Temperature Measurement System

Abstract

To provide a temperature measurement system that can contribute to improvement in temperature measurement accuracy of a measurement object.SOLUTION: A temperature measurement system 10 comprises: a light reception unit 21 that receives radiation light radiated from a measurement object 110; a luminance detection unit 22 that detects luminance in the radiation light of a wavelength corresponding to at least one of a visible light ray or a near infrared ray of the radiation light received by the light reception unit 21; a histogram creation unit that creates a histogram of a gradation and luminance of the radiation light on the basis of the luminance detected by the luminance detection unit 22; a representative luminance detection unit that detects representative luminance from the histogram created by the histogram creation unit; and a temperature calculation unit that calculates a temperature of the measurement object 110 on the basis of the luminance detected by the representative luminance detection unit.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a temperature measurement system. [Background technology]

[0002] The temperature measurement system described in Patent Document 1 measures the temperature of an object being heated in a heating furnace using a thermograph placed outside the furnace. An optical window is installed in the heating furnace, and infrared rays emitted from the object pass through the optical window and reach the thermograph. This temperature measurement system measures the temperature of the object based on the brightness of the infrared rays detected by the thermograph. The temperature measurement system measures the temperature of the object in the heating furnace in a non-contact manner. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-215084 Summary of the Invention [Problem to be solved by the invention]

[0004] The optical window is made of a material that absorbs infrared rays, such as quartz glass. Therefore, in order to accurately measure the temperature of the object to be measured, it is necessary to consider the amount of infrared rays absorbed by the optical window, i.e., the influence of the infrared emissivity of the optical window. Note that by constructing the optical window from a material that does not easily absorb infrared rays, such as sapphire, it is possible to improve the accuracy of temperature measurement without considering the influence of infrared emissivity, but this increases the manufacturing cost of the heating furnace.

[0005] An object of the present invention is to provide a temperature measurement system that can contribute to improving the accuracy of measuring the temperature of an object to be measured. [Means for solving the problem]

[0006] a histogram creating unit that creates a histogram showing a distribution of the luminance of pixels in the image data; a representative pixel number detecting unit that detects a representative pixel number from the histogram created by the histogram creating unit; a temperature calculating unit that calculates the temperature of the measurement object based on the representative pixel number detected by the representative pixel number detecting unit; and a pass filter that is disposed between the measurement object and the light receiving unit and that passes only wavelengths in a specific range among wavelengths corresponding to near-infrared rays, wherein the histogram The display device has first regions G1 to G2, second regions G2 to G3, and third regions G3 to G4 in ascending order of brightness gradation, and the first regions G1 to G2, the second regions G2 to G3, and the third regions G3 to G4 are continuous regions, and in the first regions G1 to G2, As the luminance gradation increases, the number of pixels increases from the lower limit. In the second region, the number of pixels is greater than the lower limit value, and The number of pixels varies less with increasing gradation than in the first region G1 to G2. In the third region, The number of pixels varies more significantly with increasing gradation than in the second region G2 to G3. As the number of As the gradation increases, the number of pixels increases and then decreases to a lower limit value. The maximum number of pixels is present in the third region G3 to G4. The representative pixel number detection unit detects the representative pixel number from the number of pixels in the second region G2 to G3, and the temperature calculation unit calculates the temperature by substituting the representative pixel number into a relational equation that holds between the representative pixel number and the temperature of the object to be measured and that is set corresponding to the passing wavelength region of the pass filter.

[0007] In the above configuration, luminance is detected using radiant light emitted from the object to be measured, the radiant light having wavelengths corresponding to visible light and near-infrared light, which are wavelengths that are not easily absorbed by glass, etc. Therefore, even in a heating furnace equipped with an optical window made of inexpensive quartz glass, etc., the temperature of the object to be measured can be measured with high accuracy based on the luminance of the radiant light from the object inside. Therefore, the above configuration contributes to improving the accuracy of temperature measurement of the object to be measured.

[0008] measurement The higher the temperature of the object being measured, the greater the brightness of the emitted light tends to be. Since there may be a limit to the brightness that can be detected by the brightness detection unit, in order to enable measurement over a wide temperature range, it is desirable that the difference between the brightness corresponding to low temperatures and the brightness corresponding to high temperatures is small. With the above configuration, the brightness detection unit detects not all wavelengths but only a small number of wavelengths. , by using a pass filter that passes wavelengths in a specific range among wavelengths corresponding to near-infrared rays, It is possible to detect brightness by narrowing down the wavelength to a specific range, which makes it possible to narrow down the difference between brightness corresponding to low temperatures and brightness corresponding to high temperatures and widen the measurable temperature range for the object being measured.

