JP7140694B2 - heating cooker - Google Patents

Description

The present invention relates to a heat cooker.

2. Description of the Related Art Conventionally, a heating cooker microwave-heats an object to be cooked (load) placed in a cooking chamber by radiating microwaves from a microwave generating means into the cooking chamber. This type of heating cooker is equipped with a temperature distribution detection means using an infrared sensor for detecting the temperature distribution in the cooking chamber, calculates the temperature of the food to be cooked based on the detection signal from the temperature distribution detection means, and outputs the microwave heating output. is controlled (see Patent Document 1).

Japanese Patent Application Laid-Open No. 2018-84401

In the heating cooker described in Patent Document 1, an infrared sensor detects the surface temperature of the food to be cooked, and a temperature sensor that measures the ambient temperature in the cooking chamber detects the temperature change of the food to be cooked. However, the upper limit of the temperature detection range of the infrared sensor is until steam is generated from the food to be cooked. Since steam has the property of absorbing infrared rays in any wavelength range, if the wavelength range of infrared rays measured by the infrared sensor includes the infrared absorption wavelength of steam, the infrared sensor will not be able to correctly detect the food to be cooked. For this reason, after steam is generated, the temperature measured by a temperature sensor provided separately from the infrared sensor is used to estimate the temperature of the object to be heated, and the output of microwave heating is controlled. Since the surface temperature of the food to be cooked cannot be detected with high accuracy after the steam is generated, there is a problem that the finish of the food is overheated or underheated.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heating cooker capable of accurately detecting the temperature of an object to be cooked even when steam is generated from the object to be cooked during heating. and

The present invention comprises a heating chamber that houses a load, heating means that heats the load, temperature detection means that detects the temperature of the load based on infrared rays emitted from the load heated by the heating means, wherein the temperature detection means comprises an infrared attenuator that attenuates infrared rays in the infrared absorption wavelength band of steam within an infrared detection field of view for detecting the infrared rays, and the temperature detection means includes a heat sensitive element that detects the infrared rays and A sensor section having a condenser lens made of silicon or quartz for condensing the infrared rays on the thermosensitive element, and a window having the optical characteristics of the infrared attenuation section within the infrared detection field of the heating chamber. an opening is formed in the upper wall of the heating chamber, the window member is held on the heating chamber side of the opening, and the window member is provided between the condenser lens and the window member A cooling air passage for cooling a window material is formed, and the window material is made of borosilicate glass.

ADVANTAGE OF THE INVENTION According to this invention, the heating cooker which can detect the temperature of a to-be-cooked object correctly can be provided, even in the state in which steam was generated from the to-be-cooked object at the time of heating.

It is the perspective view which looked at the heating cooker of this embodiment from the front side. FIG. 2 is a cross-sectional view taken along the line AA of FIG. 1 with the outer frame and rear plate of the heating cooker of the present embodiment removed. It is a perspective view showing an internal state with the door of the heating cooker of the present embodiment opened. It is a bottom view which shows the state of the machine room of the heating cooker of this embodiment. 4 is an enlarged view of an infrared sensor showing reference point positions; FIG. It is an enlarged view of an infrared sensor which shows an end point position. It is an enlarged view of an infrared sensor showing a state in which the observation window is closed. 1 shows the infrared sensor of the first embodiment, (a) is a perspective view, and (b) is a cross-sectional view taken along line BB. It is a sectional view explaining operation of an infrared sensor. FIG. 2 is an optical characteristic diagram of the condenser lens shown in the first embodiment; FIG. 4 is an optical characteristic diagram of vapor; FIG. 2 is a spectral radiant energy diagram of blackbody temperature calculated from Planck's distribution law. 7 is a graph showing the relationship between the incident energy of infrared rays radiated by heating food with or without steam and the temperature of the food in an infrared sensor as a comparative example. It is a graph which shows the relationship between the incident energy of the infrared rays radiated|emitted by the heating of foodstuffs by the presence or absence of steam in the infrared sensor of 1st Embodiment, and foodstuffs temperature. FIG. 11 is an enlarged cross-sectional view of a condensing lens provided with an infrared sensor of a second embodiment; FIG. 10 is an optical characteristic diagram of the vapor barrier film shown in the second embodiment; It is a graph which shows the relationship between the incident energy of the infrared rays radiated|emitted by the heating of foodstuffs by the presence or absence of steam in the infrared sensor of 2nd Embodiment, and foodstuffs temperature. It is the side schematic diagram which expanded the infrared sensor of 3rd Embodiment.

