JP5304551B2 - Induction heating cooker - Google Patents

Description

  The present invention relates to an induction heating cooker, and in particular, detects infrared rays radiated from a cooking vessel with an infrared sensor, obtains the temperature of the cooking vessel based on the detected amount of infrared rays, and controls temperature during cooking. .

The induction heating cooker is a cooker in which a heating coil is disposed below a top plate on which a cooking container is placed, and a heated object is heated in the cooking container by electromagnetic induction by passing a high-frequency current through the heating coil.

  As a conventional technique, for example, in a glass plate used as a top plate of an electromagnetic cooker that detects the temperature of an object to be heated by an infrared sensor, the glass plate is an infrared ray transmitting infrared ray transmitting portion facing the infrared sensor. And a glass plate for an electromagnetic cooker characterized in that the other part of the infrared transmitting portion of the glass plate is covered with an opaque layer (see, for example, Patent Document 1). .

Japanese Patent Laid-Open No. 10-284238 (Claim 1, FIG. 1)

  The above-mentioned glass plate for an electromagnetic cooker of Patent Document 1 has a problem regarding appearance that the inside of the heating coil and the like can be seen from the window when the cooking container is not placed on the glass plate.

The present invention has been made to solve the above-described problems, and infrared rays emitted from a cooking container even when visible light is shielded so that internal components such as a heating coil cannot be seen from the upper part of the infrared sensor. An object of the present invention is to provide an induction heating cooker capable of maintaining the detection accuracy of temperature detection means for detecting temperature by receiving light.

An induction heating cooker according to the present invention includes a top plate on which a cooking vessel is placed and transmits infrared rays, a heating coil for induction heating the cooking vessel, and a cooking plate provided below the top plate, An infrared sensor that receives infrared rays radiated from the container and passed through the top plate; control means for controlling power supplied to the heating coil based on a detection temperature of the infrared sensor; and visible light formed on the top plate surface; A dot-shaped printing unit in which innumerable dots made of a material capable of shielding infrared rays are arranged at predetermined intervals, and the dot-shaped printing unit is surrounded by the periphery, and the infrared rays emitted from the cooking container with respect to the infrared sensor An infrared transmissive window serving as a passage, and the dot-shaped printed portion in the peripheral area of the infrared transmissive window includes visible light and Has an inhibiting aperture ratio transmission of external, dot-like printing portion for covering the infrared transmission window, the to allow transmission of visible light and infrared than dots printed portion in the peripheral region of the infrared transmission window It has an aperture ratio larger than that of the dot-shaped printing portion in the peripheral area of the infrared transmission window .

  In the present invention, the infrared transmission window provided on the top plate does not obstruct the transmission of infrared rays from the cooking container to the infrared sensor, and the inside of the induction heating cooker is difficult to see through the infrared transmission window. Can do.

It is a block diagram which shows the induction heating cooking appliance which concerns on Embodiment 1 of this invention. It is a figure which shows the infrared rays transmission area | region which concerns on Embodiment 1 of this invention. It is a figure which shows the infrared rays transmission area | region which concerns on Embodiment 1 of this invention. It is a figure which shows the infrared rays transmission area | region which concerns on Embodiment 1 of this invention. It is a figure which shows the structure of the light-shielding means which concerns on Embodiment 2 of this invention. It is a diagram showing a boundary portion between the medium I of refractive index n ₁ and a medium II of the refractive index n _2. It is a graph which shows the incident angle dependence of the energy reflectivity of s-polarized light and p-polarized light concerning Embodiment 2 of this invention. It is a graph which shows the incident angle dependence of the energy reflectivity of p polarization | polarized-light which concerns on Embodiment 2 of this invention. It is a graph which shows the incident angle dependence of the energy reflectance of s-polarized light concerning Embodiment 2 of this invention. It is a top view of the induction heating cooking appliance which concerns on Embodiment 4 of this invention. It is a top view of the top plate which concerns on Embodiment 4 of this invention. It is an enlarged plan view of the induction heating part corresponding | compatible part of the top plate which concerns on Embodiment 4 of this invention. It is an enlarged plan view of the infrared rays transmission window which concerns on Embodiment 4 of this invention. It is a dot printing part enlarged view which covers the infrared rays transmission window of the top plate which concerns on Embodiment 4 of this invention. It is correspondence explanatory drawing of the dot printing part which covers the infrared sensor which concerns on Embodiment 4 of this invention, and an infrared rays transmissive window. It is correspondence explanatory drawing with the dot printing part which covers the infrared sensor which concerns on Embodiment 5 of this invention, and an infrared rays transmission window.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing an induction heating cooker 10 according to Embodiment 1 of the present invention.
The induction heating cooker 10 according to the first embodiment includes a heating coil 4 that induction-heats a cooking container 3 that heats and cooks an object to be heated, an inverter 9 that supplies high-frequency current to the heating coil 4, and a heating coil. 4 and a top plate 2 on which the cooking container 3 is placed.

An infrared sensor 5 that detects infrared rays emitted from the bottom surface of the cooking container 3 and a contact sensor 6 that contacts the lower surface of the top plate 2 and detects the bottom surface temperature of the cooking container 3 are disposed below the top plate 2. And a temperature detecting means 8a for deriving the temperature by the infrared sensor 5 and the contact type temperature sensor 6, and a control means 8 for controlling the inverter 9 in accordance with the output from the temperature detecting means 8a. The control means 8 has at least inverter control means 8b.

Further, a light shielding material is provided on the lower surface of the top plate 2 so that infrared rays from other than the cooking container 3 do not enter the infrared sensor 5. Here, the light shielding material refers to a material that can suppress transmission of infrared visible light. An inorganic pigment or an inorganic pigment containing a glass component is used as the light shielding material.