[0009] The temperature measurement system preferably includes a neutral density filter that reduces the amount of emitted light received by the light receiving section. The higher the temperature of the object to be measured, the greater the brightness of the radiated light tends to be. Since there may be a limit to the brightness that can be detected by the brightness detection unit, it is desirable to have a small difference between the brightness corresponding to a low temperature and the brightness corresponding to a high temperature in order to enable measurement over a wide temperature range. In the above configuration, the amount of radiated light received by the light receiving unit is reduced, so the difference between the brightness corresponding to a low temperature and the brightness corresponding to a high temperature in the brightness detected by the brightness detection unit can be reduced. Therefore, the above configuration makes it possible to widen the temperature range that can be measured for the object to be measured.

[0010] In the temperature measurement system, the temperature calculation unit includes a storage unit that stores a relational expression that indicates the relationship between temperature and luminance in thermal radiation of a blackbody, and a temperature calculation unit that calculates the representative temperature based on the relational expression stored in the storage unit. Number of pixels and an execution unit for calculating the temperature of the object to be measured from the temperature of the object to be measured.

[0011] The inventors have determined that the temperature of the object to be measured and the representative temperature detected from the histogram are Number of pixels Even if the emissivity of the object being measured is less than 1 or the material is different from that of a black body, the relationship between the temperature and the thermal radiation of a black body is Representative pixel count In the above configuration, the temperature in the thermal radiation of a black body and Representative pixel count and memorize the relational expression that shows the relationship between Number of pixels Since the temperature is calculated from the temperature, the temperature of the object to be measured can be calculated with high accuracy. [Effects of the Invention]

[0012] The above temperature measurement system can contribute to improving the accuracy of measuring the temperature of the object to be measured. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram illustrating a configuration of an embodiment of a temperature measurement system. [Figure 2] 10 is a graph showing the relationship between the wavelength of radiant light, the spectral radiance, and the temperature of the object to be measured. [Figure 3] 10 is a graph showing the relationship between the temperature of the object to be measured and the detected brightness. [Figure 4] FIG. 1 is a functional block diagram of an information processing device. [Figure 5] A histogram showing the distribution of pixel brightness in image data. [Figure 6] Graph showing the relationship between temperature and luminance in the thermal radiation of a black body. DETAILED DESCRIPTION OF THE INVENTION

[0014] An embodiment of a temperature measurement system will be described with reference to Figures 1 to 6. In this embodiment, the temperature measurement system that measures the temperature of a measurement object that is heated in a heating furnace will be described as an example.

[0015] As shown in FIG. 1, the heating furnace 100 includes a box-shaped case 101 having a heat source (not shown) therein. The heat source may be, for example, a flame-emitting device such as a burner. The case 101 has an opening 101A in which an optical window 102 is installed. The optical window 102 is made of quartz glass, which easily absorbs infrared rays. The case 101 contains a measurement object 110. In the heating furnace 100, the measurement object 110 is heated by the heat source.

[0016] The temperature measurement system 10 is disposed outside the heating furnace 100. The temperature measurement system 10 includes a camera 20 disposed at a distance from a case 101 of the heating furnace 100, an information processing device 30, and a display device 50. The temperature measurement system 10 also includes a neutral density filter 60 and a bandpass filter 70 disposed between the heating furnace 100 and the camera 20. The neutral density filter 60 is disposed on the furnace 100 side relative to the bandpass filter 70. As indicated by the dashed-dotted arrow in FIG. 1 , light emitted from the measurement object 110 inside the heating furnace 100 passes through the optical window 102 and reaches the outside of the heating furnace 100, then passes through the neutral density filter 60 and the bandpass filter 70 in that order, and reaches the camera 20.

[0017] The camera 20 is, for example, a CCD camera or a CMOS camera, and includes, as functional units, a light receiving unit 21 and a brightness detection unit 22. The light receiving unit 21 receives radiant light emitted from the measurement object 110. The light receiving unit 21 transmits an electrical signal corresponding to the brightness of the received radiant light to the brightness detection unit 22. The brightness detection unit 22 detects the brightness of the radiant light based on the transmitted electrical signal. Hereinafter, the brightness detected by the brightness detection unit 22 will be simply referred to as the detected brightness.

