JP7393647B2 - Temperature measuring device and temperature measuring method - Google Patents

Description

The present invention relates to a temperature measuring device and a temperature measuring method.

Radiation thermometry is a method of determining the temperature of a target object by detecting the thermal radiation emitted by the object according to its temperature using a measuring device such as a radiation thermometer. It is a remote temperature measurement method that can measure temperature. Today, many industries, including the steel industry, use such radiation thermometry methods.

In particular, in the steel industry, during the manufacturing process, water or other materials that have the property of absorbing thermal radiation in the near-infrared band are placed on the optical path between the object to be measured, such as a steel sheet material, and a measurement device such as a radiation thermometer. Absorbers such as fats and oils are often present. In such a case, a part of the thermal radiation from the object to be measured is absorbed by the absorber, causing a measurement error and making it impossible to accurately measure the temperature of the object to be measured.

Therefore, in order to suppress the measurement error caused by the absorber existing on the optical path as described above, the present inventors have developed a spectroscopic analysis of the absorber of interest, for example, as disclosed in Patent Document 1 below. We have proposed a two-color radiation thermometer that uses two wavelengths with the same absorption coefficient as measurement wavelengths. In general, a two-color radiation thermometer observes thermal radiation from an object at two different wavelengths, and its measurement principle is that the ratio of the radiance at the two wavelengths changes depending on the temperature. However, when an absorber is present on the optical path, there is a problem in that the absorber attenuates the thermal radiation differently at two wavelengths, causing an error. Therefore, in the two-color radiation thermometer disclosed in Patent Document 1, the influence of attenuation of thermal radiation light is suppressed by selecting the wavelength so that the spectral absorption coefficient of the absorber at the two wavelengths used for measurement is the same. This allows for accurate temperature measurements. In addition, in Patent Document 1, in order to detect the radiance at two wavelengths where the spectral absorption coefficient of the absorber is the same, two types of optical bandpass filters are used to extract the radiance at a desired wavelength. , the extracted radiance is detected.

JP2019-23635A

The present inventors conducted further verification using the two-color radiation thermometer disclosed in Patent Document 1 mentioned above. As a result, the transmission band of an optical bandpass filter is selected such that at a certain temperature, the attenuation of thermal radiation by the absorber is equal at two wavelengths, and the optical bandpass filter determined based on such selection is used to emit radiation. When performing temperature measurements, we found that under conditions where the temperature of the object to be measured changes significantly, the temperature measurement error may become large. Particularly in the steel industry, steel materials, which are an example of objects to be measured, often have a variety of temperatures, from around 600 degrees Celsius to over 1000 degrees Celsius, and the temperature to be measured varies widely. . Therefore, if a temperature measurement error such as that recently discovered by the present inventors occurs, it becomes impossible to determine whether the temperature measurement value is an appropriate value.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a temperature measuring device and a temperature measuring method that can further suppress temperature measurement errors. be.

In order to solve the above problem, the present inventors conducted verification and found that the temperature measurement error as described above is caused by the characteristics of the optical bandpass filter. Various general optical filters, including the optical bandpass filter used in the two-color radiation thermometer disclosed in Patent Document 1, have optical characteristics that vary at typical temperatures that the measurement target can take. It is selected and determined to achieve the desired state. Therefore, the present inventors have found that if the temperature of the object to be measured deviates significantly from the temperature at which the optical characteristics were determined, the temperature measurement error as described above will occur. This is because the optical characteristics of an optical filter have a predetermined bandwidth, so when the temperature of the object to be measured changes, its effective center wavelength is affected by the temperature-dependent blackbody radiation spectrum. This is thought to be due to a measurement error occurring due to a change in the apparent center wavelength of the transmission wavelength band in an optical bandpass filter, for example.

Based on the above findings, the inventors conducted further verification and found that the thermal radiation from the object to be measured was detected using a spectrophotometer that can continuously measure the spectrum of light. We have come up with the idea that temperature measurement errors such as those described above can be suppressed by performing predetermined data processing on the spectral luminance signal obtained by the spectroscopic luminance meter.
The gist of the present invention, which was completed based on the above findings, is as follows.

A temperature measuring device according to the present invention is a temperature measuring device that measures the temperature of a measurement target using two-color radiation thermometry, wherein an absorber whose spectral transmittance in the near-infrared band is wavelength-dependent; The spectral brightness of the thermal radiation received by the light receiving unit is measured by using a light receiving unit that receives thermal radiation from the measurement target in a state where it can exist on the optical path to the measurement target, and a spectrophotometer. The temperature of the object to be measured is determined based on a detection unit that detects a spectral luminance signal and the spectral luminance signal corresponding to two wavelengths at which the spectral transmittance of the absorber is the same, detected by the detection unit. and an arithmetic processing unit that sets a weighting function consisting of continuous non-articulated numbers in the wavelength direction, and determines one of the two wavelengths at which the spectral transmittance of the absorber is the same. In terms of wavelength, the position of the weighting function in the wavelength direction is set to the position of the one wavelength, and then the value of the spectral transmittance of the absorber obtained using the spectrophotometer is multiplied by the weighting function. By summing the first weighting data, the position of the weighting function in the wavelength direction is calculated at the other wavelength of the two wavelengths at which the spectral transmittance of the absorber is the same. , and then multiplying the spectral transmittance value of the absorber obtained using the spectral luminance meter by the weighting function and summing the values to obtain second weighting data. and comparing the first weighting data and the second weighting data while moving the predetermined position in the wavelength direction, and determining whether the first weighting data and the second weighting data have the same value. determine the predetermined position of the weighting function, set the position of the weighting function in the wavelength direction to the position of the one wavelength, and calculate the value obtained by multiplying the spectral luminance signal by the weighting function and the wavelength direction of the weighting function. is set at the determined predetermined position, and the temperature of the object to be measured is determined from the ratio of the value obtained by multiplying the spectral luminance signal by the weighting function .

The temperature measuring method according to the present invention uses two-color radiation thermometry to measure the temperature of an object to be measured. A light receiving step of receiving thermal radiation light from the measuring object in a state where it can exist on the optical path to the measuring object, and measuring the spectral brightness of the thermal radiation light received in the light receiving step using a spectrophotometer. A detection step of detecting a spectral luminance signal; and a spectral luminance signal detected in the detection step that corresponds to two wavelengths at which the spectral transmittance of the absorber is the same, and the temperature of the object to be measured is determined. and an arithmetic processing step for determining the value of one of the two wavelengths at which the spectral transmittance of the absorber is the same by setting a weighting coefficient consisting of continuous non-obvious numbers in the wavelength direction. In terms of wavelength, the position of the weighting function in the wavelength direction is set to the position of the one wavelength, and then the value of the spectral transmittance of the absorber obtained using the spectrophotometer is multiplied by the weighting function. By summing the first weighting data, the position of the weighting function in the wavelength direction is calculated at the other wavelength of the two wavelengths at which the spectral transmittance of the absorber is the same. , and then multiplying the spectral transmittance value of the absorber obtained using the spectral luminance meter by the weighting function and summing the values to obtain second weighting data. and comparing the first weighting data and the second weighting data while moving the predetermined position in the wavelength direction, and determining whether the first weighting data and the second weighting data have the same value. determine the predetermined position of the weighting function, set the position of the weighting function in the wavelength direction to the position of the one wavelength, and calculate the value obtained by multiplying the spectral luminance signal by the weighting function and the wavelength direction of the weighting function. is set at the determined predetermined position, and the temperature of the object to be measured is determined from the ratio of the value obtained by multiplying the spectral luminance signal by the weighting function .

As described above, according to the present invention, it is possible to further suppress temperature measurement errors when measuring the temperature of an object to be measured.

