JP2786749B2 - High frequency heating equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency heating apparatus provided with an absolute humidity sensor used for detecting a finish of an object to be heated, and more particularly to a high-frequency heating apparatus capable of correcting a temperature drift of the absolute humidity sensor.

[0002]

2. Description of the Related Art A conventional high-frequency heating apparatus will be described with reference to the drawings. FIG. 6 is a schematic configuration diagram of the conventional high-frequency heating device 3 as viewed from the front, FIGS. 7 and 8 are simplified circuit diagrams of the high-frequency heating device 3, and FIGS. It is a circuit diagram showing that it has a function. The portions (1) and (2) in FIG. 7 are connected to the portions (1) and (2) in FIG. 8, respectively. Further, the portions (1) to (5) in FIG. 9 are respectively connected to the portions (1) to (5) in FIG.

The absolute humidity sensor 2 shown in FIGS. 6, 7 and 9 has an open thermistor R1 exposed to the atmosphere and a closed thermistor R sealed in dry air.
2 comprises a first series circuit SR1. The first series circuit SR1 is connected in parallel with a second series circuit SR2 including two resistors R3 and R4 to form a bridge circuit 4. The midpoints M1 and M2 of the bridge circuit 4 are connected to the inputs-and + of the comparison amplifier 5, respectively. A DC power supply 6 for supplying a current to the absolute humidity sensor 2 via a current limiting resistor R5 is connected between connection points M3 and M4 between the first series circuit SR1 and the second series circuit SR2. The heating control circuit 7 includes a RAM, a CPU, and a ROM. The heating control circuit 7 receives an absolute humidity detection signal V from the absolute humidity sensor 2 via the A / D converter 8 and the interface 9. The heating control circuit 7 controls the heating time of the article to be heated 1 in response to the absolute humidity detection signal V. Reference numeral 10 denotes a microwave relay 10 which is a switch circuit that controls the supply of drive power to a microwave generation circuit including a magnetron 12 in accordance with heating and stop operation control signals from a heating control circuit 7. Reference numeral 11 denotes an FM relay 11 which is a switch circuit that controls the supply of drive power to a cooling fan motor 17 that cools the magnetron 12 and blows the air into the heating chamber 19. Generally, the DC power supply 6 includes a transformer connected to an AC power supply and a rectifier circuit, like the power supply for driving the heating control circuit 7 and the switch circuits.

When the high-frequency heating device 3 is connected to an AC power source, the DC power source 6 is driven. Then, a current I ₁ flows through the thermistor R1 and thermistor R2. Thermistor R1 and thermistor R2 are self-heated by a current I _1, lowering its resistance. This means that the current I
₁ and the thermistors R1 and R2 further increase self-heating. Eventually, the current limiting resistor R5
As a result, the current I ₁ becomes stable and constant, and the self-heating also becomes constant, so that the resistance values of the thermistors R1 and R2 become constant.

Further, one of the resistors R3 and R4 constituting the second series circuit SR2 is a variable resistor whose resistance value can be freely changed under the control of the heating control circuit 7.
The heating control circuit 7 controls the potential difference between the midpoints M1 and M2 of the bridge circuit 4 formed by connecting the first series circuit SR1 and the second series circuit SR2 in parallel within a certain range. The resistance value of one resistor of the second series circuit SR2 is changed. The potential difference between the middle points M1 and M2 is amplified by about 200 times by the comparison amplifier 5, and then the A / D
Heating control circuit 7 via converter 8 and interface 9
Is input to

