Infrared camera

Abstract

To provide an infrared camera that can accurately calculate the temperature of an imaging target.SOLUTION: An infrared camera includes: an imaging unit 6 equipped with an infrared detection element 6a; an element temperature detection sensor 7 that detects element temperature Ft; a radiance calculation unit 20 that calculates the radiance Ldn of an imaging target according to the formula 1 on the basis of temperature correction coefficients an, bn, cn, and an element output DLn; and a temperature correction coefficient calculation unit 18 that calculates the temperature correction coefficients an, bn, and cn according to the formula 2, on the basis of approximation coefficients Aan, Abn, Acn, Ban, Bbn, Bcn, Can, Cbn and Ccn. Ldn=an DLn2+bn DLn+cn (1). an=Aan Ft2+Abn Ft+Acn, bn=Ban Ft2+Bbn Ft+Bcn, cn=Can Ft2+Cbn Ft+Ccn (2).SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an infrared camera including an imaging unit configured by arranging a plurality of infrared detection elements on a two-dimensional plane.

Background Art

[0002] Conventionally, an infrared camera has been proposed in which the imaging unit is configured by a thermal uncooled infrared detection element called a bolometer (Patent Document 1). This infrared detection element changes its resistance value by absorbing infrared rays, and outputs a voltage value corresponding to the incident light amount by passing an electric current. When an imaging object is imaged, that is, when the infrared rays radiated from the imaging object are absorbed by the infrared detection element, a voltage value corresponding to the incident energy is output, and based on the sensitivity acquired in advance, the output voltage value is calibrated to calculate the temperature of the imaging object.

[0003] The sensitivity of this infrared detection element is known to have individual differences. Conventionally, generally, imaging objects with two different known temperatures T1 and T2, for example, a blackbody furnace (a device approximating a blackbody), are imaged, and the output V n of each infrared detection element n obtained at that time and the temperature T of the imaging object are used to calculate the sensitivity of each infrared detection element n.

[0004] More specifically, the relationship between the output V n and the temperature T is approximated by the following linear function using the output V1 n , V2 n at temperatures T1 and T2 and the sensitivity coefficient a n and the offset coefficient b n . V n = a n × T + b n Therefore, the temperature T of the imaging object can be calculated by the following formula. T = (V n - b n ) / a n = V n / an -b n / a n =V n ×A n +B n

[0005] Furthermore, in conventional infrared cameras, a calibration sensitivity coefficient A is used to increase the processing speed. n (=1 / a n ), and offset coefficient B n (=-b n / a n The output V of each infrared detection element n is calculated in advance and stored in memory as a data table, and according to the above formula, n The temperature T of the object being imaged is calculated based on this.

[0006] Furthermore, the infrared detection element has the characteristic that its sensitivity changes as its own temperature rises due to changes in ambient temperature. For this reason, conventionally, the calibration sensitivity coefficient A is further adjusted according to the temperature of the infrared detection element. n and calibration offset coefficient B n The calibration sensitivity coefficient A is obtained in advance and stored as a data table, and the calibration sensitivity coefficient A is determined according to the infrared detection element temperature at the time of imaging. n and calibration offset coefficient B n This is used to calculate the temperature T of the object being imaged. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2010-193194 [Overview of the project] [Problems that the invention aims to solve]

[0008] In the conventional infrared camera described above, the output V of the infrared detection element n is n And the infrared radiance Ld emitted from the object being imaged nThese are treated as having a linear correlation, and under this linear relationship, the output V of the infrared detection element n n Based on this, the infrared radiance Ld emitted from the object being imaged n The system estimates (calculates) the radiance and then estimates (calculates) the temperature of the object being imaged from the obtained radiance.

[0009] However, infrared cameras have optical mechanisms such as lenses to focus the infrared radiation emitted from the object being imaged onto the infrared detection element n, and there are individual differences in the infrared detection element n, therefore the output DL of each infrared detection element n n (=V n ) and the infrared radiance Ld emitted from the object being imaged n The relationship between these two factors is not a linear relationship as shown by the dashed line in Figure 3, but rather a nonlinear relationship approximated by a quadratic or higher equation, as shown by the solid line.

[0010] Therefore, unlike conventional infrared cameras, the output DL of the infrared detection element n n Therefore, based on the linear relationship, the radiance Ld n Estimating this, the accurate radiance Ld of the object being imaged n It is not possible to estimate this, and consequently, it is not possible to estimate the accurate temperature of the object being imaged.

[0011] This invention has been made in view of the above circumstances, and aims to provide an infrared camera that can accurately estimate the radiance and temperature of an object being imaged compared to conventional cameras. [Means for solving the problem]

