JP2013182794A - Induction heating cooker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable efficient detection of a temperature of a pot on a top plate.SOLUTION: An induction heating cooker comprises: a body 1; a glass top plate 2 which is provided above the body 1 and on which printing 35 is made; a light guide cylinder 508 provided under the top plate 2 for transmitting infrared emitted from the pot 501; a hating coil unit 200 for heating the pot 501; and an infrared sensor 12 provided under the heating coil unit 200 for receiving infrared emitted from the pot 501 through the light-guide cylinder 12. The top plate 2 has characteristics of blocking visible light.

Description

  The present invention relates to an induction heating cooker that accurately detects the temperature of a pan on a top plate.

  As shown in FIGS. 3 and 4 of Patent Document 1, the conventional induction heating cooker is entirely coated with a specific design so that the inside of the main body cannot be seen with a transparent top plate. The optical sensor window is made of a material (transparent) of the material of the top plate and a paint for dropping the infrared rays without coating in order to transmit infrared rays radiated from the bottom of the pan to the lower part of the top plate. Under the optical sensor window, a pan temperature detector and a reflective photo interrupter are arranged adjacent to each other, and infrared rays emitted from the pan are received by the thermopile of the pan temperature detector, and detected by the reflective photo interrupter. Induction heating cooker that calculates the emissivity of infrared rays radiated from the pan from the reflectance of the cooked pan, corrects the infrared rays detected by the pan temperature detection device with the emissivity, and calculates the exact temperature of the pan There is.

  Similarly, in Patent Document 2, an opaque layer is provided on the lower surface of the transparent glass plate, an infrared transmitting part is provided on the part facing the infrared sensor, and the other part is covered with the opaque layer. is there.

JP 2012-22908 A JP-A-10-284238

  As in the structures of the top plate and the glass plate described in Patent Document 1 and Patent Document 2 described above, when the light sensor window that transmits infrared rays is provided, if the light sensor window is enlarged, there is a problem that the inside of the main body can be seen. In addition, if the light sensor window is made with respect to the light receiving area of the pan temperature detecting device, the infrared light emitted from the pan due to the positional deviation between the light sensor window and the pan temperature detecting device that receives the infrared light emitted from the pan. A problem arises in that the temperature of the pan cannot be accurately detected by blocking the top plate with the paint on the top plate.

  The present invention has been made to solve the above-described problems, and is provided with a main body, a glass top plate on which a pan is placed and printed on the upper surface thereof, and a lower portion of the top plate. A light guide tube that passes infrared rays radiated from the pan, a heating coil unit that heats the pan, and an infrared sensor that is provided below the heating coil unit and receives infrared rays radiated from the pan bottom of the pan through the light guide tube The top plate has a characteristic of blocking visible light.

  According to the present invention, the use of a glass top plate with a low visible light transmittance makes it difficult to see the structure inside the main body, so that a large photosensor window can be provided. Further, since the photosensor window is provided in a large size, even if the optical sensor window and the infrared sensor are misaligned, they can be prevented from being blocked by the printing of the top plate.

It is an external appearance perspective view of the induction heating cooking appliance of one Example. It is a top view of the heating coil unit of the induction heating cooking appliance of one Example. It is a functional block diagram of the pan heating control system of the induction heating cooker of one Example. It is CC sectional drawing of FIG. 1 of the light guide cylinder and infrared sensor module of the induction heating cooking appliance of one Example. It is an enlarged view of the B section of FIG.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an external perspective view of an induction heating cooker. In FIG. 1, 1 is a main body of the induction heating cooker. Reference numeral 2 denotes a top plate, which is covered with a plate frame 2 a that protects the periphery of the top plate 2.

  The top plate 2 is made of crystallized glass with high heat resistance, and the optical characteristics of this glass are that the infrared rays are transmitted with a high transmittance and less than 10% when the visible light transmittance is 500 nm or less, 500 to 800 nm. Sometimes it is a glass with the property of blocking less than 40%. And it arrange | positions horizontally on the upper surface of the main body 1, and mounts metal loads, such as the pan 501 (FIG. 3) which consists of magnetic bodies, such as iron, or nonmagnetic bodies, such as aluminum. The inside of the main body 1 without the light source cannot be seen from above through the top plate 2.

  Only the upper surface of the top plate 2 is provided with a design print 35, and the placement portions 35a, 35b, and 35c indicating the positions where the pan 501 is placed are shown. Inside the placement portions 35a and 35c, a specific part is shown. Non-printing portions 35d and 35e that are not partially printed are arranged. The printing 35 does not need to be a solid printing that covers the entire top surface of the top plate 2, and in the present embodiment, it is a printing with a pattern such as a spot and may be a dot pattern.

  The non-printing portions 35d and 35e correspond to the optical sensor windows 31a and 31c, respectively, and the optical sensor windows 31a and 31c are not printed so that the main body 1 has a function of measuring the temperature of the pan 501 for the user. The pan 501 also has a function of suggesting placing the pan 501 on the photosensor windows 31a and 31c. The optical sensor windows 31 a and 31 c transmit the infrared rays radiated from the pan bottom to the lower side of the top plate 2.

  Then, no printing for blocking infrared rays is performed on the lower surface of the top plate 2.

  Reference numerals 3a and 3c denote two heating units disposed on the upper part of the main body 1. A heating coil unit 200 (FIG. 2) for induction heating the pan 501 placed on the top plate 2 is disposed below the heating units 3a and 3c. I have it. 3b is a heating part which has a radiant heater (not shown) which heats the pan 501 placed on the top plate 2 below the heating part 3b.

  The air inlet 4 opens downward at the front of the main body 1 and sucks air on the front side of the main body, and the air inlet 4b at the rear of the main body sucks air in the kitchen cabinet, Cooling air is taken into (not shown). The exhaust port 5 is opened upward at the rear portion of the main body 1, and discharges exhaust gas after cooling the inside of the main body 1. The grill heating unit 6 is provided on the left side of the front surface of the main body 1.

  Reference numerals 7a to 7c denote operation units which are provided on the plate frame 2a on the upper surface side of the main body 1 and perform setting and operation of heating of the heating units 3a to 3c. Reference numerals 8a to 8c denote display units which are provided on the back side of the operation units 7a to 7c on the plate frame 2a and display the energization states of the heating units 3a to 3c in conjunction with the control circuit 503.

  FIG. 2 is a top view of the heating coil unit 200 below the heating units 3a and 3c. The heating coil 209 includes an inner peripheral heating coil 201 and an outer peripheral heating coil 202 that are provided concentrically on the same plane. The outer end of the inner peripheral heating coil 201 and the inner end of the outer peripheral heating coil 202 are electrically connected, and a current in the same direction flows through both coils. In this embodiment, the inner peripheral heating coil 201 is provided at a distance of about 30 to 45 mm from the coil center, and the outer peripheral heating coil 202 is provided at a distance of about 55 to 90 mm from the coil center. And

  The coil base 203 holds the heating coil 209. Reference numeral 508 denotes a light guide tube that guides infrared rays radiated from the bottom of the pan 501 to an infrared sensor module 407 (FIG. 3) described below provided below. The light guide tube 508 is formed integrally with the coil base 203 and is provided at a distance of 45 to 55 mm from the coil center. The light guide tube 508 does not need to be integrally formed with the coil base 203, and may be formed integrally with a component part of an infrared sensor module 407, which will be described later, or another part assembled with a component part of the infrared sensor module 407.

  Reference numerals 205 to 208 denote thermistors (contact temperature sensors) that measure the temperature of the lower surface of the top plate 2.

  FIG. 3 is a functional block diagram showing the pan heating control system.

  In FIG. 3, reference numeral 501 denotes a pan that is an object to be heated. A temperature detection circuit 502 calculates the temperature of the pan 501 based on the outputs of the infrared sensor module 407 and the thermistors 205 to 208. An emissivity calculation circuit 26 calculates the emissivity of the pan 501 based on the output of the infrared sensor module 407. Reference numeral 503 denotes a control circuit that corrects the temperature calculated by the temperature detection circuit 502 based on the output of the emissivity calculation circuit 26, controls the high-frequency power supply circuit 405 according to the corrected temperature, and supplies the power supplied to the heating coil 209. Control. A light guide tube 508 guides infrared rays emitted from the pan 501 to the lower infrared sensor module 407 and prevents infrared rays emitted from the heating coil 209 from entering the infrared sensor module 407.

  Next, details of the infrared sensor module 407 and the light guide tube 508 will be described with reference to FIG. FIG. 4 is a cross-sectional view of the vicinity of the infrared sensor module 407.

  As shown in FIG. 4, the infrared sensor module 407 has the following configuration. An opening 14 is provided above the resin case 16. The outer case of the resin case 16 is covered with a magnetic shielding case 13 except for the opening 14. A window member 15 is provided in the opening 14. Inside the resin case 16, a thermal infrared detection circuit 131, a reflectance detection circuit 132, and a printed wiring board 27 are provided.

  By configuring the resin case 16 with a resin having low thermal conductivity, the temperature inside the infrared sensor module 407 is prevented from changing suddenly, and the temperature of the thermal infrared detection circuit 131 and the reflectance detection circuit 132 is rapidly increased by heat transfer. Prevents change.

  The window member 15 has an optical characteristic that cuts infrared rays (4 μm or more) having a high temperature rising effect emitted from the top plate 2, the light guide tube 508, the heating coil 209, and the like that have become hot. Therefore, infrared rays having a wavelength with a high heating effect are prevented from entering the infrared sensor module 407. That is, with this configuration, the temperature of the thermal infrared detection circuit 131 and the reflectance detection circuit 132 is prevented from suddenly changing due to infrared rays having a high temperature-raising effect. In this embodiment, the infrared transmission characteristics of the top plate 2 and the infrared transmission characteristics of the window member 15 are the same.

  The magnetic shielding case 13 is made of nonmagnetic aluminum. Electromagnetic noise that enters the infrared sensor module 407 is reduced, and radiation heat received by the magnetic shielding case 13 is easily radiated.

  Next, signal detection in the infrared sensor module 407 will be described. Infrared radiation radiated from the bottom surface of the pan 501 reaches the thermal infrared detection circuit 131 through the top plate 2, the light guide tube 508, and the window material 15. The infrared light emitted from the reflectance detection circuit 132 reaches the pan 501 through the window member 15, the light guide tube 508, and the top plate 2. Infrared light emitted from the reflectance detection circuit 132 is reflected by the pan 501 and returns to the reflectance detection circuit 132 through the top plate 2, the light guide tube 508, and the window material 15 again. Eventually, it can be seen that infrared rays reach both the thermal infrared detection circuit 131 and the reflectance detection circuit 132 through both the top plate 2 and the window material 15.

  Next, the thermal infrared detection circuit 131 will be described in detail. The thermal infrared detection circuit 131 includes an infrared sensor 12 that detects infrared rays emitted from the bottom surface of the pan 501 and an amplifier 21 that amplifies the output of the infrared sensor 12. In this embodiment, a thermopile is used for the infrared sensor 12. The infrared energy that reaches the infrared sensor 12 is weak. Therefore, by integrating the infrared sensor 12 and the amplifier 21, electromagnetic noise mixing between the infrared sensor 12 and the amplifier 21 can be reduced. Then, a signal with a low S / N ratio is output from the thermal infrared detection circuit 131 by amplifying a signal with little noise contamination after being amplified 5000 to 10,000 times by the amplifier 21.

  Next, the reflectance detection circuit 132 will be described in detail. The reflectance detection circuit 132 includes the infrared light emitting element 20 and the infrared light receiving element 19 of the reflective photointerrupter 22. The light emitting unit 20 b housed in the infrared light emitting element 20 emits light, and the light emitted from the opening 20 a spreads radially and is reflected by the pan 501. The light reflected by the pan 501 is received by the light receiving unit 19b disposed below the opening 19a. The infrared light emitting element 20 is, for example, an infrared LED having an emission wavelength of 930 nm. The infrared light receiving element 19 is, for example, a phototransistor having a peak sensitivity wavelength of 800 nm and a sensitivity at a wavelength of 930 nm of 80% of the peak sensitivity. The infrared light emitted from the infrared light emitting element 20 is reflected by the pan 501 and returns to the infrared light receiving element 19. In the infrared light receiving element 19, a voltage proportional to the amount of received infrared light is generated, and the amount of received infrared light can be known from the voltage value.

  That is, the reflectance detection circuit 132 can detect the reflectance ρ of the pan 501 from the ratio of the infrared light emission amount and the infrared light reception amount. The reason why the light emitting wavelength of the infrared light emitting element 20 is 930 nm is that it is an infrared light having a wavelength that passes through the top plate 2 and the window material 15 and an infrared light having a wavelength that is hardly included in the infrared light emitted from the pan 501. is there. It can be determined that the 930 nm infrared ray received by the infrared light receiving element 19 is the infrared ray reflected by the pan 501, and the reflectance of the pan 501 can be accurately detected based on this infrared ray.

Here, a method in which the emissivity calculation circuit 26 calculates the emissivity based on the reflectivity obtained by the reflectivity detection circuit 132 will be described. The equation (ε + ρ = 1) is established between the emissivity ε of the infrared energy (E = εσT ⁴ ) radiated from the surface of the metal material at the temperature T and the reflectance ρ of the surface according to Kirchhoff's law (however, transmission) Rate α = 0). That is, it can be understood that if the reflectance ρ of the pan 501 can be known, the emissivity ε of the pan 501 can be calculated. The control circuit 503 calculates the voltage output from the temperature detection means 131 based on the pan bottom temperature corrected by using the emissivity ε calculated by the emissivity calculation circuit 26 when the temperature detection circuit 502 calculates the pan bottom temperature. The electric power supplied to the heating coil 209 can be suitably controlled.

  Next, the structure of the light guide tube 508 will be described. As shown in FIG. 2, the light guide tube 508 is a substantially oval tube as viewed from above. 4 is a CC cross section of FIG. 1, and therefore shows a cross section in the longitudinal direction of a substantially oval light guide tube 508.

  As described above, the light guide tube 508 is formed integrally with the coil base 203.

  The light guide tube 508 is provided at a position where the upper end 508c protrudes upward from the heating coil 209, and the lower end 508a reaches the infrared sensor module 407 fixed below the coil base 203, and the lower end 508a and the infrared sensor module 407 are connected to each other. A gap is provided so that cooling air flows between them.

  The light guide tube 508 has a cylindrical shape with an opening 508f having a wider opening at the upper end 508c than at the lower end 508a. In the drawing, the upper part ¼ is widened by providing an inclined portion 508e toward the upper end 508c, and the following is a substantially vertical cylindrical portion 508d up to the lower end 508a.

  Next, the printing 35 of the top plate 2 and the light guide tube 508 will be described with reference to FIG. FIG. 5 shows a portion B in FIG. 1 and shows the opening 508 f of the light guide tube 508 and the infrared sensor module 407 through the top plate 2.

  A placement portion 35a is shown on the top surface of the top plate 2 by printing 35, and a non-printing portion 35d on which a specific part is not printed is arranged inside the placement portion 35a. The non-printing part 35d is the optical sensor window 31a. Since the light guide tube 508 is disposed below the top plate 2, the opening 508 f is disposed inside the photosensor window 31 a of the top plate 2 when the non-printing portion 35 d is seen through. That is, the photosensor window 31a indicated by the non-printing portion 35d is provided in an area larger than the opening 508f of the light guide tube 508. The reflective photo interrupter 22 and the infrared sensor 12 are disposed inside the opening 508f.

  Next, the operation of this embodiment will be described.

  The description of light emission and light reception by the reflective photo interrupter 22 of the pan 501 placed on the upper surface of the top plate 2 in FIG. 4 will be described in relation to the top plate 2, the optical sensor window 31 a, and the light guide tube 508. Since the operation of the reflectance detection circuit 132 including the reflective photointerrupter 22 is as described above, the description thereof will be omitted.

  Here, the light emitted from the reflection type photo interrupter 22 passes through the opening 508f of the light guide tube 508 from the lower surface of the top plate 2 through the plate thickness 2s to the upper surface of the top plate 2, and the optical sensor window 31a. Is reflected at the bottom of the pot 501 through the non-printing part 35d.

  The non-printing portion 35d, which is the optical sensor window 31a, is described above in terms of the configuration above the opening 508f. The top plate 2 is further separated upward by a plate thickness 2s from the lower surface of the top plate 2 that is spaced apart 2d from the opening 508f. A print 35 is applied only to the upper surface of the plate. As shown in FIG. 5, the photosensor window 31a of the non-printing part 35d has a larger area than the opening 508f and extends substantially uniformly around the entire periphery of the opening 508f.

  Thereby, a part of the pan bottom of the pan 501 placed on the top plate 2 faces the non-printing portion 35d. Light is reflected from the entire area facing the non-printing portion 35d to the opening 508f.

  Then, the light emitted from the infrared light emitting element 20 is reflected by the pan 501 on the top plate 2 and received by the infrared light receiving element 19, and the reflectance of the pan 501 is measured.

  According to the above-described embodiment, the top plate 2 made of glass in which the inside of the main body 1 cannot be seen, and the bottom surface of the top plate 2 is not subjected to printing that blocks infrared rays, and the top having the design print 35 only on the top surface. Since the plate 2 is the optical sensor window 31a indicated by the non-printing portion 35d provided in an area larger than the opening of the light guide tube 508, the upper surface of the top plate 2 is enlarged above the opening 508f of the light guide tube 508. Since it is possible to measure, in the process of emitting infrared light by the reflective photo interrupter 22 and receiving light, the opening of the light guide tube 508 from the photosensor window 31a shown by the non-printing portion 20d provided in an area larger than the opening 508f of the light guide tube 508 Infrared light is received by the whole 508f and the infrared light receiving element 19 receives the infrared light necessary for measuring the reflectance of the entire opening 508f of the light guide tube 508. The reflectance of the pan bottom of an area larger than 508 of the opening 508f can be accurately measured.

  Further, since the optical sensor window 31a is provided large, it is possible to prevent the optical sensor window 31a from being blocked by the printing 35 of the top plate 2 even if the optical sensor window 31a is misaligned with the infrared sensor.

DESCRIPTION OF SYMBOLS 1 Main body 2 Top plate 12 Infrared sensor 19 Infrared light receiving element 20 Infrared light emitting element 22 Reflection type photo interrupter 31a, 31c Photo sensor window 35 Printing 35d, 35e Non-printing part 200 Heating coil unit 407 Infrared sensor module 501 Pan 508 Light guide tube 508a Lower end 508c Upper end 508e Inclined portion 508f Opening

Claims (1)

  A main body, a glass top plate provided on the upper surface of the main body and having a pan placed thereon and printed on the upper surface, a light guide tube that is provided below the top plate and transmits infrared rays emitted from the pan, and the pan A heating coil unit for heating the infrared ray sensor and an infrared sensor for receiving infrared rays radiated from the bottom of the pan through the light guide tube provided below the heating coil unit, and the top plate has a characteristic of blocking visible light An induction heating cooker characterized by that.