As the inorganic pigment, for example, the following substances are used.
Main component, 45.0 wt% of _Cr 2 _O 3, 15.0 wt% of Co ₃ O _4, 30.0 wt% of ZnO, 5.0 wt% _Al 2 _{O 3,} and 5.0 wt. % of green pigment consisting of SiO _2.
Chrome yellow, petal, titanium white, ultramarine, etc.
Carbon black.
Black body paint.

The above-described light shielding material is provided on the entire lower surface of the top plate 2, and a region provided with the light shielding material is referred to as a light shielding region 7a. However, on the surface of the top plate 2 located above the infrared sensor 5, the visible light is partially blocked, but the infrared light is easily transmitted. That is, on the surface of the top plate 2 positioned above the infrared sensor 5, the light shielding material is thinly applied or printed, or the light shielding material is provided in a dot shape or sparsely. Thus, it can be said that the light shielding region 7a is a region of the entire lower surface of the top plate 2 provided with the light shielding material, excluding the infrared transmission region 7b.

  Next, the operation will be described. When the induction heating cooker 10 is turned on by the AC power source 1 and set to a predetermined temperature by the operation switch, electric power is supplied from the inverter 9 to the heating coil 4 under the control of the control circuit 8. When electric power is supplied to the heating coil 4, an induction magnetic field is generated in the heating coil 4, and the cooking container 3 on the top plate 2 is induction-heated. Due to this induction heating, the temperature of the cooking container 3 rises, and the object to be heated in the cooking container 3 is cooked.

  Here, the operation of the infrared sensor 5 will be described. When the temperature of the cooking vessel 3 rises, infrared rays corresponding to the temperature are emitted from the cooking vessel 3. The infrared sensor 5 is configured by a photodiode, a thermopile, or the like that can detect a wavelength of 2.5 μm or less, for example, and infrared rays that have passed through the top plate 2 are incident on the photodiode or the thermopile. Moreover, disturbance light such as sunlight or illumination may enter the infrared sensor 5 in addition to the infrared rays from the cooking container 3. For this reason, the infrared rays incident on the infrared sensor 5 from other than the cooking container 3 are blocked by the light shielding means.

With these configurations, in the first embodiment, only the infrared rays from the cooking container 3 are incident on the infrared sensor 5, converted into a voltage corresponding to the amount of infrared rays, and amplified. Based on information from the infrared sensor 5 and the contact temperature sensor 6, the temperature detection means 8 a can accurately detect the temperature of the cooking container 3. Thereby, the inverter control means 8b controls the inverter 9 correctly, controls the cooking vessel 3 so that it may become predetermined | prescribed temperature, and can cook a to-be-heated material deliciously.

  2, 3 and 4 are diagrams for explaining the infrared transmission region 7b according to the first embodiment. The infrared transmission region 7b in FIG. 2 has a higher infrared transmittance than the light shielding means provided in the light shielding region 7a, or is made of the same material as the light shielding means, but the layer is made thinner to increase the infrared transmittance. Is provided.

  Examples of the light shielding material applied to the lower surface of the top plate 2 include inorganic pigments or inorganic pigments containing glass components. The light shielding material is provided by printing or adhering to the light shielding region 7a on the top plate 2, and when the same material is used for the infrared transmitting region 7b, the amount of the light shielding material is reduced. In FIG. 2, the infrared transmission region 7 b may be configured to include a light shielding material so that the infrared transmittance gradually increases toward the center of the infrared sensor 5.

  The infrared transmission region 7b in FIG. 3 has a higher infrared transmittance than the light shielding material provided with the light shielding region 7a on the surface of the top plate 2 located on the upper side of the infrared sensor 5, or the same material as the light shielding material. Is printed or adhered in a dot shape, and infrared rays and visible light are transmitted through the gaps between the dot-shaped light shielding materials. In FIG. 4, the dot of the light shielding material is sparse in the central portion of the infrared sensor 5, and the infrared transmittance is further increased in the central portion.

  Conventionally, there is no infrared transmission region 7b that facilitates the transmission of infrared rays, and when the cooking container 3 is not placed, the heating coil 4 can be seen from the outside, and the appearance of the induction heating cooker 10 deteriorates. was there. Therefore, by providing the infrared transmission region 7b and the infrared transmission region 7b on the top plate 2 directly above the infrared sensor 5 as described above, the heating coil 4 is difficult to see from the outside. Furthermore, when the cooking vessel 3 is placed, the infrared transmission region 7b transmits infrared rays from the cooking vessel 3, so that it is possible to prevent the temperature detection accuracy from being lowered.

In the first embodiment, the light shielding region 7a and the infrared ray transmitting region 7b are provided on the back surface of the top plate 2. However, the same effect can be obtained even if the light shielding region 7a and the infrared ray transmitting region 7b are provided on the surface of the top plate 2. Further, the dot shape of the light shielding material is not limited to the square shown in FIG. 3 or FIG. 4, and can take any shape such as a circle, a triangle, a rhombus, and a hexagon.

Embodiment 2. FIG.
FIG. 5 shows the configuration of the light shielding means 7 according to Embodiment 2 of the present invention. In FIG. 5, the light shielding means 7 is formed by coating a light shielding material on the lower surface of the top plate 2. Infrared light other than the cooking container 3 is cut by the light shielding means 7. However, infrared rays other than the cooking container 3 are not cut by 100%, but only a few tens of percent are cut.

Here, in order to efficiently cut infrared rays other than the cooking vessel 3, the light reflectance at the boundary surface between the two substances will be considered using optical knowledge. If the infrared reflectivity (energy reflectivity) of the light shielding means 7 painted on the top plate 2 is lowered, the phenomenon that the infrared rays are repeatedly reflected inside the top plate 2 (see the dotted arrow in FIG. 5) can be suppressed.

