JP2003317920A - Induction heating cooking device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately detect a temperature of a pan placed on a top plate in an induction heating cooking device. <P>SOLUTION: The induction heating cooking device is provided with a heating coil 21 heating the pan 20, the top plate 23 for placing the pan 20 in an upper part of the heating coil 21, an infrared radiation sensor 22 placed in a top plate 23 lower face and detecting infrared radiation radiated from a pan bottom face, a temperature calculating means 24 for calculating a pan bottom face temperature from an output of the infrared radiation sensor 22, and a control means 25 for controlling electric power supplied to the heating coil in response to an output of the temperature calculating means 24. The temperature of the pan can be accurately measured by opening a through hole in the top plate, embedding an infrared radiation transmitting material 27, and irradiating the infrared radiation from a pan bottom on a light receiving face of the infrared radiation sensor 22. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction heating cooker capable of accurately detecting the temperature of a pan on a top plate.

[0002]

2. Description of the Related Art In an induction heating cooker for heating an object to be heated such as a pan, a method of detecting the temperature of the pan of the object to be heated is detected by a thermistor through a top plate on which the pan is placed. There is. Further, a method of detecting the temperature of the bottom of the pot by detecting infrared rays emitted from the pot is also known. This conventional example will be described with reference to FIG.

The main body 11 is provided with a magnetic field generating coil 13 for heating the pot 12 and an infrared sensor 14 for detecting the temperature. The top plate 15 provided on the upper surface of the main body 11 is
Infrared rays with a wavelength of 2.5 microns or less are well transmitted, and 2.
Infrared rays with a wavelength of 5 to 4 microns are transmitted by about 10%,
Infrared rays with a wavelength longer than 4 microns are hardly transmitted. Therefore, a wavelength component of infrared rays of 4 μm or less emitted from the pan 12 passes through the top plate 15 and the infrared sensor 14 measures the temperature of the pan bottom.

[0004]

The conventional induction heating cooker shown in FIG. 3 detects infrared rays radiated from the pot 12 through the top plate 15. Generally, the temperature of the pot 12 at the time of cooking is about 30 ° C to 230 ° C, and the peak wavelength of this temperature is 6 microns to 10 microns according to Stefan-Boltzmann's law. The wavelength that can be transmitted by the top plate 15 is an infrared ray having a wavelength of 4 microns or less.
Only about 10% of the infrared radiation energy from the bottom of the pan is absorbed, and most of the infrared radiation energy from the bottom of the pan is absorbed by the top plate 15. Therefore, the infrared energy reaching the infrared sensor 14 is weak, the S / N ratio is poor even when converted into an electric signal by the infrared sensor 14, and the accuracy in measuring the temperature during cooking is not good. Further, the infrared sensor is generally susceptible to the ambient temperature, and it has been difficult to perform accurate radiation temperature detection in a place where the ambient temperature changes greatly.

[0005]

According to the present invention, a pan for heating and cooking an object to be heated, a heating coil for heating the pan, a top plate for mounting the pan on the heating coil, and a bottom plate for the pan are provided. An infrared sensor that detects infrared rays radiated from the bottom of the pan, a temperature calculation unit that calculates the temperature of the pan bottom from the output of the infrared sensor, and a control unit that controls the power supplied to the heating coil according to the output of the temperature calculation unit. Induction heating cooker that is equipped with a through hole in the top plate and is embedded with infrared transparent material so that the infrared ray from the bottom of the pan irradiates the light receiving surface of the infrared sensor to measure the temperature of the pan with high accuracy. Is.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 is a pan for heating and cooking an object to be heated, a heating coil for heating the pan, a top plate for mounting the pan on the heating coil, and a top plate. An infrared sensor placed on the lower surface to detect infrared rays radiated from the bottom of the pan, a temperature calculation means for calculating the pan bottom temperature from the output of the infrared sensor, and the power supplied to the heating coil according to the output of the temperature calculation means Induction heating that can measure the temperature of the pan with high accuracy by arranging the control means for It is used as a cooking device.

According to the second aspect of the present invention, the infrared ray transmissive material embedded in the through hole has a length such that the infrared ray transmissive material protrudes further below the lower surface of the top plate, so that the temperature of the pan can be measured with high accuracy. It is used as a cooking device.