[0018] The light emitted from the measurement object 110 contains light with wavelengths corresponding to visible light (380 nm to 750 nm) and near-infrared light (750 nm to 2500 nm). As shown in Figure 2, the relationship between the wavelengths in these ranges of the light emitted from the measurement object 110 and the spectral radiance follows Planck's law. Furthermore, the relationship between the temperature of the measurement object 110 and the spectral radiance follows Wien's law, so that when the temperature of the measurement object 110 is high, the spectral radiance is always higher than when the temperature is low.

[0019] That is, as shown by the solid line in FIG. 2, when the temperature of the object to be measured 110 is low, for example, luminance can be detected from the radiation light with a wavelength W1 slightly longer than 800 nm, and the luminance of the radiation light tends to increase as the wavelength becomes longer. As shown by the dashed-dotted line in FIG. 2, when the temperature of the object to be measured 110 increases, the luminance of the radiation light becomes larger compared to when the temperature of the object to be measured 110 is low. When the temperature of the object to be measured 110 is high, the luminance of the radiation light with a shorter wavelength can be detected compared to when the temperature of the object to be measured 110 is low. That is, when the temperature of the object to be measured 110 is high, for example, luminance can be detected from a wavelength W2 slightly longer than 700 nm (W2 < W1). Also, even when the temperature of the object to be measured 110 is high, the luminance of the radiation light tends to increase as the wavelength becomes longer, but the amount of increase in luminance with the increase in temperature decreases as the wavelength becomes longer. Therefore, the difference between the luminance when the temperature of the object to be measured 110 is low (solid line in FIG. 2) and the luminance when the temperature of the object to be measured 110 is high (dashed-dotted line in FIG. 2) becomes smaller as the wavelength of the radiation light becomes longer. Note that the temperature of the object to be measured 110 can be accurately obtained by detecting the luminance within the range of the difference ΔLn in spectral radiance luminance due to the temperature difference indicated by the difference between the dashed-dotted line and the solid line in FIG. 2. The luminance detection unit 22 detects the luminance of the radiation light by integrating the luminance at each wavelength.

[0020] When the radiated light passes through the neutral density filter 60, the neutral density filter 60 attenuates light of wavelengths corresponding to visible light and near-infrared light at the same rate. This reduces the amount of radiated light received by the light-receiving unit 21. That is, when the temperature of the measurement object 110 is low, the luminance of the radiated light that passes through the neutral density filter 60 and reaches the light-receiving unit 21, as shown by the solid line in FIG. 2, is lower than the luminance of the radiated light that reaches the light-receiving unit 21 without passing through the neutral density filter 60, as shown by the dashed line in FIG. 2. Furthermore, when the temperature of the measurement object 110 is high, the luminance of the radiated light that passes through the neutral density filter 60 and reaches the light-receiving unit 21, as shown by the dashed line in FIG. 2, is lower than the luminance of the radiated light that reaches the light-receiving unit 21 without passing through the neutral density filter 60, as shown by the dashed line in FIG. 2. Note that because the neutral density filter 60 attenuates light of wavelengths corresponding to visible light and near-infrared light at the same rate, the degree of reduction in luminance caused by the neutral density filter 60 when the temperature of the object 110 is low, as indicated by the open arrow in FIG. 2, is smaller than the degree of reduction in luminance caused by the neutral density filter 60 when the temperature of the object 110 is high, as indicated by the black arrow in FIG. 2. Therefore, as indicated by the difference between the dashed-dotted line and the solid line in FIG. 2, the difference in luminance ΔLn caused by differences in temperature when the emitted light reaches the light-receiving unit 21 after passing through the neutral density filter 60 is smaller than the difference in luminance ΔLr caused by differences in temperature when the emitted light reaches the light-receiving unit 21 without passing through the neutral density filter 60, as indicated by the difference between the dashed-dotted line and the broken line in FIG. 2 (ΔLn<ΔLr). In this way, the neutral density filter 60 adjusts the range of the difference in luminance ΔLn of the emitted light received by the light-receiving unit 21.

