JP4345580B2 - Induction heating cooker - Google Patents

Description

  The present invention can be applied to all cooking devices that can accurately detect the temperature of a pan on a top plate.

In an induction heating cooker that heats an object to be heated such as a pot, as a method of detecting the temperature of the pot of the object to be heated, there is a method of detecting the temperature with a thermistor through a top plate on which the pot is placed. In addition, there is an apparatus for detecting the temperature by detecting the infrared ray radiated from the side surface of the pan with an infrared sensor behind the top surface of the top plate. Furthermore, an infrared sensor is arranged on the lower surface of the top plate to detect infrared rays from the pan through the top plate (for example, see Patent Document 1).
Japanese Patent Laid-Open No. 03-184295

In an induction heating cooker having a conventional configuration, a thermistor receives the temperature of a pan through a top plate and detects the temperature. Here, the top plate 2 made of ceramic has a low heat transfer coefficient, and due to a delay in the thermal response of the top plate 2, an actual pan temperature and error occur, and the temperature of the object to be heated cannot be accurately detected. It is. Further, in the induction heating cooker having the conventional configuration shown in FIG. 9, the infrared sensor 4 behind the top plate is affected by disturbance light such as sunlight or illumination, and cannot accurately detect the temperature. Furthermore, in the induction heating cooker having only the configuration in which the infrared sensor is arranged on the lower surface of the top plate, there is a large difference between the infrared radiation energy of a low temperature of 100 ° C. or less and a high temperature of about 300 ° C. Cannot support temperature detection. Moreover, since infrared radiation from the top plate is included, there is a problem that an error occurs in the detected temperature.

The present invention includes a heating coil for heating a pan, a top plate for placing the pan on top of the heating coil, an infrared detector for detecting infrared rays radiated from the pan bottom surface placed on the top plate lower side Amplifying means for amplifying the output of the infrared detecting means, switching means for switching the amplification factor of the amplifying means, temperature detecting means for detecting the pan bottom temperature by the output of the amplifying means, and output of the temperature detecting means And a control means for controlling the power supplied to the heating coil according to the automatic cooking mode for performing an automatic cooking menu for boiling or cooking rice by controlling the heating according to the temperature detected by the temperature detecting means; , and a heating mode for heating output to be set by the user, said switching means, when operating in the heating mode, was fried to lower the amplification factor or thermal cut With detecting a change to a temperature, wherein when operating in the automatic cooking mode to switch larger than the previous SL amplification factor to the amplification factor in the heating mode so as to detect a temperature in the range of 130 ° C. or less since it has, Okiki compared with the amplification factor in the heating mode so as to detect a temperature in the range of pre-Symbol amplification rate of 130 ° C. or less when operating at less kettle or cooking automatic cooking mode temperature changes Since it is switched, it is possible to detect even a slight temperature change without overlooking it, and to perform cooking with high accuracy.

According to the present invention as described above, in the configuration for detecting the temperature of the pot in the infrared detecting means through the top plate, by changing the amplification factor, which induction heating cooker wide range of temperatures detected obtain rows can be realized It is.

The invention according to claim 1 detects a heating coil that heats the pan, a top plate on which the pan is placed above the heating coil, and infrared rays that are placed on the bottom surface of the top plate and emitted from the bottom surface of the pan. Infrared detection means, amplification means for amplifying the output of the infrared detection means, switching means for switching the amplification factor of the amplification means, temperature detection means for detecting the pan bottom temperature by the output of the amplification means, and the temperature detection Control means for controlling the power supplied to the heating coil in accordance with the output of the means, and the control means performs an automatic cooking menu for boiling or cooking by performing heating control according to the temperature detected by the temperature detecting means. includes an automatic cooking mode, a heating mode for heating output to be set by the user, said switching means, when operating in the heating mode, the amplification rate lower to fried also With detecting a change to the temperature of thermal cut-out, the amplification factor in the heating mode so as to detect a temperature in the range of 130 ° C. or less before Symbol amplification rate when operating in the automatic cooking mode Compared to a large induction heating cooker.

As a result, when the switching means operates in the heating mode, it lowers the amplification factor and detects the change to the temperature of the stir-fry or the temperature rise prevention, and when operating in the automatic cooking mode of boiling water or cooking rice Since the amplification factor of the amplifying means is switched largely compared to the heating in the heating mode so as to detect a temperature in the range of 130 ° C. or less, the amplifying means is used when operating in the automatic cooking mode with little temperature change. Since the amplification factor is switched to be larger than the amplification factor in the heating mode so as to detect a temperature in the range of 130 ° C. or less, even a slight temperature change can be detected without overlooking, and high-precision cooking can be performed.

(Embodiment 1)
The following describes the first embodiment of the present invention. Figure 1 is a block diagram showing the configuration of the present embodiment. Induction heating cooker of the present embodiment, the pot 1 to cooking an object to be heated, a top plate 2 for placing a pan 1, a heating coil 3, an electromagnetic induction pot 1 by supplying a high-frequency current to heating coil 3 an inverter 5 to generate heat in a unit 6 out infrared detection, and a magnetic-shield means 7 leakage magnetic flux from the heating coil 3 is prevented pass to the infrared detector 6, efficiently guided infrared rays from the pot 1 reflecting means 8 When, with the temperature detection knowledge means 9 for detecting the temperature of the pan 1 by the output of the infrared detection means 6, and a control means 1 0 for controlling the power supplied to the heating coil in response to the output of the temperature detection known means 9 Is. Control means 1 0 is provided an automatic cooking mode in which the heating control in accordance with the detected temperature of the infrared temperature detector 6, the heating sequence and heating mode for heating output to be set by the user. Then, when operating in the automatic cooking mode, the amplification degree of the amplifying means 12 is operated so as to be largely switched as compared with the heating in the heating mode.

In the first embodiment , when a power source (not shown) is turned on and a predetermined temperature is set with the operation switch, electric power is supplied from the inverter 5 to the heating coil 3 under the control of the control means 10. When electric power is supplied to the heating coil 3, an induction magnetic field is generated in the heating coil 3, and the pan 1 on the top plate 2 is induction-heated. Due to this induction heating, the temperature of the pan 1 rises and the object to be heated in the pan 1 is cooked. Here, the operation of the infrared detecting means 6 will be described. When the temperature of the pan 1 rises, infrared rays corresponding to the temperature are emitted from the pan. Here, as shown in FIG. 2, the infrared energy radiated from an object is generally determined by its temperature, and increases as the temperature increases and also expands to the short wavelength side. The glass ceramic used for the top plate used in the cooking device of the present embodiment can transmit 90% or more for infrared rays in the wavelength region of 2.5 μm or less, so when the pan bottom temperature is 60 ° C. or more. The infrared radiation energy in the wavelength region of 2.5 μm or less is incident on the infrared detection means 6. Here, the infrared detection means 6 is 0.7-2.5.
It is composed of an InGaAs PIN photodiode or the like that has a detection performance with high sensitivity to infrared rays in the wavelength region of μm or less. With this PIN photodiode, an output current matched to the temperature of the pan bottom as shown in FIG. 3 is obtained. However, as shown in FIG. 3, the output current and the pan bottom temperature are not linearly correlated. This is because the radiant energy increases rapidly as the temperature rises. Therefore, the amplification factor must be changed according to the temperature range of temperature detection. Figure 4 is a block diagram of a temperature detection known means. 6 is an InGaAs infrared detection means.
PIN photodiode, current converts the diode current flowing in accordance with the irradiation of the infrared light to the voltage 11 - voltage converter circuit, 9 is a temperature detection known means, in its interior, 12 amplifying means, 13 of the switching means , 14 control units. When performing an automatic cooking menu such as boiling or cooking, the amplification factor is increased in order to detect a temperature in the range of 130 ° C. or lower, and the region of 60 to 130 ° C. is detected as a full range. In addition, in order to detect changes up to 350 ° C. such as stir-fried food and prevention of overheating, detection is performed with a low amplification factor. The switching is performed by the switching means 13 in accordance with the cooking menu from the control unit 14, and the temperature detection in the temperature range suitable for the menu can be accurately performed with high accuracy.

( Reference form 1 )
FIG. 5 is a block diagram showing the configuration of Reference Embodiment 1 of the present invention. The induction heating cooker of the present embodiment is different from the first embodiment only in that there is a second temperature detection means, and other parts having the same configuration and operational effects are denoted by the same reference numerals and detailed. Detailed description will be omitted, and different points will be mainly described. Reference numeral 15 denotes second temperature detection means.

In the first embodiment , the second temperature detecting means 15 is composed of a thermistor or the like that is in contact with the top plate 2 via silicon oil or the like. With this configuration, it is possible to detect the temperature of the top plate in a range where infrared rays from the pan are transmitted. The top plate 2 has a transmittance of about 90% for infrared rays in a wavelength region of 2.5 μm or less, but the remaining 10% radiates the temperature of the top plate itself to the infrared detecting means. When a kettle or the like is used, the temperature of the top plate 2 gradually approaches the pan bottom temperature although there is a delay with respect to the temperature change of the pan bottom. In the range where the temperature of the top plate 2 exceeds 60 ° C., radiant energy of 10% is incident on the infrared detecting means from the top plate, so that the detected temperature is as shown in FIG. It rises little by little as shown in (a). This effect is eliminated by correcting the influence by the temperature of the top plate by the second detection means 15. For example, by subtracting the output of the second temperature detecting means multiplied by a constant from the output of the infrared detecting means, the detected temperature at the bottom of the pan that eliminates the influence of the temperature change of the top plate as shown in FIG. Can be sought. As a result, changes such as detection of the boiling point can be detected at the inflection point without correction, but control such as low-temperature boiling to lower the temperature to a predetermined temperature after boiling stabilization, restoration after the load is applied, etc. Control is easily possible.

Further, as shown in FIG. 7, when the temperature of the top plate is as high as 150 ° C., for example, even 10% radiant energy greatly affects the temperature detection by the infrared detecting means. This effect may be used temperature detection knowledge means as shown in FIG. 8 in order to eliminate. 15 second temperature detecting means 8, 16 are temperature detection known means, 18 subtraction means 19 is a control unit. In this operation, the output of the current-voltage conversion circuit is decreased by the subtracting means 18 in accordance with the output of the second temperature detecting means 15. The subtracted output is amplified by the amplifying means 12 and input to the control unit to calculate the detected temperature. In this case, since the influence of the top plate, which is a noise component, is large, it is possible to detect the change of the infrared detecting means corresponding to the temperature change of the pan bottom with high resolution by subtracting before amplification. Thereby, the influence of the temperature of a top plate can be reduced more and the temperature detection of a pan bottom can be performed correctly.

Furthermore, the temperature detection known means, by positioning the midpoint of the inner diameter and the outer diameter of the coil most temperature rises quickly by heating distribution pan bottom, is possible to more effectively use configured such cut- it can.

  The present invention can be applied to all cooking devices that can accurately detect the temperature of a pan on a top plate.

The block diagram which shows the induction heating cooking appliance in Embodiment 1 of this invention The graph which shows the distribution of the infrared rays which permeate | transmit the top plate in Embodiment 1 of this invention, and the sensitivity wavelength range of an infrared detection means The figure which shows the relationship between the output of the infrared detection means in Embodiment 1 of this invention, and temperature. Block diagram illustrating a temperature detection knowledge means in the first embodiment of the present invention The block diagram which shows the induction heating cooking appliance in the reference form 1 of this invention (A) Graph showing temperature detection data before correction in Reference Embodiment 1 of the present invention (b) Graph showing temperature detection data after correction in Example 2 of the present invention Block diagram A graph showing temperature detection data in Reference Embodiment 1 of the present invention It shows the temperature detection knowledge means in accordance with the first reference of the present invention Block diagram of an induction heating cooker using a conventional infrared sensor

Explanation of symbols

1 pan 2 the top plate 3 heating coil 4 infrared sensor 5 inverter 6 infrared detector 7 magnetically shielded unit 8 reflecting means 9, 16 temperature detection known means 10, 17 control means 11 current - voltage converting means 12 amplifying means 13 the switching means 14 control unit 15 Second temperature detection means

Claims (1)

A heating coil for heating a pan, the top plate for placing the pan on top of the heating coil, an infrared detector for detecting infrared rays radiated from the pan bottom surface placed on the top plate lower side, the infrared detector Amplifying means for amplifying the output of the means; switching means for switching the amplification factor of the amplifying means; temperature detecting means for detecting the pan bottom temperature based on the output of the amplifying means; and a heating coil according to the output of the temperature detecting means Control means for controlling the power to be supplied to the automatic cooking mode for performing an automatic cooking menu for boiling or cooking by controlling heating according to the temperature detected by the temperature detecting means, and by the user and a heating mode for heating output to be set, the switching means, when operating in the heating mode, until the temperature of the amplification factor lower to fried or thermal cut With detecting a change, induction heating cooker to switch larger than the previous SL amplification factor to the amplification factor in the heating mode so as to detect a temperature in the range of 130 ° C. or less when operating in the automatic cooking mode.

Images