from the temperature sensor 15 and the infrared sensor 16, the time measured by the timer 22, etc.

[0044] The controller 20 performs cooking processing according to one of the modes of "microwave mode," "heater mode," and "combined mode" in response to the cooking method command inputted through the operation panel 8. In "microwave mode," the controller 20 performs only "microwave heating processing" during cooking processing. In "heater mode," the controller 20 performs only "heater heating processing" during cooking processing. In "combined mode," the controller 20 performs both "microwave heating processing" and "heater heating processing" during cooking processing.

[0045] In the heater heating process, the controller 20 activates the heater 14 to heat the food to be cooked with the heat from the heater 14.

[0046] (Microwave heating treatment) In the microwave heating process, the controller 20 activates the microwave generator 13, and the food to be cooked is heated by the microwaves output from the microwave generator 13 to the heating chamber 5.

[0047] In pattern A, the food is placed on the bottom surface 5a. In the microwave heating process, microwaves are radiated to the food, and the food is heated by the microwaves. In pattern B, a tray 9 is interposed between the bottom surface 5a and the food. In the microwave heating process, microwaves pass through the tray 9 and are radiated to the food C. The food C is heated by the microwaves within the tray 9. The temperature of the tray 9 may rise due to an increase in the temperature of the food C or the temperature inside the oven, but it is not heated by the microwaves.

[0048] In the case of pattern C, the tray 9, the lower member 10b, and the upper member 10a are interposed between the bottom surface 5a and the food. During the microwave heating process, microwaves pass through the tray 9 and are irradiated onto the lower member 10b. The lower member 10b (heat generating portion) generates heat, and the heat is transferred to the upper member 10a, causing the upper member 10a to become hot. The food C is heated by the upper member 10a due to the microwaves.

[0049] If carbide B is present in the heating chamber 5 (for example, on the bottom surface 5a), the carbide B will receive microwaves and generate heat. When the carbide B reaches a certain temperature, sparks will be generated from the carbide B. The inner bottom wall 3a forming the bottom surface 5a is microwave-transparent, and therefore microwaves can be output to the heating chamber 5. The inner bottom wall 3a is typically made of glass or ceramics, but these materials are not only microwave-transparent but also brittle. Therefore, if a spark is generated, the inner bottom wall 3a is likely to be damaged.

[0050] (Heat-generating material detection treatment, carbide detection treatment) Therefore, when carbide B is detected, the controller 20 reduces or stops the output of the microwave generator 13, ensuring the safety of the cooker 1. On the other hand, in the case of pattern C1, the heat-generating member 10 is located within the detection area 17. In general, the temperature rise of the heat-generating member 10 (the amount of heat generated by microwave absorption by the lower member 10b) is higher than the temperature rise of the carbide B (the amount of heat generated by microwave absorption by the carbide). Therefore, unless the heat generated by the heat-generating member 10 is erroneously detected as heat generated by the carbide B, there is a risk that the cooking process will end prematurely, or that so-called premature cut-off will occur. Below, with reference to Figures 5 to 9, we will explain the control executed to ensure safety and continue the cooking process appropriately at the same time.

[0051] 5 to 7 when a command for a predetermined recipe is input via the operation panel 8 and then a command to start cooking is input via the operation panel 8. Here, the cooking process is exemplified as a combined mode, in which a microwave heating process and a heater heating process are performed once each in this order.

[0052] 5, in response to input of a cooking start command, the controller 20 starts a microwave heating process (step S1). During the microwave heating process, the controller 20 executes a heat-generating member detection process to determine whether or not the heat-generating member 10 is attached to the upper support position (i.e., whether or not pattern C1 has been selected as the method of storing the food C) based on the detection value of the infrared sensor 16.

[0053] To perform the heat-generating member detection process, the controller 20 determines whether a predetermined waiting time T1 has elapsed since the start time t0 of the microwave heating process (step S2). The time is measured by the timer 22 (and so on). When the waiting time T1 has elapsed since the start time t0 (S2: YES), the controller 20 acquires the detection value (hereinafter referred to as the "first detection value") of the infrared sensor 16 at that time (calculation start time t5) (step S3). The acquired first detection value is temporarily stored in the memory 21.

[0054] Next, the controller 20 determines whether a predetermined determination time T has elapsed since the start time t0 (step S4). If the determination time T has elapsed since the start time t0 (S4: YES), the controller 20 acquires the detection value (hereinafter referred to as the "second detection value") of the infrared sensor 16 at that time (determination time t10) (step S5).