FIG. 6 is a diagram showing a boundary portion between the medium I having a refractive index n _{1 and} the medium II having a refractive index n ₂ . Consider how the infrared reflectance (energy reflectance) changes depending on the refractive index ratio n = n ₂ / n _{1 at} the interface between two different materials.
In FIG. 6, it is assumed that incident light is incident on the boundary surface with the medium II at an incident angle θ ₁ from the medium I side. At the boundary surface, the incident light is divided into one that is reflected to the medium I side at a reflection angle θ ₁ and _one that is transmitted through the medium II at a refraction angle θ ₂ .

一般に、物質の表面では、光の反射は入射角と偏光によって大きく変わる。図６において、入射光の偏光（電場ベクトルＥ）が矢印と二重黒丸で表示されている。二重黒丸で表示した部分では、物質境界面（反射面）に平行、すなわち入射面に垂直に偏光した光となっている。自然光は様々な偏光を含んでいるが、それらの偏光は全て入射面に平行な成分（ｐ偏光）と垂直な成分（ｓ偏光）に分けることができ、光のエネルギー反射率については、この２つの偏光について議論すれば足りる。 In the above case, the law of refraction (Snell's law) is established by the following relational expression. That is,

In general, on the surface of a material, the reflection of light varies greatly depending on the incident angle and polarization. In FIG. 6, the polarization of the incident light (electric field vector E) is indicated by an arrow and a double black circle. In the portion indicated by the double black circle, the light is polarized parallel to the substance boundary surface (reflection surface), that is, perpendicular to the incident surface. Natural light includes various polarized light, and all of the polarized light can be divided into a component parallel to the incident surface (p-polarized light) and a component perpendicular to the incident surface (s-polarized light). It is enough to discuss two polarizations.

Ｅ ⊥ 入射面（ｓ偏光）の場合：

In the case of n = n ₂ / n ₁ , the reflectance of p-polarized light and s-polarized light is expressed by the following formula from general optical knowledge. In the following equation, the parameter of the refraction angle θ ₂ is eliminated using Snell's law equation (1).
E // For incident plane (p-polarized light):

E 入射 For incident surface (s-polarized light):

In the above equations (2) and (3), there are two parameters n and θ ₁ . If the two parameters are changed at the same time, the energy reflectance can be plotted only in a three-dimensional graph. Therefore, here, the incident angle θ ₁ and energy when the ratio of the refractive indexes of the two media, that is, the value of n is fixed are fixed. Let us discuss the relationship of reflectance.

FIG. 7 shows the energy reflectance of the expression (2), that is, the p-polarized light when the values of n = n ₂ / n ₁ are set to n = 1.5, n = 1.3, and n = 1.1, respectively. Rp and the equation (3), that is, the dependence of the energy reflectance Rs of s-polarized light on the incident angle θ ₁ are plotted in a graph. Further, FIG. 8 is an energy reflectance Rp of the p-polarized light in FIG. 7, FIG. 9 is an independently shows an energy reflectivity R _S of s-polarized light in FIG.

In FIG. 7, the horizontal axis is the incident angle θ ₁ , and the angle is indicated by an arc degree method (radian). In the arc degree method, 180 ° is expressed as π radians, and the horizontal axis represents a range of 0 ° ≦ θ ₁ ≦ 90 °. The vertical axis indicates the energy reflectivity R of the incident light. This indicates how much incident light is reflected at the interface between the two substances.

Incidentally, when the energy reflectance R 1 is 1, all incident light is reflected at the boundary surface.
In FIG. 7, for example, in the case of the relationship between air and glass where n = 1.5, the energy reflectivity of incident light at an incident angle of 0 ° is Rs = Rp = 0.04, which is 4% incident light. It means being reflected on the glass surface.

The first point that can be read from FIG. 7 to FIG. 9 is that the energy reflectance increases rapidly as the incident angle increases, that is, when incident light is incident on the boundary surface. The second point is that as the ratio of the refractive indices of the two media, that is, the value of n increases, the energy reflectivity of s-polarized light and p-polarized light at each incident angle increases.

Furthermore, as a third point, it is also important that the energy reflectance of p-polarized light does not greatly depend on the value of n. Even if n = 1.5, n = 1.3, and n = 1.1, the energy reflectance of p-polarized light hardly changes. On the other hand, in the case of s-polarized light, when n = 1.5, n = 1.3, and n = 1.1, a significant difference appears in the change in energy reflectance.

Here, the difference in energy reflectance between s-polarized light and p-polarized light will be considered. As can be seen from FIG. 7, as the incident angle θ ₁ gradually increases, the s-polarized component has a higher energy reflectance than the p-polarized component. This indicates that “the light reflected by the boundary surface of the substance becomes light having a lot of s-polarized components”. Therefore, the s-polarized reflectance formula shown in formula (3) becomes important when considering the reflectance of light.

The above consideration regarding the reflectance is applied to the second embodiment. A light shielding hand region 7 coated with a light shielding material is provided on the lower surface of the top plate 2, and infrared rays from outside the cooking container 3 such as outside light are cut by the light shielding material. However, it is not possible to cut 100%, and only tens of percent can cut infrared rays.

Therefore, from the above consideration, when the infrared refractive index of the top plate 2 is n ₁ and the infrared refractive index of the light shielding means 7 is n ₂ , the infrared refractive index n ₂ of the light shielding material is substantially equal to the infrared refractive index ₁ of the top plate 2. By making it equal (that is, the value of n is made close to 1), infrared rays that are not cut by the light shielding material can be suppressed from being reflected inside the top plate 2.