Hereinafter, a form (this embodiment) for carrying out the present invention will be described. However, the present embodiment is not limited to the following content, and can be arbitrarily changed within the scope of the present invention. Further, the following description is based on the directions shown in FIG.

FIG. 1 is a perspective view of the heating cooker of this embodiment as seen from the front side. The heating cooker 100 stores, for example, an object to be heated (food material, object to be cooked) 60c (see FIG. 2) as a load in the heating chamber 28 (see FIG. 2), and uses microwaves, heater heat, and overheating. Steam is used to cook the object 60c to be heated.
As shown in FIG. 1, the heating cooker 100 has a main body 1 provided with a door 2 and an operation panel 4 . The main body 1 has an outer frame 7 covering an upper surface and left and right side surfaces, and a rear plate 10 covering a rear surface.

The door 2 is opened and closed in order to take the object 60c (see FIG. 2) into and out of the heating chamber 28 (see FIG. 2). The heating cooker 100 seals the heating chamber 28 by closing the door 2, prevents the leakage of the microwave used when heating the object 60c to be heated, confines the heat of the heater and superheated steam, and efficiently heats the object 60c. Allow to heat.

Door 2 also includes a handle 9 that facilitates opening and closing of door 2 . A glass window 3 is attached to the door 2. - 特許庁The glass window 3 allows the state of the object to be heated 60c being cooked to be checked from the outside. Further, the glass window 3 uses glass that can withstand high temperatures generated by heat generated by a heater or the like.

The operation panel 4 is provided on the front lower portion of the door 2 and has input means 71 . The input means 71 includes an operation section 6 for inputting the time for heating by heating means such as microwave heating and heater heating, and a display section 5 for displaying the content input from the operation section 6 and the progress of cooking. It consists of

An external exhaust duct 18 is provided on the upper portion of the rear plate 10 . Inside the body 1 to which the external exhaust duct 18 is attached, an exhaust hole 36 ( 3) are provided. Further, the external exhaust duct 18 is provided with an external exhaust port 8 that directs the exhaust air upward and toward the front side of the main body 1 .

FIG. 2 is a cross-sectional view taken along the line AA of FIG. 1 with the outer frame and rear plate of the heating cooker of this embodiment removed.
As shown in FIG. 2, the heating chamber 28 of the heating cooker 100 is surrounded by a bottom wall 28a, a rear wall 28b, a top wall 28c, a side wall 28f (only the left side is shown), and an inner wall 2a of the door 2 to form a square box. (rectangular parallelepiped).

A table plate 24 made of glass or ceramic is provided on the bottom wall 28a of the heating chamber 28. As shown in FIG. Food is placed on the table plate 24 . The food is an object to be heated 60c such as food and a container 60 containing the object to be heated 60c.

Heating cooker 100 is provided with machine chamber 20 in the space between bottom wall 28 a of heating chamber 28 and bottom plate 21 of main body 1 . The machine room 20 is provided with a magnetron 33 (heating means) that generates high frequency waves for heating the food (object to be heated 60c). A waveguide 47 is connected to the magnetron 33 . Further, on the back side of the upper wall 28c of the heating chamber 28, there is provided a heater 12 (heating means) used when grilling or oven-heating food.

Further, the machine room 20 is provided with a fan device 15 for cooling various parts described later. The fan device 15 is composed of a fan portion 15a attached to the bottom plate 21 and a casing 15b.

Further, the bottom wall 28a of the heating chamber 28 is formed so as to have a concave shape at the substantially central portion, and the rotating antenna 26 is installed therein. The microwave energy radiated from the magnetron 33 flows into the lower surface side of the rotating antenna 26 through the waveguide 47 and the opening 47a through which the output shaft 46a of the rotating antenna 26 penetrates, and is diffused by the rotating antenna 26 to be heated. radiated into the chamber 28; An output shaft 46 a of the rotating antenna 26 is connected to rotating antenna driving means 46 .

A hot air unit 11 for sending heated air into the heating chamber 28 is provided on the back side of the inner wall 28b. The hot air unit 11 is composed of a motor 13 , a heater 14 , a hot air case 11 a housing the heater 14 , and a fan 32 . Further, an intake hole 31 is formed at a position facing the fan 32 in the back wall 28b. Further, a blowout hole 30 for blowing hot air heated by the heater 14 into the heating chamber 28 is formed around the air intake hole 31 in the back wall 28b.

FIG. 3 is a perspective view showing the internal state with the door of the heating cooker of this embodiment opened. 3 shows a state in which the bottom wall 28a of the heating chamber 28 and the table plate 24 are partially cut away.
As shown in FIG. 3, the bottom wall 28a of the heating chamber 28 is provided with a plurality of weight detection means. The weight detection means includes a right weight sensor 25a and a left weight sensor 25b on the left and right sides of the front, a depth weight sensor 25c (see FIG. 2) on the center of the rear side, and a front weight sensor 25d (see FIG. 2) on the center of the front. It is composed by A table plate 24 is placed on these weight sensors 25a to 25d.

The table plate 24 is for placing food, and has heat resistance so that it can be used for both heater heating and microwave heating. It is made of materials such as

In addition, the table plate 24 is provided on the side walls 28f of the heating chamber 28 on the left and right sides of the heating chamber 28 in order to appropriately bring the food closer to the heater 12 when the food is heated using the grill heating means by the heater 12 (Fig. It is used by placing it on the shelf 27 of 3 stages).

An infrared unit 50 is provided on the far side of the upper wall 28 c of the heating chamber 28 . This infrared unit 50 detects the temperature of the entire area of the bottom wall 28a of the heating chamber 28 and detects the temperature of the food.

FIG. 4 is a bottom view showing the state of the machine room of the heating cooker of this embodiment.
As shown in FIG. 4, the machine room 20 is provided with a case 230a in which the inverter board 22 is housed in the central portion in the left-right direction. This case 230 a communicates with the cooling duct 16 . The cooling duct 16 is formed extending vertically upward between the back wall 28b and the rear plate 10 (see FIG. 3).

A control board 23 is arranged on the right side of the inverter board 22 in the machine room 20 . The control board 23 has a case 23 a covering the side surface of the control board 23 . A branch passage 23b is formed in the case 23a to guide the cooling air 39g to the depth side weight sensor 25c (see FIG. 2).

The fan device 15 is arranged on the side of the control board 23 and in front of the case 230a. The cooling air generated by the fan device 15 cools the self-heating magnetron 33 (see FIG. 2) in the machine room 20, the inverter board 22, the weight detection means (weight sensors 25a to 25d), and the like. The fan device 15 also includes a plurality of flow paths 15P, 15Q, and 15R. Cooling air 39a flows toward the left weight sensor 25b and cooling air 39b flows toward the magnetron 33 through the flow path 15P. Cooling air 39e flows toward the right weight sensor 25a (see FIG. 3) and cooling air 39f flows toward the control board 23 through the flow path 15Q. Cooling air 39 c flows through the flow path 15</b>R to the rotating antenna driving means 46 and cooling air 39 d flows toward the inverter board 22 .

Cooling air flows between the outside of the heating chamber 28 and the outer frame 7 (see FIG. 1) and between the hot air case 11a (see FIG. 2) and the rear plate 10 to cool the outer frame 7 and the rear plate 10. While passing through the exhaust hole 36 (see FIG. 3), it is discharged from the external exhaust port 8 of the external exhaust duct 18 .

The cooling duct 16 is formed in a substantially cylindrical shape and positioned between the hot air case 11 a and the rear plate 10 . Also, the upper end opening of the cooling duct 16 is connected to the infrared case 48 . Further, the cooling duct 16 is connected to the fan device 15 at its lower end opening to the blower connection port 15r of the case 230a. Also, part of the cooling air from the fan device 15 is taken into the cooling duct 16 .

FIG. 5 is an enlarged view of an infrared sensor showing reference point positions. FIG. 6 is an enlarged view of the infrared sensor showing the end position. FIG. 7 is an enlarged view of the infrared sensor showing a state in which the observation window is closed.
As shown in FIGS. 5 to 7, the infrared unit 50 includes a motor 51, an infrared sensor 52, a cylindrical unit case 54, and a shutter 55. As shown in FIG. Also, the infrared unit 50 is covered with an infrared case 48 .

On the other hand, on the far side of the upper wall 28 c of the heating chamber 28 , an arc-shaped observation portion 44 protruding inward of the heating chamber 28 is provided. An observation window 44 a is formed through the observation part 44 to open a field of view detected by the infrared sensor 52 . In addition, in order to prevent microwave leakage from the observation window 44a during microwave heating, the observation section 44 is provided with a rising wall (burring) 44b of about 2 mm outside the observation window 44a.

The motor 51 has a rotating shaft 51a, and rotates (drives) the unit case 54, thereby rotating the infrared sensor 52 housed in the unit case 54 together. Also, by rotating the substrate 53 on which the infrared sensor 52 is mounted, the direction of the condenser lens 52a of the infrared sensor 52 is directed from the back side of the bottom wall 28a of the heating chamber 28 (the back wall 28b side of the heating chamber 28) to the heating chamber. The temperature can be detected by rotationally moving within a range of about 30% from the bottom in the height direction of the opening 28d (see FIG. 9) of 28 . A stepping motor is used as the motor 51, and the rotary shaft 51a can be rotated forward, reverse, or rotated at a desired angle under the control of a control means provided on the control board 23 (see FIG. 4). ing.

The unit case 54 has the substrate 53 arranged at its maximum diameter portion, and has a window portion 54a through which the condenser lens 52a of the infrared sensor 52 faces. Further, the unit case 54 is configured to contain carbon as a material, and the characteristic of the unit case 54 is conductivity. This prevents external noise from entering the unit case 54 .

An air passage 55c formed in an arc shape is provided around the unit case 54. As shown in FIG. Further, openings 55a and 55b are formed in the case that constitutes the air passage 55c. The opening 55 a is positioned near the infrared sensor 52 .

The shutter 55 is made of a metal plate. A shutter 55 closes an observation window 44a to be described later when the infrared sensor 52 is not used.

A positioning protrusion 56 is formed in the case that constitutes the air passage 55c. When the control means controls the rotation of the motor 51 so that the detection point of the infrared sensor 52 is shown at the reference position (detection point a in FIG. 9), the positioning projection 56 positions the detection point of the infrared sensor 52 at the reference position. It is for correction. Therefore, when the observation window 44a is closed by the shutter 55, the rotating shaft 51a is caused to slip while the positioning protrusion 56 is in contact with a stopper (not shown) provided on the infrared case 48. FIG. As a result, the position of the detection point a (see FIG. 9) serving as the reference position controlled by the control means and the reference position detected by the infrared sensor 52 can be corrected.

FIG. 8 shows the infrared sensor of the first embodiment, (a) is a perspective view, and (b) is a cross-sectional view taken along line BB.
As shown in FIGS. 8A and 8B, the infrared sensor 52 is provided with a plurality of infrared detection elements 52b (for example, thermopiles). Here, an infrared sensor is used in which eight elements are arranged in a row in the direction perpendicular to the rotating shaft 51a (see FIG. 5).

The infrared sensor 52 also includes an infrared detection element 52b (see FIG. 8(b)) in which a large number of thermocouples are connected in series. The infrared detection element 52b is housed in a metal case 52e composed of a metal can 52c such as a nickel-plated steel plate and a metal stem 52d. The metal stem 52d is covered with a cylindrical metal can 52c in an inert gas such as nitrogen and welded.

An opening 52f is formed in the upper surface of the metal can 52c. A condensing lens 52a is attached to the opening 52f. The condenser lens 52a is, for example, borosilicate glass. In addition, the condenser lens 52a is provided within the infrared detection field, in other words, between the infrared rays reaching the infrared detection element 52b (on the path).

Next, the operation of detecting the temperature of food will be described with reference to FIG. FIG. 9 is a cross-sectional view explaining the operation of the infrared sensor.
As shown in FIG. 9, as an example of a container 60 with an open top containing an object to be heated (milk) 60c, a cup is placed on the table plate 24 provided on the bottom wall 28a of the heating chamber 28 and heated. is started. In this case, the observation window 44a is closed by the shutter 55 for 1 to 2 seconds when the magnetron 33 oscillates stably (see FIG. 7) to prevent noise from entering the infrared sensor 52 due to unstable oscillation when the magnetron 33 starts oscillating. do.

After the oscillation of the magnetron 33 is stabilized, the control means controls the motor 51 (see FIG. 5) to control the rotation of the rotating shaft 51a (see FIG. 5) so that it becomes the reference position (detection point a). As the rotating shaft 51a rotates to the reference position, the unit case 54 also rotates, and the direction of the condenser lens 52a of the infrared sensor 52 also rotates to a position where the detection point a at the reference position can be detected.

As the unit case 54 rotates, the detection of the temperature of the object 60c to be heated advances from the reference position (detection point a) to the detection points b and c of the table plate 24 . Further, when the unit case 54 rotates, the temperature on the outside of the container 60 is detected in the height direction, and the temperature from the detection point d to the detection point e is detected. After the detection point reaches the top of the opening of the container 60, the temperature of the surface of the object to be heated 60c is detected at the detection point f. Thereafter, the temperature inside the container 60 is detected at the detection point g, then the temperature of the table plate 24 is detected at the detection point h, and the temperature of the door 2 at the end point is detected at the detection point k. Thus, the surface temperature is detected at each detection point a to k.

The temperature detection in the temperature detection range from detection point a to detection point k may be performed both when the unit case 54 rotates back and forth. Alternatively, after the temperature is once detected up to the end point, after returning to the reference position, the detection points a to k may be sequentially performed again. Further, the number of temperature detection points can be changed as appropriate, and the detection points a to k described above are merely examples and are not limited to the present embodiment.

The end point of the temperature detection point k is set to the position where the temperature of the door 2 is detected. This is because the upper opening of the container 60 expands to a position where the surface temperature of the object 60c to be heated can be detected.

FIG. 10 is an optical characteristic diagram of the condenser lens shown in the first embodiment. In addition, in FIG. 10, the borosilicate glass of this embodiment is indicated by a dashed line. Crystallized glass is indicated by a solid line, and silicon is indicated by a broken line.
As shown in FIG. 10, borosilicate glass transmits 80% or more of light with a wavelength of 0.3 to 2.5 μm, and transmits up to about 50% of light with a wavelength of about 3.3 μm. Also, borosilicate glass hardly transmits (cuts) light with wavelengths longer than 3.5 μm and shorter than 0.2 μm. Also, borosilicate glass attenuates light with a wavelength of 2.5 to 2.9 μm in the range of 80% to 10%.

A condenser lens attached to a conventional infrared sensor is a silicon lens (silicon). The optical properties of silicon are such that approximately 50% of the light on the long wavelength side of 1 to 25 μm is transmitted, as indicated by the dashed line in FIG. Moreover, light of 0.8 μm or less and 25 μm or more is hardly transmitted.

By the way, when the food is cooked according to the contents input from the input means 71 (see FIG. 1) of the heating cooker 100, steam (vapor) is generated from the food in the case of a drink or a food containing water. FIG. 11 shows an optical characteristic diagram of vapor.
As shown in FIG. 11, steam has the property of absorbing infrared rays of a certain specific wavelength. The vapor has infrared absorption wavelengths of 2.5 to 2.9 μm (2.5 μm to 2.9 μm) and 5.0 to 7.7 μm (5.0 μm to 7.7 μm). Vapor has the characteristic of transmitting infrared rays except for such a wavelength band.

Thus, the borosilicate glass described above attenuates infrared rays in the entire band of 5.0 to 7.7 μm more than silicon glass (borosilicate glass: transmittance of 0%, silicon glass: transmittance of about 50%). ), which attenuates infrared rays in a partial band of 2.5 to 2.9 μm more than silicon glass (borosilicate glass: transmittance of about 10%, silicon glass: transmittance of about 50%).

Here, FIG. 12 shows a spectral radiant energy diagram (spectral radiant emittance of a blackbody) of the blackbody temperature calculated from Planck's distribution law. By integrating this spectral radiant energy over the entire wavelength range, the total radiant energy can be obtained, which is proportional to the fourth power of temperature (absolute temperature). This is the Stefan-Boltzmann law, and this coefficient σ is the Stefan-Boltzmann coefficient. The peak wavelength of spectral radiant energy is 7.8 μm to 11.5 μm at a cooking temperature of −20 to 100° C. according to Wien's law of displacement (see FIG. 12). A microwave-heated or grill-heated food emits infrared radiant energy E (E=εσT ⁴ ) depending on the temperature, where T is the temperature of the food and ε is the infrared emissivity of the food. The infrared sensor 52 converts and obtains the food temperature based on the detected value of the infrared radiant energy E emitted from the food.