[0012] The present invention, which solves the above problems, An imaging unit having a plurality of n infrared detection elements arranged on a two-dimensional plane, A lens that focuses infrared light emitted from the object to be imaged onto the imaging unit, An element temperature detection sensor for detecting the temperature of the infrared detection element, Regarding each of the aforementioned infrared detection elements, its output DL n And the infrared radiance Ld emitted from the object being imaged n When the correlation with the following is defined by the correlation equation in Equation 1 below, each temperature correction coefficient a in the correlation equation n , b n , c n An approximation formula for calculating the following approximation coefficients Aa in the approximation formula represented by equation 2 below. n Ab n Ac n Ba n , Bb n , Bc n Ca n , Cb n and Cc n A storage unit for approximate coefficients that stores the following, The temperature Ft of the infrared detection element detected by the element temperature detection sensor, and the approximation coefficient Aa stored in the approximation coefficient storage unit. n Ab n Ac n Ba n , Bb n , Bc n Ca n , Cb n and Cc n Based on this, the temperature correction coefficient a is calculated according to the following formula 1. n , b n , c n A temperature correction coefficient calculation unit that calculates the following: The temperature correction coefficient a calculated by the temperature correction coefficient calculation unit n , b n , c n A temperature correction coefficient storage unit that stores the following, The temperature correction coefficient a stored in the temperature correction coefficient storage unit n , b n , c n , and the output DL from each of the infrared detection elements. n Based on this, the radiance Ld related to the object being imaged is calculated according to the following formula 1. n The present invention relates to an infrared camera equipped with a radiance calculation unit that calculates a certain value. (Equation 1) Ld n =a n • DLn 2 +b n ·DL n +c n (Equation 2) a n =Aa n ·Ft 2 +Ab n ·Ft+Ac n b n =Ba n ·Ft 2 +Bb n ·Ft+Bc n c n =Ca n ·Ft 2 +Cb n ·Ft+Cc n However, n is a natural number greater than or equal to 1 and is an eigenvalue corresponding to each of the infrared detection elements.

[0013] According to the infrared camera of this aspect (the first aspect), in advance, the approximation coefficients Aa n , Ab n , Ac n , Ba n , Bb n , Bc n , Ca n , Cb n and Cc n are stored. These approximation coefficients Aa n , Ab n , Ac n , Ba n , Bb n , Bc n , Ca n , Cb n and Cc n are coefficients for calculating the temperature correction coefficients a n , b n , c n in accordance with Equation 2. As described above, Equation 2 is a correlation equation that defines the correlation between the temperature correction coefficients a n , b n , c n and the temperature of the infrared detection element (element temperature) Ft.

[0014] Then, the temperature correction coefficient calculation unit calculates the element temperature Ft detected by the element temperature detection sensor and the approximation coefficient Aa stored in the approximation coefficient storage unit. n Ab n Ac n Ba n , Bb n , Bc n Ca n , Cb n and Cc n Based on the above formula 1, the temperature correction coefficient a n , b n , c n The calculated temperature correction coefficient a is then calculated. n , b n , c n This is stored in the temperature correction coefficient storage unit.

[0015] Then, the radiance calculation unit calculates the output (element output) DL from each infrared detection element. n , and the temperature correction coefficient a stored in the temperature correction coefficient storage unit n , b n , c n Based on this, the radiance Ld for the object being imaged according to the above formula 1. n This is calculated.

[0016] Thus, according to the infrared camera of the present invention, the output DL of each infrared detection element is n And the infrared radiance Ld emitted from the object being imaged n The correlation with the output DL from each infrared detection element is defined by the quadratic equation Equation 1 above, and the output DL from each infrared detection element is defined. n Based on this, according to the above formula 1, the radiance Ld n Since it is designed to calculate (estimate) the radiance Ld based on a linear relationship, n Compared to the conventional method of calculating Ld, this method provides a more realistic and accurate calculation of radiance. n It is possible to calculate this.

[0017] Furthermore, in the infrared camera of the first embodiment described above, The temperature Ft of the infrared detection element is obtained from the element temperature detection sensor, and the output DL is obtained from each infrared detection element. n A basic data acquisition unit that acquires the data, The temperature Ft and output DL obtained by the basic data acquisition unit are as follows: n Based on this, the radiance Ld emitted from the object being imaged when the temperature Ft of the infrared detection element is at a predetermined temperature. n and the output DL from each infrared detection element n A luminance vs. output correlation acquisition unit that acquires the correlation with, The radiance Ld obtained by the luminance versus output correlation acquisition unit n and output DL n Based on the correlation with, the approximation coefficient Aa n Ab n Ac n Ba n , Bb n , Bc n Ca n , Cb n and Cc n An embodiment can be adopted that further includes an approximation coefficient calculation unit that calculates and stores in the approximation coefficient storage unit.

[0018] According to this embodiment (second embodiment) of the infrared camera, the basic data acquisition unit acquires the temperature Ft of the infrared detection element and the output DL from each infrared detection element. n Correlation data is obtained with respect to the element temperature Ft and element output DL obtained by this basic data acquisition unit. n Based on the correlation data, the luminance vs. output correlation acquisition unit determines that when the temperature Ft of the infrared detection element is at a predetermined temperature, the radiance Ld emitted from the object being imaged is... n and the element output DL from each infrared detection element n A correlation is obtained with this.

[0019] Then, the radiance Ld obtained by the luminance-to-output correlation acquisition unit n and output DL n Based on the correlation with, the approximation coefficient Aa is calculated by the approximation coefficient calculation unit. n Ab n Acn Ba n , Bb n , Bc n Ca n , Cb n and Cc n The calculated approximate coefficient Aa n Ab n Ac n Ba n , Bb n , Bc n Ca n , Cb n and Cc n This is stored in the approximation coefficient storage unit.