FIG. 2 is a graph diagram for explaining discrete signals in a spectrophotometer. FIG. 2 is an explanatory diagram for explaining a weighting function of interest in the embodiment of the present invention. FIG. 2 is an explanatory diagram for explaining a weighting function of interest in the embodiment of the present invention. FIG. 2 is an explanatory diagram for explaining a weighting function of interest in the embodiment of the present invention. FIG. 2 is an explanatory diagram for explaining a weighting function of interest in the embodiment of the present invention. FIG. 3 is an explanatory diagram for explaining a weighting function having a trapezoidal distribution. FIG. 2 is a graph diagram showing an example of a weighting function having a trapezoidal distribution. It is a graph diagram showing the spectral transmittance of a water film with a thickness of 10 mm. FIG. 2 is a graph diagram showing the wavelength distribution of blackbody spectral radiance. FIG. 2 is a graph diagram showing an example of a weighting function applied to a wavelength band on the long wavelength side. It is an explanatory view showing typically an example of composition of a temperature measurement device concerning the same embodiment. It is an explanatory view showing typically an example of composition of a temperature measurement device concerning the same embodiment. It is an explanatory view showing typically an example of composition of a measuring part with which a temperature measuring device concerning the same embodiment is provided. FIG. 2 is a block diagram schematically showing an example of the configuration of a calculation processing unit included in the temperature measurement device according to the embodiment. It is a flowchart which showed an example of the flow of the temperature measurement method implemented by the temperature measurement device concerning the same embodiment. FIG. 2 is a block diagram showing an example of the hardware configuration of an arithmetic processing unit included in the temperature measuring device according to the embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Note that, in this specification and the drawings, components having substantially the same functional configurations are designated by the same reference numerals and redundant explanation will be omitted.

(Regarding studies by the inventors)
Prior to explaining the temperature measuring device and temperature measuring method according to the embodiment of the present invention, various studies regarding the two-color radiation thermometer conducted by the present inventors will be explained in detail with reference to FIGS. 1 to 7. do.
FIG. 1 is a graph diagram for explaining discrete signals in a spectrophotometer. FIGS. 2A to 3 are explanatory diagrams for explaining the weighting functions of interest in the embodiment of the present invention. FIG. 4 is a graph diagram showing an example of a weighting function having a trapezoidal distribution. FIG. 5 is a graph showing the spectral transmittance of a 10 mm thick water film. FIG. 6 is a graph showing the wavelength distribution of blackbody spectral radiance. FIG. 7 is a graph diagram showing an example of a weighting function applied to a wavelength band on the long wavelength side.

In the two-color radiation thermometer proposed by the present inventors and disclosed in Patent Document 1, an optical band-pass filter is installed in front of a photodetector such as an InGaAs element as a method for observing light of a specific wavelength. However, other methods can be used to observe light of a specific wavelength. In order to suppress the temperature measurement error caused by the optical bandpass filter as described above, the present inventors developed a method that can continuously detect the spectrum of light instead of using a combination of an optical bandpass filter and a photodetector. In other words, we came up with the idea of using a spectrophotometer that can measure the spectral distribution of light. Such a spectrophotometer can be said to be a detector that separates incident light into wavelengths, detects the spectral brightness of the light at each wavelength, and outputs the detected spectral brightness as a spectral brightness signal.

In the temperature measuring device according to the present embodiment, after obtaining a continuous spectral luminance signal with respect to wavelength using such a spectral luminance meter, a signal in a desired wavelength band is extracted from the spectral luminance signal and used. Therefore, the same function as the two-color radiation thermometer proposed by the present inventors and shown in Patent Document 1 can be obtained.

Furthermore, in the temperature measurement device according to this embodiment, by using such a spectrophotometer, it is possible to suppress measurement errors caused by the optical bandpass filter as described above, and also to individually measure each of the plurality of measurement wavelengths. There is no need to prepare an optical bandpass filter. Therefore, measurement at each wavelength becomes easy, and it is possible to increase flexibility when changing conditions such as wavelength, and to simplify and reduce the cost of the measuring device.

On the other hand, the two-color radiation thermometer proposed by the present inventors in this embodiment can select and determine the detection wavelength very precisely, similar to the two-color radiation thermometer disclosed in Patent Document 1 above. Specifically, unless the detection wavelength is set with an accuracy of 0.5 nm or less, it is difficult to obtain sufficient accuracy. The problem here is that the spectral brightness signal obtained from a general spectrophotometer does not have a detection resolution of 0.5 nm or less. For example, in spectrophotometers currently available on the market, the spectral sampling interval (in other words, wavelength resolution) is about 1.7 nm. In other words, when using a general spectrophotometer, the wavelength at which the measured value is obtained is determined depending on the sampling interval, so the wavelength at which the measured value is obtained is approximately 1.7 nm from the arbitrary measurement wavelength at which the measured value was actually obtained. It is difficult to actually measure the spectral luminance signal at wavelengths shifted by the following wavelength widths.

Using such a spectrophotometer, the wavelength at which the spectral transmittance is the same as the spectral transmittance at a predetermined wavelength (for example, 1210 nm) is determined with a resolution smaller than the sampling interval (indicated by ■ in Figure 1). To determine, for example, in the graph of FIG. 1, draw a horizontal line from the value of spectral transmittance (S ₁₂₁₀ ) at the predetermined wavelength, find the intersection point that intersects with the graph again, and calculate the spectral transmittance shown in FIG. Among the measured values of the ratio (indicated by circles in FIG. 1), the average value may be calculated from the wavelengths of two adjacent measured values (for example, 1290 nm and 1310 nm) that straddle the intersection. A schematic representation of this concept is shown in FIG. In addition, in FIG. 1, the sampling interval of the spectrophotometer is enlarged to make the explanation easier to understand.

In the temperature measuring device according to the present embodiment, the spectral absorption coefficient (which may also be considered as spectral transmittance) of an absorber (hereinafter, water will be explained as an example) as disclosed in Patent Document 1 above. As the wavelengths at which the wavelengths (possible) are equal, we will focus on a wavelength band near 1200 nm (wavelength band on the short wavelength side) and a wavelength band near 1300 nm (wavelength band on the long wavelength side). Note that in FIGS. 1 and 2A to 2D, in order to make the explanation easier to understand, 1210 nm is used as a reference wavelength in a wavelength band on the short wavelength side.

In the two-color radiation thermometer of this embodiment, it is necessary to use spectral luminance signals of two wavelengths whose spectral transmittances of the absorber match, but this is due to the fact that this embodiment uses a spectral luminance meter. , it is not possible to actually measure the spectral brightness signal at a wavelength interval shorter than the sampling interval of the spectrophotometer. Therefore, as shown in Figure 1, the wavelengths whose spectral transmittance matches the wavelength 1210 nm (spectral transmittance is S ₁₂₁₀ ) are wavelength 1290 nm (spectral transmittance is S ₁₂₉₀ ) and wavelength 1310 nm (spectral transmittance is S ₁₃₁₀ ). ), this corresponds to wavelengths for which there are no actual measured values.

In the above case, there is no actual measured value of the long wavelength side whose spectral transmittance accurately matches the wavelength band on the short wavelength side, so calculations must be performed to divide the nearby spectral brightness signals proportionally. . In this case, if you are not concerned about the accuracy of the obtained spectral luminance signal, weighting is applied to two nearby spectral luminance signals S ₁₂₉₀ and S ₁₃₁₀ , for example, 0.4×S ₁₂₉₀ +0.6×S ₁₃₁₀ . It is only necessary to perform a computation to combine the luminance values so that the spectral transmittance is equal to that on the short wavelength side by averaging the spectral transmittance.

However, in order to maintain the same spectral transmittance of the absorber and to ensure the accuracy of the spectral luminance signal, the concept shown in Figure 1 should be generalized and the spectral luminance from the spectral luminance meter It is necessary to highly accurately determine the spectral luminance signal at a wavelength for which no actual measurement value of the signal exists. Therefore, the present inventors came up with the idea of using a weighting coefficient of 0 or more and 1 or less, and a plurality of spectral luminance signals (particularly a large number of points exceeding two points) located in the vicinity of the desired wavelength. . This concept will be explained below with reference to FIGS. 2A to 3.

The temperature measurement device according to the present embodiment is capable of measuring temperature in a state where an absorber such as water whose spectral transmittance in the near-infrared band is wavelength-dependent may exist on the optical path to the measurement target. Therefore, it is necessary to understand the optical characteristics of the absorber in advance. Therefore, the spectral transmittance of the absorber is measured for each wavelength in advance using the temperature measuring device itself according to this embodiment. For example, the spectral transmittance can be measured by measuring the spectral luminance signal while changing the presence or absence of an absorber for each wavelength. The results thus obtained are shown in the upper diagram of FIG. 2A.

The upper diagram of FIG. 2A is measured using the temperature measuring device (spectral luminance meter) according to the present embodiment, so the actual measured value of the spectral transmittance (indicated by a circle in the diagram) is the same as that of the present embodiment. Sampling interval of the temperature measuring device (spectroluminance meter) related to (indicated by Δ in the figure. Originally, for example, the interval is 1.7 nm, but in the figure it is drawn at a large interval to simplify the explanation.) They appear at wavelength intervals corresponding to .