Next, FIG. 13 and FIG. 14 show the relationship between the incident energy of the infrared ray that is incident on the infrared sensor 52 and radiated by heating the food and the temperature of the food. FIG. 13 is a graph showing the relationship between the incident energy of infrared rays radiated by heating food with or without steam and the food temperature in a conventional infrared sensor as a comparative example. FIG. 14 is a graph showing the relationship between the incident energy of infrared rays radiated by heating food with or without steam in the infrared sensor of the first embodiment and the temperature of the food. In FIGS. 13 and 14, there are two patterns of conditions, one in which steam is generated during heating of the food material, and the other in which steam is not generated.

FIG. 13 shows the result of using a silicon lens employed in a conventional heating cooker as the condenser lens 52a. FIG. 14 shows the result of using the borosilicate glass of the first embodiment for the condensing lens 52a. Incident energy of infrared rays is obtained by multiplying spectral radiant energy shown in FIG. 12 by optical characteristics (transmittance) shown in FIG. 10 and optical characteristics of vapor shown in FIG. The characteristic is obtained by integrating the entire wavelength range.

As shown in FIG. 13, when the condensing lens is made of silicon, the food temperature is defined based on the incident energy of the infrared rays. The error is 50°C at 200°C. As described above, in the conventional infrared sensor using a silicon lens for the condenser lens, when steam is generated from the food, the detection error of the food temperature is about 30° C., and the divergence from the actual temperature becomes large. In other words, when the temperature detection is set in the range of 5 to 8 μm, for example, when water vapor is generated, the incident energy of about 50% becomes zero, and the divergence from the actual temperature becomes large. As a result, there has been a problem of deterioration in heating performance, such as overheating or insufficient heating of food.

As shown in FIG. 14, when the condensing lens 52a is made of the borosilicate glass of the first embodiment, the food temperature error is 100° C. when the food temperature is defined based on the incident energy of the infrared rays. , the error is 5°C, and the error is 10°C at 200°C. In this way, the borosilicate glass condensing lens 52a is used to measure the temperature of the food in a wavelength range shifted from the infrared absorption wavelength range of steam (2.5 to 2.9 μm and 5.0 to 7.7 μm). By measuring , the effect of steam can be reduced.

Thus, by applying the infrared sensor 52 of the first embodiment, the range of the food temperature T heated by heating means such as microwave heating and grill heating is -20 ° C. to 100 ° C. Therefore, the food Food temperature can be accurately detected regardless of the presence or absence of steam generated from. That is, even in an environment where steam is generated in the heating chamber 28, the food temperature can be detected with high accuracy, so that overheating or insufficient heating of the food by the heating means can be suppressed. As a result, the food can be finished at the set temperature, and the cooking device 100 with high reliability can be provided.

As described above, the heating cooker 100 of the first embodiment includes the heating chamber 28 for storing food (load), the heating means (magnetron 33, heater 12) for heating the food, and the heating means. and an infrared sensor 52 (temperature detection means) that detects the temperature of food based on the infrared ray radiated from the food. The infrared sensor 52 includes a condensing lens 52a (infrared attenuator) for attenuating infrared rays in the infrared absorption wavelength band of vapor within an infrared detection field for detecting infrared rays. In this way, by measuring the temperature of the foodstuff (cooked food) in a wavelength band shifted from the infrared absorption wavelength band of steam, the influence of steam can be reduced.

In the first embodiment, the condenser lens 52a (infrared attenuator) uses at least part of the infrared absorption wavelength band of 2.5 to 2.9 μm and 5.0 to 7.7 μm. is attenuated. In addition, the infrared attenuator does not necessarily have to be shifted from the entire infrared absorption wavelength band of steam, and a part thereof may overlap with the infrared absorption wavelength of steam. Also, the infrared attenuator may be one that completely cuts off the infrared absorption wavelength of steam, or one that drops (attenuates) it to near zero. According to this, the temperature of the foodstuff (cooked food) can be accurately measured.

Further, in the first embodiment, the condensing lens 52a attenuates the infrared rays of the infrared absorption wavelength of vapor more than silicon (silicon lens). According to this, by attenuating the infrared absorption wavelength of steam more than silicon, the temperature difference due to the presence or absence of steam can be reduced.

In the first embodiment, the infrared sensor 52 includes an infrared detection element 52b that detects infrared rays, and a condenser lens 52a that condenses the infrared rays on the infrared detection element 52b. optical properties. This facilitates replacement with existing infrared sensors.

Further, in the first embodiment, the infrared attenuation section is made of borosilicate glass. According to this, it is resistant to thermal shock and suitable for the heating cooker 100 .

(Second embodiment)
A second embodiment of the present invention will be described with reference to FIGS. 15 to 17. FIG. FIG. 15 is an enlarged cross-sectional view of a condensing lens equipped with an infrared sensor according to the second embodiment. FIG. 16 is an optical characteristic diagram of the vapor barrier film shown in the second embodiment. FIG. 17 is a graph showing the relationship between the incident energy of infrared rays radiated by heating food with or without steam in the infrared sensor of the second embodiment and the temperature of the food. In addition, since the overall configuration of the second embodiment is the same as that of the first embodiment, the description thereof is omitted.

As shown in FIG. 15, the infrared sensor applied to the cooking device of the second embodiment has a condenser lens 150 coated with an infrared shielding film 52a1 that shields infrared rays in the infrared absorption wavelength range of steam. be. The infrared shielding film 52a1 is formed on the detection surface side of the condenser lens 150 (the side facing the food, the side facing the heating chamber 28). The condenser lens 150 is, for example, a conventional silicon lens or a quartz lens. Thus, the temperature detection means of the second embodiment is an infrared sensor including the infrared detection element 52b (see FIG. 8B) and the condenser lens 150 coated with the infrared shielding film 52a1. In addition, the infrared shielding film 52a1 is provided within the infrared detection field for detecting infrared rays (between the infrared rays reaching the infrared detecting element 52b (on the path)).

As shown in FIG. 16, the infrared shielding film 52a1 has an optical property of transmitting about 80% of infrared rays in the wavelength range of 8 to 14 μm (8 μm or more and less than 14 μm) and hardly transmitting infrared rays of less than 8 μm and 14 μm or more.

As shown in FIG. 17, the infrared incident energy is the spectral radiant energy shown in FIG. 12, the optical characteristics of the infrared shielding film 52a1 shown in FIG. , and integrated over the entire wavelength range.

If the food temperature is defined based on the incident energy of infrared rays, the temperature error in the presence or absence of steam is approximately 0°C at 100°C and 5°C at 200°C. Since the food temperature T that can be heated by heating means such as microwave heating and grill heating ranges from -20°C to 100°C, in the second embodiment, regardless of the presence or absence of steam generated from the food, the food temperature is set to the first temperature. It can be detected with higher accuracy than the one embodiment.

(Third embodiment)
The structure of the third embodiment of the invention will be described with reference to FIG. FIG. 18 is an enlarged schematic side view of the infrared sensor of the third embodiment. Note that the overall configuration of the third embodiment is the same as that of the first embodiment, so description thereof will be omitted. 3rd Embodiment arranges the optical filter 81 which suppresses the transmission of the infrared rays of the infrared absorption wavelength band of vapor|steam in the detection visual field of the to-be-heated object of the infrared sensor 52. FIG.

As shown in FIG. 18, the heating cooker includes a sensor section 57 as temperature detection means and an optical filter 81 as an infrared attenuation section. In addition, in FIG. 18, it is simplified and illustrated for convenience of explanation.

The sensor unit 57 includes an infrared detection element (heat sensitive element) 52b that detects infrared rays, and a condensing lens 150 that converges the infrared rays on the infrared detection element 52b. The infrared detection element 52b is similar to that of the first embodiment. The condenser lens 150 is, for example, a conventional silicon lens or a quartz lens.

Also, the sensor unit 57 is mounted on the substrate 53 . A sensor unit 57 mounted on the substrate 53 is housed in a tubular unit case 54 . The unit case 54 is formed with an opening window portion 54a through which the condenser lens of the sensor portion 57 is exposed. Thereby, the upper wall 28c of the heating chamber 28 is provided with an observation section 44 having an opening.

An observation section 44 formed on the upper wall 28c of the heating chamber 28 is provided with an optical filter 81 made of glass other than quartz. This optical filter 81 (window material) is held by a support portion 70 provided on the upper wall 28c. In this way, the optical filter 81 as a window material is provided within the infrared detection field for detecting infrared rays, in other words, between the infrared rays reaching the infrared detecting element (heat sensitive element) 52b (on the path).

The optical filter 81 is made of a material having optical properties of low transmittance in the vapor infrared absorption wavelength regions of 2.5 to 2.9 μm and 5.0 to 7.7 μm, and is made of borosilicate glass, for example.