When performing microwave heating, the FM relay 11 is closed and the cooling fan motor 17 is driven by a control signal from the heating control circuit 7. Outside air introduced from the outside by the cooling fan motor 17 cools the magnetron 12 and is then sent into the heating chamber 19. At the same time, the heating control circuit 7 closes the microwave relay 10 and turns on the high voltage transformer 13, the high voltage capacitor 14, and the high voltage diode 15
Is connected to a power supply, and a high voltage is applied to the magnetron 12 to oscillate the magnetron 12 at a high frequency. The microwave emitted from the magnetron 12 is guided to the heating chamber 19 by the waveguide 18,
The object to be heated 1 is heated by vibrating the water molecules of the object to be heated 1. The outside air sent into the heating chamber 19 contains water vapor generated from the inside of the heated object 1 as the temperature of the heated object 1 rises, and is sent out from the exhaust port 20 to the exhaust duct 21,
It is discharged out of the high-frequency heating device 3. The exhaust duct 21 is provided with the absolute humidity sensor 2. The absolute humidity sensor 2 has a structure in which it is emitted from the object to be heated 1 and is exposed to air containing water vapor discharged from the heating chamber 19. Since the amount of air sent into the heating chamber 19 is constant, as the temperature of the object 1 increases, the temperature of the object 1 increases.
When the amount of water vapor emitted from the air increases, the amount of water vapor contained in the discharged air increases, and the amount of water vapor contained in the discharged air exposed to the absolute humidity sensor 2 per unit volume increases. When the amount of water vapor per unit volume of the air to which the absolute humidity sensor 2 is exposed changes,
The amount of heat radiation changes from the surface of the open thermistor R1 exposed to the atmosphere, and the resistance of the thermistor R1 changes. Then, the voltage dividing ratio of the thermistor R1 and the thermistor R2 changes, and the first series circuit SR1 including the thermistor R1 and the thermistor R2 is connected in parallel to the second series circuit SR2 including the two resistors R3 and R4. The voltage between the middle points M1 and M2 of the bridge circuit 4 changes, and the absolute humidity detection signal V amplified by the comparison amplifier 5 changes. The heating control circuit 7 determines the finished state of the object 1 and controls the heating time of the object 1 in response to the absolute humidity detection signal V supplied via the A / D converter 8 and the interface 9. It has become. The heating control circuit 7
Determines that the heated object 1 is finished, the heating control circuit 7 opens the FM relay 11 to stop the cooling fan motor 17 and opens the microwave relay 10 in response to the stop control signal to open the high voltage transformer 13 and the high voltage capacitor. The supply of electric power to the half-wave voltage doubler circuit 16 composed of the high voltage diode 14 and the high voltage diode 15 is stopped to end the heating.

[0007]

By the way, in the high-frequency heating device 3 having the absolute humidity sensor 2 as described above, the air discharged from the heating chamber 19 converts the hot air into the heating chamber 19 into the first series circuit SR1. Of the heating chamber 19, the air discharged from the heating chamber 19 is exposed to the open air and the closed thermistor R sealed in the dry air.
2 will be raised. This thermistor R1
If the B constants of R2 and R2 are the same, the resistance values of the thermistors R1 and R2 change at the same ratio even if the temperature of the absolute humidity sensor 2 changes. For this reason, the balance of the bridge circuit 4 formed by connecting the first series circuit SR1 including the thermistors R1 and R2 and the second series circuit SR2 including the two resistors R3 and R4 in parallel is maintained. There is no change in the output value between points M1 and M2. However, when the B constants of the thermistors R1 and R2 are different, the voltage division ratio of the first series circuit SR1 formed by the thermistors R1 and R2 changes with the temperature change of the absolute humidity sensor 2. This causes a temperature drift of the absolute humidity detection signal V, and gives the absolute humidity detection signal V a change independent of a change in the absolute humidity amount. Therefore, the selection of the absolute humidity sensor 2 alone and the first series circuit SR1
Such as the addition of a correction resistor to the heater, and the high-frequency heating device 3
A method of reducing the temperature drift of the absolute humidity sensor 2 by adjusting and selecting the mounting position and direction of the absolute humidity sensor 2 on the absolute humidity sensor 2 is adopted.

However, by selecting the absolute humidity sensor 2 alone and adding a correction resistor, the temperature drift can be suppressed to some extent but cannot be completely eliminated.
There is a problem that the cost of the high-frequency heating device is increased due to poor yield and a large amount of work. Further, there is a problem that adjustment and selection of the mounting position and the direction of the absolute humidity sensor 2 are a great restriction in designing the high frequency heating device 3.

In recent years, in a high-frequency heating apparatus 3 having a combined oven and grill heating function, as shown in FIGS. 9 and 10, an absolute humidity sensor is used as a means for detecting the finish of the object 1 when the oven and grill are heated. It has been proposed to use 2.

However, when heating the oven and grill,
Since the amount of increase in the ambient temperature of the absolute humidity sensor 2 is much larger than that during microwave heating, the temperature drift during heating the oven / grill is greater than that during microwave heating. Therefore, even when the single unit of the absolute humidity sensor 2 is selected or the correction resistance is added, the temperature drift cannot be suppressed within an allowable range.

