JP2009236888A - Temperature distribution measuring device for microwave heating and temperature distribution measurement method for microwave heating - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a measuring device capable of measuring the temperature distribution of an object to be heated under microwave heating. <P>SOLUTION: The temperature distribution measuring device for microwave heating comprises: a microwave heater 10; an observation window 13 that transmits infrared rays radiated from a heated object to be heated and blocks the transmission of microwaves and the leakage of gas in a casing 11; and an infrared measuring instrument 20 capable of measuring the temperature distribution of the object to be heated. By the measuring device, by interposing an observation window between the object to be heated and an infrared detection section, the temperature distribution of the object to be heated under heating by the microwave heater can be measured by the infrared measuring instrument. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a microwave heating temperature distribution measuring apparatus capable of measuring a temperature distribution of an object to be heated heated by microwave irradiation, and a measuring method thereof.

  One method for efficiently heating a substance (object to be heated) is microwave heating in which the object to be heated is irradiated with microwaves. This microwave heating can be used industrially as well as home cooking. However, since microwave heating tends to intensively heat a portion that easily absorbs microwaves, in order to stably heat an object to be heated as desired, such as when uniformly heating, It is necessary to accurately grasp the heating condition (particularly the temperature distribution) of the object to be heated.

A thermocouple, a radiation thermometer, or the like is used for pinpoint temperature measurement, but when measuring the overall temperature distribution, it is conceivable to grasp the heating status using an infrared thermography. For reference, patent documents having descriptions related to these various temperature measurements are listed below.
JP 2002-349867 A JP 2007-121238 A JP-A-5-333073 JP 2005-214632 A JP 2006-111351 A

  However, although infrared thermography is generally used as a means for measuring the temperature distribution of an object to be heated, the temperature distribution of the object to be heated during microwave heating has not been measured by infrared thermography. The reason is considered as follows.

  In the first place, infrared thermography detects infrared rays (infrared radiant energy) emitted from a measurement object, displays the temperature distribution of the entire object by performing image processing or the like on the detected information. For this reason, as a premise for measuring an accurate temperature distribution, it is necessary to satisfactorily detect the infrared rays emitted from the measurement object. However, microwave heating is usually performed by housing an object to be heated in a metal casing that does not transmit infrared rays. Even when a viewing window with an electromagnetic wave shielding material is provided in a part of the casing, a plate made of glass or acrylic resin is usually attached to the viewing window. These glass or acrylic resins have many infrared absorption peaks in the vicinity of a wavelength of 10 μm, and absorb infrared rays well. In addition, since the wavelength region overlaps the detection wavelength region of the frequently used infrared thermography, the infrared thermography outside the casing cannot detect the infrared rays emitted from the heated object through the viewing window. For these reasons, it is considered that measurement of the temperature distribution of the object to be heated during microwave heating with a general infrared thermography has never been performed.

  In any case, measuring the temperature distribution of the object to be heated while performing microwave heating (In-Situ measurement) has not been done, and at the very least, as described in Patent Document 5 above, immediately after microwave heating. In addition, the microwave heater was opened and the temperature distribution of the object to be heated was measured by infrared thermography.

  The present invention has been made in view of such circumstances, and provides a temperature distribution measuring device for microwave heating and a measuring method thereof that can measure the temperature distribution of an object to be heated while performing microwave heating. For the purpose.

  As a result of extensive research and trial and error, the present inventor has developed a new temperature distribution measuring device that can measure the temperature distribution of the object to be heated during microwave heating with infrared thermography through the observation window. In fact, the temperature distribution of the object to be heated was successfully measured using this. And by developing this result, the present inventor has completed various inventions described below.