[0021] The bandpass filter 70 is a filter that passes only wavelengths in a specific range of radiant light. In this embodiment, a bandpass filter 70 that passes wavelengths from 840 nm to 860 nm is used. As a result, of the radiant light emitted from the measurement object 110, only wavelengths in a specific range Rb among wavelengths corresponding to visible light and near-infrared light reach the light receiving unit 21. Furthermore, since the wavelengths from 840 nm to 860 nm do not include wavelengths corresponding to flame radiant light, the flame radiant light emitted from the heat source in the heating furnace 100 does not pass through the bandpass filter 70 and does not reach the light receiving unit 21. The brightness detection unit 22 detects the brightness of the radiant light by integrating the brightness at each wavelength in the range Rb that reaches the light receiving unit 21. Therefore, the detected brightness can be reduced compared to when the bandpass filter 70 is not provided, i.e., when the brightness of the radiant light is detected by integrating the brightness at all wavelengths of the radiant light. Therefore, as shown in the hatched area in Figure 2, the difference (=K2) between the brightness (=K1) detected when the temperature of the object to be measured 110 is low and the brightness (=K1+K2) detected when the temperature of the object to be measured 110 is high can be reduced.

[0022] As shown in FIG. 3, the detected luminance by the luminance detection unit 22 tends to increase as the temperature of the measurement object 110 increases. When the temperature of the measurement object 110 is high, the luminance detected by the luminance detection unit 22 is limited. Therefore, it is desirable that the detected luminance does not exceed an upper limit in the desired temperature range to be measured (e.g., 700°C to 1450°C). In this embodiment, the amount of received radiant light is reduced by the neutral density filter 60, while the wavelength of the received radiant light is limited by the band-pass filter 70. This prevents the detected luminance from reaching the upper limit in the temperature range to be measured, thereby ensuring a correlation between the detected luminance and temperature. In this way, the light attenuation rate of the neutral density filter 60 and the wavelength range that can be passed by the band-pass filter 70 can be appropriately set based on the relationship between the temperature range to be measured and the detected luminance.

[0023] 1, output signals transmitted from the light receiving unit 21 and brightness detecting unit 22 of the camera 20 are input to the information processing device 30 of the temperature measurement system 10. The information processing device 30 includes a CPU 30A, a ROM 30B, and a RAM 30C. In the information processing device 30, the CPU 30A loads a program stored in the ROM 30B into the RAM 30C and executes various processes to calculate the temperature of the measurement object 110.

[0024] As shown in FIG. 4, the information processing device 30 includes, as functional units, a preprocessing unit 40, a histogram creating unit 41, a representative Number of pixels It has a detection unit 42 and a temperature calculation unit 43. The pre-processing unit 40 sets a temperature analysis range within the light receiving range of the camera 20, i.e., within the captured image, based on the output signal from the light receiving unit 21 and the output signal from the brightness detection unit 22. The pre-processing unit 40 has, as functional units, an image reading unit 40A and an analysis range designation unit 40B.

[0025] The image reading unit 40A reads image data of the measurement object 110 based on the output signal from the light receiving unit 21 and the output signal from the brightness detecting unit 22. The analysis range designation unit 40B designates a temperature analysis range based on the image data read by the image reading unit 40A. As the temperature analysis range, for example, a portion of the image data corresponding to the measurement object 110 is extracted.

[0026] The histogram creation unit 41 calculates the histogram based on the detected luminance of the luminance detection unit 22. Shows the distribution of pixel brightness in image data A histogram is created. The histogram creation unit 41 has a generation unit 41A and a correction unit 41B as functional units.

[0027] The generation unit 41A generates a temperature value in the temperature analysis range set by the pre-processing unit 40 based on the output signal of the light receiving unit 21 and the output signal of the brightness detection unit 22. Shows the distribution of pixel brightness Generate a histogram. What is gradation? Brightness In this embodiment, for example, the number of shades is 256 (=2 8) levels. Note that the gradation is not limited to 256 levels, but can be expressed in 65536 (=2 16 The steps may be changed as appropriate, such as the step 1.

[0028] As shown in FIG. 5, in the histogram generated in this embodiment, the black side portion of the gradation from 0 to G1 and the whitest side portion of the gradation from G4 to 255 are Is shining No intensity distribution occurs, and the gradation is in the intermediate range from G1 to G4. Shining A distribution of degrees occurs. Number of pixels shows a tendency to increase towards the G2 side between the gradations G1 and G2. Number of pixels Between the gradations G2 and G3, the values tend to be somewhat similar to each other, although they vary slightly depending on the gradation. Number of pixels shows values that vary greatly for each gradation between G3 and G4, and between G3 and G4, it shows a tendency to have a mountain-shaped distribution with two maximum values. Note that in the region from the gradation that shows the maximum value on the G4 side (the right side of Figure 5) of the two maximum values to the G4 side, as the gradation becomes larger Number of pixels decreases rapidly, and when the gradation is G4, Number of pixels is equal to the lower limit.

[0029] The correction unit 41B corrects the histogram generated by the generation unit 41A. In this embodiment, the correction unit 41B performs a smoothing process, such as approximating the histogram with a Gaussian function. By performing such a smoothing process, noise in the histogram can be removed. In this way, the histogram creation unit 41 corrects the histogram generated by the generation unit 41A using the correction unit 41B, and based on the luminance detected by the luminance detection unit 22, Shows the distribution of pixel brightness in image data Create a histogram.

[0030] representative Number of pixels The detection unit 42 selects a representative value from the histogram created by the histogram creation unit 41. Number of pixels Detect. Representative Number of pixels In the histogram created by the histogram creation unit 41, the detection unit 42 detects Number of pixelsThe gradation region Rh (G2 to G3) where the values are somewhat similar is extracted, and the other gradation regions (0 to G2 and G3 to 255) are deleted. Then, a representative value is extracted from the histogram within the extracted gradation region Rh. Number of pixels In this embodiment, in the region Rh, Number of pixels Represents the average value of Number of pixels It is detected as a representative Number of pixels In another example, the detection unit 42 detects the minimum and maximum values in the region Rh. Number of pixels It is also possible to detect it as

[0031] The temperature calculation unit 43 is a representative Number of pixels Representative detected by the detection unit 42 Number of pixels 4, the temperature calculation unit 43 has a storage unit 43A and an execution unit 43B as functional units.

[0032] The memory unit 43A stores a relational expression that indicates the relationship between temperature and luminance in the thermal radiation of a blackbody. This relational expression can be calculated, for example, based on experiments or simulations using a blackbody furnace. A blackbody furnace is a temperature-variable furnace that houses a blackbody and can raise, lower, and maintain its temperature. Blackbodies do not necessarily mean perfect blackbodies with an infrared emissivity of 1, but also include blackbody approximations with an infrared emissivity as close to 1 as possible. For example, flat objects such as carbon plates and cylindrical objects such as blackbody cavities, whose inner surfaces are coated with carbon nanotubes or the like, are used. In a blackbody furnace, the thermal radiation of a blackbody is generated by heating a blackbody containing such a blackbody approximation.

[0033] 6, the relationship between the temperature of a blackbody when thermal radiation is generated and the brightness of the emitted radiation is a straight line that slopes upward to the right, such that the higher the temperature of the blackbody, the greater the brightness of the emitted radiation. This straight line differs depending on the presence or absence of the neutral density filter 60 and the band-pass filter 70, the degree of neutral density of the neutral density filter 60, the passing wavelength range of the band-pass filter 70, etc. The equations that represent these straight lines are calculated in advance as the above-mentioned relational expressions and stored in the memory unit 43A.

[0034] The execution unit 43B selects a relational expression that matches the conditions of the neutral density filter 60 and the band-pass filter 70 used in measuring the measurement object 110 from among the relational expressions stored in the storage unit 43A, and calculates a representative value based on the relational expression. Number of pixels Representative detected by the detection unit 42 Number of pixels In this embodiment, the execution unit 43B calculates the temperature of the measurement object 110 by using the relational expressions selected from the relational expressions stored in the storage unit 43A. Number of pixels As a representative Number of pixels The temperature is calculated by substituting

[0035] 1 and 4, when the temperature of the measurement object 110 is calculated by the temperature calculation unit 43 of the information processing device 30, the information is transmitted to the display device 50. The display device 50 is for notifying the person taking the measurement of the temperature of the measurement object 110, and a known display or the like is used. The display device 50 has a display unit 51 as a functional unit, and the display unit 51 displays the temperature of the measurement object 110 based on the output signal from the temperature calculation unit 43. In this way, the temperature measurement system 10 measures the temperature of the measurement object 110 in the heating furnace 100 in a non-contact manner.

[0036] The operation and effects of this embodiment will be described. (1) In this embodiment, luminance is detected using radiant light emitted from the measurement object 110, the radiant light having wavelengths corresponding to visible light and near-infrared light, which are wavelengths that are not easily absorbed by glass and the like. Therefore, even in a heating furnace 100 equipped with an optical window 102 made of inexpensive quartz glass or the like, the temperature of the measurement object 110 can be measured with high accuracy based on the luminance of the radiant light from the measurement object 110 inside. This contributes to improving the accuracy of measuring the temperature of the measurement object 110.

[0037] (2) The higher the temperature of the measurement object 110, the greater the luminance of the emitted light tends to be. Since there may be a limit to the luminance that can be detected by the luminance detection unit 22, it is desirable to minimize the difference between the luminance corresponding to a low temperature and the luminance corresponding to a high temperature in order to enable measurement over a wide temperature range. This embodiment includes a bandpass filter 70 that passes wavelengths in a specific region Rb among wavelengths corresponding to visible light or near-infrared light. Therefore, the luminance detection unit 22 can detect luminance by narrowing down the wavelengths to a specific region rather than all wavelengths. Therefore, it is possible to narrow the difference between the luminance corresponding to a low temperature and the luminance corresponding to a high temperature, thereby broadening the measurable temperature range for the measurement object 110.

[0038] Furthermore, when the heating furnace 100 is equipped with a heat source such as a burner that emits a flame, when measuring temperature using conventional thermography, it is necessary to take into account the influence of the light emitted from the flame in order to accurately measure the temperature of the object 110 to be measured.

[0039] In this embodiment, the specific region Rb is set by the bandpass filter 70 so as not to include wavelengths corresponding to flame radiation among wavelengths corresponding to visible light or near-infrared light. Therefore, even when measuring through glass and through a flame, it is possible to accurately measure the temperature of the measurement object 110 in the heating furnace 100.

[0040] (3) Furthermore, this embodiment is provided with a neutral density filter 60 that reduces the amount of emitted light received by the light receiving unit 21. This further reduces the difference between the brightness corresponding to a low temperature and the brightness corresponding to a high temperature detected by the brightness detection unit 22. This makes it possible to widen the measurable temperature range for the measurement object 110.

[0041] (4) As shown by the solid line and the dashed-dotted line in Fig. 2, the difference ΔLn between the luminance when the temperature of the measurement object 110 is low and the luminance when the temperature of the measurement object 110 is high tends to become smaller as the wavelength of the emitted light becomes longer. In this embodiment, the wavelength that can be passed through the band-pass filter 70 is set to 840 nm to 860 nm. This prevents the difference ΔLn from becoming excessively small, enabling measurement over a wide temperature range while ensuring the accuracy of the temperature measurement of the measurement object 110.

[0042] (5) In this embodiment, the temperature calculation unit 43 calculates the representative value based on a relational expression that indicates the relationship between the temperature and brightness in the thermal radiation of a black body. Number of pixels The inventors calculate the temperature of the object 110 from the temperature of the object 110 and the representative value detected from the histogram. Number of pixels It has been found that the relationship between temperature and luminance in the thermal radiation of a black body is highly consistent with the relationship between temperature and luminance in the thermal radiation of a black body, even when the emissivity of the object to be measured is less than 1 or when the object to be measured is made of a material different from that of a black body. This means that even when the object to be measured 110 is white and has an emissivity less than 1, the temperature of the object to be measured 110 can be calculated with high accuracy based on the relationship in the thermal radiation of a black body. It has also been found that this consistency is maintained even when measurements are taken through glass and through a flame. In this embodiment, the relationship between temperature and luminance in the thermal radiation of a black body is stored, and then a representative value is calculated based on this relationship. Number of pixels Since the temperature is calculated from the temperature, the temperature of the object 110 can be calculated with high accuracy.

[0043] This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility. In the above embodiment, the temperature calculation unit 43 stores in advance a relational expression between temperature and brightness in thermal radiation of a black body, and calculates a representative value based on this relational expression. Number of pixels The temperature of the object 110 to be measured was calculated by substituting Number of pixelsThe method of calculating the temperature based on the above is not limited to this. For example, a map showing the relationship between temperature and brightness in the thermal radiation of a black body may be stored in the temperature calculation unit 43, and the representative temperature may be calculated by referring to this stored map. Number of pixels The temperature of the object 110 may be calculated from the above.

[0044] In the above embodiment, the neutral density filter 60 and the band-pass filter 70 are disposed at a position separate from the camera 20, but the neutral density filter 60 and the band-pass filter 70 may be provided integrally with the camera 20. In this case, they can be attached to the lens of the camera 20 for integration, or they can be integrated by providing a filter circuit with the same function as the neutral density filter 60 and the band-pass filter 70 as an electronic circuit within the camera 20.

[0045] In the above embodiment, the bandpass filter 70 is provided to pass wavelengths in a specific range Rb among wavelengths corresponding to visible light or near-infrared light. However, this configuration can be modified. For example, a lowpass filter that passes only wavelengths equal to or shorter than a first specific wavelength may be used as a pass filter that passes wavelengths in a specific range among wavelengths corresponding to visible light or near-infrared light. Furthermore, a highpass filter that passes only wavelengths equal to or longer than a second specific wavelength may be used as a pass filter that passes wavelengths in a specific range among wavelengths corresponding to visible light or near-infrared light. These lowpass and highpass filters can also be used in combination. In this case, by selecting a combination of a lowpass filter and a highpass filter that satisfies the relationship that the first specific wavelength is longer than the second specific wavelength, it is possible to pass only wavelengths between the second specific wavelength and the first specific wavelength of the emitted light, thereby achieving the same functionality as the bandpass filter 70.

[0046] At least one of the neutral density filter 60 and the pass filters may be omitted. In addition to or instead of the neutral density filter 60, the shutter speed of the camera 20 may be adjusted to reduce the amount of emitted light received by the light receiving unit 21.

[0047] The manner in which the luminance detection unit 22 detects luminance is not limited to that of the above embodiment. For example, if the temperature measurement system 10 does not include a pass filter, radiated light of all wavelengths reaches the light receiving unit 21. In this case, the luminance detection unit 22 selects an electrical signal corresponding to at least one of visible light and near-infrared light from the electrical signals transmitted from the light receiving unit 21, and detects luminance based on the selected electrical signal. Even with this configuration, the luminance detection unit 22 can detect the luminance of radiated light of wavelengths corresponding to visible light and near-infrared light among the radiated light received by the light receiving unit 21.

[0048] The information processing device 30 may be provided with a brightness amplifier as a functional unit for amplifying the brightness of the emitted light received by the light receiving unit 21. By amplifying the brightness of the emitted light by the brightness amplifier, the gradation levels in the histogram can be increased, for example, by 2. 16 Therefore, Shows the distribution of pixel brightness in image data Representative from histogram Number of pixels Even in such a case, the accuracy of detecting the temperature can be improved, and the accuracy of temperature measurement can be further improved. Shows the distribution of pixel brightness in image data It goes without saying that a histogram is created.

[0049] The range of gradations in which brightness can be detected in the histogram (G1 to G4 in this embodiment) is preferably wide in order to improve the accuracy of temperature measurement. This range can be adjusted by changing the exposure time and aperture of the camera 20.

[0050] The information processing device 30 does not necessarily have to include the pre-processing unit 40. For example, even if the temperature analysis range is not set by the functions of the image reading unit 40A and the analysis range designation unit 40B, the temperature analysis range can be determined based on the output signal from the light receiving unit 21 and the output signal from the brightness detection unit 22. Shows the distribution of pixel brightness in image data It is possible to create a histogram.

[0051] The correction unit 41B may be omitted from the histogram creation unit 41. Also, the generation unit 41A has a function of amplifying the luminance, and after amplifying the luminance detected by the luminance detection unit 22, Shows the distribution of pixel brightness in image data It is also possible to generate a histogram. In this way, even in a configuration in which the detected luminance value is not used as it is but is subjected to various corrections to generate a histogram, the generation unit 41A generates a histogram based on the luminance detected by the luminance detection unit 22. Shows the distribution of pixel brightness in image data It can be said that a histogram is being generated.

[0052] ·representative Number of pixels The detection unit 42 selects a representative region from the histogram created by the histogram creation unit 41, taking into consideration the region other than the region Rh. Number of pixels For example, it is possible to detect the average brightness value of the area where the gradation in the histogram is G1 to G4. Number of pixels It is also possible to detect it as

[0053] In the above embodiment, the representative Number of pixels The detection unit 42 represents the average value of the detected brightness in the histogram. Number of pixels However, from the viewpoint of improving the accuracy of temperature measurement, Number of pixels It is desirable to select the minimum value in the region Rh.

[0054] In the above embodiment, the information processing device 30 calculates the temperature of the object 110 by having the CPU 30A execute a program stored in the ROM 30B. That is, the information processing device 30 includes a program storage device, such as the ROM 30B, that stores all programs for calculating the temperature of the object 110, and a processing device, such as the CPU 30A, that executes processing in accordance with the programs. The information processing device 30 then executes software processing to calculate the temperature of the object 110. The information processing device 30 is not limited to performing the calculation processing solely through software processing. For example, the information processing device 30 may include a dedicated hardware circuit that executes at least a portion of the software processing executed in the above embodiment. This configuration can be realized, for example, by including a processing device and program storage device that execute a portion of the processing executed in the above embodiment in accordance with a program, and a dedicated hardware circuit that executes the remaining processing. Alternatively, for example, the information processing device 30 can be realized by including a dedicated hardware circuit that executes all of the processing executed in the above embodiment. In this way, the calculation processing can be performed by a processing circuit that includes at least one of one or more software processing circuits and one or more dedicated hardware circuits.

[0055] It is also possible to provide two or more of the camera 20, the information processing device 30, and the display device 50 as an integrated unit. For example, the information processing device 30 may be stored inside the camera 20 and integrated, or the information processing device 30 may be stored inside the display device 50 and integrated.

[0056] In the above embodiment, the temperature measurement system 10 is described as measuring the temperature of the measurement object 110 placed in the heating furnace 100, but the measurement object of the temperature measurement system is not limited to this. For example, a configuration similar to that of the above embodiment can be applied to a temperature measurement system in which the measurement object is a molten metal in a casting ladle. [Explanation of symbols]

[0057] 10...Temperature measurement system 20...Camera 21...Light receiving section 22...Luminance detection unit 30...Information processing device 30A...CPU 30B…ROM 30C…RAM 40...Pre-processing section 40A...Image reader 40B...Analysis range specification section 41...Histogram creation section 41A…Generation section 41B…Correction section 42…Representative Number of pixels Detection unit 43...Temperature calculation section 43A…Storage section 43B…Executive Department 50…Display device 51...Display section 60...Neutral density filter 70...Bandpass filter 100...Heating furnace 101...Case 101A…Opening 102...Optical window 110...Measurement object

Claims

1. a light receiving unit that receives radiant light emitted from the heated measurement object; a brightness detection unit that detects brightness of radiation having a wavelength corresponding to near-infrared rays among the radiation received by the light receiving unit; an image reading unit that reads image data of the measurement object based on the output signal from the light receiving unit and the output signal from the brightness detection unit; a histogram creation unit that creates a histogram indicating a distribution of the luminance of pixels in the image data; a representative pixel number detection unit that detects the number of representative pixels from the histogram created by the histogram creation unit; a temperature calculation unit that calculates a temperature of the measurement object based on the number of representative pixels detected by the number of representative pixels detection unit; a pass filter disposed between the object to be measured and the light receiving unit, which passes only wavelengths in a specific range among wavelengths corresponding to near-infrared rays; The histogram is The first region G1 to G2, the second region G2 to G3, and the third region G3 to G4 are arranged in order of decreasing luminance gradation, the first regions G1 to G2, the second regions G2 to G3, and the third regions G3 to G4 are continuous regions, In the first region G1 to G2, the number of pixels increases from a lower limit value as the luminance gradation increases, In the second region, the number of pixels is greater than the lower limit, and the fluctuation in the number of pixels with an increase in the gradation is smaller than in the first region G1 to G2, In the third region, the fluctuation in the number of pixels with an increase in the gradation becomes larger than in the second region G2 to G3, and the number of pixels increases with an increase in the gradation and then decreases to a lower limit value, the maximum number of pixels exists in the third region G3 to G4, the representative pixel number detection unit detects the number of representative pixels from the number of pixels in the second region G2 to G3; the temperature calculation unit calculates the temperature by substituting the number of representative pixels into a relational expression that is established between the number of representative pixels and the temperature of the object to be measured and that is set corresponding to a passing wavelength range of the pass filter. Temperature measurement system.

2. A light-receiving unit including a light-reducing filter for reducing the amount of emitted light received by the light-receiving unit. The temperature measurement system of claim 1 .

3. The temperature calculation unit has a memory unit that stores a relational expression that shows the relationship between temperature and luminance in thermal radiation of a black body, and an execution unit that calculates the temperature of the measurement object from the number of representative pixels based on the relational expression stored in the memory unit.

3. The temperature measurement system according to claim 1 or 2.

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