[0055] The controller 20 calculates the rate of increase of the detection value of the infrared sensor 16 from the first detection value and the second detection value (step S6). The rate of increase may be a value obtained by subtracting the first detection value from the second detection value (the increase in the detection value during the period T2 from the calculation start time t5 to the determination time t10), or may be a value obtained by dividing the increase by the period T2.

[0056] At this determination time point t10, the controller 20 executes a heat-generating member detection process. In this embodiment, as the heat-generating member detection process, the controller 20 determines whether the calculated rate of increase is equal to or greater than a heat-generating member detection threshold value Th1 pre-stored in the memory 21 (step S7).

[0057] If the rate of increase is equal to or greater than the heat-generating member detection threshold Th1 (S7: YES), the controller 20 determines that the heat-generating member 10 is attached to the upper support position, and the process proceeds to the flow shown in Fig. 6, where the microwave heating process continues. If the rate of increase is less than the heat-generating member detection threshold Th1 (S7: NO), the controller 20 determines that the heat-generating member 10 is not attached to the upper support position, and the process proceeds to the flow shown in Fig. 7, where the microwave heating process continues.

[0058] In the flow shown in Fig. 7, the controller 20 executes a carbide detection process in parallel with the microwave heating process, which determines whether or not carbide B is present on the bottom surface 5a of the heating chamber 5 based on the detection value of the infrared sensor 16. On the other hand, in the flow shown in Fig. 6, the controller 20 continues the microwave heating process without executing the carbide detection process.

[0059] 6, if it is determined in the heat-generating member detection process that the heat-generating member 10 is attached to the upper support position (S7: YES), the controller 20 determines whether the termination condition for the microwave heating process is met (step S11). The termination condition for the microwave heating process is, for example, a condition that a preset cooking time has elapsed since the start time t0. If the heat-generating member 10 is attached to the upper support position, the termination condition for the microwave heating process does not include a condition related to the detection of carbide B.

[0060] While the termination condition is not met (S11: NO), the controller 20 continues the microwave heating process. When the termination condition is met (S11: YES), the controller 20 ends the microwave heating process (step S12) and starts the heater heating process (step S21).

[0061] During the heater heating process, the controller 20 determines whether a termination condition for the heater heating process is met (step S22). The termination condition for the heater heating process may be, for example, that a preset cooking time has elapsed since the start of the heater heating process, or that the internal temperature detected by the temperature sensor 15 has reached a predetermined value (in other words, that steam from the food C has been detected based on the value detected by the temperature sensor 15). While the termination condition is not met (S22: NO), the controller 20 continues the heater heating process. When the termination condition is met (S22: YES), the controller 20 ends the heater heating process (step S23). This ends the cooking process.

[0062] 7, when it is determined in the heat-generating member detection process that the heat-generating member 10 is not attached to the upper support position (S7: NO), the controller 20 determines whether the detection value of the infrared sensor 16 is equal to or greater than the carbide detection threshold value Th2 pre-stored in the memory 21 (step S31). This determination process is the carbide detection process.

[0063] If the detected value is less than the carbide detection threshold Th2 (S31: NO), the controller 20 determines that carbide B is not present on the bottom surface 5a or that there is no sign of sparks from carbide B, and determines whether the termination condition for the microwave heating process is met (step S32). While the termination condition is not met (S32: NO), the controller 20 continues the microwave heating process while monitoring the detected value and continuing the carbide detection process (step S31).

[0064] If the detected value remains below the carbide detection threshold Th2 and the termination condition is met (S32: YES), the controller 20 terminates the microwave heating process (step S33). After that, the process proceeds to step S21 shown in FIG. 5, and the heater heating process is performed in the same manner as described above.

[0065] If the detection value becomes equal to or greater than the carbide detection threshold Th2 before the termination condition is met (S31: YES), the controller 20 determines that carbide B is present on the bottom surface 5a and that there are signs of a spark occurring, and reduces the output of the microwave generator 13 (step S34).

[0066] The output may be stopped. That is, the cooking process may be forcibly terminated when carbonized material B is detected. Alternatively, the output may be reduced and then stopped. The microwave heating process may be continued with the output suppressed until the termination condition is met. If the microwave heating process is continued, the heater heating process that was scheduled to be performed thereafter may or may not be performed.

[0067] 8 and 9, the solid line indicates the change in the detection value of the infrared sensor 16 when the cooking process is performed in pattern C1. The dashed line indicates the change in the detection value of the infrared sensor 16 when the cooking process is performed in pattern C2. The broken line indicates the change in the detection value of the infrared sensor 16 when the cooking process is performed in a so-called empty-baking state and carbonized matter is present on the bottom surface 5a. In patterns A, B1, and B2, the detection value of the infrared sensor 16 changes in the same way as the dashed line.

[0068] Referring to the solid line, in pattern C1, the food item C is outside the detection area 17, and the infrared sensor 16 directly detects the surface temperature of the heat-generating member 10. As a result, the detected value also rises sharply. On the other hand, referring to the dashed-dotted line, in pattern C2, the food item C is within the detection area 17, and the infrared sensor 16 detects the surface temperature of the food item C. As a result, the detected value does not rise sharply as in pattern C1.

[0069] Referring to the dashed-dotted line, during the determination time T from the start time t0 of the microwave heating process to the determination time t10, the detection value of the infrared sensor 16, i.e., the surface temperature of the food C, does not rise significantly. Therefore, at the determination time t10, the rate of increase in the detection value is significantly below the heat-generating element detection threshold Th1. The controller 20 can accurately determine that the heat-generating element 10 is not attached to the upper support position. Even during the microwave heating process after the determination time t10, the surface temperature of the food C does not rise like the heat-generating element 10 or the carbide B. Therefore, when the termination condition is met, the detection value is significantly below the carbide detection threshold Th2. The controller 20 can accurately determine that the heat-generating element 10 is not attached to the upper support position and that no carbide B is present.

[0070] For ease of comparison between the solid and dashed lines, FIGS. 8 and 9 show the case where the detection value of the infrared sensor 16 at the calculation start time t5, i.e., the first detection value Tinf_t5, is the same for both the solid and dashed lines. In this case, the detection value of the infrared sensor 16 at the determination time t10, i.e., the second detection value Tinf_t10, is higher for the solid line than for the dashed line. This indicates that the temperature rise rate of the heat-generating member 10 is higher than that of the carbide B because the heat-generating member 10 has higher microwave absorption than the carbide B. The heat-generating member detection threshold Th1 is set midway between the temperature rise gradient indicated by the solid line and the temperature rise gradient indicated by the dashed line. Therefore, by comparing the rate of rise of the detection value with the heat-generating member detection threshold Th1, the controller 20 can accurately determine whether the detection value is rising due to the presence of the heat-generating member 10 or the presence of the carbide B. A specific value of the heat-generating member detection threshold value Th1 for achieving such high determination accuracy can be obtained through testing using an actual device.

[0071] Even if the rate of increase calculated at determination time t10 is less than the heat-generating element detection threshold Th1, the presence of carbide B will cause the detection value to continue rising during the microwave heating process. Just before a spark occurs, the detection value rises to a value that would not be reached if food C were being cooked normally without carbide B present. Therefore, the carbide detection threshold Th2 is set to a value midway between the surface temperature of food C just before a spark occurs and the surface temperature of food C that can be reached when food C is being cooked normally (e.g., 100°C). Therefore, by comparing the detection value with the carbide detection threshold Th2 under circumstances in which it can be determined that the heat-generating element 10 is not attached to the upper support position, the controller 20 can accurately determine whether there are signs of a spark from carbide B, thereby preventing premature cutoff due to erroneous detection.

[0072] If the heat-generating member 10 is attached to the upper support position, the surface temperature of the heat-generating member 10 exceeds the carbide detection threshold Th2. In some cases, the temperature of the heat-generating member 10 may exceed the upper limit Tinf_M of the detection value of the infrared sensor 16 (the infrared sensor 16 may enter a saturated state). However, if the heat-generating member detection process determines that the heat-generating member 10 is attached to the upper support position, the carbide detection process is not executed. This prevents the output from being undesirably reduced or stopped, and the cooking process can be continued appropriately.

[0073] The determination time T is shorter than the time it takes for the surface temperature of the heat-generating member 10 to reach the carbide detection threshold value Th2. For example, the determination time T is set to about 10 to 20 seconds.

[0074] Of the two detection values ​​used to calculate the rate of increase, one is acquired at determination time t10 and the other is acquired at calculation start time t5, which is the time when standby time T1 has elapsed from start time t0. During this standby time T1, the temperature increase trend of the food or heat-generating component 10 is unstable due to the influence of the temperature inside the cooking chamber at start time t0 and the temperature in the room where the cooker 1 is placed. Since the rate of increase is calculated excluding detection values ​​acquired during this period, the reliability of the calculation result of the rate of increase is increased, and the heat-generating component detection process can be performed with high accuracy.

[0075] Although the embodiment has been described above, the above configuration is merely an example and can be modified as appropriate within the scope of the present invention.

[0076] For example, referring to FIG. 10, the heat generating member 10 may be tray-shaped. In the above embodiment (see FIG. 3), the heat generating member 10 is removably housed in a microwave-transparent tray 9. In contrast, in a modified example shown in FIG. 10, the upper member 10a of the heat generating member 10 is formed in a tray shape, and the lower member 10b (heat generating portion) of the heat generating member 10 is stacked on the outer bottom surface of the upper member 10a. In this case, the heat generating member 10 is supported by a support 11. This modified example also achieves the same effects as the above embodiment.

[0077] In the above embodiment and modified example, two positions, an upper support position and a lower support position, are set in the main body 2 that forms the heating chamber 5 as positions for mounting the tray 9 and the heat-generating member 10 housed therein. In addition, in the heat-generating member detection process, the controller 20 determines whether the heat-generating member 10 is mounted in the upper support position, which is an example of a predetermined position in the heating chamber 5. However, this is just one example, and the main body 2 may be set with one or three or more positions at which the heat-generating member 10 can be mounted.

[0078] The timing for acquiring the second detection value Tinf_t10 is not limited to the determination time t10, but may be a timing prior to the determination time t10. [Explanation of symbols]

[0079] 1 Cooker 1 Cooker 2 Main unit 3 Inner shell 3a Inner bottom wall 3b Inner upper wall 3c Medial posterior wall 3d inner wall 4 Outer shell 5 Heating chamber 5a Bottom 6 Outside space 7 Doors 8 Operation panel 9 trays 10 Heat generating member 10a Upper member 10b Lower member (heat generating part) 11 Support part 11a Upper support part 11b Lower support part 12 Waveguide 13 Microwave Generator 14 Heater 15 Temperature Sensor 16 Infrared sensor (radiation thermometer) 17 Detection area 20 Controller 21 Memory 22 Timer Pattern A B carbide Pattern B B1 pattern B2 pattern C Cooked food T Judgment time T1 Waiting Time T2 period t0 Start time t5 Start of calculation t10 Judgment time Th1 Heat-generating component detection threshold Th2 carbide detection threshold Tinf_M upper limit Tinf_t5 First detected value Tinf_t10 Second detection value

Claims

1. a heating chamber in which food is stored; a microwave generator that outputs microwaves to the heating chamber; a heat generating member on which an object to be cooked can be placed, which is detachable from the heating chamber, and which generates heat when the microwaves are radiated; a radiation thermometer having a detection area set in the heating chamber and capable of measuring the temperature of an object present in the detection area without contact; a controller that executes a microwave heating process to heat the food using the microwaves output from the microwave generator; Equipped with The controller a heat-generating member detection process for determining whether or not the heat-generating member is attached to a predetermined position in the heating chamber based on a detection value of the radiation thermometer during the microwave heating process; If it is determined that the heat-generating member is not attached to the predetermined position, a carbide detection process is executed during the subsequent execution of the microwave heating process, to determine whether or not carbide is present in the heating chamber based on the detection value of the radiation thermometer; If it is determined that the carbide is present, the output of the microwave generator is reduced or stopped. Cooker.

2. When the controller determines that the heat-generating member is attached to the predetermined position, the controller continues the microwave heating process without executing the carbonized matter detection process. The cooking device according to claim 1 .

3. the controller determines that the heat-generating component is attached to the predetermined position if the rate of increase of the detection value is equal to or greater than a predetermined heat-generating component detection threshold value in the heat-generating component detection process. The cooking device according to claim 1 or 2.

4. The controller executes the heat-generating member detection process at a determination time when a predetermined determination time has elapsed since the start of the microwave heating process. The cooking device according to claim 1 or 2.

5. The controller The heat-generating member detection process is executed at a determination point when a predetermined determination time has elapsed since the start of the microwave heating process. In the heat-generating member detection process, a rate of increase of the detected value is compared with a predetermined heat-generating member detection threshold value to determine whether the heat-generating member is attached to the predetermined position; The rate of increase is calculated based on the increase in the detected value from a calculation start point when a predetermined waiting time has elapsed since the start of the microwave heating process. The cooking device according to claim 1 or 2.

6. When the heat-generating member is attached to the predetermined position, the heat-generating member is located within the detection area, When the heat-generating member is removed from the heating chamber, at least a part of the bottom surface of the heating chamber is located within the detection area. The cooking device according to claim 1 or 2.

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