<Temperature distribution measuring device for microwave heating>
(1) The microwave heating temperature distribution measuring apparatus according to the present invention heats an object to be heated by irradiating the object to be heated contained in the casing with microwaves having an electromagnetic wave having a wavelength (λm) of 10 to 1000 mm. A microwave heater, an observation window that transmits infrared rays emitted from the heated object to be heated and shields transmission of the microwave and leakage of gas in the housing, and radiation from the object to be heated Comprising an infrared detector capable of measuring the temperature distribution of the object to be heated based on the detection information of the infrared detector having an infrared detector for detecting infrared rays,
The temperature distribution of an object to be heated while being heated by the microwave heater can be measured by the infrared measuring instrument through the observation window interposed between the object to be heated and the infrared detection unit. And

(2) According to the temperature distribution measuring apparatus for microwave heating of the present invention (hereinafter simply referred to as “temperature distribution measuring apparatus”), the temperature distribution of the object to be heated during microwave heating directly through the observation window. Can be measured. This enabled In-Situ observation of the sample temperature distribution during microwave heating. Moreover, the observation window of this temperature distribution measuring apparatus not only transmits infrared rays emitted from the object to be heated while blocking the transmission of the irradiated microwave, but also blocks the leakage of gas in the housing. For this reason, not only the operation environment at the time of temperature distribution measurement is excellent, but also the temperature distribution of the object to be heated can be observed and measured in a state where the inside of the housing is maintained in a desired atmosphere. Specifically, the object to be heated is performed while performing a heating process (for example, a sintering process, a firing process, etc.) for heating the object to be heated in a vacuum atmosphere or a gas atmosphere filled with a specific gas in the housing. It is possible to directly observe and measure the temperature distribution. Thereby, not only simply measuring the temperature distribution of the heated object to be heated, but also detecting, specifying, setting and heating control suitable for the heating process performed in various manufacturing processes, This can be performed using the temperature distribution measuring apparatus of the present invention. More specifically, it becomes possible to investigate the cause of a non-uniform heating state (heating unevenness) or to perform uniform heating control using microwaves. As a result, it is easy to ensure product quality even when microwave heating is used in the manufacturing process.

  As described above, the temperature distribution measuring apparatus according to the present invention can observe the temperature distribution of the sample (object to be heated) in real time, and further can perform in-situ observation of the sample temperature distribution while controlling the atmosphere during heating. The point is innovative and unprecedented, and is expected to be widely used. In addition, although a highly accurate temperature distribution measurement is possible, a commercially available infrared measuring instrument can be used, so that it is relatively simple and inexpensive.

<Temperature distribution measurement method for microwave heating>
The present invention is grasped not only as the above temperature distribution measuring apparatus but also as the following temperature distribution measuring method. This measurement method is not limited to the case where the above-described measurement apparatus is used. However, if the above measuring apparatus is used, the measuring method of the present invention is substantially used.

The method for measuring the temperature distribution for microwave heating according to the present invention includes a heating step of heating the object to be heated by irradiating the object to be heated contained in the casing with microwaves having an electromagnetic wave having a wavelength (λm) of 10 to 1000 mm. ,
An observation window that transmits the infrared rays radiated from the heated object to be heated and shields the transmission of the microwave and the leakage of gas in the housing is emitted from the object to be heated and the object to be heated. A measurement step of measuring the temperature distribution of the object to be heated that is irradiated with the microwave, based on the detection information of the infrared detection unit, interposed between the infrared detection unit and the infrared detection unit that detects infrared rays. It is characterized by.

<Additional configuration>
In addition to the above-described configuration, the microwave heating temperature distribution measuring device and the measuring method thereof according to the present invention further includes one or two or more arbitrarily selected from the configurations listed below. Is preferred. It should be noted that a configuration selected from the following can be added to a plurality of inventions in a superimposed manner and arbitrarily.