At the time of microwave heating, the temperature of the main body of the high-frequency heating device 3 gradually rises.
The heat transmitted directly to the absolute humidity sensor 2 through the main body of
Open-type thermistor R1 and closed-type thermistor R2
The heat is transmitted irrespective of the conduction direction of the heat. But,
During heating of the oven and grill, the temperature of the main body rises rapidly, so that a temperature difference occurs between the thermistor on the side closer to the heater as the heat source and the thermistor on the far side between the open-type thermistor R1 and the closed-type thermistor R2. Therefore, as in the case where the B constants of the thermistors R1 and R2 are different, the voltage division ratio of the first series circuit SR1 formed by the thermistors R1 and R2 changes, and the absolute humidity detection signal V drifts in temperature. When the position of the oven and the grill, which are heat sources, are different, the amount of temperature drift differs depending on the heating mode.

For the reasons described above, it has been difficult to realize a high-frequency heating apparatus using an absolute humidity sensor as a means for detecting the finish at the time of heating the oven and grill.

It is an object of the present invention to correct the temperature drift of an absolute humidity sensor without selecting an absolute humidity sensor and adjusting and selecting the mounting position of the absolute humidity sensor and adding a correction resistor. The absolute humidity sensor can be used to detect the finish of the object to be heated even when heating the oven or grill, which has a high temperature rise and a high rate of temperature rise. An object of the present invention is to provide a high-frequency heating device.

[0014]

In order to achieve the above object, a high-frequency heating apparatus according to the present invention comprises a heating means for heating an object to be heated, and an open type heating apparatus wherein the resistance value is changed by steam generated by the object to be heated. Absolute humidity sensor consisting of a series connection of a thermistor and a closed thermistor whose resistance value does not change due to water vapor generated by the object to be heated, a resistance value of the open thermistor and a resistance value of the closed thermistor And a humidity detection signal generating means for generating a humidity detection signal in accordance with the ratio, receiving a humidity detection signal from the humidity detection signal generating means, and heating based on the humidity detection signal. While judging the finished condition of the thing,
In a high-frequency heating device having a heating control means for controlling the heating means, a midpoint potential representing a midpoint potential of a connection point between the closed thermistor and the open thermistor is detected. A midpoint potential detecting means for generating a signal, and temperature drift information representing a change in the humidity detection signal with respect to a change in the midpoint potential when no water vapor is generated from the object to be heated by heating the heating means. Temperature drift information storage means, receiving the midpoint potential signal from the midpoint potential detection means, based on the amount of change of the midpoint potential signal and the temperature drift information stored by the temperature drift information storage means, A humidity detector for calculating a change amount of the humidity detection signal with respect to a temperature change of the absolute humidity sensor, and correcting the humidity detection signal based on the calculated change amount. It is characterized in that it comprises a signal correction means.

[0015]

The temperature drift information stored in the temperature drift information storage means is based on the change in the midpoint potential of the connection point between the closed thermistor and the open thermistor when no water vapor is generated from the object to be heated by the heating means. Indicates the amount of change of the humidity detection signal with respect to the amount. Further, the midpoint potential detecting means detects the midpoint potential and generates a midpoint potential signal representing the midpoint potential. The humidity detection signal correction means calculates a change amount of the humidity detection signal with respect to a temperature change of the absolute humidity sensor based on the temperature drift information and the change amount of the midpoint potential signal, and calculates the calculated change amount. The humidity detection signal is corrected based on the above. Therefore,
The temperature drift of the absolute humidity sensor can be accurately corrected without selecting the absolute humidity sensor and adjusting and selecting the mounting position of the absolute humidity sensor and adding a correction resistor. In addition, since adjustment and selection of the mounting position of the absolute humidity sensor are not performed, design restrictions due to the adjustment and selection of the mounting position can be eliminated. In addition, the absolute humidity sensor can be used to detect the finish of the object to be heated even when heating the oven / grill having a large temperature rise rate and a large temperature rise rate.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiments. FIGS. 1 and 2 are simplified circuit diagrams of a high-frequency heating device according to an embodiment of the present invention. FIGS. 3 and 4 are circuit diagrams showing that the high-frequency heating device has a combined function of an oven and a grill.
FIG. 5 is a schematic configuration diagram of the high-frequency heating device viewed from a side. The locations (1) and (2) in FIG. 1 correspond to (1) and (2) in FIG.
To the location of In addition, (1) to (5) in FIG.
Each of them is connected to points (1) to (5) in FIG. In the embodiment shown in FIGS. 1 to 5, the same parts as those in the conventional example shown in FIGS. 6 to 10 are denoted by the same reference numerals.