The invention described in claim 3 is an induction heating cooker capable of highly accurately measuring the temperature of a pot by embedding the tip of an optical fiber for transmitting infrared rays in a through hole.

According to a fourth aspect of the present invention, a plurality of optical fibers are embedded in a through hole, and light is emitted from a part of the fibers to the bottom of the pot and the remaining optical fibers are reflected from the bottom of the pot and emitted from the bottom of the pot. This is an induction heating cooker that can measure the temperature of the pan with high accuracy by adopting a configuration that receives infrared rays.

According to a fifth aspect of the present invention, a plurality of optical fibers are embedded in the through holes, light is irradiated from the first optical fiber to the bottom of the pot, and the second optical fiber receives the light reflected from the bottom of the pot. The induction heating cooker is capable of highly accurately measuring the temperature of the pot by receiving the infrared rays radiated from the pot bottom and measuring the amount of light emitted to the pot bottom by the fourth optical fiber.

According to a sixth aspect of the present invention, the tips of the plurality of optical fibers are embedded in different through holes formed in the top plate, so that the pot can be highly accurately prepared even if the temperature distribution is generated at the bottom of the pot. This is an induction heating cooker that can measure the temperature of.

According to the invention described in claim 7, the through hole formed in the top plate is arranged from the center of the heating coil toward the outer peripheral direction when viewed from the top surface of the top plate, so that the temperature distribution is generated at the bottom of the pan. Even so, the induction heating cooker is capable of detecting the height of the temperature in the radial direction from the center of the bottom of the pot and can measure the temperature of the pot with high accuracy.

[0013]

(Embodiment 1) A first embodiment of the present invention will be described below. FIG. 1 is a block diagram showing the configuration of this embodiment. The induction heating cooker according to the present embodiment includes a pan 20 for heating and cooking an object to be heated, and a heating coil 21 for heating the pan 20.
Infrared sensor 22 for receiving infrared rays radiated from the bottom of pot 20, top plate 23 in which a transparent material 26 that allows infrared rays to pass therethrough and which is well permeable to infrared rays is embedded, and infrared sensor 22 20 from the output signal
The temperature calculation means 24 for calculating the temperature of the heating coil 24 and the control means 25 for controlling the electric power supplied to the heating coil 21 according to the output of the temperature calculation means 24 are provided.

In the first embodiment, when a power source (not shown) is turned on and a predetermined temperature is set by the operation switch,
The control means 25 supplies electric power to the heating coil 21. When power is supplied to the heating coil 21, an induction magnetic field is emitted from the heating coil 21, and the pot 20 on the top plate 23 is induction-heated. Due to this induction heating, the temperature of the pan 20 rises and the object to be heated in the pan 20 is cooked.

In general, there is Stefan-Boltzmann's law that the infrared energy emitted from an object is proportional to the fourth power of the absolute temperature of the object. The higher the temperature, the greater the energy that is emitted as infrared rays.
The infrared sensor 22 outputs a voltage proportional to the energy of the received infrared light, and uses a thermopile or the like in which a pyroelectric element and a thermocouple are collected at one point. Because of this, pot 2
When the temperature of 0 rises, the intensity of infrared radiation from the bottom of the pan also increases, the amount of infrared energy received by the infrared sensor 22 increases, and the output signal voltage of the infrared sensor 22 increases.

The temperature calculation means 24 calculates the temperature of the pan 20 from the output signal voltage of the infrared sensor 22 and sends it to the control means 25. The control means 25 controls the electric power supplied to the heating coil 21 according to this temperature signal, and controls it to a predetermined pan temperature. In this way, the temperature of the pot 20 is embedded in the hole formed in the central portion of the top plate 23, and the infrared transparent material 2
The temperature of the pan 20 can be accurately detected by receiving the infrared ray passing through the infrared sensor 22 with the infrared sensor 22, and the object to be heated can be cooked at the optimum temperature.