In addition, any of the configurations shown below can be appropriately combined with each other across categories. For example, a configuration that appears to be relevant only to one of the measuring device or the measuring method may also be relevant to the other.
(i) The observation window includes a porous shield having a plurality of transmission holes that transmit infrared rays emitted from the heated object to be heated while shielding transmission of the microwave, and a proximity to the porous shield. And a sealed gas that seals outflow of gas in the casing while transmitting infrared rays emitted from the object to be heated.
(ii) The sealed gas is made of an infrared transmitting material having a transmittance of 60% or more in a wavelength region of 2 to 14 μm.
(iii) The infrared transmitting material includes, as an example, one or more of calcium fluoride, sapphire, or zinc selenide.
(iv) The porous shield is a metal perforated plate or a metal mesh in which a large number of pores serving as the transmission holes are formed.
(V) The porous shield has an aperture ratio (Sd / St x 100%) which is a ratio of the total area (Sd) of the transmission holes in the specific range to the total surface area (St) in the specific range. ~ 80%.
(Vi) The temperature distribution measuring apparatus for microwave heating according to claim 1 or 6, wherein the infrared measuring instrument is an infrared thermography.
(Vii) The detection wavelength of the infrared thermography is 2 to 14 μm.
(Viii) The infrared detector is a thermopile, a bolometer, InSb or PtSi.

<Others>
Unless otherwise specified, “x to y” in the present specification includes the lower limit x and the upper limit y. In addition, it should be noted that the lower limit and the upper limit described in the present specification can be arbitrarily combined to constitute a range such as “ab”.
Moreover, the to-be-heated material measured by the measuring apparatus or measuring method of this invention does not ask | require an inorganic substance, an organic substance, a metal or a metal compound, an anhydride, a hydrated substance, etc.

The present invention will be described in more detail with reference to embodiments of the invention.
It should be noted that the contents described in this specification, including the following embodiments, are applicable not only to the microwave heating temperature distribution measuring apparatus according to the present invention but also to the measuring method as appropriate. . Also, it should be noted that which embodiment is the best depends on the target, required performance, and the like.

(1) Microwave heater The microwave referred to in this specification is not particularly limited as long as microwave heating is possible, but generally has a wavelength (λm) of 10 to 1000 mm. In terms of frequency, it is 0.3 to 30 GHz.

  For the oscillation of the microwave, a solid oscillator, magnetron, klystron, gyrotron or the like is used, and any of those that are effective for microwave heating may be used. However, generally a magnetron is used. As such a heating device (microwave heater) using microwaves, a so-called microwave oven is typical, but it is not limited to household use and may be industrially large-scale.

  A microwave heater generally includes a metal casing that shields microwaves, and includes a door that allows a heated object to be taken in and out of the casing. In the case of the present invention, the object to be heated does not necessarily need to be completely enclosed or sealed, and may have an open part as long as efficient microwave heating can be performed. However, since the observation window can shield the leakage of gas in the housing, it is needless to say that a sealed space is formed by the observation window and the housing. The observation window according to the present invention may be formed by processing a part of the casing, or may be formed retrospectively by improving a part of the casing or the door.

(2) Infrared measuring device An infrared measuring device can measure the temperature distribution of a to-be-heated object based on the detection information from the infrared detection part which detects the infrared rays which a to-be-heated object discharge | releases. More specifically, for example, the infrared measuring device includes an infrared detection unit, a processing unit that performs image processing on the detection information, and a display unit that displays the processing result of the processing unit.

  The type of the infrared measuring device is not limited, but in general, infrared thermography (referred to as “thermography” as appropriate) is typical. General thermography is commercially available and can be obtained relatively inexpensively.

  The wavelength of infrared rays emitted from the object to be heated is usually 0.4 to 30 μm. Therefore, the detection wavelength of the thermography may be 2 to 14 μm accordingly. Specifically, for example, the detection wavelength (λe) of the infrared detection unit is preferably 2 to 5 μm (InSb or the like) or 8 to 14 μm (bolometer or the like). Note that the infrared detection unit is specifically composed of InSb or a bolometer through a lens or the like.