Note that in order to obtain the relationship between wavelength and spectral transmittance as shown in the upper diagram of FIG. 2A, if the temperature measurement device itself according to this embodiment is used to perform the measurement, the temperature measurement device itself This is preferable because the optical properties it has can be reflected in the measurement results. However, the method is not limited to these methods; for example, measurements may be performed using other measurement devices, or the wavelength dependence of the spectral transmittance of the absorber may be understood from known documents. You can also

Furthermore, since the temperature measuring device according to the present embodiment measures the temperature of the object to be measured using two-color radiation thermometry, it is necessary to measure the brightness of thermal radiation emitted by the object to be measured. Therefore, using the temperature measurement device (spectroluminance meter) according to the present embodiment, the spectral luminance of the measurement target is measured for each wavelength as a spectral luminance signal in a state where the absorber can exist on the optical path to the measurement target. Measure as. The results thus obtained are shown in the lower diagram of FIG. 2A.

The lower diagram of FIG. 2A is also obtained by measuring with the temperature measuring device (spectroluminance meter) according to this embodiment, so the actual measured values of spectral luminance shown in the lower diagram of FIG. ) is the wavelength interval corresponding to the sampling interval Δ of the temperature measuring device (spectroluminance meter) according to the present embodiment, and the actual measured value of the spectral transmittance in the upper diagram of FIG. 2A (indicated by a circle in the diagram). ) appears at the same wavelength.

Next, in order to obtain a spectral brightness signal at a wavelength that is outside the sampling wavelength of the spectrophotometer and for which there is no actual measured value of the spectral brightness signal (indicated by ■ in Figure 1), a distribution as shown in Figure 2B (an example A weighting function with a triangular distribution is prepared.

The weighting function is continuous in the wavelength direction (discrete values may be used as long as the interval is significantly narrower than the sampling interval Δ), and is independent of the sampling interval Δ of the spectrophotometer. It is set as a function having an anonymous number (weighting coefficient, preferably a value between 0 and 1) serving as a weight on a different axis. Further, the weighting function can be set by appropriately changing the position of its apex (indicated by ■ in FIG. 2B) in the wavelength direction.

Next, as shown in FIG. 2C, in the relationship between the wavelength and the spectral absorption coefficient shown in the upper diagram of FIG. Set to the position of the reference wavelength (1210 nm). In this state, a calculation (convolution calculation) is performed to multiply the spectral transmittance by a weighting function at each wavelength at each sampling interval Δ, and the total value thereof (hereinafter referred to as short wavelength side weighting data) is stored. In the example shown in FIG. 2C, after aligning the apex of the weighting function with S ₁₂₁₀ in the wavelength direction, the measured value of spectral transmittance is calculated centered on the range where the measured value of spectral transmittance and the weighting function overlap. Multiply a ₁ , a ₂ , a _{3 ,} ... a ₅ by weighting coefficients b ₁ , b ₂ , b ₃ ... b ₅ determined by the weighting function, and add them together (a ₁ b ₁ + a ₂ b ₂ + a ₃ b ₃ +...a ₅ b ₅ ), and short wavelength side weighted data is obtained.

Next, as shown in the upper diagram of FIG. 2D, in the relationship between wavelength and spectral transmittance shown in the upper diagram of FIG. The wavelength is set to the left (on the short wavelength side) of the wavelength 1290 nm, which has an actual measured value adjacent to the wavelength of 1210 nm, which is the standard of 1210 nm. In this state, a calculation (convolution calculation) is performed to multiply the spectral transmittance by a weighting coefficient at each wavelength at each sampling interval Δ, and the total value thereof (hereinafter referred to as long wavelength side weighting data) is stored. In the example shown in the upper diagram of FIG. 2D, after aligning the apex of the weighting function to the left side of _S1290 in the wavelength direction, the spectral transmittance is The measured values c ₁ , c ₂ , c _{3 ,} ... c ₅ are multiplied by weighting coefficients d ₁ , d ₂ , d ₃ ... d ₅ determined by the weighting function, and the values are summed (c ₁ d ₁ +c ₂ d ₂ +c ₃ d ₃ +...c ₅ d ₅ ), and long wavelength side weighted data is obtained.

Then, as shown by the weighting function indicated by the broken line in the upper part of FIG. (to the long wavelength side). Then, the spectral transmittance and the weighting coefficient are multiplied again at wavelengths at each sampling interval Δ at which a spectral luminance signal is obtained, and long wavelength side weighted data, which is the sum of these values, is stored.

As the calculations and memories associated with the movement of the weighting function are repeated, as shown in the lower diagram of Figure 2D, the position of the vertex ■ in the wavelength direction (1210 nm, which is the reference on the short wavelength side, and the spectral transmittance) While moving to the right side (long wavelength side) of wavelength 1310 nm (where there is an actual measurement value adjacent to the matching wavelength on the long wavelength side), the stored long wavelength side weighting data matches the above short wavelength side weighting data. Find out whether or not. If they match, the weighting function is fixed at the position in the wavelength direction where the weighting coefficient is located at that time.

The weighting function whose position is fixed in this way is the spectral transmittance with the center wavelength of 1210 nm as a reference wavelength in the short wavelength side wavelength band, and the spectral transmittance with no actual measured value in the long wavelength side wavelength band (between wavelengths 1290 nm and 1310 nm). ) in Figure 1 as a virtual optical filter with weighting and wavelength information such that the spectral transmittances obtained from multiple actual measured values in the surrounding area are effectively the same value. It will have a function.

Next, in order to obtain a desired spectral luminance signal, the position of the weighting function in the wavelength direction is set to a wavelength of 1210 nm for the short wavelength side, and then the weighting function is changed to the spectral luminance signal shown in the lower diagram of FIG. 2A. Multiply by the actual measured value. On the other hand, for wavelengths on the long wavelength side, the actual measured value of the spectral luminance signal shown in the lower diagram of FIG. 2A is multiplied by the above-mentioned weighting function whose position is fixed.

By doing this, the spectral brightness on the short wavelength side and the spectral brightness on the long wavelength side can be adjusted under the condition that the short wavelength side and long wavelength side have effectively the same spectral transmittance to water, which is an absorber. You can ask for.

Therefore, by calculating the ratio of the spectral brightness on the short wavelength side to the spectral brightness on the long wavelength side (dichroic ratio) without being affected by the attenuation of synchrotron radiation by water, it is possible to Therefore, the temperature of the object to be measured can be determined with high accuracy.

By applying such a weighting function to a two-color radiation thermometer using a spectroluminance meter, it is possible to solve the problem that the actual measurement of the spectrophotometer is only performed at each sampling interval, and also to solve the problem shown in Figure 1. In addition to the spectral luminance signals of only two points (S ₁₂₉₀ , S ₁₃₁₀ ) as shown in , more spectral luminance signals (measured values) can be incorporated into the convolution calculation, so spectral luminance signals with noise and variations can be taken into account. Signals can be averaged at multiple points, making it possible to further improve accuracy.

By the way, for example, in order to obtain virtual resolution at a wavelength of 1.7 nm or less, it is sufficient that the distribution of the weighting function has a region tilted in the wavelength direction that has a value greater than 0 and smaller than 1. Considering the appropriate use of the necessary number of spectral luminance signals for smoothing by multi-point averaging, even if the weighting function does not have a triangular distribution as described above, for example, as shown schematically in FIG. A weighting function having a trapezoidal distribution may also be used.

If a weighting function with a trapezoidal distribution is used, the areas around the center wavelength of each wavelength band on the short wavelength side and long wavelength side will be emphasized by being weighted with a large value, which corresponds to the upper side of the trapezoidal shape. On the other hand, wavelengths that deviate significantly from the center wavelength of each wavelength band on the short wavelength side and long wavelength side are weighted with a small value corresponding to the hypotenuse of the trapezoid shape and are weakened. This allows for more accurate selection.

In the example shown in FIG. 3, a case is illustrated in which a spectral brightness signal of a desired wavelength is obtained using spectral brightness signals of 10 points. Further, the weighting coefficients constituting the weighting function shown in FIG. 3 may be set as a continuous function, or may be made up of multiple points with narrow intervals in the wavelength direction as shown in FIG.

As mentioned above, the averaging process (convolution process) using a weighting function as shown in FIGS. 2B, 3, and 4 can be thought of as a virtual optical filter (virtual optical filter, digital filter). It can also be thought of as filter processing using In fact, such a weighting function can be determined in advance experimentally or using simulation so that temperature measurement errors due to the presence or absence of the absorber are eliminated. In this case, the number of spectral luminance signals to be used and the distribution of weighting coefficients in the weighting function (distribution of weighting coefficients as shown in Fig. 3 and Fig. It is important to determine the virtual optical filter on the short wavelength side and the virtual optical filter on the long wavelength side.

Next, the phenomenon in which the two wavelengths whose spectral transmittances of the absorber are supposed to match slightly change depending on temperature, and the fact that the above phenomenon can be solved by using a spectrophotometer will be explained below.

The two-color radiation thermometer disclosed in Patent Document 1 uses a physical optical filter (optical bandpass filter). In this case, such an optical bandpass filter is not a narrow band filter in which the light transmitted through the filter can be regarded as a single wavelength, but has a certain width of transmitted wavelength, for example, a transmitted wavelength width of about 50 nm. things are used. This is because an optical bandpass filter with a narrow transmission wavelength band may not be able to provide enough radiance to stably operate an infrared photodetector such as an InGaAs element.

The present inventors used a two-color radiation thermometer equipped with an optical bandpass filter as described above to measure the temperature of an object to be measured (a steel material) that can have a temperature of 600 to 1200°C. As a result, at 900°C, which is the temperature at which the optical characteristics of the optical bandpass filter were determined, the presence or absence of water as an absorber does not change the temperature measurement result (that is, measurement error occurs); It has been found that when the temperature of the object to be measured is 600° C. and when the temperature of the object to be measured is 1200° C., a temperature measurement error of about ±5° C. occurs depending on the presence or absence of the absorber. That is, through verification by the present inventors, it has become clear that the two wavelengths at which the spectral transmittance of water, which is an absorber, is equal to each other have a temperature dependence.

When a physical optical filter has a finite transmission wavelength width, it is important to consider the average (effective) transmittance of the transmission width. Therefore, the present inventors investigated the amount of light observed by a two-color radiation thermometer using a spectroscopic simulation. In the spectroscopic simulation shown below, the spectral transmittance of water as an absorber, the spectral transmittance of an optical filter, and the blackbody spectral radiance are expressed using discrete spectra with a sampling interval of Δ=1.7 nm. did.

First, as a weighting function on the short wavelength side, a weighting function was used in which the distribution of weighting coefficients was trapezoidal and bilaterally symmetrical as shown in FIG. 3, and which satisfied the following conditions. The weighting function has a weighting coefficient of 1 over a wavelength width of 60 nm (that is, the length of the upper base is 60 nm), and in a region with a width of 10 nm at both ends, the weighting coefficient is a trapezoid that decreases linearly from 1 to 0. Shape.

Based on the above conditions, a weighting function with a central transmission wavelength of 1200 nm is expressed in wavelength increments of sampling interval Δ=1.7 nm as shown in FIG. 4.

The same weighting function as the weighting function for the short wavelength side was used as the weighting function for the vicinity of 1300 nm, which is the long wavelength side. Here, the weighting function on the long wavelength side is set so that the principle of a two-color radiation thermometer holds true (that is, the effective transmittance of water, which is an example of an absorber, is equal to the effective transmittance on the short wavelength side). The center transmission wavelength of is searched by simulation. Here, as shown in FIG. 5, the spectral transmittance of water changes monotonically near 1300 nm. Therefore, by adjusting the center transmission wavelength, the effective transmittance based on the weighting function can be adjusted.

Known data can be used as the spectral transmittance of water, and examples of such data include the spectral transmittance of water when the thickness of the water film is 10 mm, as shown in FIG. be able to. As is clear from FIG. 5, there are two wavelengths at which the spectral transmittance is equal, near the wavelength 1200 nm and near the wavelength 1300 nm. It can be seen that the spectral transmittance of water decreases monotonically near the wavelength of 1300 nm.

As mentioned above, focusing on the spectral transmittance of water and finding the effective transmittance τ _eff of the weighting function means that if we consider it simply, the effective transmittance τ _eff shown in the following formula (1) is at a center transmission wavelength of 1200 nm. This means selecting the center transmission wavelength of the weighting function on the long wavelength side so that it is equal to the weighting function of .

Here, in the above formula (1), λ ₁ is the lower limit transmission wavelength of the weighting function, n is the number in Δ increments until reaching the upper limit transmission wavelength, and τ (λ) is the f(λ) is a weighting coefficient corresponding to the spectral transmittance of the optical filter at wavelength λ.

As described above, the center transmission wavelength at which the effective transmittance was equal to the weighting function of the center transmission wavelength of 1200 nm was determined, and the center transmission wavelength was found to be 1284.04 nm. Therefore, the central transmission wavelength is 1284.04 nm, which is symmetrical, and the weighting coefficient is 1 over a wavelength width of 60 nm, and in the 10 nm width region at both ends, the weighting coefficient decreases linearly from 1 to 0 (Fig. By using a weighting function that has the same trapezoidal shape as shown in 4, but whose center wavelength is 1284.04 nm, the effective transmittance of water, which is an absorber, can be determined from the spectral luminance signal obtained from the spectrophotometer. It is conceivable to obtain two types of spectral luminance signals whose values are equal to each other. However, the method for determining the weighting function in equation (1) cannot explain the phenomenon in which measurement errors occur due to the presence or absence of water depending on the temperature of the measurement target.

Therefore, the inventors conducted a deeper study and came up with the following idea. In other words, instead of using a weighting function that only considers the effective transmittance of the absorber as in equation (1) above, we consider the wavelength dependence of blackbody radiation in addition to the effective transmittance as explained below. Preferably, a weighting function is used.

Black body radiation emitted from a heated object has spectral characteristics depending on temperature, and the spectral radiance is not uniform even within the transmission wavelength range of an optical filter. Therefore, as the effective transmittance τ _eff , we take into account not only the weighting coefficient corresponding to the spectral transmittance of each wavelength and the spectral transmittance of water, but also the wavelength dependence (wavelength distribution) of the spectral radiance of blackbody radiation. By doing so, it becomes possible to further improve the optical characteristics (wavelength characteristics) of the weighting function. At this time, the effective transmittance τ _eff is given by the following equation (2), taking into consideration the weight w(λ) that takes into account the wavelength distribution of the spectral radiance of the black body radiation.

Here, as the weight w(λ) of the blackbody spectral radiance, it is possible to use a relative value of the blackbody spectral radiance with respect to a wavelength of 1250 nm, as illustrated in FIG. 6, for example.

Based on the effective transmittance τ _eff shown in the above equation (2), the center transmission wavelength at which the weighting function of the center transmission wavelength of 1200 nm and the effective transmittance were equal was determined. As a result, when the temperature to be measured was 600°C, the center transmission wavelength was 1287.97 nm, and when the temperature to be measured was 1200°C, the center transmission wavelength was 1286.84 nm. The distribution of weighting coefficients of these weighting functions is summarized in FIG. 7.

By using the weighting function as explained above, the spectral luminance signal of the desired wavelength can be obtained by recombining the luminance signals that have been separated into wavelengths using the continuous spectrum obtained from the spectrophotometer. It becomes possible to extract. As a result, the extracted spectral luminance signal is used to calculate the dichromatic ratio R based on the principle of the two-color radiation thermometer disclosed in Patent Document 1, and the measurement is performed based on the relationship between the dichromatic ratio and the temperature. It becomes possible to measure the temperature of the target object more accurately.

Next, we verified how the phenomenon in which the wavelength band in which the effective transmittance of the short-wavelength weighting function and the long-wavelength weighting function match differs depending on temperature affects actual temperature measurement. .

As for the optical characteristics of the weighting function of interest, a weighting function is used in which the weighting coefficient is 1 in a wavelength width range of 60 nm, and the weighting coefficient decreases linearly from 1 to 0 in a 10 nm width region at both ends. I took it as a thing. Furthermore, for the weighting function on the short wavelength side, the center transmission wavelength was fixed at 1200 nm. Then, at a temperature of 600° C., adjustment was made using the effective transmittance shown in the above equation (2) so that the measurement temperature did not change depending on the presence or absence of a water film. In this case, the center transmission wavelength of the weighting function on the long wavelength side is 1287.97 nm, as described above.

Here, if we measure the temperature of the object to be measured at a temperature of 1200°C using the above weighting function, when the thermal radiation passes through a water film with a thickness of 10 mm, the effective transmittance of the weighting function on the short wavelength side and the effective transmittance of the weighting function on the long wavelength side do not match. As a result, the ratio of effective transmittance on the short wavelength side and on the long wavelength side changes from 1 to 1.0125. This change is equivalent to a 1.25% change in the value of the dichroic ratio R used when calculating temperature with a two-color radiation thermometer. If a change in the two-color ratio of 1.25% is converted into a temperature change amount from the relationship between the two-color ratio and temperature as disclosed in Patent Document 1, the measurement error will be 17.5°C.

From the above verification, when the temperature of the object to be measured can change significantly, the weighting function when measuring the temperature around 600°C, the weighting function when measuring the temperature around 800°C, the weighting function when measuring the temperature around 1000°C, etc. We prepare multiple weighting functions in advance according to the temperature of the object to be measured, such as a weighting function when measuring temperature near 1200℃, a weighting function when measuring temperature near 1200℃, etc., and calculate the approximate value of the object to be measured. It is preferable to perform switching so that an appropriate weighting function is selected and set with reference to the temperature of .

More specifically, first, using the temperature measuring device of this embodiment, the approximate temperature of the object to be measured is measured using two-color radiation thermometry. At this point, it is not necessary that the optimal weighting function has been selected; at that point, it is only necessary that the temperature can be measured with coarse accuracy (for example, a weighting function suitable for 600°C can measure 1200°C). If the temperature of the object is measured and there is a 10 mm thick water film on the optical path, a measurement error of 17.5° C. will occur as described above). Then, based on the measured (rough) temperature, a weighting function is selected according to the temperature that is closer among the multiple weighting functions (corresponding to the possible temperatures of the measurement object) stored in the storage unit. , that is, select an appropriate weighting function. Thereafter, using the appropriate weighting function, the temperature of the object to be measured is measured by the temperature measuring device of this embodiment.

In this way, by measuring the approximate temperature in advance, it is possible to select an appropriate weighting function even in environments where temperature measurement is difficult, such as in the presence of absorbers. It becomes possible to measure the temperature of the object to be measured without reducing accuracy. It is difficult to achieve this kind of function with a physical optical filter, so by configuring a spectrophotometer that can continuously observe the optical spectrum and a weighting function like the one above, the above function can be achieved. Realized.

In the above explanation, a detailed explanation was given focusing on water as an absorber. However, absorbers other than water (e.g., oil, fat, solution, glass, resin, etc.) It is possible to similarly configure a weighting function and deal with cases that may exist.

Below, a temperature measuring device and a temperature measuring method according to an embodiment of the present invention obtained based on the above findings will be described in detail.

(Embodiment)
<About the configuration of the temperature measuring device>
Below, first, the overall configuration of the temperature measuring device 10 according to the embodiment of the present invention will be described in detail with reference to FIGS. 8A and 8B. 8A and 8B are explanatory diagrams showing an example of the overall configuration of the temperature measuring device 10 according to the present embodiment.

The temperature measuring device 10 according to the present embodiment has an absorber having a spectral absorption coefficient wavelength dependent in the near-infrared band, which absorbs thermal radiation in the near-infrared band emitted by the object to be measured, on at least a part of the optical path. This device measures the temperature of the object to be measured based on the detection result of the radiance of thermal radiation. Here, examples of the absorber whose spectral absorption coefficient has wavelength dependence in the near-infrared band include at least one of water, water vapor, fats and oils, solutions, glass, and resins. Further, in this embodiment, the near-infrared band is particularly focused on the band from 940 nm to 1350 nm. The reason why the lower limit is set to 940 nm is that water becomes a semitransparent substance with strong wavelength dependence at wavelengths of 800 nm or more (particularly 940 nm or more) belonging to the near-infrared band. Moreover, the reason why the upper limit is set to 1350 nm is that at 1350 nm or more, water becomes opaque when the water film thickness is 10 mm or more.

The temperature measuring device 10 mainly includes a measuring section 101, an arithmetic processing section 103, and a storage section 105, as shown in FIG. 8A, for example.

The measurement unit 101 measures thermal radiation (observation) emitted from an object to be measured that emits thermal radiation belonging to the near-infrared band (for example, a band of 940 nm to 1350 nm), such as a steel plate in a high temperature state. measuring the size of light). More specifically, the measurement unit 101 is a detector that spectrally enters the thermal radiation of the object to be measured into wavelengths, detects the brightness at each wavelength, and outputs the detection result as a spectral brightness signal. Measurement is performed using a spectrophotometer to generate measurement data regarding the spectral brightness signal of thermal radiation light.

This measuring section 101 corresponds to, for example, an optical system comprised of various lenses/lens groups, a spectrophotometer, etc. in a two-color radiation thermometer. A more detailed configuration of the measurement unit 101 will be explained below.

When the measurement unit 101 measures the magnitude of thermal radiation of the object to be measured and generates measurement data indicating the detection result of the radiance of the thermal radiation, the measurement unit 101 sends the generated measurement data to an arithmetic processing unit 103, which will be described later. Output.

The arithmetic processing unit 103 is realized by a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), a communication device, and the like. The calculation processing unit 103 performs overall control of the measurement processing performed by the measurement unit 101. Further, the arithmetic processing unit 103 performs arithmetic processing for calculating the temperature of the object to be measured based on the measurement data measured by the measurement unit 101. More specifically, the arithmetic processing unit 103 performs measurement based on the measurement data generated by the measurement unit 101 and a relational expression between spectral radiance and temperature derived from Planck's blackbody radiation equation. Calculate the temperature of the object. The information regarding the temperature of the object to be measured calculated by the arithmetic processing unit 103 is outputted as an image via a display screen or the like, outputted as a printed matter via a printer or the like, or outputted as data itself.

Note that the detailed configuration of the arithmetic processing unit 103 will be explained in detail below.

The storage unit 105 is realized, for example, by a RAM, a storage device, or the like included in the temperature measuring device 10 according to the present embodiment. The storage unit 105 stores various parameters and data such as the spectral absorption coefficient of the absorber of interest, the spectral emissivity of the object to be measured, and the weighting function. In addition to these data, the storage unit 105 also stores various parameters that need to be saved when the temperature measuring device 10 according to the present embodiment performs some processing, the progress of the processing, etc. Various databases, programs, etc. are recorded as appropriate. This storage unit 105 allows the measuring unit 101, the arithmetic processing unit 103, and the like to freely read/write data.

Furthermore, the storage unit 105 according to this embodiment holds data regarding weighting functions as described above. It is preferable that the temperature range within which the weighting function is allowed to be applied is set in advance in the data regarding the individual weighting functions held, based on the desired temperature measurement accuracy and the like. Moreover, it is preferable that data regarding a plurality of weighting functions is held in accordance with the possible temperatures of the measurement target of interest. By appropriately using the weighting function held in the storage unit 105, the arithmetic processing unit 103 can generate a spectral brightness signal of a desired wavelength based on the spectral brightness signal obtained by the spectrophotometer. Become.

These measuring section 101, arithmetic processing section 103, and storage section 105 may be realized inside one measuring device as, for example, a function of a two-color radiation thermometer, as schematically shown in FIG. 8A. Further, the measuring section 101, the arithmetic processing section 103, and the storage section 105 may be distributed and implemented in a plurality of devices, for example, as shown in FIG. 8B. In the example shown in FIG. 8B, the functions of the measurement unit 101 and the storage unit 105 are implemented inside a measurement unit that functions as a two-color radiation thermometer, and the functions of a personal computer, various servers, various process computers, etc. A case is illustrated in which the functions of the arithmetic processing unit 103 and the storage unit 105 are implemented inside the processing device. Note that in FIG. 8B, the storage section 105 is implemented as storage sections 105a and 105b in the measurement unit and the arithmetic processing device, respectively, but the storage section 105 may be implemented only inside the measurement unit, or It may be implemented only inside the arithmetic processing device.

<About the configuration example of the measurement section>
Next, a configuration example of the measurement unit 101 according to the present embodiment will be described in detail with reference to FIG. 9. FIG. 9 is an explanatory diagram schematically showing an example of the configuration of a measuring section included in the temperature measuring device according to the present embodiment.

The measurement unit 101 according to the present embodiment corresponds to the optical system in a two-color radiation thermometer, and operates under the control of the arithmetic processing unit 103 to measure heat in the near-infrared band emitted by an object to be measured. Measure synchrotron radiation. As schematically shown in FIG. 9, this measuring section 101 includes a light receiving section 111 that receives thermal radiation from an object to be measured, a detecting section 113 that detects the thermal radiation received by the light receiving section 111, have.

In the measuring section 101 according to the present embodiment, the light receiving section 111 and the detecting section 113 as described above may be optically connected by various known optical transmission mechanisms. Examples of such a light transmission mechanism include various known optical fibers OF. By connecting the light receiving section 111 and the detecting section 113 using a light transmission mechanism such as an optical fiber OF, it becomes possible to arrange the light receiving section 111 separately from the detecting section 113, and according to the present embodiment. The convenience of using the temperature measuring device is further improved.

The light receiving unit 111 detects thermal radiation from the object to be measured, in the case where an absorber such as water whose spectral absorption coefficient in the near-infrared band is wavelength-dependent may exist on the optical path to the object to be measured. As shown in FIG. 9, there is a light-receiving lens 121 that receives the thermal radiation from the object to be measured, and the thermal radiation from the object that has passed through the sensing lens 121 is transferred to the optical fiber OF. It has a connection coupler 123 for connecting to. The light-receiving lens 121 and the connection coupler 123 function as a light-guiding optical system that guides thermal radiation to the detection section 113.

Here, the specific configuration of the light receiving section 111 according to this embodiment is not particularly limited. For example, in FIG. 9, one biconvex lens is illustrated as the light receiving lens 121, but the light receiving lens 121 may be a lens group composed of a plurality of optical elements. Further, the lens used for the light receiving lens 121 is not particularly limited, and any known optical element such as a spherical lens or an aspherical lens may be appropriately used. The connection coupler 123 and the optical fiber OF are also not particularly limited, and various known connection couplers and optical fibers can be used.

Thermal radiation from the object to be measured, which has absorbers (water in FIG. 9) with various thicknesses on at least a portion of its surface, is turned into a substantially parallel beam by the light receiving lens 121 of the light receiving unit 111, and connected. It reaches the coupler 123. The connection coupler 123 connects the thermal radiation guided from the light receiving lens 121 to one end of the optical fiber OF. Thermal radiation from the object to be measured is received by the light receiving section 111 and then transmitted through the optical fiber OF, and is guided to the detecting section 113.

The detection unit 113 uses a spectrophotometer to detect the spectral brightness of the thermal radiation of the measurement object received by the light receiving unit 111 as a spectral brightness signal, and as illustrated in FIG. It has a connecting coupler 151, a condensing lens 153, and a spectrophotometer 155 that are optically connected.

Thermal radiation from the object to be measured, which has passed through the connection coupler 151, is focused onto the spectrophotometer 155 by the condenser lens 153. The spectral luminance meter 155 spectrally spectrally enters the thermal radiation light from the object to be measured, detects a spectral luminance value for each wavelength, and generates measurement data regarding the spectral luminance signal. Thereafter, the spectral luminance meter 155 outputs measurement data regarding the obtained spectral luminance signal to the arithmetic processing unit 103.

In addition, although the condensing lens 153 is schematically illustrated using one biconvex lens in FIG. 9, the condensing lens 153 may be a lens group composed of a plurality of lenses. Further, the lens used for the condensing lens 153 is not particularly limited, and known optical elements such as a spherical lens or an aspherical lens can be appropriately used.

The configuration example of the measurement unit 101 according to the present embodiment has been briefly described above with reference to FIG.

<About the configuration example of the arithmetic processing unit 103>
Next, a configuration example of the arithmetic processing unit 103 according to this embodiment will be described with reference to FIG. 10. FIG. 10 is a block diagram showing a configuration example of the arithmetic processing unit 103 according to this embodiment.

The arithmetic processing unit 103 according to the present embodiment calculates the temperature of the measurement target based on the spectral luminance signal of the measurement target detected by the detection unit 113, and as illustrated in FIG. 171, a data acquisition section 173, a brightness data generation section 175, a temperature calculation section 177, a result output section 179, and a display control section 181.

The measurement control unit 171 is realized by, for example, a CPU, a ROM, a RAM, an input device, an output device, a communication device, and the like. The measurement control unit 171 is a processing unit that centrally controls the functions of the temperature measurement device 10 according to the present embodiment. The measurement control unit 171 controls the operation of the measurement unit 101 including the spectrophotometer so as to measure the thermal radiation from the object to be measured. Furthermore, the measurement control unit 171 provides the luminance data generation unit 175 and the temperature calculation unit 177 with various types of information, such as measurement conditions for thermal radiation light and information for specifying the type of weighting function to be used, as necessary. It is also possible to output the setting value.

The measurement control unit 171 also refers to the information regarding the temperature measurement result of the measurement object calculated from the temperature calculation unit 177, and determines whether the calculated temperature of the measurement object is acceptable for the weighting function currently used. It may also be determined whether the temperature falls within the temperature range. At this time, if the calculated temperature of the measurement object does not belong to the temperature range allowed by the currently set weighting function, the measurement control unit 171 adjusts the temperature of the measurement object to the calculated temperature of the measurement object. Preferably, another suitable weighting function is set. Then, the measurement control unit 171 causes the luminance data generation unit 175 to perform the luminance data generation process again, which will be described later, using another weighting function that has been set, and also causes the temperature calculation unit 177 to The temperature calculation process is executed again. Thereby, the temperature measuring device 10 according to the present embodiment can measure the temperature of the object to be measured even more accurately.

The data acquisition unit 173 is realized by, for example, a CPU, ROM, RAM, communication device, etc. The data acquisition section 173 acquires data of the spectral luminance signal generated by the measurement section 101, and outputs it to the luminance data generation section 175, which will be described later. Further, the data acquisition unit 173 may associate the data of the acquired spectral brightness signal with time information regarding the date and time when the data of the spectral brightness signal was acquired, and store the data in the storage unit 105 as history information.

The brightness data generation unit 175 is realized by, for example, a CPU, ROM, RAM, or the like. In explaining the function of the brightness data generation unit 175, below, a band of a predetermined wavelength width that includes one of the two wavelengths at which the spectral absorption coefficient (or spectral transmittance) of the absorber is the same as each other will be described. will be referred to as a first wavelength band, and a band with a predetermined wavelength width that includes the other wavelength will be referred to as a second wavelength band.

The brightness data generation unit 175 refers to the data of the spectral brightness signal output from the data acquisition unit 173 and generates measurement data of the spectral brightness signal in the first wavelength band and measurement data of the spectral brightness signal in the second wavelength band. , extract. Thereafter, the brightness data generation unit 175 uses the data regarding the weighting function as described above, which is set in advance by the measurement control unit 171, to generate each of the measurement data in the first wavelength band and the measurement data in the second wavelength band. Add up while weighting. As a result, the brightness data generation unit 175 generates first brightness data that is brightness data of spectral radiance regarding the first wavelength band, and second brightness data that is brightness data of spectral radiance regarding the second wavelength band. do. The two types of brightness data generated in this manner correspond to brightness signals of thermal radiation light at two types of wavelengths at which the spectral absorption coefficients (or spectral transmittances) of the absorber are the same.

After generating the first brightness data and the second brightness data, the brightness data generation unit 175 outputs the generated brightness data to the temperature calculation unit 177, which will be described later.

The temperature calculation unit 177 is realized by, for example, a CPU, ROM, RAM, or the like. The temperature calculation unit 177 uses two types of brightness data (first brightness data and second brightness data) output from the brightness data generation unit 175 to convert the brightness signal in one brightness data into the brightness signal in the other brightness data. The dichromatic ratio divided by the signal (in other words, the ratio of spectral radiance) is calculated. Furthermore, the temperature calculation unit 177 calculates the temperature of the measurement target using the calculated two-color ratio and the relational expression between the two-color ratio and the temperature.

As disclosed in Patent Document 1, the dichroic ratio R can be calculated by dividing one of the luminance signals at two wavelengths by the luminance signal of the other wavelength. On the other hand, in the temperature measuring device 10 according to the present embodiment, absorption of thermal radiation by the absorber is taken into consideration, as shown in equations (11) and (12) below. Therefore, the dichroic ratio R is expressed by the following equation (13) when the equation is derived in the same manner as in Patent Document 1 using the following equations (11) and (12).

Here, in the above equations (11) and (12), τ ₁ is the spectral transmittance of water at wavelength λ ₁ , and τ ₂ is the spectral transmittance of water at wavelength λ ₂ . Further, the spectral transmittance τ of water is a function of the spectral absorption coefficient of water, the thickness of water, and the interface reflectance determined from the refractive index of both water and air at the interface. In this case, if interface reflection is omitted, the spectral transmittances τ ₁ and τ ₂ of water can be expressed as τ ₁ =exp(-α ₁ ×t) and τ ₂ =exp(-α ₂ ×t), respectively. can. Here, α ₁ is the spectral absorption coefficient of water at wavelength λ ₁ , α ₂ is the spectral absorption coefficient of water at wavelength λ ₂ , and t is the thickness of the water film.

As explained earlier, the brightness data generation unit 175 according to this embodiment calculates the spectral transmittance of the absorber (more precisely, since the detection wavelength is not a single wavelength but has a bandwidth, the effective transmittance in that wavelength band) ) is the same as each other, data processing is performed using a weighting function. Therefore, the term related to absorption by the absorber shown in the first term on the middle side of the above equation (13) cancels each other in the numerator and denominator, and has a value of 1. Therefore, R _λ and Λ on the right side of the above equation (13) are as shown in the following equations (14a) and (14b).

Here, R _λ and Λ shown in equations (14a) and (14b) are determined from the center transmission wavelength defined by the set of weighting functions (weighting functions on the short wavelength side and long wavelength side) used. Becomes a constant. Therefore, the temperature calculation unit 177 can calculate the temperature T of the measurement target using the calculated two-color ratio R and the relational expression (leftmost side = rightmost side) in the above equation (13). It becomes possible.

Note that when the temperature calculation unit 177 calculates the dichromatic ratio R, it is particularly important to determine which of the two wavelengths λ ₁ and λ ₂ the luminance signal is used as the denominator and which luminance signal is used as the numerator. The present invention is not limited to this, and it is sufficient that the reference luminance signal is not changed during the calculation process.

Further, the temperature calculation unit 177 may directly calculate the temperature using the above equations (11) and (12) without using the two-color ratio R expressed by the above equation (13). That is, if the emissivity ε at two types of wavelengths λ ₁ and λ ₂ is known, the two unknowns in the above equations (11) and (12) are the temperature T and the water film thickness t. Therefore, the temperature calculation unit 177 can calculate the temperature T by combining the above equations (11) and (12) and finding a solution to the simultaneous equations. Furthermore, even if the emissivity ε at the two wavelengths λ ₁ and λ ₂ is unknown, if the emissivity ε at the wavelength λ ₁ and the emissivity ε at the wavelength λ ₂ are equal to each other, the above formula can be similarly obtained. It is possible to directly calculate the temperature T by combining equations (11) and (12). Here, the method of solving the simultaneous equations is not particularly limited; for example, if it can be solved analytically, it may be solved analytically, it may be solved by numerical calculation, or it may be solved as an optimal value problem. It's okay.

The temperature calculation section 177 outputs information regarding the temperature T of the measurement object calculated as described above to the measurement control section 171 and a result output section 179, which will be described later.

The result output unit 179 is realized by, for example, a CPU, ROM, RAM, output device, communication device, etc. The result output unit 179 outputs information regarding the temperature T of the measurement object output from the temperature calculation unit 177 to the user of the temperature measurement device 10. Specifically, the result output unit 179 associates the data corresponding to the temperature measurement result with time data regarding the date and time when the data was generated, etc., and outputs the data to various servers or control devices, or outputs the data to a printer or the like. Use a device to output it as a paper medium. Further, the result output unit 179 may output data corresponding to the measurement results to various information processing devices such as an external computer, or to various recording media.

In addition, the result output unit 179 outputs data corresponding to the temperature measurement result to an output device such as a display provided in the temperature measuring device 10 or a display of various devices provided externally. , outputs the measurement results in cooperation with a display control section 181, which will be described later.

The display control unit 181 is realized by, for example, a CPU, ROM, RAM, output device, communication device, etc. The display control unit 181 performs display control when displaying data corresponding to temperature measurement results on various display devices such as a display. Thereby, the user of the temperature measuring device 10 can grasp the measurement result regarding the temperature of the object to be measured on the spot.

An example of the functions of the arithmetic processing unit 103 according to this embodiment has been described above. Each of the above components may be constructed using general-purpose members and circuits, or may be constructed using hardware specialized for the function of each component. Further, the functions of each component may be entirely performed by a CPU or the like. Therefore, it is possible to change the configuration to be used as appropriate depending on the technical level at the time of implementing this embodiment.

Note that it is possible to create a computer program for realizing each function of the arithmetic processing unit according to the present embodiment as described above, and to implement it in a personal computer or the like. Further, a computer-readable recording medium storing such a computer program can also be provided. The recording medium is, for example, a magnetic disk, an optical disk, a magneto-optical disk, a flash memory, or the like. Further, the above computer program may be distributed via a network, for example, without using a recording medium.

The configuration of the temperature measuring device 10 according to this embodiment has been described above in detail with reference to FIGS. 8A to 10.

<About temperature measurement method>
Next, an example of the flow of the temperature measurement method performed by the temperature measurement device 10 according to the present embodiment will be briefly described with reference to FIG. 11. FIG. 11 is a flow chart showing an example of the flow of the temperature measurement method according to the present embodiment.

In the temperature measurement method according to the present embodiment, first, under the control of the measurement control unit 171 of the arithmetic processing unit 103, the measurement unit 101 equipped with a spectrophotometer measures thermal radiation from the measurement target (step S101). Thereby, the thermal radiation from the object to be measured is detected while being spectrally divided, and measurement data regarding the spectral luminance signal is generated. Measurement data regarding the generated spectral luminance signal is output to the data acquisition section 173 of the arithmetic processing section 103.

The data acquisition section 173 of the arithmetic processing section 103 outputs measurement data regarding the spectral luminance signal output from the measurement section 101 to the luminance data generation section 175.

The brightness data generation unit 175 uses the measurement data regarding the spectral brightness signal output from the data acquisition unit 173 and the weighting function set in advance by the measurement control unit 171 to generate two types of brightness data (i.e., the first luminance data and second luminance data) are generated (step S103). After generating the two types of brightness data, the brightness data generation unit 175 outputs the generated two types of brightness data to the temperature calculation unit 177.

The temperature calculation unit 177 calculates the two-color ratio R using the two types of generated brightness data (first brightness data and second brightness data) (step S105). Thereafter, the temperature calculation unit 177 calculates the temperature of the measurement target based on the relational expression indicating the relationship between the two-color ratio and the temperature and the calculated two-color ratio R (step S107). The temperature calculation section 177 outputs the obtained information regarding the temperature of the measurement object to the measurement control section 171 and the result output section 179.

The measurement control unit 171 determines whether the calculated temperature is within the allowable temperature range set in the weighting function used (step S109). If the calculated temperature is not within the allowable temperature range (step S109 - NO), the measurement control unit 171 changes the weighting function to one suitable for the calculated temperature (step S111), and returns to step S103. Go back and let the process continue.

On the other hand, if the calculated temperature is within the allowable temperature range (step S109-YES), the result output unit 179 outputs the temperature of the object to be measured calculated by the temperature calculation unit 177 as a measurement result. (Step S113).

Thereby, in the temperature measurement method according to the present embodiment, it is possible to measure the temperature of the object to be measured while further suppressing temperature measurement errors.

An example of the flow of the temperature measurement method according to the present embodiment has been briefly described above with reference to FIG. 11.

<About hardware configuration>
Next, with reference to FIG. 12, the hardware configuration of the arithmetic processing unit 103 included in the temperature measuring device 10 according to the present embodiment will be described in detail. FIG. 12 is a block diagram for explaining the hardware configuration of the arithmetic processing unit 103 according to this embodiment.

The arithmetic processing unit 103 mainly includes a CPU 901, a ROM 903, and a RAM 905. The arithmetic processing unit 103 further includes a bus 907, an input device 909, an output device 911, a storage device 913, a drive 915, a connection port 917, and a communication device 919.

The CPU 901 functions as a central processing device and control device, and controls the entire operation or a part of the operation within the arithmetic processing unit 103 according to various programs recorded in the ROM 903, RAM 905, storage device 913, or removable recording medium 921. do. The ROM 903 stores programs, calculation parameters, etc. used by the CPU 901. The RAM 905 temporarily stores programs used by the CPU 901 and parameters that change as appropriate during program execution. These are interconnected by a bus 907 constituted by an internal bus such as a CPU bus.

The bus 907 is connected to an external bus such as a PCI (Peripheral Component Interconnect/Interface) bus via a bridge.

The input device 909 is, for example, an operation means operated by a user such as a mouse, a keyboard, a touch panel, a button, a switch, a lever, or the like. Further, the input device 909 may be, for example, a remote control means (so-called remote control) using infrared rays or other radio waves, or an external connection device 923 such as a PDA that is compatible with the operation of the temperature measuring device 10. It's okay. Further, the input device 909 includes, for example, an input control circuit that generates an input signal based on information input by the user using the above-mentioned operating means and outputs it to the CPU 901. By operating this input device 909, the user can input various data to the temperature measuring device 10 and instruct processing operations.

The output device 911 is configured of a device that can visually or audibly notify the user of the acquired information. Examples of such devices include display devices such as CRT display devices, liquid crystal display devices, plasma display devices, EL display devices, and lamps, audio output devices such as speakers and headphones, printer devices, mobile phones, and facsimiles. The output device 911 outputs, for example, the results obtained by various processes performed by the arithmetic processing unit 103. Specifically, the display device displays the results obtained by various processes performed by the arithmetic processing unit 103 in text or images. On the other hand, the audio output device converts an audio signal consisting of reproduced audio data, audio data, etc. into an analog signal and outputs the analog signal.

The storage device 913 is a data storage device configured as an example of a storage section of the arithmetic processing section 103. The storage device 913 is configured of, for example, a magnetic storage device such as an HDD (Hard Disk Drive), a semiconductor storage device, an optical storage device, a magneto-optical storage device, or the like. This storage device 913 stores programs executed by the CPU 901, various data, and various data acquired from the outside.

The drive 915 is a reader/writer for a recording medium, and is either built into the arithmetic processing unit 103 or attached externally. The drive 915 reads information recorded on an attached removable recording medium 921 such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory, and outputs it to the RAM 905. The drive 915 can also write records on a removable recording medium 921, such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory. The removable recording medium 921 is, for example, CD media, DVD media, Blu-ray (registered trademark) media, or the like. Further, the removable recording medium 921 may be a CompactFlash (registered trademark) (CF), a flash memory, an SD memory card (Secure Digital memory card), or the like. Furthermore, the removable recording medium 921 may be, for example, an IC card (Integrated Circuit card) equipped with a non-contact IC chip, an electronic device, or the like.

The connection port 917 is a port for directly connecting a device to the arithmetic processing unit 103. Examples of the connection ports 917 include a USB (Universal Serial Bus) port, an IEEE1394 port, a SCSI (Small Computer System Interface) port, an RS-232C port, and an HDMI (registered trademark) (High-Definition Mu ltimedia Interface) port, etc. By connecting the externally connected device 923 to this connection port 917, the arithmetic processing unit 103 can directly acquire various data from the externally connected device 923 or provide various data to the externally connected device 923.

The communication device 919 is, for example, a communication interface configured with a communication device for connecting to the communication network 925. The communication device 919 is, for example, a communication card for wired or wireless LAN (Local Area Network), Bluetooth (registered trademark), or WUSB (Wireless USB). Further, the communication device 919 may be a router for optical communication, a router for ADSL (Asymmetric Digital Subscriber Line), a modem for various types of communication, or the like. This communication device 919 can transmit and receive signals, etc., to and from the Internet or other communication devices, for example, in accordance with a predetermined protocol such as TCP/IP. Further, the communication network 925 connected to the communication device 919 is configured by a wired or wirelessly connected network, and may be, for example, the Internet, a home LAN, an in-house LAN, infrared communication, radio wave communication, or satellite communication. It's okay.

An example of the hardware configuration capable of realizing the functions of the arithmetic processing unit 103 according to the embodiment of the present invention has been described above. Each of the above components may be constructed using general-purpose members, or may be constructed using hardware specialized for the function of each component. Therefore, it is possible to change the hardware configuration to be used as appropriate depending on the technical level at the time of implementing this embodiment.

Although preferred embodiments of the present invention have been described above in detail with reference to the accompanying drawings, the present invention is not limited to such examples. It is clear that a person with ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea stated in the claims. It is understood that these also naturally fall within the technical scope of the present invention.

10 Temperature measuring device 101 Measuring section 103 Arithmetic processing section 105 Storage section 111 Light receiving section 113 Detecting section 121 Light receiving lens 123, 151 Connection coupler 153 Condensing lens 155 Spectroluminance meter 171 Measurement control section 173 Data acquisition section 175 Brightness data generation section 177 Temperature calculation section 179 Result output section 171 Display control section

Claims (4)

In a temperature measuring device that measures the temperature of a measurement target using two-color radiation thermometry,
a light receiving unit that receives thermal radiation from the object to be measured, in a state where an absorber whose spectral transmittance in the near-infrared band is wavelength dependent may be present on the optical path to the object to be measured;
a detection unit that uses a spectrophotometer to detect the spectral brightness of the thermal radiation received by the light receiving unit as a spectral brightness signal;
an arithmetic processing unit that calculates the temperature of the measurement target based on the spectral luminance signals corresponding to two wavelengths at which the spectral transmittance of the absorber is the same, detected by the detection unit;
has
The arithmetic processing unit is
Set a weighting function consisting of continuous anonymous numbers in the wavelength direction,
At one wavelength of the two wavelengths at which the spectral transmittance of the absorber is the same, the position of the weighting function in the wavelength direction is set to the position of the one wavelength, and then using the spectrophotometer. calculating first weighting data by multiplying the obtained spectral transmittance value of the absorber by the weighting function and summing the results;
At the other wavelength of the two wavelengths at which the spectral transmittance of the absorber is the same, the position of the weighting function in the wavelength direction is set to a predetermined position near the other wavelength, and then the spectral luminance is adjusted. calculating second weighting data by multiplying the value of the spectral transmittance of the absorber obtained using the meter by the weighting function and summing the values;
The first weighting data and the second weighting data are compared while moving the predetermined position in the wavelength direction, and the first weighting data and the second weighting data become the same value. Determine the predetermined position,
The position of the weighting function in the wavelength direction is set to the position of the one wavelength, and the value obtained by multiplying the spectral luminance signal by the weighting function, and the predetermined position where the position of the weighting function in the wavelength direction is determined. The temperature measuring device determines the temperature of the object to be measured from a ratio of the weighting function to a value obtained by multiplying the spectral luminance signal by the weighting function . a storage unit storing a plurality of weighting functions according to the temperature of the measurement object;
The arithmetic processing unit is
Measuring the approximate temperature of the measurement target using the temperature measurement device,
The temperature measuring device according to claim 1, wherein an optimal weighting function is selected and set from among a plurality of weighting functions stored in the storage unit based on the obtained temperature. The temperature measuring device according to claim 1 or 2 , wherein the absorber is at least one of water, oil, solution, glass, or resin. In a temperature measurement method for measuring the temperature of a measurement target using two-color radiation thermometry,
a light receiving step of receiving thermal radiation from the object to be measured in a state where an absorber whose spectral transmittance in the near-infrared band is wavelength dependent may be present on the optical path to the object to be measured;
a detection step of detecting the spectral brightness of the thermal radiation received in the light receiving step as a spectral brightness signal using a spectrophotometer;
an arithmetic processing step of determining the temperature of the object to be measured based on the spectral luminance signals corresponding to two wavelengths at which the spectral transmittance of the absorber is the same, detected in the detection step;
has
The arithmetic processing step is
Set a weighting coefficient consisting of continuous anonymous numbers in the wavelength direction,
At one wavelength of the two wavelengths at which the spectral transmittance of the absorber is the same, the position of the weighting function in the wavelength direction is set to the position of the one wavelength, and then using the spectrophotometer. calculating first weighting data by multiplying the obtained spectral transmittance value of the absorber by the weighting function and summing the results;
At the other wavelength of the two wavelengths at which the spectral transmittance of the absorber is the same, the position of the weighting function in the wavelength direction is set to a predetermined position near the other wavelength, and then the spectral luminance is adjusted. calculating second weighting data by multiplying the value of the spectral transmittance of the absorber obtained using the meter by the weighting function and summing the values;
The first weighting data and the second weighting data are compared while moving the predetermined position in the wavelength direction, and the first weighting data and the second weighting data become the same value. Determine the predetermined position,
The position of the weighting function in the wavelength direction is set to the position of the one wavelength, and the value obtained by multiplying the spectral luminance signal by the weighting function, and the predetermined position where the position of the weighting function in the wavelength direction is determined. , and the temperature of the object to be measured is determined from a ratio of the value obtained by multiplying the spectral luminance signal by the weighting function .

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