The absolute humidity sensor 2 of the high-frequency heating device 300 having the combined function of an oven and a grill comprises an open thermistor R1 exposed to the atmosphere and a closed thermistor R2 enclosed in dry air. It comprises a first series circuit SR1. The high-frequency heating device 300 includes:
Second series circuit SR2 including two resistors R3 and R4
And a bridge circuit 4 formed by connecting the first series circuit SR1 in parallel with the first series circuit SR1. The midpoints M1 and M2 of the bridge circuit 4 are connected to the inputs-and + of the comparison amplifier 5, respectively. A DC power supply 6 for supplying a current to the absolute humidity sensor 2 via a current limiting resistor R5 is connected between connection points M3 and M4 between the first series circuit SR1 and the second series circuit SR2. The heating control circuit 700 is a RAM,
Includes CPU and ROM. The heating control circuit 700
The absolute humidity detection signal V from the comparison amplifier 5 is received via the / D converter 8 and the interface 9. On the other hand, the middle point M1 of the first series circuit SR1 forming the absolute humidity sensor 2
Is supplied to the heating control circuit 700 via the A / D converter 80 and the interface 9. The heating control circuit 700 has an electrically erasable programmable ROM (hereinafter referred to as “E ²
PROM ". ) 220 are connected. This E ²
The PROM 220 includes a heating control circuit 700 and an E ² PR
Even after the power supply to the OM 220 is cut off, the OM 220 has a function of keeping the stored contents.

Further, the high-frequency heating device 300 shown in FIG.
As shown in FIG.
And a microwave relay 10 for controlling the supply of drive power to a half-wave voltage doubler circuit 16 composed of a high voltage diode 15 and a cooling fan motor 17 for cooling the magnetron 12 and sending air to the heating chamber 19. And a CM relay 2 which is a switch circuit for controlling driving power supply to the convection motor 23.
7, an oven relay 28 which is a switch circuit for controlling the supply of drive power to the heater 24 for the oven, and a grille relay 29 which is a switch circuit for controlling the supply of drive power to the heater 30 for the grill. The microwave relay 10, the FM relay 11, the CM relay 27, the oven relay 28, and the grille relay 29 are controlled by heating and stop operation control signals generated by the heating control circuit 700.

On the rear side of the heating chamber 19, there are provided an oven heater 24, a convection motor 23, a convection fan 25, and a convection fan duct 26 for fixing these and adjusting the wind direction. A grill heater 30 as a heat source for grill heating is provided on the top surface of the heating chamber 19, and a reflector 32 is provided so as to cover the grill heater 30.

When performing microwave heating, the high-frequency heating device 300 closes the FM relay 11 according to an operation control signal from the heating control circuit 700, and
7 is driven. Outside air introduced from the outside by the cooling fan motor 17 cools the magnetron 12 and is then sent into the heating chamber 19. At the same time, the heating control circuit 7
00, the microwave relay 10 is closed, a power supply is connected to a half-wave voltage doubler circuit 16 including a high-voltage transformer 13, a high-voltage capacitor 14, and a high-voltage diode 15, and a high voltage is applied to the magnetron 12 so that the magnetron 12 is turned off. Oscillate at high frequency. The microwave emitted from the magnetron 12 is guided to the heating chamber 19 by the waveguide, and
The object to be heated 1 is heated by vibrating the water molecules. Heating room 1
The outside air sent into 9 includes steam generated from inside heated object 1 as the temperature of heated object 1 rises, is sent out from air outlet 20 to exhaust duct 21, and is discharged outside high frequency heating device 300. You.