(3) Observation Window The observation window shields the transmission of microwaves and the leakage of gas in the housing while transmitting infrared rays radiated from the heated object to be heated. As a specific example, there is an observation window in which the above-described porous shield and sealed gas are combined. This observation window is preferably provided with a microwave heater casing (including a door) as a frame, which simplifies the measurement apparatus. There are no restrictions on the outer shape, size, or thickness of the observation window. For example, the observation window may be circular or rectangular. In short, it is only necessary to measure the temperature distribution of the object to be heated while suppressing the transmission of microwaves and the leakage of gas in the housing.
It is preferable that the observation window is kept airtight with a window frame of the casing through packing or the like. When the observation window is composed of a porous shield and a sealed gas, it is preferable that the metal porous shield is in contact with the metal housing at least at the outer periphery thereof, etc., so that the microwave is reliably shielded. It is.

(i) Porous shield A typical example of the porous shield is an electromagnetic wave shielding member made of a metal porous plate in which a large number of openings are provided in a metal net or a metal plate. As long as the microwave is shielded, the material of the porous shield is not limited, but a metal, particularly an iron-based material, is preferable because it is inexpensive. In addition, the porous shield may be made of copper (or copper alloy), aluminum (aluminum alloy), nickel (nickel alloy) or brass.

  As such an electromagnetic wave shielding member, there are a punching metal obtained by drilling pores having a diameter of several millimeters on a metal plate having a thickness of several millimeters, and a metal mesh (expanded metal or the like) that can form a mesh-like opening when deployed. A wide variety of such electromagnetic shielding materials are commercially available and can be obtained at low cost.

The lower limit of the thickness of the porous shield is preferably 0.1 mm, 0.3 mm, 0.5 mm, 0.7 mm or even 1 mm. The upper limit is preferably 3 mm, 2 mm, 1.5 mm or even 1.2 mm. These upper and lower limits can be arbitrarily combined. For example, the thickness is preferably 0.5 to 2 mm.
If the thickness of the porous shield is too small, microwave leakage becomes excessive, which is not preferable. If the thickness is excessive, the infrared rays emitted from the object to be heated are difficult to reach the infrared detection unit such as a thermography accurately, and an error is likely to occur in the measurement temperature. In addition, even if the porous shield is thin and its strength and rigidity are reduced, there is not much problem because it is reinforced with a sealed gas.

For example, if the microwave frequency is 2.45 GHz (wavelength: 122 mm), the lower limit of the diameter of the transmission hole is preferably 0.5 mm, 0.7 mm, 1 mm, 1.2 mm, or 1.5 mm. The upper limit of the hole diameter is preferably 3.5 mm, 3 mm, 2.5 mm or even 2.0 mm. These upper and lower limits can be arbitrarily combined. For example, the pore diameter is preferably 1 to 2.5 mm.
When the hole diameter is too small, infrared rays are hardly transmitted. When the pore diameter is excessive, although it depends on the wavelength of the microwave, the leakage of the microwave is excessive, which is not preferable.

  The opening ratio (Sd / St x 100%), which is the ratio of the total area (Sd) of the permeation holes in the specific range to the total surface area (St) in the specific range of the porous shield, has a lower limit of 35%, It is preferable to be 40%, 50%, 60% or even 65%. Further, the upper limit is preferably 85%, 80% or less, 75% or even 70%. These upper and lower limits can be arbitrarily combined. For example, the opening ratio is preferably 40 to 80%.

  If the aperture ratio of the porous shield is too small, the relative intensity of the infrared rays emitted from the object to be heated is lowered, and the infrared detector cannot be detected sufficiently, and the temperature error can be increased. On the other hand, an excessively high aperture ratio is not preferable because rigidity and strength of the porous shield are insufficient and microwave leakage also increases.

  When the present inventor investigated the relationship between the wavelength of the microwave and the size (pore diameter) of the transmission hole of the porous shield, the average diameter (d of the transmission hole of the porous shield with respect to the wavelength of the microwave (λm: mm) (d The lower limit of the aperture diameter ratio (d / λm) which is a ratio of: mm) is preferably 1/300, more preferably 1/120. The upper limit is preferably 1/40 or even 1/50. These upper limits and lower limits can be arbitrarily combined. For example, the opening diameter ratio is preferably 1/120 to 1/50. Also in this case, if the aperture diameter ratio is too small, the intensity of transmitted infrared light is reduced, and if the aperture diameter ratio is excessively large, microwave leakage increases.