That is, if the infrared refractive index of the top plate 2 and the light shielding means 7 are different, infrared reflection occurs at the boundary surface between the two, but the infrared light is attenuated inside the top plate 2 as indicated by the dotted arrow in FIG. The reflection will be repeated. However, the infrared reflectance can be suppressed by setting the refractive indexes of both to substantially the same value (n is made close to 1), and infrared rays from other than the cooking container 3 reach the infrared sensor 5. The rate of detection is greatly reduced.

In the second embodiment, it was experimentally found that the difference in refractive index between the two is preferably within 10%. Examples of the difference between the top plate 2 and the bending rate within 10% include an inorganic pigment containing a glass component, and the inorganic paint is applied to the back surface of the top plate 2. In this case, most of the infrared rays other than the infrared rays emitted from the cooking vessel 3 pass through the light shielding means as they are, so that the influence of the infrared rays other than the cooking vessel 3 on the infrared sensor 5 can be eliminated, and the temperature of the cooking vessel 3 is set correctly. Can be detected.

Embodiment 3 FIG.
In the third embodiment, the knowledge obtained in the second embodiment, that is, the difference between the infrared bending rate of the top plate 2 and the light shielding material within 10% is applied to the first embodiment. is there. In the first embodiment, the difference between the infrared bending rate of the light shielding material coated on the infrared transmission region 7b and the infrared bending rate of the top plate 2 is set to 10% or less, so that the infrared rays inside the top plate 2 are reduced. The reflectance can be suppressed, and the effect of increasing the amount of infrared rays transmitted from the cooking container 3 and greatly reducing the rate at which infrared rays from other than the cooking container 3 arrive at the infrared sensor 5 is detected.

Embodiment 4 FIG.
In the fourth embodiment, as described in the first embodiment, “the light shielding region 7a and the infrared transmission region 7b are provided on the back surface of the top plate 2, and the light shielding material is provided in the dot shape on the back surface of the top plate 2”. Further, the light shielding material is provided on both the front surface (upper surface) and the back surface of the top plate 2.

  The top plate 2 in the present embodiment is a rectangular flat plate made of a translucent material that transmits infrared rays, such as heat-resistant tempered glass or crystallized glass. At present, it is difficult to make the top plate 2 itself completely non-transparent, so that the built-in induction heating cooker, for example, the induction heating coil 4 cannot be seen by the user from above the top plate 2. Therefore, the entire back surface is provided with a back surface coating that blocks visible light. More on this later.

  In FIG. 10, reference numerals 11, 12, 13, and 14 denote metal protective plates, and the front, rear, left and right outer peripheral end surfaces of the top plate 2 are protected by these protective plates. The four protective plates may be joined together in advance to form a frame-like frame, and the top plate 2 may be fitted so as to cover the inner opening of the frame. The top plate 2 is fixed to the upper surface of the induction heating cooker by these protective plates 11 to 14.

  The induction heating cooker shown in FIG. 10 has two induction heating coils 4 arranged on the front and rear center line X when viewed in plan from above (hereinafter, the right coil is 4R and the left coil is the left one). 4L). That is, the intersection OX between the straight line Y1 that crosses the upper left portion of the induction heating cooker in the front-rear direction and the center line X coincides with the center position of the left induction heating coil 4. In this coil, about 30 thin wires of about 0.1 mm are bundled, and this bundle (collecting wire) is wound in a spiral shape while twisting one or a plurality of wires, so that the outer shape finally becomes a disk shape. . The maximum outer diameter is about 180 mm. The induction heating coil 4 is supported by a spring or the like from below so as to be as close as possible to or close to the lower surface of the top plate 2.

  On the surface of the top plate 2, a double circular guide mark 29ML centering on the intersection of the straight lines X and Y1 is formed. This is formed by dot printing of a light shielding material described later. It should be noted that the outermost peripheral position of the guide mark does not completely (strictly) coincide with the outermost peripheral position of the left induction heating coil 4L. The guide mark 29ML indicates a guideline for an appropriate induction heating area, and the user is expected to place a pan or the like in the guide mark.

As shown in FIG. 10, the right induction heating coil 4 </ b> R is installed at a position in contrast to the left induction heating coil 4 </ b> L across the left and right center line CL of the entire induction heating cooker. This coil has substantially the same configuration as the left coil 4L.

  Reference numeral 20 denotes a radiant central electric heating source (hereinafter referred to as “central heating source 7”). The central heating source 7 is located near the rear portion of the top plate 2 so as to straddle the left-right center line CL, and is installed in the space below the top plate 2 so as to radiate heat rays toward the lower surface thereof. Yes. The central heating source 7 uses an electric heater (for example, a nichrome wire, a halogen heater, or a radiant heater) that is heated by radiation, and heats an object to be heated such as a pan through the top plate 21 from below. Instead of a radiant heat source, an induction heating heat source such as the induction heating coil 5L may be used. On the top plate 2, a circular guide mark 29MR indicating a proper heating position as a guide corresponding to the upper side of the central heating source 20 is displayed by a method such as printing. In the case of carrying out the present invention, this heating source has no influence even if it is an induction heating type.

As shown in FIG. 10, a central operation unit 15, a right operation unit 16, and a left operation unit 17 are provided on the protective plate 11 at the front position of the top plate 2. The central operation unit has various input keys for setting energization conditions (thermal power, energization time, etc.) of the central heating source 20. The right operation unit 16 has various input keys for setting energization conditions (thermal power, energization time, heating control temperature, etc.) of the right induction heating coil 5R. Similarly, the left operation unit 16 has various input keys for setting energization conditions (thermal power, energization time, heating control temperature, etc.) of the left induction heating coil 5L.

When various input keys of the central operation unit 15, the right operation unit 16, and the left operation unit 17 are operated, the operation information is input to the control means 8 as shown in FIG. 1, and various heating operations are started, stopped, and adjusted. Etc. can be done.

In FIG. 10, the protective plate 12 at the rear of the top plate 2 has intake ports 18R and 18L serving as air intake ports on the left and right, and an exhaust port 19 opened in the center. Yes. Although not shown, a blower is installed in the internal space of the induction heating cooker, and indoor air is introduced from the intake ports 18R and 18L by the operation thereof, and electric heating parts such as the left and right induction heating coils 5R and 5L, inverters Important components such as power semiconductor elements of the circuit 9 are cooled and forcibly discharged from the exhaust port 19.

  In FIG. 10, a central display window 21 for integrated display means (not shown) is provided on the front side at the center in the left-right direction of the top plate 2. The integrated display means is mainly composed of a liquid crystal panel, and is provided in the vicinity of the lower surface of the top plate 2 so that display light is emitted from the lower surface of the liquid crystal panel through the top plate 2 (transmitted). Moreover, the integrated display means confirms the energization condition setting results of various heating sources such as the left heating coil 4L, the right heating coil 4R, and the central heating source 20, and displays the progress of cooking as characters and symbols as needed. It is something that can be done. Further, this integrated display means is also a means for the control means 8 to display various alarms and abnormal temperature based on the temperature information detected by the infrared sensor 5 and the contact temperature sensor 6. That is, all operations of the integrated display means are controlled by the control means 8 as shown in FIG.

  22R and 22L are a right display window and a left display window provided on the top plate 2 so as to be symmetric with respect to the center line CL. The magnitude of the heating power of the right heating coil 4R can be expressed by letters or graphs. A right heating power display lamp (not shown) for displaying in the form of a left heating power display lamp (not shown) for displaying the size of the heating power of the left heating coil 4L in letters, graphs, etc. In the position. Therefore, the display light from the left and right thermal power indicator lamps is emitted above the top plate 2 via the left and right display windows 22R and 22L of the top plate 2, and the user can easily visually check the thermal power from above the top plate 2. It is like that.

  23R and 23L are caution warning display portions provided on the left and right rear portions of the top plate 2, and the cautions for use and the warning items for safety are displayed in characters. As a display means, there are a method of making a sticker on which a warning warning is written and sticking it, and a method of printing directly on the upper surface of the top plate 2.

  As shown in FIGS. 10 and 11, the top plate 2 includes a left-right center line CL, a front-rear straight line Y1 passing through the left induction heating coil 4L, and a front-rear straight line passing through the right induction heating coil 4R. It is divided into six parts by Y2 (it does not mean that it is physically partitioned). That is, the front part includes three parts, ie, the central part FM, the right part FR, and the left part FL, and the rear part includes the central part RM, the right part RR, and the left part RL.

The top plate 2 has the entire lower surface, that is, the front center portion FM, the right side portion FR, the left side portion FL, and the rear center portion RM, the right side portion RR, and the left side portion RL, all of the first embodiment. A thin film is formed of the light shielding material as described in 1. above. In practice, an inorganic pigment or an inorganic pigment containing a glass component is fixed by painting (hereinafter referred to as “light-shielding coating”). However, since the following six portions are not light-shielded, the transmittance of visible light or infrared rays in those portions is the same as that of the glass material constituting the top plate 2. Further, by not painting, areas such as the central display window 21 and the infrared transmission windows 30R and 30L become clear and they are formed.
(1) Central display window 21.
(2) Right display window 22R.
(3) Left display window 22L.
(4) A portion 20A directly above the central heating source 20.
(5) Infrared transmitting window 30R provided at a portion corresponding to right induction heating coil 4R.
(6) An infrared transmission window 30L provided at a portion corresponding to the left induction heating coil 4L.

As described above, the right induction heating coil 4R and the left induction heating coil 4L are installed at opposite positions with the left and right center line CL interposed therebetween, but the infrared transmission window 30R and the infrared transmission window 30L are also symmetrical. And are the same size. Therefore, the left infrared transmission window 30L will be described in more detail.

  As shown in FIG. 13, the infrared transmission window 30L has a vertical dimension W1 of 15 mm, a horizontal dimension W2 of 15 mm, and a radius of curvature of four corners of 5 mm. As shown in FIG. 12, the infrared transmission window 30L is in an inner region of an inner mark 31ML provided on the inner side of the guide mark 29ML.

  An intersection OY1 between the vertical center line YA and the horizontal center line XA of the infrared transmission window 30L coincides with the center point OY2 of the light receiving window of the infrared sensor 5. In other words, the infrared sensor 5 is located just in the middle of the infrared transmission window 30L. As shown in FIG. 15, the light receiving window 5A of the infrared sensor 5 is an inlet that can take in infrared rays that reach the infrared sensor 5. In the fourth embodiment, the aperture OP is 5.5 mm (5.5 φ). . Note that the outer diameter OB of the introduction tube portion 5B having the infrared light receiving window 5A at the top is 7 mm or 8 mm.

The fourth embodiment is characterized in that the light shielding region 7a as described in the first embodiment is provided on the back surface and top surface (upper surface) of the top plate 2, but the back surface of the top plate 2 has infrared rays. Except for some special places such as the transmission windows 30R and 30L, the entire area was covered with a light shielding material. On the other hand, the surface is provided with a light shielding material in the form of dots.

The top plate 2 has the entire upper surface, that is, the front center part FM, the right side part FR, the left side part FL, and the rear center part RM, right side part RR, left side part RL, all of the first embodiment. The light-shielding material as described in (1) is scattered innumerably at fine points (small area) at predetermined intervals (hereinafter, this state is referred to as “dot shape”). Actually, fine dots made of an inorganic pigment or an inorganic pigment containing a glass component are fixed by painting (hereinafter referred to as “dot printing”). However, dot printing is not performed on the following six portions.
(1) Central display window 21.
(2) Right display window 22R.
(3) Left display window 22L.
(4) A portion 20A directly above the central heating source 20.
(5) Caution warning display portions 23R and 23L.

The dot printing on the top plate 2 will be described in detail.
As shown in FIG. 14, the dot DT simple substance shape of the light shielding material is a square. There are three types of the size of one dot DT, and there are a vertical W3 of 0.8 mm, a horizontal W4 of 0.8 mm, a vertical and horizontal of 0.7 mm, and a vertical and horizontal of 0.6 mm. The interval between the dots DT, that is, the pitch dimension, has three types of combinations in the vertical P1 and horizontal P2 as follows.
(1) High density (small aperture ratio): P1 is 1.2 mm, P2 is 1.2 mm
(2) Intermediate density (medium aperture ratio): P1 is 1.5 mm, P2 is 1.5 mm
(3) Coarse density (large aperture ratio): P1 is 2.0 mm, P2 is 2.0 mm
Note that the aperture ratio can be determined by comparing the size per unit area (for example, 1 cm square, that is, 100 mm ² ). When the aperture ratio is high, the transmission degree (transmittance) of visible light and infrared rays is also high. Become. A comparison may be made per aperture OP of the light receiving window 5A of the infrared sensor 5. In this embodiment, since it is 5.5 mm, when compared for each aperture OP, comparison is made at approximately 23.75 mm ² (= 2.75 mm × 2.75 mm × π). This is an example, and even if it is compared at 24 mm ² , the effect of the present invention is not hindered.

Calculation based on the above-described pitches P1 and P2 of the dot DT and the size of the single unit (area = W3 × W4) is as follows.
High density (small aperture ratio) part:
(A) Area of dot DT simple substance: 0.64 mm ² (= 0.8 mm × 0.8 mm)
(A) Area of one section: 1.44 mm ² (= 1.2 mm × 1.2 mm)
(C) the area of the ^{opening: 0.8mm 2 (= 1.44mm 2 -0.64mm} 2)
(D) Opening ratio: about 55.6% (= 0.8 ÷ 1.44)
Intermediate density (medium aperture ratio) part:
(A) Area of dot DT simple substance: 0.49 mm ² (= 0.7 mm × 0.7 mm)
(I) Area of one section: 2.25 mm ² (= 1.5 mm × 1.5 mm)
(C) Area of opening: 1.76 mm ² (= 2.25 mm ² −0.49 mm ² )
(D) Opening ratio: about 78.2% (= 1.76 ÷ 2.25)
Rough density (large aperture ratio):
(A) Area of dot DT simple substance: 0.36 mm ² (= 0.6 mm × 0.6 mm)
(A) Area of one section: 4.0 mm ² (= 2.0 mm × 2.0 mm)
(C) the area of the ^{opening: 3.64mm 2 (= 4.0mm 2 -0.36mm} 2)
(D) Opening ratio: 91% (= 3.64 ÷ 4.0)

As shown in FIG. 12, the high density portion (small aperture ratio) as described above is an outer portion surrounding the infrared transmission windows 30R and 30L and an inner region of the inner mark 31ML.

The intermediate density portion (medium aperture ratio is medium) as described above is a portion immediately outside the high density (small aperture ratio) portion, and the guide mark 29ML (29MR on the right side) shown in FIG. Is the inner area of

Further, there are two parts having a coarser density (a larger aperture ratio), one of which is the entire upper surface of the top plate 2, that is, the front center part FM, the right side part FR, the left side part FL, the rear center part RM, and the right side part. RR, left side RL. However, the following six parts are excluded.
(1) Central display window 21.
(2) Right display window 22R.
(3) Left display window 22L.
(4) A portion directly above the central heating source 20.
(5) Caution warning display portions 23R and 23L.

Another part of the coarser density (large aperture ratio) is the part of the two infrared transmission windows 30R and 30L. That is, the entire area of the transmission windows 30R and 30L of the infrared sensor 5 that detects the amount of infrared radiation emitted from the cooking container 3 is subjected to dot printing with an aperture ratio set to about 55.6%.

  In the fourth embodiment, the entire lower surface (back surface) of the top plate 2 (excluding specific parts such as the infrared transmitting windows 30R and 30L) is used to suppress (unnecessary) infrared rays that reach the infrared sensor from other than the cooking container. Is provided with a back surface coating using a light shielding material that blocks visible light, so that the detection accuracy of the infrared sensor 5 can be maintained.

Further, in the state where the cooking container 3 is not placed, the heating coils 4R, 4L, etc., which are built-in components, can be seen from above the top plate 2, and the backside of the conventional problem that the appearance has been impaired. Can be prevented by painting. In particular, the infrared transmission windows 30R and 30L are often directly above the center of the induction heating coils 4R and 4L due to the installation position of the infrared sensor 5, and the transmission windows 30R and 30L are flat for receiving infrared rays. Even if the area and diameter are reduced, there is a limit, and it is possible for the user to visually recognize that there is a hole or window of a certain size. The problem can be solved in the fourth embodiment.

Furthermore, the fourth embodiment also solves the concern that the internal structure can be seen through the infrared transmission windows 30R and 30L. That is, when the cooking container 3 is not placed, there is a concern that the heating coils 4R, 4L, which are built-in components, can be seen from the top plate 2 through the infrared transmission windows 30R, 30L. The induction heating coils 4R and 4L located near the infrared sensor 5 are usually formed of a metal object such as a copper wire as it is, so that unlike the black electric parts, the user can set the infrared transmission windows 30R and 30L. When seen unconsciously, you may see the metallic glow of the heating coil. The infrared transmissive windows 30R, 30L are often directly above the center of the induction heating coils 4R, 4L due to the installation position of the infrared sensor 5, and the transmissive windows 30R, 30L are plane areas for receiving infrared rays. Even if the diameter is reduced, there is a limit, and since there is a hole and window of a certain size and the user can visually recognize it, there is a concern that the built-in objects can be seen through here.

However, in Embodiment 4, since dot printing with coarse density (large aperture ratio) is applied to the entire infrared transmission windows 30R and 30L, the user's vision is influenced by the fine dots DT of the dot printing, The inside see-through is hindered by the action of the dot DT group, and it is difficult to look into the inside. In particular, when the dot DT is made into a white system called an expansion color, for example, when it is made pure white, light yellow, cream, etc., light such as room illumination for the top plate 2 is reflected on the dot DT and enters the user's eyes. Therefore, an effect that can be said to be a kind of blind action can be expected. Moreover, even in such dot printing, the aperture ratio should be secured above a certain level so that the amount of infrared radiation emitted from the cooking container 3 is not excessively cut and attenuated at the transmission windows 30R and 30L of the infrared sensor 5. Therefore, the detection accuracy of the infrared sensor 5 can be maintained.

Moreover, in the fourth embodiment, the entire upper surface of the top plate 2 is patterned by dot printing. That is, the guide marks 29MR and 29ML for guiding the proper placement position of the cooking container 3 with respect to the left and right induction heating coils 4R and 4L are represented by the difference in the density of the dot printing, and the outer side thereof is the dot printing with a lower density. Therefore, the user can understand that it is a cooker with a design that uniformly adopts dot printing with different densities as a whole. Therefore, the user does not pay particular attention to the portions of the infrared transmissive windows 30R and 30L having a certain size (small) from the top plate 2, and hardly feels discomfort or disgust at the portions. For this reason, it is not necessary to install a concealing member (for example, a mica plate that is expensive and requires a device for attachment, etc.) in consideration of being looked into from the outside at the portions of the infrared transmitting windows 30R and 30L.

In the fourth embodiment, the intersection point OY1 of the longitudinal center line YA and the lateral center line XA of the infrared transmission window 30L and the center point OY2 of the light receiving window of the infrared sensor 5 are aligned in a straight line, and are viewed finely. And the center point OY1 of the four dots DT at the center of the infrared transmission windows 30R and 30L are completely aligned with the center axis OY2 so that the center point OY2 of the light receiving window 5A of the infrared sensor 5 is aligned. Thus, the infrared rays from the cooking container 3 reach the infrared sensor 5 light receiving window 5A through the gap between the dots DT even if they are not in such a fine positional relationship. This is also related to the aperture ratio of dot printing and the size (area) of the dot DT. In the example described above, the area of the dot DT alone is 0.64 mm ² , whereas the area of the infrared light receiving window 5A is very large (about 37 times. The area of the light receiving window 5A is about 23.75 mm ² = 2. .75 mm × 2.75 mm × π), the applicant has confirmed with actual products that each dot DT itself does not interfere with infrared light reception.

Moreover, in the dot printing part like this Embodiment 4, since a fine uneven part is formed by the dot DT on the surface of a glass top plate, a micro gap is formed between the bottom of the cooking container 3 and the surface of the top plate. Is done. For this reason, even when a hot pan is placed directly on the surface of the top plate, it is difficult to form a sealed space between the bottom of the pan and the surface of the top plate. For this reason, the phenomenon that the air, the steam, etc. which were heated and expanded suddenly blows off from the pan bottom in the lateral direction is also suppressed. Even if the surface is soiled with food soup, etc., the height of the unevenness is low and the dot DT itself is small, so that the cleanability of the top plate surface can be maintained and the cooking container 3 such as a pan slides in the horizontal direction. A secondary effect is also expected to be suppressed.

In Embodiment 4, the density is highest in the entire upper surface of the top plate 2, that is, in the front center portion FM, the right side portion FR, the left side portion FL, and the rear center portion RM, the right side portion RR, and the left side portion RL. However, it is also possible to increase the density of dot-like printing in that portion (reduce the aperture ratio) to reduce the transmittance of visible light and infrared rays. In this way, it is possible to eliminate the need for the back coating provided on the lower surface of the top plate 2 and to block visible light and infrared rays, reduce the amount of use, or only provide a partial coating. For example, the position directly corresponding to the outer periphery of the bottom surface of the cooking container 3 or the area directly below the guide marks 29MR and 29ML, with the center directly above the infrared sensor 5, can be used. Even in this case, it is necessary to reduce the density of dot-like printing in the infrared transmission windows 30R and 30L serving as infrared paths for the infrared sensor 5.

Embodiment 5 FIG.
The fifth embodiment is a further development of the configuration of the fourth embodiment, and is a collection of dots DT made of a light shielding material, and a dot printing section that allows transmission of infrared rays and visible rays. The infrared transmitting windows 30R and 30L are provided on both the upper surface and the back surface.

  As shown in FIG. 16, in the fifth embodiment, a printing unit in which a large number of dots DT are arranged is provided in the entire area of the infrared transmission windows 30 </ b> R and 30 </ b> L. It is provided not only on the (upper surface) but also on the back surface (lower surface). In this case, since the dots DT are provided in two upper and lower stages, even if the visible light transmittance on the surface side of the top plate 2 alone is increased from that of the embodiment 4, the effect of blocking the user's vision can be maintained. That is, since the aperture ratio of dot printing can be further increased, the size (area) of the dot DT can be further reduced, and the pitches P1 and P2 described in the fourth embodiment can be further increased. It becomes.

