JP2508494Y2 - Open range - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an oven range having a turntable for heating an oven and a turntable for heating a microwave.

<Prior Art> Conventionally, as this type of microwave oven, for example, there is one as shown in FIGS. 4 to 6.

FIG. 4 is a side view showing the state during microwave heating, and the arrow in the figure shows the reflected state of radio waves. FIG. 5 is a side view showing a state during heating in an oven, and arrows in the figure show a circulating state of hot air. FIG. 6 is a circuit diagram.

In FIG. 6, 4 is RAM4a, CPU4b and ROM4c
Is a heating control circuit that includes open / close of the microwave heating key 2 and the oven heating key 3 of the operation panel 1, and controls the switch circuits 6 to 10 via the interface 5 according to each heating mode. A switch circuit 6 (hereinafter referred to as an oven lamp relay 6) controls the drive power supply to the interior lamp 13, and a switch circuit 7 (hereinafter referred to as the CM relay 7) is a drive power source to the convection motor (CM) 14. Control supply. Further, a switch circuit 8 (hereinafter, referred to as a heater relay 8) controls driving power supply to an oven heater 15, and a switch circuit 9 (hereinafter, referred to as a TTM relay 9) supplies a turntable motor (TTM) 16 to the turntable motor (TTM) 16. Controls drive power supply. The switch circuit 10 (hereinafter, referred to as a micro relay 10) controls driving power supply to a microwave generation circuit 20 including a high voltage transformer 21, a high voltage capacitor 22, a high voltage diode 23, and a magnetron 24. The heating control circuit 4 also A / Ds a signal from a temperature detection circuit 30 including a thermistor 27, a fixed resistor 28 and a constant voltage power supply 29.
It is received via the converter 31 and the interface 5 and controls the heater relay 8. That is, since the resistance value R3 of the thermistor 27 changes with temperature, this thermistor 27
The voltage across 27 changes according to the voltage division ratio between its resistance R3 and the resistance R4 of the fixed resistor 28. The heating control circuit 4 determines the temperature of the heating chamber from the change in the voltage and controls the heater relay 8 to keep the temperature of the heating chamber at a temperature suitable for the object to be heated.

Next, the operation when performing micro heating will be described with reference to FIG.

The heating control circuit 4 which has detected the opening and closing of the microwave heating key 2 closes the microwave relay 10 to turn on the microwave generation circuit 20.
Supply power to. Then, a high voltage is applied to the magnetron 24 by the half-wave voltage doubler circuit composed of the high voltage transformer 21, the high voltage capacitor 22, and the high voltage diode 23, and the magnetron 24 transmits at a high frequency. The microwave emitted from the magnetron 24 is guided to the heating chamber 36 by the waveguide 35 and vibrates the water molecules of the object to be heated 37 to heat the object to be heated 37. On the other hand, since the strength of the electric field in the heating chamber 36 is not uniform, the turntable plate 38 is fixed to the rotating shaft of the turntable motor 16 fixed to the bottom surface of the heating chamber 36 so as to penetrate the bottom surface of the heating chamber 36, A heating turntable 39 with a heated object 37 extended thereon is placed on the heating control circuit 4
By closing the TTM relay 9 and supplying power to the turntable motor 16 to rotate the rotary shaft, the object to be heated 37 is rotated and the irradiation of microwaves is equalized to reduce uneven heating. There is. Further, the range turntable 39 used during microwave heating also irradiates the object to be heated 37 with the reflection of microwaves from the bottom surface of the heating chamber 36,
In order to irradiate a large amount of microwaves to the central portion of the object to be heated 37, which is hard to hit the microwaves, to further reduce uneven heating, a glass material having a high microwave transmittance is often used. A heater for the oven is provided on the rear surface of the heating chamber 36.
15, a convection motor 14, a thermistor 27, a convection fan 42, and a convection duct 43 that fixes them and regulates the flow of air are provided.

Next, the operation in the case of performing oven heating will be described with reference to FIG.