[0020] Thus, according to this infrared camera, the temperature correction coefficient a according to the above formula 2 is obtained. n , b n , c n The approximation coefficient Aa for calculating n Ab n Ac n Ba n , Bb n , Bc n Ca n , Cb n and Cc n Since this can be calculated using internal functions, efficient measurement of the object being imaged (the object being measured) can be performed.

[0021] Furthermore, in the infrared camera of the second embodiment described above, The temperature Ft and output DL of the infrared detection element are acquired by the basic data acquisition unit. n Based on this, an output-to-temperature correlation acquisition unit obtains an output-to-temperature correlation formula, Based on the output-to-temperature correlation equation obtained by the output-to-temperature correlation acquisition unit, interpolation processing is performed to obtain the temperature Ft and output DL of each infrared detection element. n The system further comprises an interpolation processing unit that calculates correlation data with, The luminance-to-output correlation acquisition unit acquires temperature Ft and output DL obtained by the basic data acquisition unit. n , as well as the temperature Ft and output DL calculated by the interpolation processing unit. nBased on the radiance Ld n and the aforementioned output DL n An embodiment can be adopted that is configured to obtain a correlation with [the specified value].

[0022] According to this embodiment (third embodiment) of the infrared camera, The temperature Ft and output DL of the infrared detection element are acquired by the basic data acquisition unit. n Based on this, the output-to-temperature correlation acquisition unit acquires the correlation equation between output and temperature.

[0023] Then, based on the output-temperature correlation formula obtained by the output-temperature correlation acquisition unit, the interpolation processing by the interpolation processing unit is performed, and the temperature Ft of the infrared detection element and the output DL are obtained. n Interpolation of the correlation data is performed, and based on the correlation data with improved accuracy in this way, the luminance vs. output correlation acquisition unit performs the radiance Ld n and the aforementioned output DL n A correlation is obtained with this.

[0024] Thus, according to this infrared camera, the temperature Ft and output DL of the infrared detection element are determined. n Since highly accurate and precise correlation data can be obtained, the temperature correction coefficient a according to the above formula 2 can be obtained. n , b n , c n The approximation coefficient Aa for calculating n Ab n Ac n Ba n , Bb n , Bc n Ca n , Cb n and Cc n This can improve accuracy.

[0025] Furthermore, in any of the infrared cameras described in the first to third embodiments above, The radiance Ld calculated by the radiance calculation unit n An embodiment can be adopted that further includes a temperature data calculation unit that calculates temperature data relating to the object to be imaged based on the above.

[0026] According to this embodiment (the fourth embodiment), the infrared camera can calculate the temperature of the object being imaged with greater accuracy compared to conventional methods. Furthermore, it can obtain low-noise images with less variation between pixels. [Effects of the Invention]

[0027] As described above, according to the infrared camera of the present invention, the output DL of each infrared detection element n And the infrared radiance Ld emitted from the object being imaged n The correlation with the output DL from each infrared detection element is defined by the quadratic equation Equation 1 above, and the output DL from each infrared detection element is defined. n Based on this, according to the above formula 1, the radiance Ld n Since it is designed to calculate (estimate) the radiance Ld based on a linear relationship, n Compared to the conventional method of calculating Ld, this method provides a more realistic and accurate calculation of radiance. n This allows for the calculation of the temperature of the object being imaged, and consequently, enables the calculation of a more accurate temperature of the object compared to conventional methods. [Brief explanation of the drawing]

[0028] [Figure 1] This is a block diagram showing the configuration of an infrared camera according to a specific embodiment of the present invention. [Figure 2] This is an explanatory diagram showing the relationship between radiance and blackbody temperature. [Figure 3] This is an explanatory diagram showing the relationship between radiance and element output. [Figure 4] This is an explanatory diagram showing the structure of the infrared camera according to this embodiment. [Figure 5] This is an explanatory diagram showing how to calibrate the infrared camera according to this embodiment. [Figure 6] This is an explanatory diagram showing the basic data acquired when calibrating the infrared camera according to this embodiment. [Figure 7] This is an explanatory diagram illustrating the process for obtaining the output versus temperature correlation according to this embodiment. [Figure 8] This is an explanatory diagram illustrating the processing in the interpolation processing unit according to this embodiment. [Figure 9] This is an explanatory diagram illustrating the processing in the luminance-to-output correlation acquisition unit according to this embodiment. [Figure 10] This is an explanatory diagram illustrating the processing in the approximation coefficient calculation unit according to this embodiment. [Figure 11] This is an explanatory diagram illustrating the processing in the approximation coefficient calculation unit according to this embodiment. [Figure 12] This is an explanatory diagram illustrating the processing in the approximation coefficient calculation unit according to this embodiment. [Figure 13] This is a block diagram showing the configuration of an infrared camera according to another embodiment of the present invention. [Figure 14] This is a block diagram showing the configuration of an infrared camera according to yet another embodiment of the present invention. [Modes for carrying out the invention]

[0029] Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

[0030] Figure 1 is a block diagram showing the schematic configuration of an infrared camera according to one embodiment of the present invention. As shown in Figure 1, the infrared camera 1 of this example consists of a housing 2, a lens 3, an imaging unit 6, an element temperature detection sensor 7, and a data processing unit 8, all of which are disposed within the housing 2.

[0031] The lens 3 is positioned in the opening of the housing 2 so as to close the opening, and focuses infrared light emitted from the object to be imaged onto the imaging unit 6, which is arranged at appropriate intervals behind it.

[0032] The imaging unit 6 has a plurality of infrared detection elements 6a arranged in double rows and double columns on a two-dimensional plane. n It is equipped with an infrared detection element 6a. n This is a thermal, uncooled element called a bolometer, and each infrared detection element 6a nThe device outputs a voltage value corresponding to the amount of incident light and inputs it to the data processing unit 8. Furthermore, the imaging unit 6 is equipped with an element temperature detection sensor 7, and this element temperature detection sensor 7 transmits light to the infrared detection element 6a n Temperature data is input to the data processing unit 8. Note that this element temperature detection sensor 7 is an infrared detection element 6a n The overall temperature is detected. Furthermore, n is a natural number greater than or equal to 1, corresponding to the number of infrared detection elements, and the specific numerical value is an eigenvalue corresponding to each of the aforementioned infrared detection elements. Unless otherwise specified, n is used with the same intent below.

[0033] The data processing unit 8 consists of A / D converters 9 and 10, a basic data acquisition unit 12, an output-to-temperature correlation acquisition unit 13, an interpolation processing unit 14, a luminance-to-output correlation acquisition unit 15, an approximation coefficient calculation unit 16, an approximation coefficient storage unit 17, a temperature correction coefficient calculation unit 18, a temperature correction coefficient storage unit 19, a radiance calculation unit 20, a temperature data calculation unit 21, a D / A converter 22, and an input / output interface 23, among others.

[0034] Furthermore, this data processing unit 8 can be composed of a computer including a CPU, RAM, ROM, etc. Specifically, the A / D converters 9, 10, basic data acquisition unit 12, output vs. temperature correlation acquisition unit 13, interpolation processing unit 14, luminance vs. output correlation acquisition unit 15, approximation coefficient calculation unit 16, temperature correction coefficient calculation unit 18, radiance calculation unit 20, temperature data calculation unit 21, D / A converter 22, and input / output interface 23 can be configured such that their functions are realized by a computer program. Alternatively, the A / D converters 9, 10, basic data acquisition unit 12, output vs. temperature correlation acquisition unit 13, interpolation processing unit 14, luminance vs. output correlation acquisition unit 15, approximation coefficient calculation unit 16, temperature correction coefficient calculation unit 18, radiance calculation unit 20, temperature data calculation unit 21, D / A converter 22, and input / output interface 23 can each be realized by an electronic device equipped with appropriate electronic circuits. In addition, the approximation coefficient storage unit 17 and temperature correction coefficient storage unit 19 can be composed of appropriate storage media such as RAM.

[0035] The A / D converter 9 receives the infrared detection element 6a output from the element temperature detection sensor 7. n The A / D converter 10 inputs temperature data, performs A / D conversion, and inputs the converted element temperature Ft to the temperature correction coefficient calculation unit 18 and the basic data acquisition unit 12. n The output from is converted using A / D conversion, and the converted element output DL n This data is transmitted to the basic data acquisition unit 12, the radiance calculation unit 20, or the input / output interface 23, which are selectively connected via the changeover switch 11. The element temperature Ft is also input to the basic data acquisition unit 12 via the changeover switch 11.

[0036] The basic data acquisition unit 12, output vs. temperature correlation acquisition unit 13, interpolation processing unit 14, luminance vs. output correlation acquisition unit 15, and approximation coefficient calculation unit 16 perform a calibration operation to calculate the approximation coefficient Aa n Ab n Ac n Ba n , Bb n , Bc n Ca n , Cb n and Cc n This is the function unit that calculates [the value].

[0037] This approximation coefficient Aa n Ab n Ac n Ba n , Bb n , Bc n Ca n , Cb n and Cc n Each infrared detection element 6a n Output (element output) DL n And the infrared radiance Ld emitted from the object being imaged n When the correlation with is defined by the quadratic equation (correlation equation) in Equation 1 below, each temperature correction coefficient a in the said correlation equation n , b n , c n This is a coefficient used to calculate [the value]. (Equation 1) Ld n=a n • DL n 2 +b n • DL n +c n Furthermore, radiance Ld n This is the infrared detection element 6a n This is the radiance of the imaged object in the corresponding portion.

[0038] Specifically, the approximation coefficient Aa n Ab n Ac n Ba n , Bb n , Bc n Ca n , Cb n and Cc n Based on the element temperature Ft, the temperature correction coefficient a is calculated using the quadratic equation (correlation equation) in Equation 2 below. n , b n , c n This is a coefficient used when calculating [the value]. (Equation 2) a n =Aa n · Ft 2 +Ab n · Ft+Ac n b n =Ba n · Ft 2 +Bb n Ft+Bc n c n =Ca n · Ft 2 +Cb n Ft+Cc n

[0039] According to the inventors' findings, each infrared detection element 6a n Output DL n And the infrared radiance Ld emitted from the object being imaged n This is because the relationship is not linear as shown by the dashed line in Figure 3, but nonlinear as shown by the solid line. nThere is an optical mechanism such as lens 3 for focusing light (see Figure 4), and an infrared detection element 6a n This is because there are individual differences. Therefore, in this embodiment, the element output DL is determined according to the above equation 1, which is a quadratic equation. n Therefore, the radiance Ld of the object being imaged n We decided to calculate (estimate) this. In Figure 4, reference numeral 4 is a holding part that holds the lens 3, and reference numeral 5 is a holding part fixed to the holding part 4 that holds the imaging unit 6.

[0040] The basic data acquisition unit 12, in accordance with the command input from the input / output interface 23, adjusts the approximation coefficient Aa n Ab n Ac n Ba n , Bb n , Bc n Ca n , Cb n and Cc n The basic data shown in Figure 6 for calculating the infrared detection element 6a n The temperature is also acquired from the element temperature detection sensor 7 via the A / D converters 9 and 10 and the changeover switch 11, respectively.

[0041] During this calibration operation, the infrared camera 1 is housed in a constant temperature case 100, as shown in Figure 5, and images the blackbody 103. The constant temperature case 100 is temperature-controlled by a Peltier element 101, and a shutter 102 is positioned between the lens 3 and the blackbody 103. The blackbody 103 is also adjusted to a predetermined temperature by a temperature controller (not shown).

[0042] As shown in Figure 6, the basic data is obtained by setting the temperature of the constant temperature case to four levels (Rt1 to Rt4) at 10°C intervals, for example, from 10°C, and setting the temperature of the blackbody 103 to three levels (T1 to T3) at 10°C intervals. For each element temperature Ft1 to Ft4, when the temperature of the blackbody 103 is T1 to T3, the shutter 102 is opened to each infrared detection element 6a n Element output DL output fromn T1~DL n This is T3. Note that the temperature interval and set temperature are merely examples and are not limiting.

[0043] The output-to-temperature correlation acquisition unit 13 acquires each infrared detection element 6a acquired by the basic data acquisition unit 12. n The element temperature Ft and element output DL n Based on this, a correlation equation between output and temperature is obtained. The basic data obtained by the basic data acquisition unit 12 is used for the element output DL n The relationship between this and the element temperature Ft is as shown in Figure 7.

[0044] In Figure 7, each infrared detection element 6a n Element output DL n The correlation between and the element temperature Ft can be approximated by the following approximate formulas when the temperature of the blackbody 103 is T1, T2, and T3, respectively. DL n T1=A n1 · Ft 3 +B n1 · Ft 2 + C n1 Ft+D n1 DL n T2=A n2 · Ft 3 +B n2 · Ft 2 + C n2 Ft+D n2 DL n T3=A n3 · Ft 3 +B n3 · Ft 2 + C n3 Ft+D n3 Note that the coefficient A in each approximation formula n1 ~A n3 B n1 ~B n3 , C n1 ~C n3 , D n1 ~D n3 These can each be calculated using methods such as the least squares method. However, the approximation formula is not limited to this cubic equation; a quadratic equation or a higher-order equation of degree 4 or higher may also be used.

[0045] The interpolation processing unit 14 is a functional unit that performs data interpolation using the above-mentioned equations obtained by the output-temperature correlation acquisition unit 13. Figure 8 shows an example of interpolating data between Ft1 and Ft2. In Figure 8, the values ​​plotted as black circles are measured values, and the values ​​plotted as white circles are interpolated values. In this example, interpolation is performed every 2.5°C between Ft1 and Ft2, but this is just one example and is not limited to this. Interpolation may also be performed between Ft2 and Ft4.

[0046] The luminance-to-output correlation acquisition unit 15 acquires the element temperature Ft and element output DL obtained by the basic data acquisition unit 12. n , as well as the element temperature Ft and element output DL calculated by the interpolation processing unit 14 n Based on the radiance Ld n and the aforementioned output DL n This is a functional unit that obtains correlations with [the specified value].

[0047] First, the luminance-to-output correlation acquisition unit 15 calculates the radiance of the blackbody 103 for each temperature T1 to T3 of the blackbody 103 according to the following formula 3. (Equation 3) However, Lt is the radiance (W·sr -1 ·m -2 ) and Ld corresponds to the value obtained by scaling Lt to a digital level (2 to the power of n). Furthermore, λ is the wavelength (m) of the radiation emitted from the object, and λ1 to λ2 are the sensitivity wavelength range of the infrared detection element 6a. Furthermore, T is the absolute temperature (K) of the object, and corresponds to the temperature of the blackbody 103 and the object being imaged. Furthermore, C1 and C2 are emission constants, C1=c 2 h = 5.9548 × 10 -17 (W·m 2 ) C1 = ch / k = 0.014388 (m·K) Furthermore, c is the speed of light in a vacuum (c = 2.99792458 × 10⁻¹⁸). 8 m·s -1 ), h is Planck's constant (h = 6.6256 × 10⁻¹⁶). -34 J·s), where k is Boltzmann's constant (k = 1.38054 × 10⁻¹⁴). -23 J.K. -1 )

[0048] Furthermore, as can be seen from equation 3 above, the radiance Ld of blackbody 103 n The radiance LdT1 to LdT3 for each temperature T1 to T3 of the blackbody 103 is obtained as a unique value. Then, the luminance-to-output correlation acquisition unit 15 obtains the radiance LdT1 to LdT3 for each temperature T1 to T3 of the blackbody 103, and the radiance Ld n and the aforementioned output DL n The relationship is obtained for each element temperature Ft.

[0049] The radiance Ld n and the aforementioned output DL n The correlation with Ft is shown in Figure 9. In Figure 9, the element temperature Ft is Ft1 and Ft 1+1 , Ft 1+2 , Ft 1+3 , the radiance Ld when Ft2 n and the aforementioned output DL n The correlation is shown, and each correlation can be approximated by the following quadratic equation. Note that the element temperature Ft 1+1 , Ft 1+2 , Ft 1+3 This is an interpolated value. Ld nFt1 =a nFt1 • DL nFt1 2 +b nFt1 • DL nFt1 +c nFt1 Ld nFt1+1 =a nFt1+1 • DL nFt1+1 2 +b nFt1+1 • DL nFt1+1 +c nFt1+1 Ld nFt1+2=a nFt1+2 • DL nFt1+2 2 +b nFt1+2 • DL nFt1+2 +c nFt1+2 Ld nFt1+3 =a nFt1+3 • DL nFt1+3 2 +b nFt1+3 • DL nFt1+3 +c nFt1+3 Ld nFt2 =a nFt2 • DL nFt2 2 +b nFt2 • DL nFt2 +c nFt2 However, the approximation formula is not limited to this quadratic equation; it may also be approximated by a higher-order equation of degree two or higher.

[0050] In the above equation, Ld nFt1 This is the radiance when the element temperature is Ft1, and similarly, Ld nFt1+1 The element temperature is Ft 1+1 Radiance at that time, Ld nFt1+2 The element temperature is Ft 1+2 Radiance at that time, Ld nFt1+3 The element temperature is Ft 1+3 Radiance at that time, Ld nFt2 This is the radiance when the element temperature is Ft2. Also, DL nFt1 This is the element output when the element temperature is Ft1, and similarly, DL nFt1+1 The element temperature is Ft 1+1 Element output at that time, DL nFt1+2 The element temperature is Ft 1+2 Element output at that time, DL nFt1+3 The element temperature is Ft 1+3 Element output at that time, DL nFt2 This is the element output when the element temperature is Ft2.

[0051] Furthermore, the above a nFt1 a nFt1+1 a nFt1+2 a nFt1+3 a nFt2 , b nFt1 , bnFt1+1 , b nFt1+2 , b nFt1+3 , b nFt2 , c nFt1 , c nFt1+1 , c nFt1+2 , c nFt1+3 , +c nFt2 The element temperatures Ft are Ft1 and Ft 1+1 , Ft 1+2 , Ft 1+3 , the radiance Ld when Ft2 n and the aforementioned output DL n This is a temperature correction coefficient used to define the correlation with [the given value].

[0052] The approximation coefficient calculation unit 16 uses the radiance Ld obtained by the luminance-to-output correlation acquisition unit 15. n and the aforementioned output DL n Based on the correlation data, each temperature correction coefficient a n , b n , c n The correlation between the element temperature Ft is obtained, and from the obtained correlation, each temperature correction coefficient a is determined. n , b n , c n Approximation coefficient Aa to calculate n Ab n Ac n Ba n , Bb n , Bc n Ca n , Cb n and Cc n The process of calculating this is performed.

[0053] Figure 10 shows the coefficient a n The relationship between the element temperature Ft and the coefficient b is shown in Figure 11. n The relationship between the element temperature Ft and the coefficient c is shown in Figure 12. n This shows the relationship between the coefficient a and the element temperature Ft. n , b n , c n Each of these can be approximated by the following formulas. a n =Aa n · Ft 2 +Ab n· Ft+Ac n b n =Ba n · Ft 2 +Bb n Ft+Bc n c n =Ca n · Ft 2 +Cb n Ft+Cc n

[0054] And the approximation coefficient Aa in each approximation formula n Ab n Ac n Ba n , Bb n , Bc n Ca n , Cb n , Cc n Each of these can be calculated using methods such as the least squares method, and the approximation coefficient calculation unit 16 calculates the approximation coefficient Aa in this way. n Ab n Ac n Ba n , Bb n , Bc n Ca n , Cb n , Cc n The result is stored in the approximation coefficient storage unit 17.

[0055] The temperature correction coefficient calculation unit 18, radiance calculation unit 20, temperature data calculation unit 21, and D / A converter 22 are functional units that capture an image of an object using the infrared camera 1 according to this embodiment and generate an image which is the temperature data of that object.

[0056] Specifically, the temperature correction coefficient calculation unit 18 calculates the element temperature Ft output from the element temperature detection sensor 7 and input via the A / D converter 9, and the approximation coefficient Aa stored in the approximation coefficient storage unit 18. n Ab n Ac n Ba n , Bb n , Bc n Ca n, Cb n and Cc n Based on this, the temperature correction coefficient a is calculated according to the above formula 2. n , b n , c n The calculated temperature correction coefficient a n , b n , c n The process involves storing the result in the temperature correction coefficient storage unit 19.

[0057] The radiance calculation unit 20 receives the element output DL, which is output from each of the infrared detection elements 6a and input via the A / D converter 10. n , and the temperature correction coefficient a stored in the temperature correction coefficient storage unit 19 n , b n , c n Based on this, according to the above formula 1, the radiance Ld n The process of calculating this is performed.

[0058] Furthermore, the temperature data calculation unit 21 calculates the radiance Ld calculated by the radiance calculation unit 20. n Based on this, a process is performed to calculate the temperature of the part of the object corresponding to each infrared detection element 6a of the object being imaged. n The conversion from this to temperature data can be calculated, for example, using the inverse function of equation 3 described above. It is preferable that this temperature data be expressed in Celsius.

[0059] The D / A converter 22 is a processing unit that converts temperature data into analog data (image data), and the image data thus converted is output to the outside via the input / output interface 23.

[0060] According to the infrared camera 1 of this example, which has the above configuration, before capturing a temperature image of the object to be imaged, a calibration process is first performed, thereby determining the approximation coefficient Aa, which is a parameter necessary for generating the temperature image. n Ab n Ac n Ba n , Bb n , Bc n Can and Cb n and Cc n can be obtained.

[0061] Then, the obtained approximate coefficients Aa n Ab n Ac n Ba n Bb n Bc n Ca n Cb n and Cc n are stored in the approximate coefficient storage unit 17.

[0062] In this way, after obtaining the approximate coefficients Aa n Ab n Ac n Ba n Bb n Bc n Ca n Cb n and Cc n the imaging target is imaged by the infrared camera 1, and an image which is the temperature data of the imaging target is generated.

[0063] As described above, according to the infrared camera 1 of this example, the element output DL n of each infrared detection element 6a and the radiation luminance Ld n of the infrared rays radiated from the imaging target are defined by the above formula 1 which is a quadratic equation, and based on the element output DL n from each infrared detection element 6a, the radiation luminance Ld n is calculated (estimated) according to the formula 1. Therefore, compared with the conventional method of calculating the radiation luminance Ld n based on a linear relationship, a more realistic and accurate radiation luminance Ld n can be calculated, and thus, compared with the prior art, a more accurate temperature of the imaging target can be calculated.

[0064] Also, according to the infrared camera 1 of this example, the temperature correction coefficients a n b n cn the approximation coefficients Aa for calculating n , Ab n , Ac n , Ba n , Bb n , Bc n , Ca [[ID=十四]] n , Cb n and Cc n can be calculated by the basic data acquisition unit 12, the output-to-temperature correlation acquisition unit 13, the interpolation processing unit 14, the luminance-to-output correlation acquisition unit 15, and the approximation coefficient calculation unit 16, which are internal functions. Therefore, efficient temperature measurement of the imaging object can be performed.

[0065] Also, according to the infrared camera 1 of this example, based on the output-to-temperature correlation formula acquired by the output-to-temperature correlation acquisition unit 13, interpolation processing by the interpolation processing unit 14 is performed, and the element temperature Ft and the element output DL of each infrared detection element 6a n and the correlation data therebetween are interpolated. Based on the correlation data with enhanced accuracy obtained in this way, the radiation luminance Ld n and the output DL n and the correlation therebetween are acquired.

[0066] Thus, according to the infrared camera 1 of this example, accurate and detailed correlation data between the temperature Ft of the infrared detection element 6a and the output DL n can be obtained. Therefore, the approximation coefficients Aa n , b n , c n for calculating the temperature correction coefficients a n , Ab n , Ac n , Ba n , Bb n , Bc n , Ca n , Cb n and Cc n can be improved, and thus, a more accurate and precise temperature of the imaging object can be calculated.

[0067] Although one embodiment of the present invention has been described above, the specific embodiments that the present invention can take are not limited to the embodiments described above.

[0068] For example, in the above example, an output-to-temperature correlation acquisition unit 13 and an interpolation processing unit 14 are provided to acquire the element temperature Ft and the element output DL. n Although we attempted to interpolate the correlation data with this, this is not the only way to do so, and a reasonably accurate approximation coefficient Aa n Ab n Ac n Ba n , Bb n , Bc n Ca n , Cb n and Cc n If it is possible to calculate this, the infrared camera 1' can be configured in a way that omits the output-to-temperature correlation acquisition unit 13 and the interpolation processing unit 14, as shown in Figure 13.

[0069] Furthermore, in the above example, the basic data acquisition unit 12, output vs. temperature correlation acquisition unit 13, interpolation processing unit 14, luminance vs. output correlation acquisition unit 15, and approximation coefficient calculation unit 16, which are functional units for calibration, are provided internally. However, the system is not limited to this configuration, and these may be configured as external calibration devices. An infrared camera 1" in this configuration is shown in Figure 14.

[0070] In this case, the element temperature Ft and element output DL during calibration are used. n The output is sent from the input / output interface 23 to the calibration device via switch 11. The approximate coefficient Aa calculated by this calibration device is then output. n Ab n Ac n Ba n , Bb n , Bc n Ca n , Cb n and Cc n This is stored in the approximation coefficient storage unit 17 via the input / output interface 23.

[0071] Furthermore, although a temperature data calculation unit 21 is provided in the above example, it is not limited to this, and in cases where temperature data calculation is unnecessary, i.e., the radiance Ld calculated by the radiance calculation unit 20 is used. n When generating image data, the temperature data calculation unit 21 can be omitted in the infrared camera 1 shown in Figure 1, the infrared camera 1' shown in Figure 13, and the infrared camera 1'' shown in Figure 14.

[0072] Furthermore, in the above example, the radiance Ld calculated by the radiance calculation unit 20 n If the configuration is adopted in which the data is output directly to the outside via the input / output interface 23, the temperature data calculation unit 21 and the D / A converter 22 can be omitted in the infrared camera 1 shown in Figure 1, the infrared camera 1' shown in Figure 13, and the infrared camera 1'' shown in Figure 14. [Explanation of symbols]

[0073] 1. Infrared camera 2 cabinets 3 lenses 6. Imaging Unit 6a Infrared detection element 7-element temperature detection sensor 8. Data Processing Unit 9,10 A / D converters 11. Changeover switch 12 Basic Data Acquisition Unit 13 Output vs. Temperature Correlation Acquisition Unit 14 Interpolation Processing Unit 15. Luminance vs. Output Correlation Acquisition Unit 16. Approximation coefficient calculation unit 17 Approximation coefficient storage unit 18. Temperature Correction Coefficient Calculation Unit 19 Temperature Correction Coefficient Storage Unit 20 Radiance Calculation Unit 21 Temperature data calculation unit 22 D / A Converters 23 Input / Output Interfaces

Claims

1. An imaging unit having a plurality of n infrared detection elements arranged on a two-dimensional plane, A lens that focuses infrared light emitted from the object to be imaged onto the imaging unit, An element temperature detection sensor for detecting the temperature of the infrared detection element, Regarding each of the infrared detection elements, its output DL ｎ and the radiation luminance Ld of the infrared rays radiated from the imaging object ｎ When the correlation with is defined by the correlation formula of the following formula 1, the coefficients in the correlation formula, each temperature correction coefficient a for defining the correlation between the radiation luminance Ld n and the output DL n ｎ , b ｎ , c ｎ An approximation formula for calculating, each approximation coefficient Aa in the approximation formula represented by the following formula 2 ｎ , Ab ｎ , Ac ｎ , Ba ｎ , Bb ｎ , Bc ｎ , Ca ｎ , Cb ｎ and Cc ｎ An approximation coefficient storage unit that stores The temperature Ft of the infrared detection element detected by the element temperature detection sensor, and the approximation coefficient Aa stored in the approximation coefficient storage unit. ｎ Ab ｎ , Ac ｎ Ba ｎ , Bb ｎ , Bc ｎ Ca ｎ , Cb ｎ and Cc ｎ Based on this, the temperature correction coefficient a is calculated according to the following formula 2. ｎ , b ｎ , c ｎ A temperature correction coefficient calculation unit that calculates the following: The temperature correction coefficient a calculated by the temperature correction coefficient calculation unit ｎ , b ｎ , c ｎ A temperature correction coefficient storage unit that stores the following, The temperature correction coefficient a stored in the temperature correction coefficient storage unit ｎ , b ｎ , c ｎ , and the output DL from each of the infrared detection elements ｎ Based on this, the radiance Ld for the object being imaged is calculated according to the following formula 1. ｎ An infrared camera characterized by comprising a radiance calculation unit that calculates a certain value. (Equation 1) Ld ｎ =a ｎ ・DL ｎ ２ +b ｎ ・DL ｎ +c ｎ (Equation 2) a ｎ =Aa ｎ ・Ft ２ +Ab ｎ ・Ft+Ac ｎ b ｎ =Ba ｎ ・Ft ２ +Bb ｎ ・Ft+Bc ｎ c ｎ =Ca ｎ ・Ft ２ +Cb ｎ ・Ft+Cc ｎ However, n is a natural number greater than or equal to 1, and is an eigenvalue corresponding to each of the infrared detection elements.

2. The temperature Ft of the infrared detection element is obtained from the element temperature detection sensor, and the output DL from each infrared detection element is obtained. ｎ A basic data acquisition unit that acquires the data, The temperature Ft and output DL obtained by the aforementioned basic data acquisition unit. ｎ Based on this, the radiance Ld emitted from the object being imaged when the temperature Ft of the infrared detection element is at a predetermined temperature. ｎ and the output DL from each infrared detection element ｎ A luminance vs. output correlation acquisition unit that acquires the correlation with, The radiance Ld obtained by the luminance versus output correlation acquisition unit ｎ and output DL ｎ Based on the correlation with, the approximation coefficient Aa ｎ Ab ｎ , Ac ｎ Ba ｎ , Bb ｎ , Bc ｎ Ca ｎ , Cb ｎ and Cc ｎ The infrared camera according to claim 1, further comprising: an approximation coefficient calculation unit that calculates and stores in the approximation coefficient storage unit.

3. The temperature Ft and output DL of the infrared detection element acquired by the basic data acquisition unit. ｎ Based on this, an output-to-temperature correlation acquisition unit obtains an output-to-temperature correlation formula, Based on the output-temperature correlation formula obtained by the output-temperature correlation acquisition unit, interpolation processing is performed to determine the temperature Ft of the infrared detection element and the output DL. ｎ The system further comprises an interpolation processing unit that calculates correlation data with, The luminance versus output correlation acquisition unit acquires temperature Ft and output DL obtained by the basic data acquisition unit. ｎ , as well as the temperature Ft and output DL calculated by the interpolation processing unit. ｎ Based on the radiance Ld ｎ and the output DL ｎ The infrared camera according to claim 2, characterized in that it is configured to obtain a correlation with

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