Specifically, in the fifth embodiment, as shown in FIG. 16, a dot printing portion composed of a large number of dots DT <b> 1 (front side) is provided on the surface side of the top plate 2, while a large number of dots are also formed on the back surface side of the top plate 2. A dot printing part composed of the dots DT2 is provided (back side), and infrared transparency is ensured in the two-layer printing part. Since the dot DT1 is a thin layer or is made of a material having a low light shielding effect and a part of visible light passes through the dot DT1, the lower dot DT2 blocks the dot DT1 and DT2. In the overlapping portion, a light shielding effect can be expected as in the fourth embodiment. As a result, a so-called blind effect can be expected for a mechanically built-in object such as a heating coil. In the fifth embodiment, the dots DT1 on the surface side of the top plate 2 do not exhibit the visible light and infrared light shielding effects, but are applied to the entire surface side of the top plate 2 (in this case, the density is uniformly set). Or may be applied only to the infrared transmission window. This is because visible light and infrared rays that pass through the top plate 2 and escape to the back side may be shielded by a light shielding layer provided on the back side. As an example of this light shielding layer, dot printing with increased density may be employed.

1 AC power supply, 2 top plate, 3 cooking container, 4 heating coil, 5 infrared sensor, 5A light receiving window, 6 contact temperature sensor, 7a light shielding area, 7b infrared transmission area, 8 control means, 8a temperature detection means, 8b inverter Control means, 9 inverter, 10 induction heating cooker, 11 protective plate, 12 protective plate, 13 protective plate, 14 protective plate, 20 central heating source (radiant electric heating source), 21 central display window, 22R right display window, 22L Left display window, 23R Caution warning display section, 23L Caution warning display section, 29MR guidance mark, 29ML guidance mark, 30R infrared transmission window, 30L infrared transmission window, 31MR inner mark, 31ML inner mark, DT light shielding material dot, OX intersection, P1 pitch, P2 pitch, theta ₁ incident angle, theta ₂ refraction angle, _{n 1} the refractive index, _{n 2} the refractive index, refractive and n the refractive index _{n 1} The ratio of the rate _{n 2.}

Claims (6)

A top plate on which the cooking container is placed and which transmits infrared rays;
A heating coil for inductively heating the cooking vessel;
An infrared sensor that is provided below the top plate and receives infrared rays emitted from the cooking container and passed through the top plate;
Control means for controlling the power supplied to the heating coil based on the temperature detected by the infrared sensor;
A dot-shaped printing unit in which innumerable dots DT formed of a material capable of shielding visible light and infrared light formed on the top plate surface are arranged at predetermined intervals;
An infrared transmission window provided by being surrounded by the dot-shaped printing unit and serving as an infrared path radiated from the cooking container to the infrared sensor;
With
The dot-shaped printing portion in the peripheral area of the infrared transmission window has an aperture ratio that suppresses transmission of visible light and infrared light,
The dot-shaped printing portion covering the infrared transmission window is more than the dot-shaped printing portion in the peripheral area of the infrared transmission window so as to allow the transmission of visible light and infrared rays than the dot-shaped printing section in the peripheral area of the infrared transmission window. An induction heating cooker characterized by having a large opening ratio. The induction heating cooker according to claim 1, wherein a layer that shields infrared light and visible light is formed on the back surface of the top plate so as to avoid the infrared transmitting window and to widen the periphery of the top plate. The plane area of each dot DT of the dot-shaped printing portion applied to the infrared transmission window portion is smaller than the plane area of the infrared light receiving window, and the dots are arranged at a constant pitch P1, P2. The induction heating cooker according to claim 1, wherein: The dot-like printed part on the top plate surface is divided into three parts with different aperture ratios,
The first part with the highest aperture ratio is located directly above the heating coil,
A second portion having a lower aperture ratio is provided outside the center of this portion, and the aperture ratio is further reduced in a wide area extending to the outer peripheral edge of the top plate surface outside the second portion. Providing a third part,
The infrared transmitting window is in the first portion;
2. The induction heating cooker according to claim 1, wherein only the dot-shaped printing portion in the infrared transmission window has a low aperture ratio equivalent to that of the third portion. A top plate on which the cooking container is placed and which transmits infrared rays;
A heating coil for inductively heating the cooking vessel;
An infrared sensor that is provided below the top plate and receives infrared rays emitted from the cooking container and passed through the top plate;
Control means for controlling the power supplied to the heating coil based on the temperature detected by the infrared sensor;
A light shielding layer made of a material provided on the back surface of the top plate and capable of shielding visible rays and infrared rays;
A dot-shaped printing unit in which innumerable dots DT formed of a material capable of shielding visible light and infrared light formed on the top plate surface are arranged at predetermined intervals;
With
The dot printing part is composed of at least two parts,
The first dot printing part is located directly above the heating coil and has an aperture ratio that suppresses transmission of visible light and infrared light,
The second dot printing unit covers an infrared transmission window provided on the top plate and serving as an infrared path radiated from the cooking container 3 and transmits more visible light and infrared light than the first dot printing unit. An induction heating cooker characterized in that the opening ratio is set to be larger than that of the first dot printing section so as to allow. A top plate on which the cooking container is placed and which transmits infrared rays;
A heating coil for inductively heating the cooking vessel;
An infrared sensor that is provided below the top plate and receives infrared rays emitted from the cooking container and passed through the top plate;
Control means for controlling the power supplied to the heating coil based on the temperature detected by the infrared sensor;
A light-shielding layer made of a material provided on the top surface or the back surface of the top plate and capable of shielding visible light and infrared light;
An infrared transmission window provided on the top plate and serving as an infrared passage radiated from the cooking container;
With
Positioning the infrared transmitting window in an area surrounded by the light shielding layer;
Either one or both of the front and back surfaces of the infrared transmission window is covered with a dot-shaped printing unit in which a large number of dots DT made of a material capable of shielding visible light and infrared light are arranged at predetermined intervals.
The induction heating cooker, wherein the dot-shaped printing portion is set to an aperture ratio that allows visible light and infrared light to be transmitted through a region outside the infrared transmitting window .

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