When performing oven heating, the heating control circuit 7
00 turns on the oven relay 28 and the CM relay 27 by the operation control signal, and
When the heat is generated, the convection motor 23 is rotated. The convection fan 25 fixed to the rotation shaft of the convection motor 23
The hot air heated by 4 is blown out from a blower port 31 of a rear plate of the heating chamber 19. This hot air bake the heated object 1 in the heating chamber 19. The amount of water vapor emitted from the object to be heated 1 increases as the temperature of the object to be heated 1 increases, and is sent out to the exhaust duct 21 by blowing air from the convection motor 23.
On the other hand, the heat of the oven heater 24 is transmitted to the rear surface of the heating chamber 19 via the convection duct 26 and transmitted to the absolute humidity sensor 2 via the exhaust duct 21.

When performing grill heating, the heating control circuit 70
0 turns on the grill relay 29 and the FM relay 11 according to the control signal, and supplies power to the grill heater 30 and the cooling fan motor 17. Then, the grill heater 30 heats the object to be heated 1 by the heat rays emitted from the grill heater 30. Outside air introduced from the outside by the cooling fan motor 17 passes through the magnetron 12 by blowing air from the cooling fan motor 17, and is then guided into the heating chamber 19, and contains water vapor, smoke, odor and the like in the heating chamber 19. Is discharged to the exhaust duct 21 as exhaust. The amount of water vapor contained in the exhaust gas increases as the temperature of the article 1 to be heated rises, similarly to the time of heating the oven and the time of heating the microwave. On the other hand, the heat generated by the grill heater 30 is transmitted to the top surface of the heating chamber 19 via the reflection plate 32 and transmitted to the absolute humidity sensor 2 via the exhaust duct 21.

Prior to shipment from the factory, the high-frequency heating apparatus 300 performs heating for a certain period of time in a heating mode in which a finish is detected by the absolute humidity sensor 2 in a state where there is no load or a load which does not generate steam. The high-frequency heating device 300 heated in this state sends out hot air in the heating chamber 19 in which the amount of water vapor is constant to the exhaust duct 21 to increase the temperature of the absolute humidity sensor 2. On the other hand, as described above, the oven heater 24 and the grill heater 30
Generates a temperature difference between the thermistor R1 and the thermistor R2 due to heat transmitted through the main body of the high-frequency heating device 300, and the absolute humidity detection signal V and the thermistors R1 and R2
The thermistor signal VR2, which is the potential of the midpoint M1. At this time, the change amount Vth of the thermistor signal VR2
, The variation Vah of the absolute humidity detection signal V and the correction coefficient Q
Is given by the following equation (1).

[0024]

## EQU1 ## Q = Vah / Vth

Then, the above relational expression is converted to the above E ² PROM
220 is stored. Midpoint M1 immediately before the heating
Is the potential VR20, the heating control circuit 700 corrects the absolute humidity detection signal V according to the following equation ² based on the thermistor signal VR2 and the correction coefficient Q received from the EEPROM 220.

[0026]

Vh = V− (VR20−VR2) × Q

The heating control circuit 700 determines the finishing condition of the article to be heated 1 based on the corrected absolute humidity detection signal Vh. Thus, the high-frequency heating device 300
The temperature of the absolute humidity sensor 2 is determined based on the correction coefficient Q stored in the E ² PROM 220 without selecting the absolute humidity sensor 2 or adjusting and selecting the mounting position of the absolute humidity sensor 2 and adding a correction resistor. Drift can be corrected accurately. In addition, since adjustment and selection of the mounting position of the absolute humidity sensor are not performed, design restrictions due to the adjustment and selection of the mounting position can be eliminated. Further, the temperature drift of the absolute humidity detection signal V can be completely corrected by setting the correction coefficient Q for each heating mode. Therefore, the above embodiment can realize an inexpensive, highly reliable, and high-performance absolute humidity detection system. Also, as described above, the high-frequency heating device 30
0 means that the temperature drift of the absolute humidity sensor 2 can be corrected even when heating the oven grill having a large temperature rise rate and temperature rise rate. Therefore, the absolute humidity sensor 2 is used to detect the finish of the object 1 to be heated when the oven grill is heated. it can.

[0028]

As is apparent from the above description, in the high-frequency heating apparatus of the present invention, the temperature drift information stored in the temperature drift information storage means is used when the heating means does not generate steam from the object to be heated. The change amount of the humidity detection signal with respect to the change amount of the midpoint potential at the connection point between the closed thermistor and the open thermistor is shown. The midpoint potential detecting means detects a midpoint potential of a connection point between the closed thermistor and the open thermistor, and generates a midpoint potential signal representing the midpoint potential. The humidity detection signal correction means calculates a change amount of the humidity detection signal with respect to a temperature change of the absolute humidity sensor based on the temperature drift information and the change amount of the midpoint potential signal, and calculates the calculated change amount. The humidity detection signal is corrected based on the above.

Therefore, according to the present invention, the selection of the absolute humidity sensor and the adjustment and selection of the mounting position of the absolute humidity sensor, and the addition of the correction resistor are performed without performing.
It is possible to accurately correct the temperature drift of the absolute humidity sensor, and to realize a high-frequency heating device equipped with an inexpensive, reliable, and high-performance absolute humidity detection system. Further, since there is no need to adjust and select the mounting position of the absolute humidity sensor, it is possible to eliminate the design restriction due to the adjustment and selection of the mounting position. In addition, the absolute humidity sensor can be used to detect the finish of the object to be heated even when the oven and the grill are heated with a large amount and a high rate of temperature rise.

[Brief description of the drawings]

FIG. 1 is a simplified circuit diagram of an embodiment of a high-frequency heating device according to the present invention.

FIG. 2 is a simplified circuit diagram of one embodiment of the high-frequency heating device of the present invention.

FIG. 3 is a circuit diagram showing that the high-frequency heating device of the embodiment has a combined function of an oven and a grill.

FIG. 4 is a circuit diagram showing that the high-frequency heating device of the embodiment has a combined function of an oven and a grill.

FIG. 5 is a schematic view of the high-frequency heating device of the above embodiment as viewed from the side.

FIG. 6 is a schematic configuration diagram of a conventional high-frequency heating device viewed from the front.

FIG. 7 is a simplified circuit diagram of a conventional high-frequency heating device.

FIG. 8 is a simplified circuit diagram of a conventional high-frequency heating device.

FIG. 9 is a circuit diagram of a conventional high-frequency heating device.

FIG. 10 is a circuit diagram of a conventional high-frequency heating device.

[Explanation of symbols]

1 Heated object, 2 Absolute humidity sensor, 3,300 high frequency heating device, 4 Bridge circuit, 5 Comparative amplifier, 6 DC power supply, 7,700 Heating control circuit, 8,80 A / D
Converter, 9 interface, 10 microwave relay, 11 FM relay, 12 magnetron, 13 high-voltage transformer, 14 high-voltage capacitor, 15 high-voltage diode, 16 half-wave double voltage circuit, 17 cooling fan motor, 18 waveguide, 19 heating room , 20 exhaust port, 21 exhaust duct, 220 E ² PRO
M, 23 convection motor, 24 oven heater, 25 convection fan, 26 convection duct, 27 CM relay, 28 oven relay, 29 grill relay, 30 grill relay, 31 oven air vent, 32 reflector.

Claims (1)

(57) [Claims] 1. A heating means for heating an object to be heated, an open thermistor whose resistance value changes by steam generated by the object to be heated, and a closed type thermistor whose resistance value does not change by steam generated by the object to be heated. An absolute humidity sensor having a thermistor connected in series and a ratio between the resistance value of the open thermistor and the resistance value of the closed thermistor are detected, and a humidity detection signal corresponding to the ratio is generated. A humidity detection signal generating means, and a heating control means for receiving a humidity detection signal from the humidity detection signal generating means, determining a finishing condition of the object to be heated based on the humidity detection signal, and controlling the heating means. A high-frequency heating device provided with a high-frequency heating device, which detects a midpoint potential of a connection point between the closed thermistor and the open thermistor, and generates a midpoint potential signal representing the midpoint potential. Midpoint potential detecting means, and temperature drift information storing temperature drift information representing a change amount of the humidity detection signal with respect to a change amount of the midpoint potential when water vapor is not generated from the object to be heated by heating of the heating means. Storage means, receiving the midpoint potential signal from the midpoint potential detection means, and detecting the absolute humidity sensor based on the amount of change of the midpoint potential signal and the temperature drift information stored by the temperature drift information storage means. A high-frequency heating device comprising: a humidity detection signal correction unit that calculates a change amount of the humidity detection signal with respect to the temperature change, and corrects the humidity detection signal based on the calculated change amount.