Although the top plate 23 transmits only infrared rays having a wavelength of 4 microns or less, the top plate 2
A hole is made in the central portion of 3 and an infrared transmitting material 26 that allows infrared rays to pass therethrough is embedded. The infrared transparent material 26 extends downward from the lower surface of the top plate 23 to the light receiving surface of the infrared sensor 22. Therefore, the infrared rays radiated from the bottom of the pot 20 are incident from the upper surface of the top plate of the infrared transmitting material 26, are propagated downward in the infrared transmitting material 26 by the principle of the optical fiber, and are emitted toward the light receiving surface of the infrared sensor 22. To do. Therefore, infrared rays having a wavelength of 6 to 10 microns, which are radiated by many objects having a temperature of 30 to 200 ° C., which is the temperature when cooking, are well transmitted through the central portion of the top plate 23, and the infrared sensor 22
Can receive infrared rays from the bottom of the pot 20 with almost no attenuation, and since the infrared transparent material 26 extends downward from the lower surface of the top plate 23, the infrared sensor 22 serves as a heat source. It is possible to dispose the infrared sensor 22 away from, and it is possible to suppress the influence of the ambient temperature change of the infrared sensor 22, and it is possible to measure the temperature with higher accuracy.

In particular, in the first embodiment, the temperature of the bottom of the pot is not guided to the temperature sensor by using heat conduction, but the temperature of the bottom of the pot can be detected in a non-contact manner. It is possible to realize the necessary delicate heat adjustment.

The infrared transmitting material 26 may be a single crystal of silicon or germanium, or a resin material such as polyethylene.

(Embodiment 2) FIG. 2 is a block diagram showing the configuration of Embodiment 2 of the present invention. In the induction heating cooker of the present embodiment, the tips of the three optical fibers are embedded in the through holes formed in the top plate. The first optical fiber 30 transmits infrared rays from the upper surface of the top plate 23 to the infrared sensor 22, and measures the intensity of infrared rays emitted from the bottom of the pot 20. Second optical fiber 3
1 indicates the light from the light emitting diode 35 to the top plate 23
Is transmitted to the top plate 23 to irradiate the bottom of the pot 20 with light. The third optical fiber 32 is for transmitting the light from the light emitting diode 35 to the photodiode 34, and for measuring the light emission amount of the photodiode 34 by the light amount detection unit 36 connected to the photodiode 34. The fourth optical fiber 33 transmits the light from the light emitting diode 35 reflected from the pot bottom of the pot 20 from the top surface of the top plate 23 to the photodiode 34, and measures the amount of light reflected from the pot bottom of the pot 20. Is.

As described above, there is Stefan-Boltzmann's law that the infrared energy emitted from an object is proportional to the fourth power of the absolute temperature of the object, and as the temperature rises, a large amount of energy is accelerated and emitted as infrared rays. However, the radiation intensity of infrared rays also depends on the emissivity of the surface of the object. The emissivity of a black body is 1, but the emissivity decreases as it gets closer to the mirror surface, and the energy of infrared rays emitted becomes small even at a high temperature.
Therefore, even if the infrared sensor measures the intensity of infrared rays radiated from the pot bottom, an accurate temperature cannot be calculated unless the emissivity of the pot bottom is known.

In the present invention, when the light emitting diode 35 emits light, the light is emitted from the upper surface of the top plate 23 toward the bottom of the pan 20 by the second optical fiber. The light that hits the bottom of the pot is reflected and the top plate 2 again.
Part of the light returns to the upper surface of 3 and enters the fourth optical fiber 33 and is transmitted to the photodiode 34. Therefore, by looking at the output of the light quantity detection unit 36, the light quantity of the light reflected by the bottom of the pan can be measured. In addition, since a part of the light from the light emitting diode 35 is received by the photodiode 34 by the third optical fiber 32 and the light amount can be measured by the light amount detection unit 36, when the pot is not placed on the top plate 23. The light quantity of the light emitting diode 35 is measured,
Next, by comparing with the output of the light amount detection unit 36 when the pot is placed on the top plate 23, the reflectance of the pot bottom of the pot 20 can be easily measured. Since the emissivity can be easily calculated from the reflectance, the infrared amount from the pan bottom received by the infrared sensor 22 can be corrected with the emissivity to accurately calculate the temperature of the pan bottom.

As described above, according to the second embodiment, the infrared sensor can be more freely arranged in a place where it is not easily affected by temperature, and after accurately determining the emissivity of the bottom of the pan 20,
The infrared sensor 22 provided in the lower central portion of the top plate 23 receives infrared rays from the bottom of the pan 20 to calculate the temperature of the pan 20 with high accuracy, and the induction heating cooking can cook the object to be heated at the optimum temperature. Can be realized.

If the first optical fiber 30 for receiving the infrared rays radiated from the bottom of the pot and transmitting it to the infrared sensor 22 is arranged not at one place on the top plate 23 but at a plurality of places, the temperature at the bottom of the pot has a distribution. However, the temperature of each part can be measured accurately.

Further, if a plurality of first optical fibers 30 are arranged on the top plate 23 in the radial direction from the center of the pot bottom, the temperature distribution from the center of the pot bottom to the outer periphery can be detected, and the heating of cooking can be optimized. Can be controlled.

[0026]

As described above, according to the first to seventh aspects of the present invention, the temperature of the pot can be measured with high accuracy. Further, the infrared sensor can be kept away from a heat source such as a pan, and the temperature of the pan can be measured with higher accuracy. Furthermore, it can be placed in a place where the influence of temperature is small, and the temperature of the pot can be measured with high accuracy. The emissivity of the bottom of the pan can be automatically measured, and the infrared intensity received by the infrared sensor can be corrected with this emissivity to accurately measure the temperature of the pan. In addition, since the amount of light reflected by the light emitting diode is measured after each measurement, the emissivity of the pot bottom is always accurately measured even if the amount of light emitted from the light emitting diode changes due to voltage fluctuations or temperature changes. By measuring the infrared intensity received by the infrared sensor with this emissivity, the pot temperature can be measured with high accuracy. Even if there is temperature distribution on the bottom of the pan, it is possible to measure the temperature of the pan with high accuracy, and even if there is distribution of temperature on the bottom of the pan, it is possible to detect the height of the temperature in the radial direction from the center of the pan bottom with high accuracy. It is possible to realize an induction heating cooker capable of measuring the temperature.

[Brief description of drawings]

FIG. 1 is a block diagram showing an induction heating cooker according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing an induction heating cooker according to a second embodiment of the present invention.

FIG. 3 is a block diagram showing a conventional induction heating cooker.

[Explanation of symbols]

20 pans 21 heating coil 22 Infrared sensor 23 Top Plate 24 Temperature calculation means 25 Control means 26 Infrared transparent material 30, 31, 32, 33 Optical fiber 34 Photodiode 35 light emitting diode 36 Light intensity detector

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Katsunori Zaizen             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Hirofumi Inui             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F term (reference) 3K051 AA08 AB02 AB04 AC09 AC32                       AC33 AC42 AD04 AD28 AD29                       CD03 CD42

Claims (7)

[Claims] 1. A heating coil for heating a pan, a top plate for mounting the pan on the heating coil, an infrared sensor placed on the lower surface of the top plate for detecting infrared rays radiated from the bottom of the pan, and an infrared sensor The infrared sensor comprises a temperature calculating means for calculating the bottom temperature of the pan from the output, and a control means for controlling the electric power supplied to the heating coil according to the output of the temperature calculating means. An induction heating cooker in which a transparent material is embedded and infrared radiation from the bottom of the pan is received by the light receiving surface of the infrared sensor. 2. The induction heating cooker according to claim 1, wherein the infrared transparent material embedded in the through hole has a length protruding further below the lower surface of the top plate. 3. The induction heating cooker according to claim 1, wherein the tip of an optical fiber through which infrared rays pass is embedded in a through hole. 4. The method according to claim 3, wherein a plurality of optical fibers are embedded in the through holes, light is emitted from a part of the fibers to the pot bottom, and the remaining optical fibers receive the light reflected from the pot bottom and the infrared rays emitted from the pot bottom. The induction heating cooker described. 5. An infrared ray emitted by burying a plurality of optical fibers in a through hole, irradiating light from the first optical fiber to the bottom of the pot, receiving light reflected from the bottom of the pot by the second optical fiber, and radiating from the pot bottom by the third optical fiber. 5. The light quantity of the light radiated to the bottom of the pan is measured by the fourth optical fiber which receives the light.
Induction heating cooker according to. 6. The induction heating cooker according to claim 1, wherein the tips of the plurality of optical fibers are embedded in separate through holes formed in the top plate. 7. The induction heating cooker according to claim 6, wherein the through holes formed in the top plate are arranged from the center of the heating coil toward the outer peripheral direction when viewed from the top surface of the top plate.