  The hole shape of the transmission hole does not need to be circular, and various shapes such as a square, a rectangle, a star, and a trapezoid are conceivable. The same applies to expanded metal. In addition, when a hole shape is not circular, the upper and lower limit of the said hole diameter is applied with respect to the hole diameter converted from the opening area (converted hole diameter).

(ii) Sealing gas The sealing gas is provided in the vicinity of the porous shield and transmits infrared rays emitted from the object to be heated and seals outflow of gas. This sealed gas is sufficient if it can prevent leakage of gas from the porous shield. That is, at least in the present invention, it is sufficient that the airflow is inhibited within a range in which the sealed gas is provided. However, as described above, when performing a microwave heater or the like while controlling the atmosphere in the housing, the sealed gas is preferably one that can be kept airtight in cooperation with the overall structure of the housing. .
As long as the sealed gas is such, the form (outer shape, size, thickness, transparency, color, etc.) does not matter. Arrangement of the porous shield and the sealed gas is also free. For example, even when the porous shield is inside the casing and the sealed gas is outside the casing, the opposite is also possible. Furthermore, a sealed gas may be provided on both sides of the porous shield. In any case, since the porous shield and the sealed gas are basically separate members, the observation window is obtained by joining, bonding, bonding, and the like.

  Of course, it may be a composite of both in production. For example, in addition to the case where the sealed gas covers the entire surface of the porous shield, an infrared transmitting material constituting the sealed gas may be integrally or individually filled or embedded in each transmission hole of the porous shield. . In any case, an observation window is sufficient if the sealed gas and the porous shield cooperate to shield microwaves, transmit infrared rays, and prevent airflow.

  Examples of the infrared transmitting material forming the sealed gas include sapphire (Al2O3), calcium fluoride (CaF2), magnesium fluoride (MgF2), and lithium fluoride (LiF). The transmission wavelength range of these infrared transmitting materials is mainly 2 to 5 μm. Examples of other infrared transmitting materials include zinc selenide (ZnSe), zinc sulphide (ZnS), and barium fluoride (BaF2). The transmission wavelength range of these infrared transmitting materials is mainly 8 to 14 μm or 2 to 5 μm. Which infrared transmitting material is used may be selected according to the infrared detection wavelength (λe) of the above-described infrared thermography, for example, 2 to 5 μm (InSb or the like) or 8 to 14 μm (bolometer or the like). Of course, conversely, an infrared thermography having a detection wavelength corresponding to the transmission wavelength of the infrared transmission material may be used. Further, in addition to the above infrared transmitting material exemplified, a plate material made of Ge or Si coated with an antireflection film (AR) on the surface can be used. When AR coating is applied to both sides of the Ge plate, the transmittance is 80 to 95% in the transmission wavelength region: 8 to 14 μm. When AR coating is performed on both sides of the Si plate, the transmittance is 65 to 90% in the transmission wavelength region: 8 to 14 μm. In either case, infrared transmission can be improved by AR coating.

Moreover, as long as the infrared ray of the wavelength which can be detected with an infrared measuring device is permeate | transmitted, the infrared rays transparent material may be single type, or multiple types combining them.
Whichever infrared ray transmitting material is used, a material having a high infrared transmittance within a detection wavelength range (2 to 14 μm, particularly 2 to 5 μm or 8 to 14 μm) of generally used infrared thermography. It is good to choose. Specifically, it is preferable to select one having an infrared transmittance of 60% or more, 70% or more, 72% or more, 80% or more, or 85% or more. If the transmittance is too small, the amount of correction increases, making it difficult to measure the temperature distribution of the sample with high accuracy. Of course, the higher the transmittance, the better. However, in consideration of the search, cost, measurement accuracy, and the like of such an infrared transmitting material, an excessive transmittance is not necessarily required.