When the oven heating key 3 on the operation panel 1 is pressed, the heating control circuit 4 receives the control signal from the heater relay 8 and the CM.
The hot air warmed by the oven heater 15 is controlled by controlling the relay 7 and closing the circuit to supply power to the oven heater 15 to generate heat and rotate the convection fan motor 14 to rotate the convection fan motor 14 to fix the convection fan 42 to the rotary shaft. Is squirted from the blower ports 45a, 45a of the rear plate 45 of the heating chamber 36, and then sucked again from the intake port 45b of the plate to circulate in the heating chamber 36. The heating control circuit 4 receives the signal from the temperature detection circuit 30 as described above, and maintains the temperature in the heating chamber 36 at a temperature suitable for the object to be heated 47. On the other hand, since the heat source for heating the oven is located on the rear surface of the heating chamber 36, the object to be heated 47
Since the rear part is more likely to be burned than the front part and heating unevenness is likely to occur, place the turntable 49 for the oven with the object 47 to be heated on the turntable plate 38 and rotate it as in the case of microwave heating. To achieve even baking. Further, the turntable 49 for the oven used for heating the oven is provided with an air vent hole for the purpose of creating hot air flowing between the lower surface of the table and the turntable plate 38 so that the surface of the object to be heated 47 on the turntable side is also baked. The open legs 49a are attached, and the material of the turntable 49 for the oven is often iron, which is easy to process and has good thermal conductivity.

In addition, in order to make it easy to see the finish of the objects to be heated 37, 47 at the time of heating both during microwave heating and during oven heating, the interior lamp 13 is turned on.

<Problems to be solved by the invention> By the way, in the above conventional microwave oven, since the turntable placed on the turntable plate 38 cannot be discriminated as the range turntable 39 or the oven turntable 49, respectively. There is a possibility that a wrong turntable may be used in the heating mode of the above, and there were the following problems.

For example, when microwave heating is performed using the oven turntable 49, the microwave reflected on the bottom surface of the heating chamber 36 is reflected by the iron oven turntable 49 and reaches the center of the object to be heated. On the other hand, it is difficult to heat the oven uniformly using the range turntable 39, and because hot air does not easily flow under the range turntable 39, the hot air does not reach the center of the range turntable 39. The lower central part of the object to be heated is not heated, and it is difficult to perform uniform heating.

Further, in the case of the microwave oven in which the weight of the object to be heated as shown in FIG. 7 is measured and the heating time is automatically adjusted according to the weight, there are the following problems.

In this microwave oven, a weight sensor 60 is attached below a bottom surface 71 of the heating chamber so that a shaft 61 projects into the heating chamber. The shaft 61 is fixed to the outer shell 63 of the weight sensor 60 via a leaf spring 62, and slides up and down according to the weight of an object to be measured 74 placed on a turntable 73 on a turntable plate 72 on the shaft 61. To do. On the other hand, the lower electrode 64 is fixed to the other end of the leaf spring 62, and the weight sensor 60
The upper electrode 65 is fixed to the outer shell 63 of the shaft 61.
The lower electrode 64 moves up and down in conjunction with the vertical movement of
Give a change of distance between 65. The change in this distance is taken out as a change in the electric capacitance between both electrodes, and the weight of the DUT 74 is calculated by the change amount. In the automatic heating, heating is performed by calculating a heating time suitable for heating the DUT 74 from the measured weight.

By the way, the measurement of the weight of the DUT 74 is defined by the change in the distance between the lower electrode 64 and the upper electrode 65 caused by the deflection of the leaf spring 62 due to the total weight of the DUT 74 and the turntable 73. Therefore, the electric capacitance value (initial weight value) between both electrodes of the turntable 73 on which the DUT 74 is not placed and between the electrodes of the turntable 73 on which the DUT 74 is placed Since the weight of the object to be measured 74 can be calculated only by comparing with the electric capacity value (measured weight value), it is necessary to measure the initial weight value before heating and then measure the measured weight value again. Therefore, for the purpose of omitting the measurement of the initial weight value, the initial weight value W ₀ is stored in the memory in advance at the time of factory shipment, and the initial weight value W ₀ and the measured weight value W are compared during automatic heating to be measured. Generally, the weight of the object 74 is obtained so that heating can be started immediately after the object 74 to be measured is placed on the turntable 73.

In the microwave oven adopting such a method, the measured weight value W measured in conjunction with the opening and closing of the door and the initial weight value W ₀ prestored in the memory are used for the purpose of correcting the temporal change of the initial weight value. When the difference is smaller than the predetermined value, the initial weight value W ₀ is replaced with the measured weight value W, and the replaced value is newly set as the initial weight value W ₀ . If the difference is larger than the predetermined value, it is determined that the DUT 74 is placed on the turntable 73, and the initial weight value W ₀ is not updated.

By the way, when two types of turntables, a range turntable and an oven turntable, are used as the turntable 73, it is necessary to set the initial weight value of each turntable. In this case, an object is placed on the lighter turntable of the two turntables, and the difference between the total weight of the two turntables and the weight of the heavier turntable of the two turntables is greater than the predetermined value. If it is too small, there is a disadvantage that the initial weight value of the heavier turntable is updated by mistake. Therefore, the initial weight value can be set only on the lighter turntable, and as a result, in the case of cooking using the heavier turntable, the weight sensor 60 cannot perform automatic cooking.

In order to eliminate the above problems, it is only necessary to identify whether the turntable placed on the turntable plate is the range turntable or the oven turntable.

As this identification method, conventionally, there is a method as shown in FIG. 8 to FIG. In this method, as shown in FIG. 8, a photoconductive cell 81 for receiving light from the interior lamp 13 is provided on the bottom surface of the heating chamber 36 between the photoconductive cell 81 and the interior lamp 13. Fix it at the place where the turntable is located. And
As shown in FIG. 10, a photodetector circuit 80 including the photoconductive cell 81, the fixed resistor 82 and the constant voltage power source 83 is provided, and the heating control circuit 4 converts the signal from the photodetector circuit 80 into an A / D converter. 31) It receives via the interface 5, and tries to judge which turntable is placed from the signal.

The resistance value of the photoconductive cell 81 changes according to the illuminance of the light illuminating the light receiving portion, and its value decreases as the illuminance increases. As shown in FIG. 8, when the glass range turntable 39 is placed on the turntable plate 38, the light transmittance of the glass is high and the light emitted from the interior lamp 13 is in the range. Cell through the turntable 39 for
Since the light receiving portion of 81 is illuminated, the resistance value R5 of the photoconductive cell 81 is low. On the other hand, as shown in FIG. 9, when the iron turntable 49 for the oven is placed on the turntable plate 38, the light of the interior lamp 13 is blocked by the turntable 38 and is transmitted to the photoconductive cell 81. Not reaching photoconductive cell
Increase the resistance value R5 of 81. The voltage across the photoconductive cell 81 is determined by the voltage division ratio between the resistance value R5 of the photoconductive cell 81 and the resistance value R6 of the fixed resistor 82, and changes according to the change of the resistance value R5 of the photoconductive cell 81. The heating control circuit 4 judges from the voltage value across the photoconductive cell 81 obtained via the A / D converter 31 and the interface 5 whether or not the photoconductive cell 81 is exposed to light, and the turntable Recognize the type and stop heating if it is not a turntable suitable for that heating mode. In the case of automatic cooking using the weight sensor as described above, the initial weight value is set according to the recognized type of turntable.

However, in addition to the glass-made turntables, there are ceramic turntables. Glass-made ones transmit light, while ceramic ones are the same as iron-made oven turntables. When using a ceramic range turntable, the conventional method of illuminating the light-receiving part of the photoconductive cell with the light of the interior lamp is the same as that of the oven turntable and range. There is a problem in that it cannot be distinguished from the commercial turntable.

Therefore, an object of the present invention is to provide an oven range capable of distinguishing between a range turntable and an oven turntable even when a range turntable that reflects light such as a ceramic turntable is used. It is in.

<Means for Solving the Problems> In order to achieve the above object, the first invention has a turntable for oven heating and a turntable for microwave heating, and which turntable is used. In the microwave oven that identifies the table and prohibits heating when a turntable different from the heating mode is used, the difference in the amount of reflected or transmitted light depending on the color of the above two types of turntable The stored light quantity storage means, the light emitting element that emits light toward the lower surface of the turntable being used, and the light from the light emitting element reflected by the lower surface of the turntable being used are detected. Which turntable is used depending on the detection element and the detection result of the detection element and the difference in the light amount stored in the light amount storage means. It is characterized in that it is provided with a discriminating means for discriminating whether or not it is present, and a prohibiting means for prohibiting heating when a turntable different from the heating mode is used in response to the discrimination result of the discriminating means.