A cooling air passage P through which the cooling air 39 flows is formed between the sensor section 57 and the optical filter 81 . A part of the cooling air 39 blown from the cooling duct 16 (see FIG. 2) to the unit case 54 is introduced into the cooling air passage P. As shown in FIG.

By the way, in the configuration in which the temperature of the object to be heated (food material, load) is detected in the sensor unit 57 via the optical filter 81, the infrared rays due to the temperature change of the optical filter 81 are measured. When the indoor temperature of the heating chamber 28 rises due to the heating means for the object to be heated and the temperature of the optical filter 81 rises, the infrared rays emitted from the optical filter 81 become thermal disturbance and enter the sensor section 57, resulting in the temperature of the object to be heated. It becomes a factor of detection error. Therefore, in the third embodiment, the cooling air 39 is supplied to the optical filter 81 to cool the optical filter 81, thereby suppressing the thermal disturbance of the optical filter 81 and correctly detecting the temperature of the object to be heated in the heating chamber 28 where steam is generated. can do.

As described above, the relationship between the incident energy of the infrared rays radiated by the heating of the food and the food temperature, which is incident on the sensor unit 57 for detecting the temperature of the food to be heated via the optical filter 81, is the same as the diagram described in the first embodiment. It has characteristics similar to 14. Steam is generated from the object to be heated (food) heated by the heating means (heater 12, magnetron 33) of the heating cooker, and the temperature of the object to be heated can be accurately detected even after the steam is generated.

Thus, the temperature detection means mounted on the cooking device of the third embodiment includes the infrared detection element 52b for detecting infrared rays and the sensor section 57 having the condenser lens 150 for condensing the infrared rays on the infrared detection element 52b. and an optical filter 81 having optical characteristics of an infrared attenuator within the infrared detection field of the heating chamber 28 . According to this, the existing sensor unit 57 (infrared sensor) can be used, which is advantageous in terms of cost.

Further, in the third embodiment, the optical filter 81 is made of borosilicate glass. According to this, the infrared attenuation unit can be configured at low cost.

Also, the optical filter 81 may be made of crystallized glass instead of borosilicate glass. As shown by the solid line in FIG. 10, the optical characteristics of the crystallized glass are such that light of 0.9 to 2.8 μm and light of 3.6 μm are transmitted by about 60%, and light of 0.4 μm or less and 5.0 μm or more is transmitted. is almost impenetrable. According to this, it is excellent in thermal shock and can be suitably arranged in the heating chamber 28 .

Further, in the third embodiment, a cooling air passage P for cooling the optical filter 81 is formed between the condenser lens 150 and the optical filter 81 . According to this, it is possible to suppress an error in the temperature of the object to be heated due to the thermal disturbance of the infrared rays emitted from the optical filter 81, and it is possible to accurately detect the temperature of the object to be heated.

As described above, the present embodiment has been described with reference to the drawings, but the present embodiment is not limited to the contents described above, and includes various modifications. For example, as the heating means, the heating cooker 100 including the heater 12 and the magnetron 33 was taken as an example, but it can be applied to a heating cooker including only the magnetron 33 (so-called microwave oven function only). good too.

1 main body 12 heater (heating means)
28 heating chamber 33 magnetron (heating means)
50 infrared unit 52 infrared sensor (temperature detection means)
52a condenser lens (infrared attenuation part)
52b Infrared detection element (heat sensitive element)
52c metal can 52d metal stem 52e metal case 52f opening 52a1 infrared shielding film (infrared attenuation portion)
57 sensor unit (temperature detection means)
60c Object to be heated (load)
81 optical filter (temperature detection means, infrared attenuation unit)
100 heating cooker P cooling air passage

Claims (1)

a heating chamber containing a load;
heating means for heating the load;
temperature detection means for detecting the temperature of the load based on infrared rays emitted from the load heated by the heating means;
The temperature detection means includes an infrared attenuation unit that attenuates infrared rays in the infrared absorption wavelength band of steam within an infrared detection field for detecting the infrared rays,
The temperature detection means includes a sensor unit including a thermal element for detecting the infrared rays and a condenser lens made of silicon or quartz for concentrating the infrared rays on the thermal element, and the infrared rays in the heating chamber. a window material having the optical properties of the infrared attenuator within the detection field of view,
an opening is formed in the upper wall of the heating chamber and the window material is held on the heating chamber side of the opening;
A cooling air passage for cooling the window material is formed between the condenser lens and the window material,
The heating cooker, wherein the window material is made of borosilicate glass.

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