The present invention will be described more specifically with reference to examples.
<Temperature distribution measuring device for microwave heating>
(1) A microwave heating temperature distribution measuring apparatus (hereinafter simply referred to as “measuring apparatus”) according to an embodiment of the present invention is shown in FIG. The measuring apparatus 1 includes a microwave heater 10 including a magnetron that generates microwaves as electromagnetic waves, and an uncooled infrared thermography 20 that measures the temperature distribution of a sample S heated by the microwave heater 10. (Infrared measuring device).

The microwave heater 10 includes a rectangular parallelepiped casing 11 made of a soft iron steel plate, an openable / closable door 12 attached to one side of the casing 11, and an observation window 13 provided facing the door 12. It consists of. The door 12 is also made of a soft iron steel plate. In addition, this door 12 may also have the observation window 113 like the door 112 of the conventional microwave heater 110 shown in FIG. 4 mentioned later.
As shown in FIG. 2, the observation window 13 of the present embodiment includes an electromagnetic shield plate 30 (porous shield) made of punching metal and fitted on a part of the housing 11, and one side thereof (the outer surface of the housing 11). And an infrared transmitting plate 40 (sealed gas) made of an infrared transmitting material provided on the side. The electromagnetic shield plate 30 and the infrared transmission plate 40 are mechanically contacted with each other, and a sealing material for maintaining airtightness is interposed around the outer periphery of the infrared transmission plate 40, and is fastened to the housing 11 with screws.
As shown in FIG. 3, the electromagnetic shield plate 30 is obtained by punching a large number of openings 32 (transmission holes) in a metal plate 31 made of a soft iron steel plate. The specifications are a substantially rectangular shape of 130 × 250 mm, a thickness of 0.5 mm, an opening diameter of the opening 32 formed in the metal plate 31 is φ1.5 mm, and an opening ratio is 60%.
The infrared transmitting plate 40 is a transparent plate made of calcium fluoride and having a thickness of 2 mm, and its transmittance is 92%.

  The specifications of the microwave heater 10 used in this example were as follows: frequency of irradiated microwave: 2.45 GHz (wavelength: λm = 122 mm), output: 200 to 750 W.

  An infrared thermography 20 (hereinafter simply referred to as “thermography 20”) includes an infrared detection unit 21 that detects infrared rays through a lens, and performs image processing based on detection information detected from the infrared detection unit 21 to be heated. And a display unit 22 for displaying an image of the temperature distribution. For the thermography 20 of this example, a commercially available infrared thermography (manufactured by Nippon Avionics Co., Ltd.) was used. The infrared detection wavelength (λe) of the thermography 20 is 2 to 5 μm.

(2) FIG. 4 shows a conventional microwave heating temperature distribution measuring apparatus as a comparative example to the above-described embodiment. This measuring apparatus 100 is also similar to the measuring apparatus 1 of the above embodiment in that it includes a microwave heater 110 and a thermography 20. However, the structures of the casing 111 and the door 112 of the microwave heater 110 are different. In the microwave heater 100, a viewing window 113 is provided on the door 112 as in a commercially available microwave oven.

  The viewing window 113 has a structure in which both sides of the electromagnetic shield plate 130 are sandwiched and reinforced by a transparent heat-resistant glass 140. The electromagnetic shield plate 130 was the same as the electromagnetic shield plate 30 described above. As the heat-resistant glass 140, borosilicate glass having a thickness of 1.5 mm was used. The heat-resistant glass 140 has a number of infrared absorption peaks in the vicinity of a wavelength of 10 μm, like ordinary glass and resin.

<Temperature distribution measurement method for microwave heating>
Place the sample S in the center of the case (11 or 111) of the microwave heater, place eight samples (8 x 16 mm) made of ceramics (zinc oxide fired body (purity 100%)) at regular intervals, and make thermography from outside the case. The temperature distribution of each sample was measured using 20. The measurement distance from each sample to the thermography 20 was about 30 cm.
Microwave heating was performed by irradiating these samples S with microwaves having an output of 500 W for 30 seconds.