A second invention has a turntable for heating an oven and a turntable for heating a microwave, and a weight sensor for measuring the weight of the used turntable and the object to be measured on the turntable. A weight storage means for storing the initial weight of each of the tables, and the weight measured by the weight sensor is one of the initial weights stored in the weight storage means and a predetermined value. When not separated from each other, the initial weight is updated with the weight measured by the weight sensor, and the weight of the measured object is calculated from the updated initial weight and the weight measured by the weight sensor thereafter, and In the microwave oven that automatically adjusts the heating time based on the calculated weight, the difference in the amount of reflected or transmitted light depending on the color of the above two types of turntables. A light amount storage means for storing,
A light emitting element that irradiates light toward the lower surface of the turntable that is used, a detection element that detects light from the light emitting element that is reflected on the lower surface of the turntable that is used, and detection of the detection element Discrimination means for discriminating which turntable is used from the result and the difference in the light quantity stored in the light quantity storage means, and the discrimination result of the discrimination means for the above-mentioned turntable used. And an updating means for updating the initial weight stored in the weight storage means and the weight measured by the weight sensor with the weight measured by the weight sensor when the weight measured by the weight sensor is not more than the predetermined value. It is characterized by that.

<Operation> In the first invention, the light emitting element that emits light toward the lower surface of the turntable used is caused to emit light.
Then, the detection element detects the light from the light emitting element reflected on the lower surface of the used turntable. Which of the turntables is used by the discriminating means based on the detection result of the detecting element and the difference in the reflected or transmitted light amount according to the colors of the two types of turntables stored in the light amount storage means. The prohibition means receives the discrimination result of the discrimination means and prohibits heating when a turntable different from the heating mode is used.

In the second invention, the light emitting element that emits light toward the lower surface of the turntable being used emits light. Then, the detection element detects the light from the light emitting element reflected on the lower surface of the used turntable. Which of the turntables is used by the discriminating means based on the detection result of the detecting element and the difference in the reflected or transmitted light amount according to the colors of the two types of turntables stored in the light amount storage means. The updating means determines that the initial weight stored in the weight storage means of the turntable being used and the weight measured by the weight sensor are not apart from each other by a predetermined value or more based on the determination result of the determination means. In that case, the initial weight is updated with the weight measured by the weight sensor. Then, the weight of the measured object is calculated from the updated initial weight and the weight subsequently measured by the weight sensor, and the heating time is automatically adjusted based on the calculated weight.

Therefore, in both the first device and the second device, even if both the range turntable and the oven turntable are made of a material that reflects light, the difference can be identified. In the second invention, the initial weight of the turntable can be set and automatic cooking can be performed in any heating mode without causing uneven heating due to the wrong use of the turntable.

<Embodiment> Hereinafter, the present invention will be described in detail with reference to an illustrated embodiment.

FIG. 1 is a sectional view of a main part of an embodiment of the microwave oven of the present invention, and FIG. 2 is a circuit diagram of the above embodiment.

In FIG. 1, 101 is a heating chamber, 102 is a turntable plate, 103 is a turntable, 104 is provided on the bottom of the heating chamber 101, and light is emitted toward the bottom of the turntable 103 through a hole 105 in the bottom. The light emitting diode 106 is a photoconductive cell that is provided on the bottom surface of the heating chamber 101, is reflected by the turntable 103, and receives the light from the light emitting diode 104 that has passed through the hole 107 on the bottom surface of the heating chamber 101. . The arrow shown in the figure indicates the path of light from the light emitting diode 104.

As the turntable 103, two types of turntables are used: a microwave turntable used for microwave heating and an oven turntable used for oven heating. The turntable for the range is made of ceramic and has a white color which is a natural color of ceramic. A black iron turntable is used as the oven turntable. By color-coding the two types of turntables in this way,
Reflection efficiency changes depending on the turntable used,
The amount of light reaching the light receiving portion of the photoconductive cell 106 changes.
That is, since the range turntable is white, the reflection efficiency is high, and a relatively large amount of reflected light reaches the light receiving portion of the photoconductive cell 106. On the other hand, since the oven turntable is black, the reflection efficiency is low, and the reflected light reaching the light receiving portion of the photoconductive cell 106 is considerably smaller than that of the range turntable. The photoconductive cell has a characteristic that its resistance value changes according to the illuminance of the light illuminating the light receiving portion, and its value decreases as the illuminance increases. Therefore, the resistance value of the photoconductive cell 106 is small when the range turntable is used, and the resistance value of the photoconductive cell 106 is increased when the oven turntable is used.

As shown in FIG. 2, the light emitting diode 104 and the photoconductive cell 106 include a fixed resistor 108 and a constant voltage power source 109 to form a photodetection circuit 11.
Make up 0. The circuit shown in FIG. 2 uses the photodetector circuit 110 instead of the photodetector circuit 80 of the conventional circuit shown in FIG. 10, and the other structures are the same as those of the conventional one. The same components are given the same numbers and their explanations are omitted.

The voltage V across the photoconductive cell 106 is determined by the voltage division ratio of the resistance value R1 of the photoconductive cell 106 and the resistance value R2 of the fixed resistor 108, and changes according to the change of the resistance value R1 of the photoconductive cell 106. .

The heating control circuit 4 stores in advance the difference in the reflected light amount depending on the colors of the range turntable and the oven turntable in the ROM 4c as the light amount storage means, and the microwave heating key 2 on the operation panel 1 or the oven heating When the key 3 is pressed, the light emitting diode 104 is turned on before the heater relay 8 or the micro relay 10 is closed and heating is performed. And A / D converter 31, interface 5
From the value of the voltage V across the photoconductive cell 106 detected through the reference voltage value V ₀ set based on the difference in the amount of reflected light according to the colors of the two turntables, the turntable plate 102 The type of turntable on the top is determined, and if the turntable is different from the heating mode, heating is not performed.

The microwave oven of this embodiment has a weight sensor as shown in FIG. 7 to measure the weight of the object to be heated and automatically adjust the heating time according to the weight. The heating control circuit 4 previously stores the initial weight value W ₁ of the oven turntable and the initial weight value W ₂ of the range turntable in the ROM 4a. The weight value is corrected and the initial weight value is updated with the corrected initial weight value, the weight of the object to be heated is calculated based on the updated initial weight value, and the heating time is automatically adjusted according to the weight.

The update operation of the initial weight value of the turntable will be described below according to the flow of FIG.

When the power is turned on in step S1, the heating control circuit 4
Stores the initial weight values W ₁ and W ₂ stored in the ROM 4a in the RAM 4c in step S2. And step S3
The door opening / closing operation is monitored by the door switch that opens / closes the contacts in synchronization with the opening / closing of the door, and when the door is opened, the process proceeds to step S4 to light the light emitting diode 104. The light from the light-emitting diode 104 is reflected by the turntable and irradiates the photoconductive cell 106, and the resistance value of the photoconductive cell 106 is increased.
Change R1. The heating control circuit 4 detects the voltage V of the photoconductive cell 106 in step S5. Then, in step S6, the detected voltage V is compared with the reference voltage value V ₀ to determine whether the turntable used is an oven turntable or a range turntable. Ie V
If it is <V ₀ , it is determined to be a range turntable, otherwise it is determined to be an oven turntable. If it is determined that the turntable range proceeds to step S7, comparing the initial weight value W ₂ of the range for the turn table stored in the measured weight value W and RAM4c measured by the weight sensor. Only when the difference is a small amount (within a predetermined value), it is determined that nothing is on the turntable, and the process proceeds to step S8, where the initial weight value W ₂ stored in the RAM 4c is set as the measured weight value W. replace. On the other hand, if the difference is equal to or more than the predetermined value, it is determined that the object to be measured is placed on the turntable, and the initial weight value is not updated. Step
If it is determined in S6 that the turntable is for an oven, the process proceeds from step S9 to step S10 to perform the same processing as above.

In this way, the difference in the amount of reflected light according to the colors of the range turntable and the oven turntable is stored in advance, the light from the light emitting diode 104 is reflected on the turntable, and the reflected light is converted into a photoconductive cell. Since the two turntables are discriminated from each other by irradiating the light receiving portion of the photoconductor with the change in the resistance value of the photoconductive cell, the turntables can be discriminated regardless of the material of the turntable.

Note that the ROM 4c stores in advance the difference in the amount of transmitted light depending on the color of the turntable, transmits the light from the light emitting diode 104 to the turntable, and irradiates the received light of the photoconductive cell 106 with the transmitted light. The type of turntable may be determined from the change in the resistance value of the photoconductive cell 106.

<Effect of Device> As is apparent from the above, the microwave oven of the first device is the amount of reflected or transmitted light depending on the color of the two types of turntables for the oven heating turntable and microwave heating turntable. Difference storage means, a light emitting element for irradiating light toward the lower surface of the turntable used, and light emitted from the light emitting element reflected on the lower surface of the turntable used. A detection element for detecting, a determination means for determining which turntable is used from the detection result of the detection element and the difference in the light amount stored in the light amount storage means, and the determination result of the determination means Therefore, the above two turntables are provided with a prohibition means for prohibiting heating when a turntable different from the heating mode is used. Can be identified regardless of the material, and even if a ceramic turntable is used as the range turntable, cooking unevenness does not occur.

A microwave oven according to a second aspect of the present invention is a light quantity storage means for storing a difference in reflected or transmitted light quantity depending on the color of two kinds of turntables, that is, a turntable for oven heating and a turntable for microwave heating. A light emitting element that irradiates light toward the lower surface of the turntable being used, and a detection element that detects light from the light emitting element reflected by the lower surface of the turntable being used,
Discriminating means for discriminating which turntable is used from the detection result of the detecting element and the difference in the light amount stored in the light amount storing means, and the weight storing means based on the determination result of the determining means. Update means for updating the initial weight of the used turntable stored in the table with the weight measured by the weight sensor, if the initial weight is not separated by a predetermined value or more. Since the above two turntables can be identified regardless of their material, even if a ceramic turntable is used as the range turntable, the initial weight of the turntable can be set and automatic cooking is possible. It is possible.

[Brief description of drawings]

FIG. 1 is a sectional view of a main portion of an embodiment of the microwave oven of the present invention, FIG. 2 is a circuit diagram of the embodiment, and FIG. 3 is a flow chart showing a process of updating the initial weight value of the turntable in the embodiment. FIG. 4 is a side view showing a state of the conventional microwave oven during microwave heating, FIG. 5 is a side view showing a state of the above conventional oven range during oven heating, and FIG. 6 is a view of the above conventional oven range. Circuit diagram, No. 7
FIG. 8 is a schematic sectional view showing a general weight sensor used in a microwave oven, FIGS. 8 and 9 are views for explaining a conventional turntable identification method, and FIG. 10 is a conventional turntable identification method. FIG. 6 is a circuit diagram including a light detection circuit used for 1 ... Operation panel, 2 ... Microwave heating key, 3 ...
Oven heating key, 4 ... Heating control circuit, 4a ... RAM, 4
b ... CPU, 4c ... ROM, 15 ... Oven heater, 20 ...
… Microwave generation circuit, 30… Temperature detection circuit, 60… Weight sensor, 101… Heating chamber, 102… Turntable plate, 103… Turntable, 104… Light emitting diode, 106… Photoconductive cell , 110 …… Photodetector circuit.

Claims (2)

(57) [Scope of utility model registration request] 1. A turntable for heating an oven and a turntable for heating a microwave are provided, and which turntable is used is identified,
In a microwave oven in which heating is prohibited when a turntable different from the heating mode is used, a light quantity storage means for storing a difference in reflected or transmitted light quantity according to colors of the two types of turntables. A light emitting element for irradiating light toward the lower surface of the used turntable; a detection element for detecting light reflected from the lower surface of the used turntable from the light emitting element; Discriminating means for discriminating which turntable is used from the detection result of the above and the difference in the light amount stored in the light amount storing means, and the turntable different from the heating mode based on the discrimination result of the discriminating means. And a prohibition means for prohibiting heating when the microwave oven is used. 2. A turntable for heating an oven and a turntable for heating a microwave, and a weight sensor for measuring the weight of the turntable used and the object to be measured on the turntable, and each of the above. A weight storage means for storing the initial weight of the table, and the weight measured by the weight sensor is separated from any one of the initial weights stored in the weight storage means by a predetermined value or more. If not, update the initial weight with the weight measured by the weight sensor, calculate the weight of the DUT from the updated initial weight and the weight subsequently measured by the weight sensor, and calculate the calculated weight. In the microwave oven that automatically adjusts the heating time based on, the difference in the amount of reflected or transmitted light according to the color of the above two types of turntables is stored. And a light emitting element for irradiating light toward the lower surface of the turntable used, and a detection element for detecting light from the light emitting element reflected on the lower surface of the turntable used. A discriminating unit that discriminates which turntable is used from the detection result of the detection element and the difference in the light amount stored in the light amount storage unit; and When the initial weight stored in the weight storage means of the turntable and the weight measured by the weight sensor are not separated from each other by the predetermined value or more, the initial weight is updated with the weight measured by the weight sensor. A microwave oven, characterized by comprising: