Infrared imaging device

Abstract

To provide an infrared imaging device capable of stably acquiring a thermal image, without using a mechanical shutter.SOLUTION: The infrared imaging device includes: an infrared imaging part (1) for storing an infrared image sensor (4); an internal temperature measurement sensor (3) for measuring an internal temperature of the infrared imaging part (1); a temperature control part (130) for controlling the internal temperature of the infrared imaging part (1) on the basis of a measurement result of the internal temperature measurement sensor (3); and a correction calculation part (150) for correcting output information of a light-receiving element (21) of the infrared image sensor (4). The temperature control part (130) keeps the internal temperature of the infrared imaging part (1) at a reference temperature which is a fixed temperature. The correction calculation part (150) corrects an error between the light-receiving elements (21) of the infrared image sensor (4) and converts output data after the correction into an absolute temperature.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to an infrared imaging device. [Background technology]

[0002] An infrared imaging device is equipped with an infrared image sensor in which imaging elements that detect infrared rays are arranged in a two-dimensional array, and obtains a thermal image by focusing the infrared rays emitted from a subject as an image using a lens located in front of the infrared image sensor.Since the output of the infrared image sensor changes in temperature over time due to changes in the environmental temperature or temperature increases inside the sensor, in order to accurately correspond the pixel values ​​that make up each pixel of the infrared image to the absolute temperature of the subject, it was necessary to calibrate the signal output by the infrared image sensor by converting an offset value, etc. into absolute temperature for each pixel.

[0003] Conventional infrared imaging devices require a thermometer to be placed on the surface of the shutter to accurately measure the temperature of the shutter surface, convert the value of each pixel captured with the shutter closed to the temperature of the shutter, and then accurately convert the difference in the thermal image when the shutter is open into an absolute temperature value of the thermal image (see, for example, Patent Document 1).

[0004] Furthermore, Patent Document 2 listed below describes a method for performing offset calibration in a short time by maintaining high speed opening and closing of the shutter in order to shorten the time during which a thermal image cannot be acquired during the shutter opening and closing operation. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4742883 [Patent Document 2] Patent No. 6540519 Summary of the Invention [Problem to be solved by the invention]

[0006] However, even when a method for correcting the shutter at high speed is applied, there are issues such as the fact that the correction process occurs frequently during periods when the device temperature is prone to change, such as immediately after the sensor is started, making it impossible to measure the temperature of the subject, or that even if temperature data is obtained, the accuracy of the temperature measurement is low because the internal temperature is not stable.

[0007] The present disclosure discloses a technique for solving the above-mentioned problems, and aims to provide an infrared imaging device that can stably acquire thermal images without using a mechanical shutter. [Means for solving the problem]

[0008] The infrared imaging device of the present disclosure includes: An infrared imaging device that captures infrared light emitted from a subject, an infrared image sensor having a plurality of light receiving elements arranged therein for receiving infrared rays from the subject; an infrared imaging unit that houses the infrared image sensor; an internal temperature measuring sensor for measuring an internal temperature of the infrared imaging unit; a temperature control unit that controls the internal temperature of the infrared imaging unit based on the measurement result of the internal temperature measurement sensor; a correction calculation unit that corrects output information of the light receiving element of the infrared image sensor, the temperature control unit maintains an internal temperature of the infrared imaging unit at a constant temperature, The correction calculation unit corrects errors between the light receiving elements of the infrared image sensor and converts the corrected output data into absolute temperature. [Effects of the Invention]

[0009] According to the infrared imaging device of the present disclosure, it is possible to stably acquire thermal images without using a mechanical shutter. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a block diagram showing the configuration of an infrared imaging device equipped with a temperature control mechanism according to a first embodiment. [Figure 2] 1 is a schematic diagram showing an infrared image sensor according to a first embodiment. [Figure 3] 3 is a block diagram showing a processing flow of the infrared imaging device equipped with the temperature control mechanism according to the first embodiment. FIG. [Figure 4] 4 is a graph showing the relationship between the output voltage Vf of the light receiving element, the internal temperature of the infrared imaging unit, and the temperature of the subject according to the first embodiment. [Figure 5] 4 is a graph showing differences in characteristics between light receiving elements of the infrared image sensor according to the first embodiment. [Figure 6] FIG. 1 is a diagram showing a state in which an infrared image sensor is used to capture an image of a subject with a uniform surface temperature. [Figure 7] 10 is a graph showing the relationship between the output voltage of the light receiving element and the temperature of the object. [Figure 8] FIG. 3 is a diagram showing a correction matrix according to the first embodiment. [Figure 9] 4 is a flowchart showing temperature control of the infrared imaging unit according to the first embodiment. [Figure 10] FIG. 10 is a block diagram showing the configuration of an infrared imaging device equipped with a temperature control mechanism according to a second embodiment. [Figure 11] 1 is a temperature model showing the relationship between the internal temperature of the infrared imaging unit and time. [Figure 12] FIG. 10 is a block diagram showing a processing flow of an infrared imaging device equipped with a temperature control mechanism according to a second embodiment. [Figure 13] 10 is a flowchart showing temperature control of an infrared imaging unit according to the second embodiment. [Figure 14] FIG. 10 is a diagram showing a correction matrix according to the second embodiment. [Figure 15] FIG. 2 is a diagram illustrating an example of hardware of a control device used in the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] First, an overview of the infrared imaging device of the present disclosure will be described. The infrared imaging device disclosed herein can reduce the effects of the surrounding environment and the rise in internal temperature on the light receiving elements used in the infrared image sensor of the infrared imaging unit by maintaining the internal temperature of the infrared imaging unit at a constant temperature using a temperature control mechanism capable of heating and cooling. Since the internal temperature of the infrared imaging unit is constant, if a subject with a uniform temperature is photographed in advance and a correction matrix is ​​created that records the correction coefficients for each light-receiving element based on the results of measuring the errors between the light-receiving elements, there is no need to update the correction matrix, so a shutter is not required to perform the correction process, and it is possible to reduce the amount of time during measurement when measurements cannot be taken due to the correction process. In addition, in the past, the correlation data between the output of the light receiving element and the temperature of the subject changed depending on the internal temperature of the infrared imaging unit, so it was necessary to record multiple patterns of that correlation data.However, since the internal temperature is constant, the temperature of the subject can be calculated by preparing correlation data for a specific internal temperature. The following describes details of an embodiment of an infrared imaging device according to the present disclosure.

[0012] Embodiment 1 FIG. 1 is a block diagram showing the configuration of an infrared imaging device equipped with a temperature control mechanism according to the first embodiment. In FIG. 1, the infrared imaging unit 1 includes an infrared image sensor 4 for receiving infrared rays 10 emitted from a subject 9, a lens 2 arranged in front of the infrared image sensor 4 for focusing the infrared rays 10 emitted from the subject 9 onto the infrared image sensor 4, an internal temperature measurement sensor 3 for measuring the internal temperature of the infrared imaging unit 1, and an infrared imaging unit board 5 on which the internal temperature measurement sensor 3 and the infrared image sensor 4 are mounted. As shown in FIG. 2, the infrared image sensor 4 is configured by arranging light receiving elements 21 for detecting infrared rays in a two-dimensional array. The internal temperature measuring sensor 3 is intended to measure the internal temperature required for calculating the absolute temperature inside the infrared imaging unit 1. An infrared imaging unit board 5 of the infrared imaging unit 1 is held on a main board 8 by a support 6 .

[0013] Mounted on the main board 8 are an infrared imaging unit 1 held by a support 6, a temperature control mechanism 11 with heating and cooling functions such as a Peltier element for the purpose of controlling the temperature of the infrared imaging unit 1, a heat conduction unit 7 such as an aluminum block for the purpose of uniformly transmitting the temperature control by the temperature control mechanism 11 to the entire infrared imaging unit 1, a control microcomputer 12, and a non-volatile memory 13. As shown in FIG. 3 , which will be described later, the control microcomputer 12 includes a pixel sensitivity error correction unit 110 that acquires the electrical signal output from the light receiving element 21 of the infrared image sensor 4 and corrects the sensitivity error of the light receiving element 21, an absolute temperature calculation unit 120 that calculates the absolute temperature from the data corrected by the pixel sensitivity error correction unit 110, and a temperature control unit 130 that controls the temperature of the temperature control mechanism 11 based on the measurement value of the internal temperature measurement sensor 3. The pixel sensitivity error correction unit 110 and the absolute temperature calculation unit 120 are collectively referred to as a correction calculation unit 150. The nonvolatile memory 13 stores a correction matrix MX used in the correction process for pixel sensitivity errors and correlation data between the output voltage of the light receiving element 21 and the absolute temperature used in calculating the absolute temperature. In this disclosure, the nonvolatile memory 13 may be referred to as a storage unit. On the main board 8, wiring is provided for the purpose of communication between the infrared imaging unit 1, the temperature control mechanism 11, the control microcomputer 12, and the nonvolatile memory 13.

[0014] FIG. 2 is a plan view schematically illustrating the infrared image sensor according to the first embodiment, showing how light receiving elements 21 are arranged two-dimensionally on the infrared image sensor 4 shown in FIG. The light receiving element 21 is an element that outputs an electric signal in response to receiving infrared light, such as a thermal diode, a thermopile, a bolometer, or a current collection sensor. In the present embodiment, the infrared image sensor 4 will be described below by taking as an example an infrared image sensor 4 in which light receiving elements 21 are arranged in a 5×5 matrix as shown in FIG.

[0015] FIG. 3 is a block diagram showing a process flow of the infrared imaging device having a temperature control mechanism according to the first embodiment. In FIG. 3, the infrared imaging unit 1 includes an infrared image sensor 4, an internal temperature measuring sensor 3, and a temperature control mechanism 11. The control microcomputer 12 includes a correction calculation unit 150 including a pixel sensitivity error correction unit 110 and an absolute temperature calculation unit 120, and a temperature control unit . In the present disclosure, the control microcomputer 12 and the nonvolatile memory 13 are collectively referred to as a control device 15.

[0016] First, the control of the internal temperature of the infrared imaging unit 1 will be briefly described with reference to FIG. The internal temperature measuring sensor 3 measures the internal temperature of the infrared imaging unit 1 and transmits the measured temperature to the temperature control unit 130. The temperature control unit 130 controls the temperature control mechanism 11 so that the internal temperature of the infrared imaging unit 1 is kept constant.

[0017] Next, the signal processing of the infrared image sensor will be described with reference to FIG. The subject 9 emits infrared rays 10 corresponding to the temperature of the subject 9 through thermal radiation. Infrared rays 10 emitted from the subject 9 are received by the infrared image sensor 4 of the infrared imaging unit 1 . When the infrared image sensor 4 receives the infrared rays 10, each light receiving element 21 such as a thermal diode on the infrared image sensor 4 outputs a voltage Vf based on the temperature on each light receiving element 21 caused by the incident infrared rays 10. As will be explained in FIG. 4 below, it is generally known that the magnitude of the output voltage Vf varies depending on the internal temperature of the infrared imaging unit 1.

[0018] FIG. 4 is a graph showing the relationship between the output voltage Vf of the light receiving element 21, the internal temperature of the infrared imaging unit 1, and the temperature of the subject 9. In FIG. FIG. 4 shows characteristic lines T10, T20, and T30 of the output voltage of the light receiving element 21 when the object temperatures are 10°C, 20°C, and 30°C, for example. In FIG. 4, when the object temperature is higher than the internal temperature, a positive voltage corresponding to the magnitude is generated, and when the object temperature is lower than the internal temperature, a negative voltage corresponding to the difference is generated. That is, for example, when the subject temperature is 10°C (solid line), the output voltage Vf decreases as the internal temperature rises, and when the internal temperature is below 10°C, a positive output voltage Vf corresponding to the difference between the subject temperature and the internal temperature is output, when the internal temperature is 10°C the output voltage Vf becomes zero, and when the internal temperature exceeds 10°C a negative voltage Vf corresponding to the difference between the subject temperature and the internal temperature is output. As described above, the magnitude of the output voltage Vf of the light receiving element 21 varies depending on the internal temperature of the infrared imaging unit 1.

[0019] FIG. 5 is a graph showing the difference in characteristics between the light receiving elements of the infrared image sensor. As shown in FIG. 5, variations in the characteristics of light receiving elements (for example, light receiving elements A, B, and C) cause errors in the offset direction (offset value) and gain (gradient of the graph). Here, the offset error (offset value) is a value that represents the distance along the horizontal axis when the output voltage Vf is zero for each of the light receiving elements A, B, and C. The gain error is a value that represents the slope of the graph for each of the light receiving elements A, B, and C. If errors in the offset direction and gain remain, when measuring the temperature of the object 9, even if the object 9 is at the same temperature, temperature errors will occur for each light receiving element 21, i.e., for each pixel. Furthermore, as shown in Figure 4, the output voltage Vf of the light receiving element 21 also changes due to the influence of the internal temperature of the infrared imaging unit 1, so in the conventional method it was necessary to correct the error between the light receiving elements using a shutter with a uniform temperature each time the internal temperature changed.

[0020] Therefore, in this embodiment, the temperature control mechanism 11 controls the internal temperature of the infrared imaging unit 1 to be constant, so there is no need to consider changes in the characteristics of the light receiving element 21 due to changes in the internal temperature. Therefore, as will be explained in Figure 6 below, if an image of a subject 9A with a uniform temperature is captured in advance and the errors between the light receiving elements 21 are measured, a correction matrix MX is created that records the correction coefficients of each light receiving element 21 based on the results, and this correction matrix MX is constantly applied, eliminating the need to update the correction coefficients. Therefore, it is not necessary to use a shutter to correct for changes in the internal temperature during measurement.

[0021] That is, as shown in FIG. 6, a plurality of subjects 9A having a uniform surface temperature but different surface temperatures are prepared. Then, a plurality of subjects 9A are arranged so that the angle of view of the infrared imaging unit 1 is covered with the subjects 9A, and measurements of the plurality of subjects 9A are carried out. As shown in Figure 6, when a measurement is performed on subject 9A, a value corresponding to the subject temperature and output voltage is output for each light receiving element (pixel) 21 of the infrared image sensor 4, as shown in Figure 7, as plotted by △. In this embodiment, the temperature-output voltage characteristic of the light-receiving element 21 is assumed to be a straight line, and an approximate straight line is derived by connecting the triangle plots. A correction coefficient is derived so that this approximate straight line fits on an ideal curve obtained from the data sheet of the light-receiving element 21, etc. The correction method is as follows: in the case of a linear function, the correction coefficients are a1 and b1, so that the slope (gain) a and offset value b of the approximate line expressed as y = ax + b can be corrected in the form of y = (a × a1) x + (b + b1). The correction coefficients a1 and b1 are derived from the difference between the approximate line and the ideal line, and the correction coefficients a1 and b1 are prepared for each light receiving element (pixel) 21 of the infrared image sensor 4. Then, the correction coefficient Xa=(a1, b1) is prepared for the light receiving element 21a. Similarly, for the light receiving elements 21b, 21c, etc., correction coefficients Xb=(a2, b2), Xc=(a3, b3) are prepared, and correction coefficients Xa, Xb, and Xc are prepared for each of the light receiving elements 21a, 21b, 21c, etc., to create the correction matrix MX shown in FIG. 8. Then, the correction matrix MX as shown in FIG. 8 is stored in the nonvolatile memory 13 shown in FIGS.

[0022] Returning to FIG. 3, data on the voltage Vf output from the light receiving element 21 of the infrared image sensor 4 is input to the pixel sensitivity error correction unit 110 of the control microcomputer 12 as an electrical signal. The pixel sensitivity error correction unit 110 of the control microcomputer 12 uses the correction matrix MX stored in the nonvolatile memory 13 to correct the error in the output voltage Vf for each light receiving element (pixel) 21.

[0023] The absolute temperature calculation unit 120 converts the electrical signal output from the light receiving element 21 into an absolute temperature based on the data corrected by the pixel sensitivity error correction unit 110 . To convert the electrical signal into absolute temperature, an image of the subject 9, whose temperature is known in advance, is captured, and the electrical signal output value of the light receiving element 21 of the infrared image sensor 4 at that time is measured. The relationship between this subject temperature and the electrical signal output value is recorded in nonvolatile memory 13 as correlation data between the output of the light receiving element 21 and the subject temperature, and during actual measurement, the correlation data between the output of the light receiving element 21 and the subject temperature stored in nonvolatile memory 13 is used to calculate the temperature of the subject 9.

[0024] In the past, when converting the output voltage of the light receiving element 21 into absolute temperature, the output voltage Vf changed depending on the internal temperature of the infrared imaging unit 1, so it was necessary to have correlation data between the output voltage of the light receiving element 21 and the temperature of the subject for each internal temperature of the infrared imaging unit 1. However, in this embodiment, the internal temperature of the infrared imaging unit 1 is fixed, so it is only necessary to prepare correlation data for a specific internal temperature (reference temperature).

[0025] FIG. 9 is a flowchart showing the temperature control of the infrared imaging unit according to the first embodiment. The temperature control of the infrared imaging unit according to the first embodiment will be described with reference to FIG. In step S100, the temperature control unit 130 acquires the internal temperature T measured by the internal temperature measuring sensor 3 mounted on the infrared imaging unit 1. In step S101, the temperature control unit 130 calculates the temperature difference ΔT between the internal temperature T and the reference temperature Tx. In step S102, if the temperature difference ΔT is greater than a specified value (for example, 1° C.), the process proceeds to step S103, where the internal temperature T is compared with the reference temperature Tx. In step S103, if the internal temperature T is higher than the reference temperature Tx, the process proceeds to step S104, where the temperature control mechanism 11 performs a cooling process. In step S103, if the internal temperature T is lower than the reference temperature Tx, the process proceeds to step S105, where the temperature control mechanism 11 performs a heating process. By periodically repeating the above flow, the internal temperature T of the infrared imaging unit 1 can be controlled to a constant reference temperature Tx.

[0026] As described above, according to the first embodiment, An infrared imaging device that captures infrared light emitted from a subject, an infrared image sensor having a plurality of light receiving elements arranged therein for receiving infrared rays from the subject; an infrared imaging unit that houses the infrared image sensor; an internal temperature measuring sensor for measuring an internal temperature of the infrared imaging unit; a temperature control unit that controls the internal temperature of the infrared imaging unit based on the measurement result of the internal temperature measurement sensor; a correction calculation unit that corrects output information of the light receiving element of the infrared image sensor, the temperature control unit maintains the internal temperature of the infrared imaging unit at a reference temperature, which is a constant temperature; The correction calculation unit corrects errors between the light receiving elements of the infrared image sensor and converts the corrected output data into absolute temperature. There is no need to correct the shutter in response to changes in the internal temperature of the infrared imaging unit, and there are no periods when measurements cannot be made or when accuracy is reduced, making it possible to acquire thermal images stably.

[0027] Further, the correction calculation unit a pixel sensitivity error correction unit that corrects an error in an offset direction and an error in gain between the light receiving elements when the internal temperature of the infrared imaging unit is the reference temperature; The absolute temperature calculation unit calculates the absolute temperature based on the output data of each of the light receiving elements after correction, based on correlation data between the output of the light receiving elements when the internal temperature of the infrared imaging unit is the reference temperature and the temperature of the object. This eliminates the need to correct offset errors and gain errors between the light receiving elements when the temperature is other than the reference temperature, and eliminates the need to prepare correlation data between the output of the light receiving elements and the temperature of the subject when the temperature is other than the reference temperature.

[0028] Furthermore, the pixel sensitivity error correction unit can perform correction based on a correction matrix in which correction coefficients for correcting offset direction errors and gain errors for each of the light receiving elements are arranged, the correction matrix being stored in a storage unit at a reference temperature; The absolute temperature calculation section can calculate the absolute temperature based on correlation data between the output of the light receiving element and the temperature of the object stored in the storage section in the case of a reference temperature.

[0029] Embodiment 2 FIG. 10 is a block diagram showing the configuration of an infrared imaging device equipped with a temperature control mechanism according to the second embodiment. The configuration of the infrared imaging device of embodiment 2 in Fig. 10 is different from embodiment 1 in that it adds an environmental temperature measuring sensor 14 for measuring the temperature around the substrate of the infrared imaging device. Also, it differs from embodiment 1 in the control method by temperature control unit 130. The other configurations and operations are the same as those of embodiment 1, so explanations will be omitted where appropriate.

[0030] In the second embodiment, it is assumed that the infrared imaging device will be used in an environment (for example, 10° C. to 40° C.) such as an indoor environment where there is little change in the temperature around the device (for example, 10° C. to 40° C.). When there is little change in the ambient temperature of the infrared imaging device, the rise in the internal temperature of the infrared imaging unit 1 described in embodiment 1 is mainly caused by heat generated by continuous use of the control microcomputer 12 or the light receiving element 21 of the infrared image sensor 4. This heat generation begins to increase immediately after startup, and if the device is operated continuously for a long period of time, it converges to a stable temperature Th, as shown in the temperature model showing the relationship between the internal temperature of the infrared imaging unit 1 and time in Fig. 11. However, this stable temperature Th changes depending on the ambient temperature of the operating environment.

[0031] FIG. 12 is a block diagram showing a process flow of the infrared imaging device having a temperature control mechanism according to the second embodiment. Compared to the first embodiment, the temperature control process by the temperature control unit 130 is changed. In FIG. 12, the temperature control unit 130 receives the internal temperature measured by the internal temperature measurement sensor 3, as well as the environmental temperature measured by the environmental temperature measurement sensor 14, and data on the amount of internal temperature rise of the infrared imaging unit 1 from the non-volatile memory 13. The data on the amount of internal temperature rise of the infrared imaging unit 1 is data that represents the relationship between the environmental temperature and the amount of internal temperature rise of the infrared imaging unit 1, which is obtained by measuring the amount of internal temperature rise of the infrared imaging unit 1 in advance in response to the environmental temperature.

[0032] FIG. 13 is a flowchart showing temperature control of the infrared imaging unit according to the second embodiment. The temperature control of the infrared imaging unit according to the first embodiment will be described with reference to FIG. In step S200, the temperature control unit 130 acquires the environmental temperature measured by the environmental temperature measurement sensor 14. In step S201, the temperature control unit 130 calculates the stable temperature Th from the environmental temperature and the data on the amount of rise in the internal temperature of the infrared imaging unit 1. In step S202, the internal temperature T of the infrared imaging unit 1 is acquired by the internal temperature measuring sensor 3. In step S203, the temperature difference ΔT between the internal temperature T of the infrared imaging unit 1 and the stable temperature Th is calculated. In step S204, if the temperature difference ΔT is greater than the specified value, the process proceeds to step S205, where the temperature control mechanism 11 continues heating the infrared imaging unit 1. If the temperature difference ΔT is less than the specified value, the heating process is terminated. After the heating process is completed, the internal temperature of the infrared imaging unit 1 stabilizes at the stable temperature Th.

[0033] Then, a plurality of correction matrices MX are prepared in advance for when the internal temperature of the infrared imaging unit 1 becomes stable within a temperature range assumed as a stable temperature. As shown in FIG. 14, the correction matrix MX is prepared by deriving correction coefficients for each light receiving element in a manner similar to that of embodiment 1 at multiple stable temperatures, for example, stable temperature Ta, stable temperature Tb, stable temperature Tc, stable temperature Td, and stable temperature Te. Then, a plurality of correction matrices MX corresponding to stable temperatures (for example, Ta, Tb, Tc, Td, and Te) as shown in FIG. Then, when the infrared imaging unit 1 reaches the stable temperature Th, the pixel sensitivity error correction unit 110 corrects the output voltage Vf output from the light receiving element 21 of the infrared image sensor 4 using the correction matrix MX for the temperature closest to the stable temperature Th.

[0034] As described above, according to the second embodiment, in an environment where there is little change in the ambient temperature of the infrared imaging device, by utilizing the property that the internal temperature of the infrared imaging unit 1 does not change after reaching a stable temperature, it is no longer necessary to consider changes in the characteristics of the light receiving element 21 due to changes in the internal temperature of the infrared imaging unit 1. Therefore, after the internal temperature of the infrared imaging unit 1 reaches a stable temperature, by using the correction matrix MX for each stable temperature acquired from the nonvolatile memory 13, it becomes unnecessary to update the correction coefficients. In this case, by preparing the correction matrix MX when the internal temperature of the infrared imaging unit 1 is at a stable temperature Th, and correlation data between the output voltage of the light receiving element and the temperature of the object, it is possible to obtain the same effect as in the first embodiment. Furthermore, the temperature control by the temperature control unit 130 is only required to be performed from immediately after startup until the temperature reaches the stable temperature Th, so that power consumption can be reduced while obtaining the same effect as in the first embodiment.

[0035] The control device 15 used in the above embodiment is configured from a processor 1000 and a storage device 1010, as shown in FIG. 15 as an example of hardware. The storage device 1010 includes a volatile storage device such as a random access memory and a nonvolatile storage device such as a flash memory (nonvolatile memory 13), both of which are not shown. Alternatively, an auxiliary storage device such as a hard disk may be included instead of the flash memory. The processor 1000 executes a program input from the storage device 1010. In this case, the program is input from the auxiliary storage device to the processor 1000 via the volatile storage device. The processor 1000 may also output data such as calculation results to the volatile storage device of the storage device 1010, or may store the data in the auxiliary storage device via the volatile storage device.

[0036] Although the present disclosure describes various exemplary embodiments and examples, the various features, aspects, and functions described in one or more embodiments are not limited to application to a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless variations not exemplified are conceivable within the scope of the technology disclosed in this specification, including, for example, cases where at least one component is modified, added, or omitted, and cases where at least one component is extracted and combined with components of another embodiment.

[0037] Various aspects of the present disclosure are summarized below as appendices.

[0038] (Appendix 1) An infrared imaging device that captures infrared light emitted from a subject, an infrared image sensor having a plurality of light receiving elements arranged therein for receiving infrared rays from the subject; an infrared imaging unit that houses the infrared image sensor; an internal temperature measuring sensor for measuring an internal temperature of the infrared imaging unit; a temperature control unit that controls the internal temperature of the infrared imaging unit based on the measurement result of the internal temperature measurement sensor; a correction calculation unit that corrects output information of the light receiving element of the infrared image sensor, the temperature control unit maintains the internal temperature of the infrared imaging unit at a reference temperature, which is a constant temperature; The correction calculation unit corrects errors between the light receiving elements of the infrared image sensor and converts the corrected output data into absolute temperature. (Appendix 2) The correction calculation unit a pixel sensitivity error correction unit that corrects an error in an offset direction and an error in gain between the light receiving elements when the internal temperature of the infrared imaging unit is the reference temperature; An infrared imaging device as described in Appendix 1, including an absolute temperature calculation unit that calculates absolute temperatures based on the corrected output data of each of the light receiving elements based on correlation data between the output of the light receiving elements when the internal temperature of the infrared imaging unit is the reference temperature and the temperature of the subject. (Appendix 3) the pixel sensitivity error correction unit performs correction based on a correction matrix in which correction coefficients for correcting offset direction errors and gain errors for each of the light receiving elements are arranged, the correction coefficients being stored in a storage unit; 3. The infrared imaging device according to claim 2, wherein the absolute temperature calculation unit calculates the absolute temperature based on correlation data between the output of the light receiving element and the temperature of the subject, which data is stored in the storage unit. (Appendix 4) an environmental temperature measuring sensor for measuring an environmental temperature outside the infrared imaging unit; 2. The infrared imaging device according to claim 1, wherein the temperature control unit maintains an internal temperature of the infrared imaging unit at a stable temperature based on a measurement result of the environmental temperature measurement sensor. (Appendix 5) The correction calculation unit calculating the stable temperature from the environmental temperature measured by the environmental temperature measuring sensor and an increase in the internal temperature of the infrared imaging unit when the infrared imaging unit is operated; 5. The infrared imaging device according to claim 4, wherein the temperature control unit performs temperature control to stabilize the internal temperature of the infrared imaging unit at the stable temperature. (Appendix 6) The correction calculation unit a pixel sensitivity error correction unit that corrects an error in an offset direction and an error in gain between the light receiving elements when the internal temperature of the infrared imaging unit is the stable temperature; and an absolute temperature calculation unit that calculates an absolute temperature based on the corrected output data of each of the light receiving elements and correlation data between the output of the light receiving elements and the temperature of the subject when the internal temperature of the infrared imaging unit is the stable temperature. (Appendix 7) the pixel sensitivity error correction unit performs correction based on a correction matrix in which correction coefficients for correcting offset direction errors and gain errors for each of the light receiving elements are arranged, the correction coefficients being stored in a storage unit; the absolute temperature calculation unit calculates the absolute temperature based on correlation data between the output of the light receiving element and the temperature of the object stored in the storage unit; 7. The infrared imaging device according to claim 6, wherein the temperature control unit controls the temperature based on data on an amount of rise in internal temperature of the infrared imaging unit stored in the storage unit. (Appendix 8) The infrared imaging device according to any one of Supplementary Note 1 to Supplementary Note 7, wherein the temperature control unit controls a Peltier element having heating and cooling functions as a temperature control mechanism of the infrared imaging unit. [Explanation of symbols]

[0039] 1 infrared imaging unit, 2 lens, 3 internal temperature measurement sensor, 4 infrared image sensor, 5 infrared imaging unit board, 6 support, 7 heat conduction unit, 8 main board, 9 subject, 10 infrared light, 11 temperature control mechanism, 12 control microcomputer, 13 non-volatile memory, 14 environmental temperature measurement sensor, 15 control device, 21 light receiving element, 110 pixel sensitivity error correction unit, 120 absolute temperature calculation unit, 130 temperature control unit, 150 correction calculation unit, 1000 processor, 1010 storage device.

Claims

1. An infrared imaging device that captures infrared light emitted from a subject, an infrared image sensor having a plurality of light receiving elements arranged therein for receiving infrared rays from the subject; an infrared imaging unit that houses the infrared image sensor; an internal temperature measuring sensor for measuring an internal temperature of the infrared imaging unit; a temperature control unit that controls the internal temperature of the infrared imaging unit based on the measurement result of the internal temperature measurement sensor; a correction calculation unit that corrects output information of the light receiving element of the infrared image sensor, the temperature control unit maintains the internal temperature of the infrared imaging unit at a reference temperature, which is a constant temperature; The correction calculation unit corrects errors between the light receiving elements of the infrared image sensor and converts the corrected output data into absolute temperature.

2. The correction calculation unit a pixel sensitivity error correction unit that corrects an error in an offset direction and an error in gain between the light receiving elements when the internal temperature of the infrared imaging unit is the reference temperature; 2. The infrared imaging device according to claim 1, further comprising an absolute temperature calculation unit that calculates an absolute temperature based on the corrected output data of each of the light receiving elements, based on correlation data between the output of the light receiving elements when the internal temperature of the infrared imaging unit is the reference temperature and the temperature of the subject.

3. the pixel sensitivity error correction unit performs correction based on a correction matrix in which correction coefficients for correcting offset direction errors and gain errors for each of the light receiving elements are arranged, the correction coefficients being stored in a storage unit; 3. The infrared imaging device according to claim 2, wherein the absolute temperature calculation unit calculates the absolute temperature based on correlation data between the output of the light receiving element and the temperature of the subject, the correlation data being stored in the storage unit.

4. an environmental temperature measuring sensor for measuring an environmental temperature outside the infrared imaging unit; 2. The infrared imaging device according to claim 1, wherein the temperature control section keeps the internal temperature of the infrared imaging section at a stable temperature based on the measurement result of the environmental temperature measurement sensor.

5. The correction calculation unit calculating the stable temperature from the environmental temperature measured by the environmental temperature measuring sensor and an increase in the internal temperature of the infrared imaging unit when the infrared imaging unit is operated; The infrared imaging device according to claim 4 , wherein the temperature control section performs temperature control to stabilize the internal temperature of the infrared imaging section at the stable temperature.

6. The correction calculation unit a pixel sensitivity error correction unit that corrects an error in an offset direction and an error in gain between the light receiving elements when the internal temperature of the infrared imaging unit is the stable temperature; 6. The infrared imaging device according to claim 4, further comprising an absolute temperature calculation unit that calculates an absolute temperature based on the corrected output data of each of the light receiving elements and correlation data between the output of the light receiving elements and the temperature of the subject when the internal temperature of the infrared imaging unit is at the stable temperature.

7. the pixel sensitivity error correction unit performs correction based on a correction matrix in which correction coefficients for correcting offset direction errors and gain errors for each of the light receiving elements are arranged, the correction coefficients being stored in a storage unit; the absolute temperature calculation unit calculates the absolute temperature based on correlation data between the output of the light receiving element and the temperature of the object stored in the storage unit; The infrared imaging device according to claim 6 , wherein the temperature control section controls the temperature based on data on an amount of rise in the internal temperature of the infrared imaging section stored in the storage section.

8. 5. The infrared imaging device according to claim 1, wherein the temperature control section controls a Peltier element having heating and cooling functions as a temperature control mechanism for the infrared imaging section.

Images