JP2006260940A - Heating cooker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heating cooker measuring temperature of a bottom face of a pot with good precision, so as to have an excellent cooking property. <P>SOLUTION: The heating cooker is composed of: a heating means 13 heating the pot 11 put on a top plate 10; a temperature calculation means 24 calculating the temperature of the bottom face of the pot 11 from the output of an infrared-ray sensor 14 detecting the strength of infrared-ray irradiated from the bottom face of the pot; a light emitting means 19 making near-infrared-ray incident from an end face of the top plate 10; a radiation area 21 irradiating the near-infrared-ray arranged in a heating area 20 of the top plate 10; an irradiation rate conversion means 23 converting the radiation rate of the bottom face of the pot 11 depending on the output of a reflection sensor 22 detecting the strength of the reflection from the bottom face of the pot 11, arranged at an end face facing the light emitting means 19 of the top plate 10; and a control means 25 controlling the heating means 13 according to the heat defined as an output of the temperature calculation means 24. The temperature calculation means 24 is made to correct the temperature calculated from the output of the infrared-ray sensor 14 depending on the converted radiation rate. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cooking device, and more particularly to a method for detecting the temperature of the bottom of a pan placed on a top plate.

  As a conventional cooking device of this type, there is one that indirectly detects the temperature of the bottom of the pan with a temperature sensitive element such as a thermistor that is in contact with the back of the top plate on which the pan to be heated is placed. . In addition, there is also a type of detecting the temperature of the pan bottom directly and non-contactingly by detecting infrared rays emitted from the bottom of the pan with an infrared sensor through the top plate. As a means for correcting the difference in the emissivity of the bottom of the pot in this method, a light emitting means for irradiating the bottom of the pot is provided, and the light reflected from the light emitting means is reflected by the light receiving means to reflect the reflectance. In some cases, the influence of the difference in emissivity is eliminated by correcting the amount of infrared rays of the infrared sensor using the emissivity converted from the reflectivity (see, for example, Patent Document 1).

  In addition, there is also an apparatus in which the infrared emissivity of the pan bottom is calculated from the output of the temperature sensing element when the temperature gradient is stabilized and the output of the infrared sensor, and the output of the infrared sensor is corrected (for example, see Patent Document 2). ).

  In general, the top plate of an induction heating type cooking device is a crystallized glass in which fine crystals are precipitated by reheating a glass having a special composition in order to increase strength while having heat resistance (for example, "Lithia-based ceramics" Li2O-AL2O3-SiO2) is used, light having a wavelength of 0.5 μm to 2.6 μm is transmitted by 80% or more, and light having a wavelength of 3 to 4 μm is transmitted by approximately 30%. Light having a wavelength longer than 4 μm and a wavelength shorter than 0.5 μm hardly passes.

  On the other hand, the bottom temperature of the pan 2 during cooking is about 30 ° C. to 230 ° C., and the total amount of radiant energy per unit time (W / m 2) at this temperature is 1.1 μm to 30 μm from Stefan-Boltzmann's law. The peak is at a wavelength of 4 to 10 microns.

  FIG. 6 shows a conventional cooking device described in Patent Document 1. As shown in FIG. 6, the arithmetic control unit 1 controls the light emission control circuit 4 to turn on the light emitting element 7, and receives the light from the light emitting element 7 reflected from the bottom of the pan 11 placed on the top plate 10. Light is received by the sensor 9, converted into a voltage amount by the reflection detection circuit 6, and input to the arithmetic control unit 1. The emissivity of the bottom of the pan 11 is calculated by an arithmetic expression indicating the correlation between the input voltage amount and the reflectance and emissivity stored in the arithmetic control unit 1.

Next, infrared rays radiated from the bottom of the pan 11 are received by the infrared sensor 8, converted into a voltage amount by the radiation detection circuit 5, and input to the arithmetic control unit 1. Like the input voltage amount, the temperature of the bottom of the pan 11 is calculated by a temperature calculation formula for converting the infrared ray amount and the emissivity ε stored in the arithmetic control unit 1 into a temperature.
Japanese Patent Laid-Open No. 11-225881 JP 2003-249341 A

  The cooking device has many parameters that determine the intensity of reflected light, such as the material, shape, dimensions, surface condition, warpage, etc. of the pan bottom, and the position where it is placed by the user every time or during cooking. Therefore, in the conventional method of detecting the reflected light intensity at one center of the heating coil for induction heating of the pan, the “reflected light intensity is high, therefore, the bottom of the pan with low emissivity” and “reflected light intensity is low”. Therefore, there were rare cases where it was mistaken for “a pan bottom with a high emissivity”.

  In particular, as shown in the bottom view of the pan in FIG. 7, a heating source that can be used (gas, electric stove, electromagnetic cooker, infrared heating cooker using a radiant heater or halogen heater), In the case of a pan that has been engraved with information on the material, etc., the engraved portion 11b has a low reflectance due to the embossed and embedded black colored characters, and the peripheral portion 11c of the engraved portion 11b is a SUS mirror surface with other parts. Since the reflectance is higher than that of the pan bottom 11a, there is a problem in that the correct emissivity of the pan bottom cannot be calculated.

  In addition, in an induction heating method or a radiant heater type cooking device, in order to project and receive light through the top plate, the reference light (near infrared light) emitted from the light emitting means and the reflected light from the pan bottom About 15% of each is absorbed by the top plate, and only a relatively strong reflected light component can be detected. Therefore, there is a problem that it is not possible to deal with all kinds of pans having various parameters related to reflectance and cooking scenes.

  The present invention solves the above-mentioned conventional problems, and the mounting position of the pan is shifted every time it is used, and there is a stamping, hairline processing, ring processing, driving-in processing on the pan bottom, in a special pan bottom surface state Even if there is, it is possible to accurately measure the reflectance of the pan bottom, and to provide a cooking device capable of detecting the temperature of the pan bottom accurately and non-contactingly and realizing good cooking and heating control by the calculated emissivity. With the goal.

  In order to solve the above-described conventional problems, a heating cooker according to the present invention includes a top plate on which a pan is placed, a heating unit that heats the pan, and an infrared ray that detects infrared intensity emitted from the bottom surface of the pan. A sensor, a temperature calculating means for calculating the temperature of the bottom surface of the pan from the output of the infrared sensor, a light emitting means for injecting near infrared light from an end face of the top plate, and a heating means provided in the heating area of the top plate. A radiation area that emits infrared light; a reflection sensor that is provided on an end surface of the top plate that faces the light-emitting means; and that detects the intensity of reflected light from the bottom surface of the pan; Emissivity conversion means for converting emissivity; and control means for controlling the amount of power supplied to the heating means in accordance with the output of the temperature calculation means and a set thermal power, and the temperature The calculating means corrects the temperature calculated from the output of the infrared sensor based on the converted emissivity, detects reflected light over a wide range of the bottom of the pan, Since the temperature of the bottom surface can be accurately measured, a cooking device having excellent cooking performance can be provided.

  The cooking device of the present invention includes a top plate for placing a pan, a heating means for heating the pan, an infrared sensor for detecting infrared intensity emitted from the bottom of the pan, and an output of the infrared sensor. Temperature calculating means for calculating the temperature of the bottom surface of the pan from, a light introducing part abutting or adhered to the top plate, a light emitting means for emitting near infrared light incident on the top plate from the light introducing part, From a radiation region that radiates the near infrared ray provided in a heating region of a top plate, a light derivation unit that emits reflected light from the bottom surface of the pan provided at a position facing the light emitting means, and the light derivation unit A reflection sensor for detecting the intensity of the reflected light emitted, an emissivity conversion means for converting the emissivity of the bottom surface of the pan from the output of the reflection sensor, and an output of the temperature calculation means. Control means for controlling the amount of electric power supplied to the heating means according to thermal power, and the temperature calculating means corrects the temperature calculated from the output of the infrared sensor based on the converted emissivity. The near-infrared light is transmitted through the top plate by total reflection and the amount of light can be increased, increasing the reflected light intensity and measuring the temperature at the bottom of the pan with high accuracy. It is possible to provide a heating cooker capable of good cooking heating control.

  The cooking device of the present invention includes a top plate for placing a pan, a heating means for heating the pan, an infrared sensor for detecting infrared intensity emitted from the bottom of the pan, and an output of the infrared sensor. Temperature calculating means for calculating the temperature of the bottom surface of the pan, a light diffusing light guide that contacts or adheres to the top plate, a reflective layer provided on the bottom surface of the diffusing light guide, and the light diffusing light guide A light emitting means for emitting near-infrared rays to irradiate a boundary surface between the body and the reflective layer, a radiation area for emitting near-infrared rays provided in a heating area of the top plate, and a position facing the light emitting means. A light deriving unit for emitting reflected light from the bottom surface of the pan, a reflection sensor for detecting the intensity of the reflected light emitted from the light deriving unit, and an emissivity of the bottom surface of the pan from the output of the reflection sensor Convert radiation A conversion means; and a control means for controlling the amount of power supplied to the heating means in accordance with the output of the temperature calculation means and a set thermal power, the temperature calculation means based on the converted emissivity, The temperature calculated from the output of the infrared sensor is corrected, the detection sensitivity of the reflected light is increased, and the reflectance can be measured with higher accuracy, and the temperature of the bottom surface of the pan can be measured with higher accuracy.

  The heating cooker of the present invention is excellent in heating cooking performance because it can accurately estimate the emissivity of the bottom of the pan and measure the temperature of the bottom of the pan that is non-contact and responsive, with high accuracy. .

  1st invention is the top plate which mounts a pan, the heating means which heats the said pan, the infrared sensor which detects the infrared intensity radiated | emitted from the bottom face of the said pan, and the output of the said infrared sensor WHEREIN: A temperature calculating means for calculating the temperature of the bottom surface, a light emitting means for injecting near-infrared rays from an end face of the top plate, a radiation area for radiating the near-infrared rays provided in a heating area of the top plate, and the top plate A reflection sensor that is provided on an end surface facing the light emitting means and detects the intensity of reflected light from the bottom surface of the pan; an emissivity conversion unit that converts the emissivity of the bottom surface of the pan from the output of the reflection sensor; Control means for controlling the amount of power supplied to the heating means in accordance with the output of the temperature calculation means and the set thermal power, the temperature calculation means based on the converted emissivity. The temperature calculated from the output of the infrared sensor is corrected so that the reflected light can be detected over a wide range of the bottom of the pan and the temperature of the bottom of the pan can be accurately measured. A cooking device having excellent cooking performance can be provided.

  According to a second aspect of the present invention, there is provided a top plate for placing the pan, a heating means for heating the pan, an infrared sensor for detecting infrared intensity emitted from the bottom surface of the pan, and an output of the infrared sensor from the pan of the pan. A temperature calculating means for calculating the temperature of the bottom surface; a light introducing portion that contacts or adheres to the top plate; a light emitting means that emits near-infrared light incident on the top plate from the light introducing portion; and heating the top plate A radiation region that emits near-infrared rays provided in a region, a light derivation unit that emits reflected light from a bottom surface of the pan provided at a position facing the light emitting means, and the light emitted from the light derivation unit According to a reflection sensor for detecting the intensity of reflected light, emissivity conversion means for converting the emissivity of the bottom surface of the pan from the output of the reflection sensor, and the output of the temperature calculation means and the set thermal power Control means for controlling the amount of power supplied to the heating means, and the temperature calculating means corrects the temperature calculated from the output of the infrared sensor based on the converted emissivity. Because near infrared rays are transmitted through the top plate by total reflection and the amount of light can be increased, the reflected light intensity can be increased and the temperature at the bottom of the pan can be measured with high accuracy. A heating cooker that can be controlled can be provided.

  In particular, the third invention is provided with antifouling and reflective materials on both the upper and lower surfaces of the top plate of the first or second invention other than the radiation region, the portion where the near infrared ray is incident, and the portion where the reflected light is emitted. With the coating, the detection sensitivity of reflected light is increased, and the reflectance can be measured more accurately, and the temperature of the bottom surface of the pan can be accurately measured.

  In the fourth invention, in particular, a metal for antifouling and reflection is provided on both the upper and lower surfaces of the top plate of the first or second invention other than the radiation region, the portion where the near infrared ray is incident, and the portion where the reflected light is emitted. By vapor deposition or printing, the detection sensitivity of reflected light further increases, the reflectance can be measured with higher accuracy, and the temperature of the bottom surface of the pan can be measured with higher accuracy.

  5th invention is the top plate which mounts a pan, the heating means which heats the said pan, the infrared sensor which detects the infrared intensity radiated | emitted from the bottom face of the said pan, and the output of the said infrared sensor WHEREIN: Temperature calculating means for calculating the temperature of the bottom surface, a light diffusion light guide that is in contact with or adhered to the top plate, a reflective layer provided on the lower surface of the diffusion light guide, the light diffusion light guide and the reflection A light emitting means for emitting near infrared rays to irradiate the boundary surface with the layer, a radiation area for emitting near infrared rays provided in the heating area of the top plate, and a position of the pan provided at a position facing the light emitting means. A light deriving unit for emitting reflected light from the bottom surface, a reflection sensor for detecting the intensity of the reflected light emitted from the light deriving unit, and radiation for converting the emissivity of the bottom surface of the pan from the output of the reflection sensor Rate conversion means and Control means for controlling the amount of power supplied to the heating means in accordance with the output of the temperature calculation means and the set thermal power, the temperature calculation means based on the converted emissivity of the infrared sensor The temperature calculated from the output is corrected, the detection sensitivity of the reflected light is increased, the reflectance is measured with higher accuracy, and the temperature of the bottom surface of the pan can be measured with higher accuracy.

  In particular, the sixth and seventh inventions are the boundary between the radiation region and the region surrounding the region where the near infrared ray is incident and the region where the reflected light is emitted, of the top plate of any one of the first to fifth inventions. This is a photonic band gap in which air holes or cylinders adjusted to have a low refractive index are arranged like a crystal in order to reduce the loss of light at both ends of the path and measure the reflectivity more accurately. Thus, the temperature of the bottom surface of the pan can be measured with high accuracy.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited by this embodiment.

(Embodiment 1)
FIG. 1 (1) is a block diagram showing a configuration of a heating cooker according to the first embodiment of the present invention, and (2) is a plan view of the heating cooker. FIG. 2 is a graph showing the relationship between the reflectance of the pan bottom of the cooking device and the output of the reflection sensor.

  In FIG. 1, the heating cooker in the present embodiment supplies a high-frequency current to a top plate 10 on which a pan (to-be-heated object) 11 for cooking cooking is placed, a heating coil 12, and the heating coil 12. Then, the heating means 13 for induction heating the pan 11, the infrared sensor 14 that is arranged on the lower surface of the top plate 10 to detect the intensity of infrared rays emitted from the bottom surface of the pan 11, and the near infrared ray is incident from the end surface of the top plate 10. A light emitting means 19 that radiates near infrared rays upward in a heating area 20 indicated by a pattern (not shown) on the top plate 10, and the light emitting means 19 on the top plate 10. A reflection sensor 22 provided on the end face for detecting near-infrared intensity including reflected light from the bottom surface of the pan 11, and the emissivity of the bottom surface of the pan 11 from the output of the reflection sensor 22. The emissivity conversion means 23 for calculating, the temperature calculation means 24 for calculating the temperature of the bottom surface of the pan 11 from the converted emissivity and the output of the infrared sensor 14, and the output according to the output of the temperature calculation means 24 A control means 25 for controlling the heating means 13 so as to change the amount of power supplied to the heating coil 12 and a touch panel type operation unit 26 are provided.

  The light emitting means 19 is driven by a modulation means 27 that modulates at a high frequency (carrier frequency 30 kHz to 600 kHz) to distinguish it from the background light around the cooking device, and the output of the reflection sensor 22 is detected by the detection means 28. The Further, optical couplers 29 and 30 for efficiently emitting light are mounted between the light emitting means 19 and the reflection sensor 22 and both end faces of the top plate 10, and between the infrared sensor 14 and the heating coil 12. A shield plate 31 for reducing interference due to electromagnetic waves is provided.

  About the cooking-by-heating machine comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

  First, when the user places the pan 11 with the food on the heating area 20 and operates the “ON / OFF” key 26 a in the operation unit 26 to enter the “heating mode”, the light emitting means 19 is at the top. Near infrared rays having a predetermined wavelength are incident on the top plate 10 from the end face of the plate 10.

  The incident near infrared ray travels straight through the top plate 10. A part of this light is emitted from the radiation region 21 to the outside. At this time, the radiation region 21 is one side of the top plate 10 which is a rectangular parallelepiped and is a plane, and the light reflection layer 32 is provided on the other side, so that the radiation of light from the radiation region 21 (light emitting surface) is emitted. Parallel and hardly diffuse.

  For this reason, uniform irradiation light can be obtained with respect to the bottom surface of the pan 11. The light reflecting layer 32 is provided with extremely fine irregularities on the surface by mechanical means such as polishing the surface of the top plate 10 or chemical means such as etching the surface, or in a process under recrystallization. It is formed by adjusting the refractive index of the surface portion to be low by ion implantation or the like. The light reflecting layer 32 is not provided in the range of φ20 mm at the center of the lower surface of the top plate 10 corresponding to the visual field of the infrared sensor 14. Then, the reflected light from the bottom surface of the pan 11 enters the top plate 10 again from the radiation region 21 and propagates through the top plate 10.

The intensity of the light combined with a part of the reflected light and a part of the transmitted light traveling straight from the light emitting means 19 is detected by the reflection sensor 22, detected by the detecting means 28 and output. Then, the emissivity conversion means 23 first converts the reflectance of the bottom surface of the pan 11 from the output of the detection means 28 using a conversion table or a relational expression. According to Kirchhoff's law, of the unit incident energy that reaches the surface of a substance, the intrinsic emissivity ε is a constant of 0 <ε <1, which is equal to the absorption rate of the substance's radiation. For opaque objects (transmittance α = 0),
Emissivity ε (λ) + reflectivity R (λ) = 1 −−−−−−−−−− (1)
The relationship is established. Therefore, the emissivity can be obtained by subtracting the converted reflectance R from 1. The emissivity calculated in this way is input, and the temperature calculation unit 24 corrects the temperature value calculated from the output of the infrared sensor 14 and outputs the corrected value.

  Next, the control means 25 controls the heating means 13 so as to achieve the desired heating power set by the user pressing the up key (right arrow) and the down key (left arrow) of the operation unit 26, and heating is performed. A predetermined high frequency power is supplied to the coil 12. When a high frequency current is supplied to the heating coil 12, an induction magnetic field is generated from the heating coil 12, and the pan 11 placed on the top plate 10 is induction heated. The temperature of the pan 11 rises due to this heat, and the food in the pan 11 is cooked.

  Since the infrared sensor 14 outputs a voltage proportional to the received infrared energy, when the temperature of the pan 11 rises, the infrared radiation intensity from the bottom surface of the pan 11 increases, and the amount of infrared energy received by the infrared sensor 14 increases. As a result, the output signal voltage of the infrared sensor 14 increases and the calculated temperature value also increases.

  The control means 25 receives the temperature value output from the temperature calculation means 24, and continues to instruct the heating means 13 to perform heating if it is below a predetermined value (such as an over-rise prevention temperature or a boiling temperature). When the “heating mode” is stopped by the “ON / OFF” key 26a, and when the temperature value output from the temperature calculating means 24 exceeds the predetermined value, the heating means 13 is instructed to stop heating. The cooking is done safely.

  As described above, according to the present embodiment, the light emitting means 19 that is incident from the end face of the top plate 10 on which the pan 11 is placed and the radiation that radiates near infrared rays provided in the heating region 20 of the top plate 10. A reflection sensor 22 provided on the end face of the region 21 facing the light emitting means 19 of the top plate 10 and detecting the reflected light intensity from the bottom surface of the pan 11, and the emissivity of the bottom surface of the pan 11 is converted from the output of the reflection sensor 22. By providing the emissivity conversion means 23 that performs the calculation and the temperature calculation means 24 that calculates the temperature of the bottom surface of the pan 11 from the converted emissivity and the output of the infrared sensor 14, the accurate reflectance of the bottom of the pan 11 is provided. Can be measured, and the emissivity of the field of view of the infrared sensor 14 can be accurately estimated from the reflectance. By measuring the reflection from the bottom of the pan 11 on the wide radiation area 21, the influence of the shape and surface state of the pan 11 can be eliminated, and stable measurement can be performed even through the top plate. Therefore, a high temperature measurement is possible without contact with the bottom of the pan 11, and the cooking device is capable of delicate heating.

  Moreover, according to this Embodiment, since uniform irradiation light can be irradiated with respect to the bottom face of the pan 11 from the radiation | emission area | region 21 (light emission surface), in order to detect the reflected light of the wide range of the bottom face of the pan 11 The dependency of the amount of reflected light on the distance to the pan 11 is small, and the diffuse reflection component and the regular reflection component from the bottom surface of the pan 11 can be detected together. Therefore, the correct reflectance can be measured even if irregular reflection is caused depending on the material of the pot 11, the surface state such as engraving, black lettering, and driving.

  In the present embodiment, the width of the radiation region 21 is about φ90 mm, but may be a value larger than the maximum diameter (about 60 mm) of the stamp and smaller than the minimum outer diameter (about 150 mm) of the pan 11. In a state where the pan 11 is not placed on the radiation area 21, a part of the incident near infrared rays is radiated outward from the radiation area 21, so that the light intensity detected by the reflection sensor 22 is a very small value. Become. On the other hand, in the state where the pan 11 is placed, the bottom of the pan 11 serves as a reflection layer, so that it is not radiated from the radiation region 21 to the outside. Therefore, a change in light intensity according to the reflectance of the bottom of the pan 11 (FIG. 2) can be detected by the reflection sensor 22.

  In the present embodiment, the radiation area 21 is provided with an antireflection (AR) coating. Alternatively, near infrared rays can be easily radiated into the air by heat treatment so that the refractive index changes stepwise in the crystallization heat treatment step.

  In this embodiment, the infrared sensor 14 is provided with a PIN photodiode (measurement wavelength band of 0.9 to 2.6 μm) used for optical communication and a radiation thermometer as a main application, and the light emitting means 19 is provided with a remote controller. A photodiode commercially available for use (wavelength band of 0.6 to 0.9 μm) is used, and a phototransistor also commercially available for remote control is used for the reflection sensor 22. Therefore, since the reflectance is measured by the infrared sensor 14 in a wavelength band different from the wavelength band in which the infrared self-emission at the bottom of the pan 11 is measured, the infrared self from the bottom of the pan 11 is measured for the reflectance. Radiation has no effect. As shown in equation (1), if the emissivity of an object is a function of wavelength, the emissivity is wavelength dependent. However, as shown in the graph of FIG. 2, between the reflectance in the measurement wavelength band of the infrared sensor 14 of the pan 11 generally used at home and the detection output of the reflection sensor 22 in the present embodiment. Have a good correlation, and conversion from the detection output of the reflection sensor 22 to the emissivity in the measurement wavelength band of the infrared sensor 14 can be easily performed.

(Embodiment 2)
FIG. 3 shows a cross-sectional view of a main part of a heating cooker according to the second embodiment of the present invention. In addition, about the same part as the heating cooker in the said 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  As shown in FIG. 3, the heating cooker according to the present embodiment is incident on the top plate 10 from the light introducing portion 35 that is in contact with or bonded to the top plate 10 on which the pan 11 is placed. A light emitting means 36 that emits near infrared rays, a radiation area 21 that is provided in the heating region 20 of the top plate 10 and emits near infrared rays, a light reflecting layer 32, and a pan provided at a position facing the light emitting means 36. A light deriving unit 37 that emits reflected light from the bottom surface of 11, a reflection sensor 38 that detects the intensity of the emitted light, and an emissivity conversion means 23 that converts the emissivity of the bottom surface of the pan 11 from the output of the reflection sensor 38. It has.

  About the cooking-by-heating machine comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

  First, when the user places the pan 11 with the food on the heating area 20 and operates the “ON / OFF” key 26 a in the operation unit 26 to enter the “heating mode”, the light emitting means 36 emits light. Infrared light having a predetermined wavelength enters the top plate 10 from the introducing portion 35. Incident near infrared rays propagate through the top plate 10 while repeating total reflection. As shown in FIG. 3 (2), in the state where the pan 11 is not placed, most of this light is radiated to the outside from the upper surface of the radiation region 21 and is not detected by the reflection sensor 38. On the other hand, as shown in FIG. 3 (1), in the state where the pan 11 is placed, the incident near-infrared rays are uniformly irradiated from the radiation region 21 to the bottom surface of the pan 11.

  Reflected light from the bottom surface of the pan 11 enters the top plate 10 again from the radiation region 21 and propagates through the top plate 10 while repeating total reflection (here, according to Kirchhoff's law, the bottom surface of the pan 11 Is a constant larger than 0 and smaller than 1 and is equal to the absorption rate of radiation, so that the reflected light intensity from the bottom surface of the pan 11 is inversely proportional to the emissivity of the bottom surface of the pan 11). The intensity of the transmitted light is detected by the reflection sensor 22, detected by the detection means 28, and output.

  The emissivity conversion means 23 first converts the reflectance R of the bottom surface of the pan 11 from the output of the detection means 28, and subtracts the reflectance R from 1 to obtain the emissivity. The calculated emissivity is input, and the temperature calculation unit 24 corrects the temperature value calculated from the output of the infrared sensor 14 and outputs the corrected value.

  As described above, in the present embodiment, the light introducing portion 35 that is in contact with or bonded to the top plate 10 on which the pan 11 is placed, and the near-infrared light incident on the top plate 10 from the light introducing portion 35 is emitted. The light emitting means 36, the radiation area 21 that is provided in the heating area 20 of the top plate 10 and emits near infrared rays, the light reflecting layer 32, and the light emitting means 36 are provided at positions facing the light emitting means 36 from the bottom surface of the pan 11. By providing a light derivation unit 37 that emits reflected light, a reflection sensor 38 that detects the intensity of the emitted light, and an emissivity conversion means 23 that converts the emissivity of the bottom surface of the pan 11 from the output of the reflection sensor 38. The accurate reflectance of the bottom of the pan 11 can be measured, and the emissivity of the field of view of the infrared sensor 14 can be accurately estimated from this reflectance.

  As described above, by measuring the reflection from the bottom of the pan 11 on the wide radiation area 21, the influence of the shape and surface state of the bottom of the pan 11 is eliminated, and stable measurement is performed even through the top plate 10. be able to. Therefore, it is possible to provide a cooking device capable of performing advanced temperature measurement without contact with the bottom of the pan 11 and capable of delicate heating and cooling.

  In the present embodiment, the light emitting means 36 is a photodiode, the reflection sensor 38 is a phototransistor, and both have a wavelength band of 0.6 to 0.9 μm that is commercially available for remote control. Can be configured.

  Further, in the present embodiment, the light reflecting layer 32 is formed by adjusting the refractive index of only the surface portion by ion implantation or the like in the tempered glass recrystallization step, and the incident near infrared rays are generated in the top plate 10. Is transmitted by total reflection at the refractive index interface, so that there is very little energy loss during reflection. Even an excellent metal surface reflection usually has a loss of about 10% to 15%. Therefore, if the light is transmitted through the top plate 10 having a transmittance of about 85% while repeating the reflection three times, the light energy is reduced to less than half. However, this does not occur in total reflection at the refractive index interface, and the light efficiency as the light guide is considerably high.

  In the present embodiment, the light introduction part 35 and the light lead-out part 37 are made of a material having the same refractive index (about 1.54) as that of the top plate 10 and are in contact with the top plate 10 or bonded with an optical adhesive. Therefore, energy loss at the time of incidence and emission can be reduced.

  Further, in the present embodiment, antifouling / reflective materials are coded on the radiation area 21 on the upper surface of the top plate 10, and on the upper and lower surfaces of the infrared sensor 14 on the lower surface and on the upper and lower surfaces other than the light introducing portion 35 and the light guiding portion 37. is doing. As a result, the surface of the plate is less likely to get dirty, and even if seasonings, foods, etc. are spilled, it becomes easier to wipe off. Furthermore, by adjusting the average transmittance in the wavelength band of 0.9 to 2.6 μm to 85% or more and the average transmittance in the wavelength band of 0.6 to 0.9 μm to be less than 5%, the top plate 10 The field of view of the infrared sensor 14 on the lower surface can also be coated with antifouling and reflective material. Further, the radiation region 21 can be made easy to radiate near infrared rays into the air by controlling the antireflection coating or the refractive index stepwise.

  Further, a metal having a thickness of 2 μm or less by an evaporation method for antifouling and reflection on the upper and lower surfaces of the radiation area 21 on the upper surface of the top plate 10, the visual field portion of the infrared sensor 14 on the lower surface and the light introducing portion 35 and the light guiding portion 37 If a film is formed, the surface of the top plate 10 is less likely to become dirty, and even if seasonings, foods, etc. are spilled, it is easy to wipe off. Furthermore, by changing the material of the film, various colors can be developed, and because it has a dense structure, it has excellent chemical durability, even if it is a very thin film of 2 μm or less. Since the rate is high and it has a high light shielding ability with respect to visible light, the internal structure of the cooking device can be concealed, and the top plate 10 having a very excellent function can be obtained.

  Since the volume resistivity is increased due to the skin effect due to the thickness of 2 μm or less, it is difficult to receive induction heating, but by covering and vapor-depositing with a mask pattern of a predetermined shape, it is difficult to flow eddy current, It can also be set as the structure which is hard to receive induction heating.

  Moreover, by forming a reflective dot (not shown) on the lower surface of the top plate 10 opposite to the radiation area 21, incident near infrared rays hit the reflective dot, the traveling direction changes, and the bottom surface of the pan 11 is irradiated. Therefore, the reflected light from the bottom surface of the pan 11 can easily travel in the direction of the reflection sensor 38. There are several ways to make reflective dots, such as a printing method and an injection (injection molding) method. Here, the printing method will be described. The reflective dot is a top plate 10 according to a gradation pattern by screen printing using a reflective ink prepared by kneading a pigment having high optical reflectance and an optically non-absorbing pigment such as titanium white (TiO2) or precipitated barium sulfate (BaSO4). Apply to the back of the. The size of the reflective dot is increased as it gets closer to the light deriving portion 37 so that the irradiation light becomes more uniform.

(Embodiment 3)
FIG. 4 shows a cross-sectional view of a main part of a heating cooker according to the third embodiment of the present invention. In addition, about the same part as the heating cooker in the said embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  As shown in FIG. 4, the temperature detection means of the bottom surface of the pan 11 of the heating cooker in the present embodiment includes a light diffusion light guide 40 that is in contact with or bonded to a top plate on which the pan 11 is placed, and a light diffusion. A reflection sheet 41 provided on the lower surface of the light guide 40, a light emitting means 36 that emits near infrared light on the boundary surface between the light diffusion light guide 40 and the reflection sheet 41, and a heating area 20 of the top plate 10. A radiation region 21 that emits near infrared rays, a light derivation unit 37 that is provided at a position facing the light emitting means 36 and emits reflected light from the bottom surface of the pan 11, and an intensity of light emitted from the light derivation unit 37. A reflection sensor 38 to be detected and an emissivity conversion means 23 for converting the emissivity of the bottom surface of the pan 11 from the output of the reflection sensor 38.

  About the cooking-by-heating machine comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

  First, when the user places the pan 11 with the food on the heating area 20 and operates the “ON / OFF” key 26 a in the operation unit 26 to enter the “heating mode”, the light emitting means 36 emits light. Infrared rays having a predetermined wavelength are irradiated toward the boundary surface between the diffusion light guide 40 and the reflection sheet 41. As shown in FIG. 4 (1), in the state where the pan 11 is placed on the top plate 10, the near-infrared rays totally reflected at the boundary surface are uniformly irradiated from the radiation region 21 to the bottom surface of the pan 11. . Reflected light from the bottom surface of the pan 11 enters the top plate 10 again from the radiation region 21, propagates through the top plate 10 while repeating total reflection, and reaches the light outlet 37. The intensity of the transmitted light is detected by the reflection sensor 22, detected by the detection means 28, and output. The emissivity conversion means 23 first converts the reflectance R of the bottom surface of the pan 11 from the output of the detection means 28 and subtracts the reflectance R from 1 to obtain the emissivity.

  The calculated emissivity is input, and the temperature calculation means 24 corrects the temperature value calculated from the output of the infrared sensor 14 and outputs the corrected value. On the other hand, the infrared rays self-radiated from the pan 11 proceed in a direction facing the light diffusing light guide 40 and the reflection sheet 41, particularly in the field of view of the infrared sensor 14. Since light having a component smaller than the total reflection angle is transmitted, the infrared light emitted from the pan 11 can be detected by the infrared sensor 14 with almost no reflection. In addition, as shown in FIG. 4B, in the state where the pan 11 is not placed, most of the near infrared rays totally reflected by the boundary surface between the light diffusing light guide 40 and the reflection sheet 41 are the upper surface of the radiation region 21. It is emitted to the outside and is not detected by the reflection sensor 38.

  As described above, according to the present embodiment, the light diffusing light guide 40 in contact with or adhering to the top plate 10 on which the pan 11 is placed, and the reflection sheet 41 provided on the lower surface of the light diffusing light guide 40. A light emitting means 36 that emits near-infrared light on the boundary surface between the light diffusing light guide 40 and the reflection sheet 41, a near-infrared radiation area 21 provided in the heating area 20 of the top plate 10, and the light emitting means. A light deriving unit 37 that emits reflected light from the bottom surface of the pan 11, a reflection sensor 38 that detects the intensity of the emitted light, and an emissivity of the bottom surface of the pan 11 from the output of the reflection sensor 38. By providing the emissivity conversion means 23 for converting the above, it becomes possible to measure the accurate reflectance of the bottom of the pan 11, and the emissivity of the field of view of the infrared sensor 14 can be accurately estimated from this reflectance. By measuring the reflection from the bottom of the pan 11 on a wide radiation area, the influence of the shape and surface state of the bottom of the pan 11 is eliminated, and stable temperature measurement can be performed even through the top plate 10. Therefore, it is possible to provide a cooking device capable of performing advanced temperature measurement without contact with the bottom of the pan 11 and capable of delicate heating and cooling.

  Also in this embodiment, the light emitting means 36 is a photodiode, the reflection sensor 38 is a phototransistor, and both have a wavelength band of 0.6 to 0.9 μm commercially available for remote control. It can be configured at low cost.

(Embodiment 4)
FIG. 5: is principal part sectional drawing of the heating cooker in the 4th Embodiment of this invention, and the partial top view of a top plate. In addition, about the same part as the heating cooker in the said embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  As shown in FIG. 5, the temperature detecting means of the bottom surface of the pan 11 of the heating cooker in the present embodiment includes a light introducing portion 35 that contacts or adheres to the top plate 10 on which the pan 11 is placed, and this light introducing portion. A light emitting means 36 for emitting near infrared rays incident on the top plate 10 from the portion 35, a radiation region 21 provided in the heating region 20 of the top plate 10 for emitting near infrared rays, the light reflecting layer 32, and the light emission. A light deriving portion 37 that is provided at a position facing the means 36 and emits reflected light from the bottom surface of the pan 11; an end surface of a region surrounding the radiation region 21 and the light introducing / exiting portions 35 and 37 of the top plate 10; and From the photonic band gap 43 in which air holes are regularly arranged like a crystal on the outer periphery, a reflection sensor 38 for detecting the intensity of light emitted from the light derivation unit 37, and the output of the reflection sensor 38 It is constituted by emissivity conversion means 23 for converting the emissivity of the bottom surface 11.

  About the cooking-by-heating machine comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

  First, when the user places the pan 11 with the food on the heating area 20 and operates the “ON / OFF” key 26 a in the operation unit 26 to enter the “heating mode”, the light emitting means 36 emits light. Infrared light having a predetermined wavelength enters the top plate 10 from the introducing portion 35. Incident near infrared rays propagate through the top plate 10 while repeating total reflection. In a state where the pan 11 is not placed, most of the light is radiated to the outside from the upper surface of the radiation region 21 and is not detected by the reflection sensor 38.

  On the other hand, as shown in FIG. 5 (1), in the state where the pan 11 is placed, the incident near-infrared rays are uniformly irradiated from the radiation region 21 to the bottom surface of the pan 11. Reflected light from the bottom surface of the pan 11 enters the top plate 10 again from the radiation region 21, propagates through the top plate 10 while repeating total reflection, and reaches the light outlet 37. The intensity of the transmitted light is detected by the reflection sensor 22, detected by the detection means 28, and output. The emissivity conversion means 23 first converts the reflectance R of the bottom surface of the pan 11 from the output of the detection means 28, and subtracts the reflectance R from 1 to obtain the emissivity.

  The calculated emissivity is input, and the temperature calculation means 24 corrects the temperature value calculated from the output of the infrared sensor 14 and outputs the corrected value. Further, as shown in FIG. 5 (2), since the photonic band gap 43 is provided on the outer peripheral portion, near infrared rays traveling in the cross-sectional direction other than the direction of the reflection sensor 38 are also totally reflected by the photonic band gap 43. Since it returns to the direction of the reflection sensor 38, the amount of light received by the reflection sensor 38 increases, and the detection sensitivity is improved.

  As described above, according to the present embodiment, the light introducing portion 35 that is in contact with or bonded to the top plate 10 on which the pan 11 is placed, and the near infrared ray that is incident on the top plate 10 from the light introducing portion 35 is emitted. The light emitting means 36 that performs this, the near-infrared radiation area 21 provided in the heating area 20 of the top plate 10, the light reflecting layer 32, and the reflection from the bottom surface of the pan 11 that is provided at a position facing the light emitting means 36. A photonic band in which air holes are neatly arranged like a crystal in a light deriving portion 37 that emits light, an end surface of a region surrounding the radiation region 21 and the light introducing / exiting portions 35 and 37 of the top plate 10, and an outer peripheral portion. By providing the gap 43, the reflection sensor 38 for detecting the intensity of the emitted light, and the emissivity conversion means 23 for converting the emissivity of the bottom surface of the pan 11 from the output of the reflection sensor 38, the bottom of the pan 11 is provided. The exact reflectance becomes measurable, the emissivity of the field of view of the infrared sensor 14 can be accurately estimated from this reflectance.

  As described above, by measuring the reflection from the bottom of the pan 11 on the wide radiation area 21, the influence of the shape and surface state of the bottom of the pan 11 is eliminated, and stable measurement is performed even through the top plate 10. be able to. Therefore, it is possible to provide a cooking device capable of performing advanced temperature measurement without contact with the bottom of the pan 11 and capable of delicate heating and cooling.

  In the above embodiment, a photonic band gap in which air holes are arranged in an orderly manner like a crystal is used, but a cylinder whose refractive index is adjusted to be low by ion implantation or the like in a recrystallization process of tempered glass is like a crystal. Orderly arranged photonic band gaps may be used, and incident near infrared rays are propagated by total reflection at the refractive index interface of the photonic band gap, so there is very little energy loss during reflection, reducing the intensity The light efficiency as a light guide can be made considerably high.

  As described above, the cooking device according to the present invention is a non-contact type that accurately detects the temperature of the bottom of the pan and has excellent cooking performance, and is not limited to the cooking device. It can be applied to various devices.

(1) Block diagram showing the configuration of the cooking device according to Embodiment 1 of the present invention (2) Plan view of the cooking device A graph showing the relationship between the reflectance of the bottom of the pan and the output of the reflection sensor (1) Main part sectional drawing which shows the state in which the pan of the heating cooker in Embodiment 2 of this invention was mounted (2) Main part sectional drawing which shows the state in which the pan of the same heating cooker is not mounted (1) principal part sectional view showing the state where the pan of the heating cooker in Embodiment 3 of the present invention was placed (2) principal part sectional view showing the state where the pan of the heating cooker is not placed (1) Main part sectional drawing of the heating cooker in Embodiment 4 of this invention (2) Partial top view of the top plate of the heating cooker Block diagram showing the configuration of a conventional cooking device Bottom view of pan

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Top plate 11 Pan 13 Heating means 14 Infrared sensor 19 Light emission means 20 Heating area 21 Radiation area 22 Reflection sensor 23 Emissivity conversion means 24 Temperature calculation means 25 Control means 35 Light introduction part 37 Light extraction part 40 Light diffusion light guide plate 41 Reflection Sheet (reflection layer)
43 photonic band gap

Claims (7)

A top plate on which the pan is placed, heating means for heating the pan, an infrared sensor for detecting the infrared intensity emitted from the bottom surface of the pan, and the temperature of the bottom surface of the pan are calculated from the output of the infrared sensor. Temperature calculating means, light emitting means for injecting near infrared rays from the end face of the top plate, radiation area provided in the heating area of the top plate for emitting the near infrared rays, and the light emitting means of the top plate are opposed to the light emitting means. A reflection sensor that is provided on the end face and detects the intensity of reflected light from the bottom surface of the pan; an emissivity conversion unit that converts the emissivity of the bottom surface of the pan from the output of the reflection sensor; and an output of the temperature calculation unit. Control means for controlling the amount of electric power supplied to the heating means in accordance with the set thermal power, the temperature calculating means based on the converted emissivity, the infrared Heating cooker so as to correct the temperature calculated from the output of the capacitor. A top plate on which the pan is placed, heating means for heating the pan, an infrared sensor for detecting the infrared intensity emitted from the bottom surface of the pan, and the temperature of the bottom surface of the pan are calculated from the output of the infrared sensor. A temperature calculating means; a light introducing portion abutting or adhering to the top plate; a light emitting means for emitting near infrared light incident on the top plate from the light introducing portion; and a heating area of the top plate, A radiation region that emits near infrared rays, a light derivation unit that emits reflected light from the bottom surface of the pan provided at a position facing the light emitting means, and detects the intensity of the reflected light emitted from the light derivation unit A reflection sensor, an emissivity conversion means for converting the emissivity of the bottom surface of the pan from the output of the reflection sensor, and the heating means according to the output of the temperature calculation means and the set thermal power And control means for controlling the amount of power supplied, the temperature calculation section, based on the conversion by said emissivity, heating cooker so as to correct the temperature calculated from the output of the infrared sensor. The cooking device according to claim 1 or 2, wherein antifouling and reflecting materials are coated on both the upper and lower surfaces of the top plate other than the radiation region, the portion where the near infrared ray is incident, and the portion where the reflected light is emitted. The cooking device according to claim 1 or 2, wherein an antifouling and reflecting metal is vapor deposited or printed on both the upper and lower surfaces of the top plate other than the radiation region, the portion where the near infrared ray is incident, and the portion where the reflected light is emitted. A top plate on which the pan is placed, heating means for heating the pan, an infrared sensor for detecting the infrared intensity emitted from the bottom surface of the pan, and the temperature of the bottom surface of the pan are calculated from the output of the infrared sensor. To a boundary surface between the temperature diffusing light guide and the reflective layer, a temperature calculating means, a light diffusing light guide in contact with or adhering to the top plate, a reflective layer provided on the lower surface of the diffusing light guide Light emitting means for emitting near infrared rays to irradiate, a radiation area for emitting near infrared rays provided in the heating area of the top plate, and reflected light from the bottom surface of the pan provided at a position facing the light emitting means. A light deriving unit for emitting, a reflection sensor for detecting the intensity of the reflected light emitted from the light deriving unit, an emissivity conversion means for converting the emissivity of the bottom surface of the pan from the output of the reflection sensor, Temperature calculation Control means for controlling the amount of power supplied to the heating means according to the output of the stage and the set thermal power, and the temperature calculation means is calculated from the output of the infrared sensor based on the converted emissivity A cooker designed to compensate for the temperature. A photonic band gap in which air holes are arranged in an orderly manner like a crystal is provided at a boundary portion between a radiation region and a region surrounding a region where a near infrared ray is incident and a region where reflected light is emitted. The heating cooker according to any one of 5. A photonic band gap in which cylinders adjusted to have a low refractive index are neatly arranged like a crystal at the boundary between the radiation area of the top plate and the area surrounding the part where the near infrared ray is incident and the part where the reflected light is emitted. The cooking device according to any one of claims 1 to 5.

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