<Evaluation 1>
(1) First, when the temperature distribution of the sample S heated through the viewing window 113 was measured with the thermography 20 using the measurement apparatus 100 of the comparative example, no infrared rays were detected, and the temperature of the sample S by the thermography 20 was detected. Distribution measurement was not possible.

  Next, immediately after heating using the microwave heater 110 of the comparative example (within 1 second after the end of heating), the door 112 of the microwave heater 110 is opened, and the temperature distribution of the sample S is directly measured by thermography. Measured at 20. Also at this time, the distance between the sample S and the infrared detector 21 of the thermography 20 was set to 30 cm. A measurement image of the temperature distribution obtained in this way is shown in FIG. As is clear from FIG. 5, it was confirmed that the left and right samples showed a high temperature distribution and the central right portion showed a low temperature distribution.

(2) FIG. 6 shows the result of the same measurement using the measuring apparatus 1 as an example. As apparent from FIG. 6, according to the present example, it was confirmed that the temperature distribution of the sample S can be similarly measured by the thermography 20 even when measuring through the observation window 13. Moreover, this measurement result showed a temperature distribution similar to that observed when the door 112 was opened (in the case of FIG. 5), although the absolute peak values were different.

<Evaluation 2>
(1) From the above-described calcium fluoride as the infrared transmitting material, sapphire (infrared transmittance 83%, thermographic detection wavelength 2 to 5 μm), zinc selenide (infrared transmittance 72%, detection wavelength 8 to 14 μm) or germanium ( Using the infrared transmission plate 40 changed to an infrared transmittance of 50% and a detection wavelength of 8 to 14 μm, the same measurement as described above was performed. Further, the infrared transmission plate 40 was changed to a quartz glass plate (detection wavelength: 8 to 14 μm), and the same measurement was performed. In addition to the thermography having a detection wavelength of 2 to 5 μm, a thermography having a detection wavelength of 8 to 14 μm was appropriately used in accordance with the material change of the infrared transmission plate 40.
The temperature distribution measurement results obtained in this way are summarized in FIG. Note that “actual temperature” in FIG. 7 is obtained by directly measuring the temperature distribution of the sample S by opening the door 12 immediately after microwave heating by the measuring apparatus 1. In addition, the sample No. in FIG. 1 to 8 correspond to the respective samples shown in FIGS. 5 and 6 in the order counted from the left side.

The following can be seen from FIG. First, when the sealed gas was quartz glass (infrared transmittance: 0%), the temperature distribution of the sample in the housing could not be measured at all, as in the case where borosilicate glass was used in the measuring apparatus 100. Next, when germanium (infrared transmittance: 50%) was used, a part of the temperature distribution having a tendency similar to the actual temperature was observed, but the overall observation was difficult. When calcium fluoride (infrared transmittance: 92%), sapphire (infrared transmittance: 83%) and zinc selenide (infrared transmittance: 72%) are used, the actual temperature depends on the transmittance. Although lower, the temperature distribution of the actual temperature and the overall trend were close.
From these results, it can be seen that by using a glass material having an infrared transmittance of 60% or more, more preferably 72% or more, the measured temperature distribution can be approximated to the actual temperature distribution as an overall tendency.

<Supplement>
(1) The measurement result of the temperature distribution as described above was the same even when the atmosphere in the casing was filled with nitrogen gas or the like or was evacuated.
(2) Microwave leakage when heated by the above-described measuring apparatus 1 was 0.1 mW / cm 2 in both the example and the comparative example. It was the following.
(3) The same measurement was performed by replacing the heat-resistant glass of the viewing window 113 of the measuring apparatus 100 with a transparent heat-resistant resin material (polymethylpentene, polyzarphone, etc.). The detected infrared ray was not detected at all, and the temperature distribution could not be measured.

(4) In the measurement described above, the temperature distribution of the sample S after 30 seconds from the end of the microwave heating was measured. However, according to the present example, the temperature distribution of the sample S during the heating is also measured. Needless to say, it can be done. That is, by using the measuring apparatus according to the present invention, so-called In-Situ measurement, which has been difficult until now, can be easily performed even during microwave heating. As described above, if the present invention is used, the temperature distribution of the object to be heated can be measured not only in real time, but also highly accurate microwave heating control can be performed relatively easily based on the real time measurement information. .

It is a schematic diagram which shows the temperature distribution measuring apparatus for microwave heating which concerns on this invention. It is a block diagram of the observation window used with the measuring device. It is an enlarged view of the electromagnetic shielding board used with the measuring device. It is a schematic diagram which shows the conventional temperature distribution measuring apparatus for microwave heating. It is an image figure of the infrared thermography which shows the temperature distribution measured by opening after microwave heating. It is an image figure of the infrared thermography which shows the temperature distribution measured using the temperature distribution measuring apparatus for microwave heating which concerns on this invention. It is a graph which shows each temperature distribution measured through various observation windows.

Explanation of symbols

1 Temperature distribution measuring device for microwave heating (Example)
10 Microwave Heater 13 Observation Window 20 Infrared Thermography 30 Electromagnetic Shield Plate (Porous Shield)
32 Opening (transmission hole)
40 Infrared transmitting plate (sealed gas)
100 Temperature distribution measuring device for microwave heating (comparative example)

Claims (8)

A microwave heater that heats the object to be heated by irradiating the object to be heated contained in the case with a microwave that is an electromagnetic wave having a wavelength (λm) of 10 to 1000 mm;
An observation window that shields transmission of the microwave and leakage of gas in the housing while transmitting infrared rays emitted from the heated object to be heated;
An infrared detector that has an infrared detector that detects infrared rays emitted from the object to be heated, and that can measure the temperature distribution of the object to be heated based on the detection information of the infrared detector;
The temperature distribution of an object to be heated while being heated by the microwave heater can be measured by the infrared measuring instrument through the observation window interposed between the object to be heated and the infrared detection unit. A temperature distribution measuring device for microwave heating. The observation window has a porous shield having a plurality of transmission holes that transmit infrared rays radiated from the heated object to be heated while shielding transmission of the microwaves;
2. The temperature distribution measurement for microwave heating according to claim 1, comprising: a sealed gas that is provided in the vicinity of the porous shield and transmits an infrared ray radiated from the object to be heated and seals outflow of gas in the housing. apparatus.   The temperature distribution measuring device for microwave heating according to claim 2, wherein the sealed gas is made of an infrared transmitting material having a transmittance of 60% or more in a wavelength range of 2 to 14 µm.   The temperature distribution measuring device for microwave heating according to claim 2 or 3, wherein the infrared transmitting material is made of one or more of calcium fluoride, sapphire, or zinc selenide.   The temperature distribution measuring device for microwave heating according to claim 2 or 4, wherein the porous shield is a metal perforated plate or a wire mesh in which a large number of pores serving as the transmission holes are formed.   The porous shield has an aperture ratio (Sd / St x 100%) that is a ratio of the total area (Sd) of the transmission holes in the specific range to the total surface area (St) in the specific range of 40 to 80%. The temperature distribution measuring device for microwave heating according to claim 2 or 5.   The temperature distribution measuring apparatus for microwave heating according to claim 1 or 6, wherein the infrared measuring instrument is an infrared thermography having a detection wavelength of 2 to 14 µm. A heating step of heating the object to be heated by irradiating the object to be heated contained in the case with microwaves having a wavelength (λm) of 10 to 1000 mm;
An observation window that transmits the infrared rays radiated from the heated object to be heated and shields the transmission of the microwave and the leakage of gas in the housing is emitted from the object to be heated and the object to be heated. A measurement step of measuring the temperature distribution of an object to be heated that is irradiated with the microwave based on detection information of the infrared detection unit, interposed between the infrared detection unit and infrared detection unit;
A temperature distribution measuring method for microwave heating, comprising: