JP6540519B2 - Infrared imaging device - Google Patents

Description

  BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to an infrared imaging apparatus for imaging infrared radiation emitted by an object.

  The infrared imaging device receives light with an infrared sensor configured by two-dimensionally arraying elements that detect infrared rays emitted by a subject, and absorbs infrared rays emitted from the subject and outputs signals according to temperatures of the respective elements that have risen in temperature The infrared image is obtained by outputting. Since the output signal of the infrared sensor changes due to environmental temperature change, time lapse, etc., in order to make the pixel value constituting each pixel of the infrared image correspond to the absolute temperature of the subject, the signal output by the infrared sensor A calibration is required to be associated with pixel values representing absolute temperatures.

  In the conventional infrared imaging device, a temperature sensor is mounted on the surface of the shutter, the surface temperature of the shutter is acquired, and the output value of each element constituting the infrared sensor when imaging is performed in the state where the shutter is closed is The offset correction value for each element is corrected as needed to obtain a pixel value corresponding to the acquired shutter surface temperature (see, for example, Patent Document 1).

JP 2007-201807 A

  In the conventional infrared imaging device described in Patent Document 1, a temperature sensor is mounted on the surface of the shutter to measure the surface temperature of the shutter, and the infrared intensity radiated from the shutter surface with the shutter closed and At the same time, the offset correction value is corrected every time with respect to all the two-dimensionally arranged elements of the infrared sensor so that the temperature of the shutter surface measured by the temperature sensor coincides with each other. Thus, the pixel value of each pixel of the captured image can be made to correspond to the absolute temperature of the subject. However, in order to mount the temperature sensor on the surface of the shutter, it is necessary to increase the strength of the shutter blade, and as a result, the entire weight of the shutter blade including the temperature sensor becomes heavy, and it takes time to open and close the shutter. there were. In addition, at the time of offset calibration in which the pixel value of each pixel is associated with the temperature of the subject, the offset correction value is corrected with respect to all elements of the two-dimensional array of infrared sensors, so it takes a long time for offset calibration There was a problem.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an infrared imaging device capable of performing offset calibration in a short time while maintaining high-speed opening and closing of a shutter.

The infrared imaging device according to the present invention includes a case having a window to which infrared rays are incident from the outside, a shutter support portion provided inside the case, and the shutter support portion supported by the window and in a closed state from the window A movable part formed of an openable and closable shutter for blocking incident infrared light, and provided inside the housing, detects the infrared light incident from the window when the shutter is open, and the shutter is closed An infrared sensor for detecting an infrared ray emitted by the shutter, a first temperature sensor provided at a fixed portion inside the casing and measuring a temperature of a provided place, and a measurement result of the first temperature sensor A temperature estimation circuit for estimating the temperature of the shutter based on the output signal of the infrared sensor is converted into a subject temperature, and the shutter estimation estimated by the temperature estimation circuit when the shutter is in a closed state Degrees and calculating the offset calibration value from the difference between the shutter imaging temperature obtained by converting the output signal of the infrared sensor, e Bei and a correction circuit for calibrating the object temperature based on the offset calibration value, said temperature estimation circuit When the measurement result of the first temperature sensor is input, the temperature of the shutter is determined based on an estimated temperature table in which the temperature of the place where the first temperature sensor is provided and the temperature of the shutter are associated in advance. presume.

  According to the infrared imaging device of the present invention, since the shutter surface temperature can be estimated based on the measurement result of the temperature sensor provided in the fixed portion inside the casing of the infrared imaging device, the shutter surface temperature can be maintained while maintaining high speed opening and closing of the shutter. Offset calibration can be performed.

It is a block diagram which shows the structure of the infrared imaging device in Embodiment 1 of this invention. It is a schematic cross section which shows the structure of the infrared imaging device in Embodiment 1 of this invention. It is a schematic cross section which shows the structure of the other infrared imaging device in Embodiment 1 of this invention. It is a schematic cross section which shows the structure of the other infrared imaging device in Embodiment 1 of this invention. It is a block diagram which shows the structure of the infrared imaging device in Embodiment 1 of this invention. It is a block diagram which shows the other structure of the infrared imaging device in Embodiment 1 of this invention. It is a block diagram which shows the infrared imaging device in Embodiment 2 of this invention. It is a block diagram which shows the other structure of the infrared imaging device in Embodiment 2 of this invention. It is a block diagram which shows the infrared imaging device in Embodiment 3 of this invention. It is a schematic cross section which shows the infrared imaging device in Embodiment 3 of this invention. It is a block diagram which shows the structure of the other infrared imaging device in Embodiment 3 of this invention. It is a block diagram which shows the other structure of the infrared imaging device of Embodiment 3 of this invention. It is a block diagram which shows the structure of the infrared imaging device in Embodiment 4 of this invention. It is a block diagram which shows the other structure of the infrared imaging device in Embodiment 4 of this invention.

Embodiment 1
First, the configuration of the infrared imaging device in the first embodiment of the present invention will be described. FIG. 1 is a block diagram showing a configuration of an infrared imaging device according to Embodiment 1 of the present invention.

  In FIG. 1, the infrared imaging device 100 has a shutter 1 for controlling passage and shielding of infrared rays incident from the outside of the infrared imaging device 100 and an infrared ray collected through the shutter 1 on the imaging surface of the infrared sensor 3. A lens 2 for forming an image, an A / D converter 4 for converting an analog signal picked up and output by the infrared sensor 3 into a digital signal, and correction of a captured image which is a digital signal output from the A / D converter 4 Correction circuit 5, an output terminal 6 for outputting a captured image corrected by the correction circuit 5, a memory 7 for storing a correction value used for correction by the correction circuit 5, and the temperature inside the infrared imaging device 100 The temperature sensor 8 includes a temperature estimation circuit 9 that estimates the surface temperature of the shutter 1 from the measurement result of the temperature sensor 8 and a control circuit 10 that controls the opening and closing of the shutter 1. In addition, the infrared rays said in this invention are infrared rays of a far infrared region whose wavelength is about 8-14 micrometers.

  The infrared imaging device 100 operates at an arbitrary frame rate such as 60 Hz, 30 Hz, and 7.5 Hz, for example. The infrared imaging device 100 outputs an infrared moving image by outputting an infrared image of a subject captured by the infrared sensor 3 at a predetermined frame frequency. An infrared image of one frame is composed of n-rows and m-columns of two-dimensionally arranged pixels. Hereinafter, in the present invention, an infrared image of one frame is referred to as a screen, and a signal of the screen is referred to as an imaging signal. Also, the magnitude of the signal of each pixel is called a pixel value. That is, the imaging signal is configured by a two-dimensional array of pixel values of m rows and n columns (m, n is an arbitrary integer). Further, since the signal of the infrared moving image is a signal in which the screen signal which is an infrared image (still image) is continuously output at a predetermined frame rate, the infrared moving image is not particularly required to be distinguished. The signal of the image is also called an imaging signal.

  The shutter 1 is a planar infrared shielding member, and the control circuit 10 controls the opening and closing of the shutter 1 and is a movable portion that is openable and closable by the power of a motor. When the shutter 1 is in the open state, infrared rays incident to the inside of the infrared imaging device 100 from the outside of the infrared imaging device 100 are allowed to pass, and when the shutter 1 is in the closed state, the infrared imaging device 100 from the outside of the infrared imaging device 100 To block the infrared rays incident on the inside of the In addition, the lens 2 condenses infrared light from a subject incident on the lens 2 and focuses on an imaging surface of the infrared sensor 3 to form a subject image. In the present invention, although the infrared imaging device 100 in which the shutter 1 is disposed in front of the lens 2 will be described, the lens 2 is in front of the shutter 1, that is, the shutter 1 is between the lens 2 and the infrared sensor 3 The infrared imaging device 100 may be disposed.

  The infrared sensor 3 is configured by an imaging unit having an imaging surface in which infrared detection elements having sensitivity to infrared rays of approximately 8 to 14 micrometers are arranged in a two-dimensional plane of m rows and n columns. Each infrared detection element absorbs the incident infrared ray and rises in temperature, and outputs an analog pixel value of a size corresponding to the temperature of each element. Therefore, the infrared sensor 3 outputs an analog imaging signal according to the incident infrared intensity. Further, the A / D converter 4 converts an analog imaging signal output from the infrared sensor 3 into a digital imaging signal, and outputs the digital converted imaging signal to the correction circuit 5.

  The correction circuit 5 includes a signal correction unit 51 and a temperature correction unit 52. The signal correction unit 51 performs gain correction and offset correction on the imaging signal input from the A / D converter 4, and outputs the corrected imaging signal to the temperature correction unit 52. The temperature correction unit 52 performs temperature correction to correct each pixel value of the imaging signal input from the signal correction unit 51 to a pixel value proportional to the absolute temperature of the subject, and outputs the temperature value from the output terminal 6. That is, an infrared image representing the absolute temperature of the subject is output from the output terminal 6 at a predetermined frame rate, and an infrared moving image is obtained.

  The memory 7 has a gain correction value storage area for signal correction, an offset correction value storage area, and a look-up table for temperature correction. The gain correction value storage area stores a gain correction value to be used by the signal correction unit 51 for gain correction. The gain correction value is measured in the adjustment process at the time of manufacture, and is written in the gain correction value storage area of the memory 7. The offset correction value storage area stores an offset correction value for use by the signal correction unit 51 for offset correction. The offset correction value is updated as needed, for example, by calculating a new offset correction value from the image pickup signal acquired when the signal correction unit 51 is in the closed state of the shutter 1 and writing the new offset correction value in the memory 7. The method of acquiring the offset correction value is not limited to this. For example, there is a method of acquiring the offset correction value without closing the shutter 1, and such an offset correction value is acquired without closing the shutter 1. May be The look-up table stores correction values for correcting the pixel values output from the respective elements of the infrared sensor 3 to pixel values proportional to the absolute temperature of the subject. The look-up table is written to the memory 7 in the adjustment process at the time of manufacture.

  The temperature sensor 8 is configured of, for example, a thermistor or a semiconductor temperature sensor, and is disposed inside the infrared imaging device 100. The temperature sensor 8 also has an A / D converter, converts the measured temperature into a digital value, and outputs the digital value to the temperature estimation circuit 9. The analog value of the temperature measured by the temperature sensor 8 may be output to the temperature estimation circuit 9 and the temperature estimation circuit 9 may perform A / D conversion. The temperature estimation circuit 9 estimates the surface temperature of the shutter 1 based on the measurement result of the temperature sensor 8, and outputs the estimated surface temperature of the shutter 1 to the temperature correction unit 52. The temperature correction unit 52 calculates the offset calibration value so that the imaging signal obtained by imaging the infrared ray emitted from the shutter 1 in the closed state matches the estimated surface temperature of the shutter 1. Then, the temperature correction unit 52 calibrates the imaging signal corrected by the look-up table using the calculated offset calibration value.

  FIG. 2 is a schematic cross-sectional view showing the structure of the infrared imaging device in Embodiment 1 of the present invention. As shown in FIG. 2, the infrared imaging device 100 includes a lens barrel 21, a shutter support 22, and substrates 25, 26, 27 inside a housing 20 having an opening window 23 through which infrared light passes. The respective substrates 25, 26, 27 are connected by flat cables 28, 29, and electrical signals and power are mutually supplied to the respective substrates via the flat cables 28, 29. Although the infrared imaging device 100 of FIG. 2 includes three substrates of the substrate 25, the substrate 26, and the substrate 27, one or three or more substrates may be provided. Moreover, although it is set as an opening, without providing in the opening window 23 in FIG. 2, you may provide the window material formed with materials, such as a germanium window which permeate | transmits infrared rays whose wavelength is 8-14 micrometers.

  The substrate 25 is provided with an infrared sensor 3 and a temperature sensor 8 next to the infrared sensor 3. By arranging the temperature sensor 8 and the infrared sensor 3 on the same substrate 25 as described above, the wiring pattern of the temperature sensor 8 can be formed simultaneously with the wiring pattern of the infrared sensor 3. As a result, the manufacturing process can be simplified and the reliability of the temperature sensor 8 can be improved. Further, the A / D converter 4, the correction circuit 5, the memory 7, the temperature estimation circuit 9 and the control circuit 10 shown in FIG. 1 are provided on the substrates 25, 26 and 27 (not shown). The substrate on which the A / D converter 4, the correction circuit 5, the memory 7, the temperature estimation circuit 9 and the control circuit 10 are provided is not particularly limited as long as it is provided on any of the substrates 25, 26 and 27. Furthermore, the substrate 27 is provided with the output terminal 6, one end of the output terminal 6 is exposed to the outside of the housing 20, and the infrared moving image picked up outside the infrared imaging device 100 through the output terminal 6 is output .

  A lens 2 is provided on the lens barrel 21 so that the infrared sensor 3 and the optical axis coincide with each other. The lens 2 is formed of a material such as germanium which transmits infrared light having a wavelength of 8 to 14 micrometers. Furthermore, between the opening window 23 of the housing 20 and the lens 2, there is provided a planar shutter 1 which is moved by the power of the motor 24 to open and close. The shutter 1 and the motor 24 are fixed to the shutter support 22. The motor 24 is wired to the control circuit 10 provided on any of the substrates, and generates power for opening and closing the shutter 1 according to the output from the control circuit 10. Note that, as described above, the shutter 1 may be provided between the lens 2 and the infrared sensor 3. Further, although the lens barrel 21 and the shutter support 22 are both fixed to the substrate 25 via the legs 21 a and 22 a in FIG. 2, the configuration of the lens barrel 21 and the shutter support 22 is not limited thereto. For example, the configuration may be fixed to the inner wall of the housing 20. That is, the member provided with the lens 2 is the lens barrel 21, and the member provided with the shutter 1 is the shutter support 22.

  FIG. 3 is a schematic cross-sectional view showing the structure of another infrared imaging device according to Embodiment 1 of the present invention. The infrared imaging device 100 shown in FIG. 3 is different from the infrared imaging device 100 shown in FIG. 2 in the place where the temperature sensor 8 is disposed. In the infrared imaging device 100 shown in FIG. 2, the temperature sensor 8 is provided next to the infrared sensor 3 inside the lens barrel 21. However, as shown in FIG. Good.

  The temperature sensor 8 is connected to the substrate 25 by the wiring 30, and the temperature measured by the temperature sensor 8 is input to the temperature estimation circuit 9 provided on any of the substrates. As shown in FIG. 3, by providing the temperature sensor 8 in the shutter support portion 22, the difference between the temperature measured by the temperature sensor 8 and the surface temperature of the shutter 1 is reduced, and the shutter 1 estimated by the temperature estimation circuit 9 is An error between the surface temperature and the actual surface temperature of the shutter 1 can be made smaller.

  Furthermore, FIG. 4 is a schematic cross-sectional view showing the structure of another infrared imaging device according to Embodiment 1 of the present invention. The infrared imaging device 100 shown in FIG. 4 differs from the infrared imaging device 100 shown in FIG. 2 in the location where the temperature sensor 8 is disposed, and the temperature sensor 8 is provided on the inner wall of the housing 20.

  In FIG. 4, a circle 31 indicated by a broken line is a sphere whose center is the center Q of the shutter 1 and whose radius is the width L of the shutter 1. Here, the width L of the shutter 1 may be the diameter when the shutter 1 is circular, and may be the longest diagonal length when the shutter 1 is a polygon such as a rectangle. As shown in FIG. 4, the temperature sensor 8 is disposed inside the infrared imaging device 100 and at a position closer than a circle 31 which is a distance L of the shutter 1 from the center Q of the shutter 1. By setting the distance between the temperature sensor 8 and the center Q of the shutter 1 equal to or less than the width L of the shutter 1 in this way, the distance between the temperature sensor 8 and the shutter 1 becomes short, so the temperature measured by the temperature sensor 8 and the shutter The difference with the surface temperature of 1 becomes smaller, and the error between the surface temperature of the shutter 1 estimated by the temperature estimation circuit 9 and the surface temperature of the actual shutter 1 can be made smaller. Therefore, the temperature sensor 8 may be provided in the lens barrel 21 as long as it is inside the circle 31 indicated by the broken line in FIG. 4 or may be provided in another place.

  However, it is not desirable to provide the temperature sensor 8 in the lens 2 which is an optical member or the infrared sensor 3 which is an optical member. When the temperature sensor 8 is provided to these optical members, the temperature sensor 8 blocks infrared light from the subject, and a good infrared image can not be obtained. When the temperature sensor 8 is provided to these optical members, it may be provided at a portion corresponding to the end of the infrared image, such as the end of the lens 2 or the corner of the infrared sensor 3. Further, the temperature sensor 8 needs to be provided inside the casing of the infrared imaging device and at a fixed portion other than the shutter 1 which is a movable portion. Here, the fixed portion is a portion other than the movable portion whose relative position moves with respect to the housing 20 like the shutter 1, and is the inner wall of the housing 20, the lens barrel 21, the shutter support portion 22, the substrate 25, It is 26, 27 mag. It is desirable that the shutter 1 be opened and closed at high speed, but if the temperature sensor 8 is provided on the shutter 1, the weight of the shutter 1 is increased, making high-speed opening and closing difficult. Further, since the stress is applied to the wiring 30 electrically connecting the temperature sensor 8 and the temperature estimation circuit 9 by opening and closing the shutter 1, the reliability of the infrared imaging device 100 is lowered. Therefore, the temperature sensor 8 may be provided inside the casing 20 of the infrared imaging device 100 and at a fixed portion, and particularly preferably at a fixed portion formed of a non-optical member. It is more preferable to provide at the fixed part which consists of non-optical members of width L or less.

  The infrared imaging device 100 is configured as described above.

  Next, the operation of the infrared imaging device 100 will be described. The operation of the infrared imaging apparatus 100 includes an imaging operation for capturing an infrared image of an object, an offset correction value acquiring operation for removing fixed pattern noise, and an offset calibration value acquiring operation for performing temperature calibration of an imaging signal. There is. By performing the imaging operation after acquiring the offset correction value and the offset calibration value, fixed pattern noise is removed, and an infrared moving image corresponding to the absolute temperature of the subject can be imaged.

  First, the offset correction value acquisition operation will be described. The acquisition of the offset correction value is performed, for example, when the temperature of the infrared imaging device 100 changes or every predetermined time. The temperature of the infrared imaging device 100 may be measured by the temperature sensor 8 shown in FIGS. 1 and 2 to 4 or may be measured separately from the temperature sensor 8 by providing a temperature sensor. The offset correction value when the temperature measured by the temperature sensor changes beyond a predetermined threshold, such as 1 ° C. or 2 ° C., or when a predetermined time, such as 5 minutes, has elapsed since the previous offset correction value acquisition operation An acquisition operation is performed.

  When the offset correction value acquisition operation is started, the control circuit 10 closes the shutter 1. When the shutter 1 is closed, the subject of the infrared sensor 3 becomes the surface of the shutter 1, so the infrared radiation emitted from the surface of the shutter 1 enters the infrared sensor 3. Since the shutter 1 is flat and the surface temperature is almost uniform, infrared rays of uniform intensity are incident on the respective infrared detection elements of the infrared sensor 3. After the shutter 1 is completely closed, the signal correction unit 51 acquires imaging signals of a predetermined number of frame periods, repeats writing to the memory 7 and reading from the memory 7, and performs averaging processing. The signal correction unit 51 closes the shutter 1 for 16 frame periods, for example, and images the surface of the shutter 1, and writes an image pickup signal obtained by averaging the images into the offset correction value storage area of the memory 7 as an offset correction value. Thus, the offset correction value acquisition operation is completed. The offset correction value is acquired for each pixel constituting the screen.

  When the offset correction value acquisition operation is completed, the control circuit 10 opens the shutter 1 and an imaging operation is performed. In the imaging operation, the signal correction unit 51 of the correction circuit 5 reads the offset correction value acquired by the offset correction value acquisition operation from the offset correction value storage area of the memory 7 and captures an image of the object converted into digital by the A / D converter 4 Apply to the signal to perform offset correction. Thereby, fixed pattern noise is removed from the imaging signal.

  Next, the offset calibration value acquisition operation will be described. The offset calibration value acquisition operation may be performed simultaneously with the offset correction value acquisition operation, or may be performed separately from the offset correction value acquisition operation. Further, as in the offset correction value acquisition operation, the offset calibration value acquisition operation may be performed when the temperature of the infrared imaging device changes by a predetermined amount or after a predetermined time has elapsed from the previous offset calibration value acquisition operation.

  When the offset calibration value acquisition operation is started, the control circuit 10 closes the shutter 1. When the shutter 1 is closed, as described above, infrared rays of substantially uniform intensity emitted from the surface of the shutter 1 enter each infrared detection element of the infrared sensor 3. The analog image pickup signal output from the infrared sensor 3 is converted to a digital image pickup signal by the A / D converter 4, and the signal correction unit 51 of the correction circuit 5 performs gain correction and offset correction. Is input to The temperature correction unit 52 converts the input imaging signal into an imaging signal corresponding to an absolute temperature using a lookup table. That is, the imaging signal converted using the look-up table is an infrared image representing the surface temperature of the shutter 1 as the subject. An infrared image representing the surface temperature of the shutter 1 captured at this time is referred to as a shutter imaging temperature. However, an error may occur due to a temperature change of the infrared sensor 3 or the like between the actual temperature of the shutter 1 surface and the shutter imaging temperature converted using the look-up table. It is the offset calibration value that calibrates this error.

  The surface temperature of the shutter 1 is estimated by the temperature estimation circuit 9 based on the temperature measured by the temperature sensor 8 provided inside the infrared imaging device 100. The surface temperature estimation method of the shutter 1 by the temperature estimation circuit 9 will be described later. The temperature estimation circuit 9 outputs the estimated surface temperature of the shutter 1 to the temperature correction unit 52. The surface temperature of the shutter 1 estimated by the temperature estimation circuit 9 is called a shutter estimated temperature. The temperature correction unit 52 calculates the offset calibration value such that the shutter imaging temperature representing the surface temperature of the shutter 1 converted using the lookup table becomes the estimated shutter temperature estimated by the temperature estimation circuit 9.

  For example, when the actual surface temperature of the shutter 1 is 25 ° C., the temperature estimation circuit 9 estimates that the surface temperature of the shutter 1 is 25 ° C., and outputs the estimated shutter temperature 25 ° C. estimated to the temperature correction unit 52 Do. On the other hand, when the imaging signal obtained by imaging the surface of the shutter 1 is converted to an infrared image which is a shutter imaging temperature corresponding to an absolute temperature by a lookup table, a value obtained by averaging the pixel values of m × n pixels is 23 ° C. If so, the magnitude of the error is 2 ° C. That is, since the shutter estimated temperature is 25 ° C. and the shutter imaging temperature is 23 ° C., the difference between the shutter estimated temperature and the shutter imaging temperature is 2 ° C. Therefore, the offset calibration value is 2 ° C. because it is the difference between the estimated shutter temperature and the shutter imaging temperature. When the subject is imaged by the imaging operation, the imaging signal of the infrared sensor 3 is associated with the absolute temperature using the look-up table, and becomes an infrared image which is the subject temperature. By adding 2 ° C. of the offset calibration value to the pixel value of each pixel of this infrared image, the temperature indicated by the infrared image comes to coincide with the absolute temperature.

  Since the offset calibration value is calculated by averaging the pixel values of a total of m × n pixels of a screen formed of a two-dimensional array of m rows and n columns, even from the screen imaged in one frame period Averaging process with sufficiently high accuracy can be performed. Therefore, the offset calibration value acquisition operation can be performed in a shorter time than the above-described offset correction value acquisition operation, and the time during which the subject can not be imaged by the offset calibration value acquisition operation can be shortened. The acquired offset calibration value may be stored in the memory 7 but may be stored in the temperature correction unit 52 because the data size is small. As a matter of course, the offset calibration value may be calculated from the screen captured in a plurality of frame periods.

  Thus, the offset calibration value acquiring operation is completed. When the offset correction value acquisition operation and the offset calibration value acquisition operation are performed and the offset correction value and the offset calibration value are acquired, the infrared imaging device 100 captures an infrared image corresponding to the absolute temperature of the subject by the imaging operation. Can.

  Next, the imaging operation will be described. The following description is an operation for one frame, and the infrared imaging device 100 outputs an infrared moving image by repeatedly performing the operation for one frame described below.

  In the imaging operation, the control circuit 10 opens the shutter 1. When the shutter 1 is in the open state, the lens 2 focuses and couples infrared rays emitted by an object outside the infrared imaging device 100 to the imaging surface of the infrared sensor 3, and an analog imaging signal is output from the infrared sensor 3. It is output. The analog imaging signal is converted into a digital imaging signal by the A / D converter 4, and is input to the signal correction unit 51 of the correction circuit 5. The signal correction unit 51 reads the gain correction value from the gain correction value storage area of the memory 7 and reads the offset correction value from the offset correction value storage area. The gain correction value and the offset correction value have values for each pixel constituting the screen. The pixel value of the imaging signal input to the signal correction unit 51 is SI (i, j) for the pixel (i, j) in the i-th row and the j-th column of the screen formed of the m-row n-column two-dimensional array When the gain correction value is G (i, j) and the offset correction value is O (i, j), the signal correction unit 51 performs the correction described by the following equation (1), and the signal correction unit The pixel value SO (i, j) is output to the temperature correction unit 52.

  SO (i, j) = G (i, j) · SI (i, j) + O (i, J) (1)

  The temperature correction unit 52 converts each pixel value of the image pickup signal input from the signal correction unit 51 into a pixel value proportional to the absolute temperature by a lookup table, and then performs temperature calibration using the offset calibration value. The pixel value SO (i, j) input to the temperature correction unit 52 is proportional to the absolute temperature according to the following equation (2) when the input / output function of the look-up table is LUT and the offset calibration value is OC. It is converted to the pixel value TO (i, j).

  TO (i, j) = LUT {SO (i, j)} + OC (2)

  The pixel value TO (i, j) is a value indicating the absolute temperature of the pixel in the i-th row and the j-th column, and the temperature correction unit 52 performs temperature correction so that the pixel values of all pixels in the captured screen are absolute. It becomes a value indicating the temperature. That is, an infrared image indicating the absolute temperature of the subject is obtained. The infrared image corrected by the temperature correction unit 52 is output from the output terminal 6 and continuously output over a plurality of frame periods to obtain an infrared moving image.

  The infrared imaging device 100 operates as described above.

  Next, a method of estimating the surface temperature of the shutter 1 from the temperature measured by the temperature sensor 8 by the temperature estimation circuit 9 will be described.

  FIG. 5 is a block diagram showing the configuration of the infrared imaging device in the first embodiment of the present invention. The point which the temperature estimation circuit 9 has the presumed temperature table 11 differs from the block diagram which shows the structure of the infrared imaging device 100 shown in FIG. The infrared imaging device 100 shown in FIG. 5 is an example specifically showing the configuration of the temperature estimation circuit 9 in the infrared imaging device shown in FIG.

  In the estimated temperature table 11, data is stored that associates the temperature measured by the temperature sensor 8 with the surface temperature of the shutter 1. When the temperature measured by the temperature sensor 8 is input to the temperature estimation circuit 9, the temperature estimation circuit 9 reads the surface temperature of the shutter 1 corresponding to the temperature measured by the temperature sensor 8 written in the estimated temperature table 11, The read temperature is output to the temperature correction unit 52 of the correction circuit 5 as the surface temperature of the shutter 1 estimated by the temperature estimation circuit 9. As a result, the temperature correction unit 52 can know the surface temperature of the shutter 1 and calculates the offset calibration value using the surface temperature of the shutter 1 as described above.

  The data of the estimated temperature table 11 is written to the estimated temperature table 11 in the temperature estimation circuit 9 in the adjustment process at the time of production. The data generation method of the estimated temperature table 11 will be described below.

  First, the infrared imaging device 100 is turned on, and the shutter 1 is closed, the infrared imaging device 100 is installed inside the thermostatic bath, and left until the temperature of the infrared imaging device 100 is stabilized due to the heat generation of the internal electric circuit. Do. After the temperature of the infrared imaging device 100 is sufficiently stabilized, the surface temperature of the shutter 1 is measured, and at the same time, the temperature measured by the temperature sensor 8 is recorded. The surface temperature of the shutter 1 may be measured by a contact type temperature sensor such as a thermocouple previously attached to the surface of the shutter 1, or may be measured by a radiation thermometer in a noncontact manner. Also, a wire that outputs the temperature measured in advance by the temperature sensor 8 can be recorded from the inside to the outside of the infrared imaging device 100 so that the temperature measured by the temperature sensor 8 can be recorded by a data logger or the like outside the infrared imaging device 100. You should pull it out. Then, by recording the surface temperature of the shutter 1 and the temperature measured by the temperature sensor 8 with a data logger or the like, the temperature measured by the temperature sensor 8 can be associated with the surface temperature of the shutter 1.

  The temperature of the thermostatic chamber is set, for example, in the range of -20 ° C to 60 ° C in 0.1 ° C steps. After setting the temperature of the thermostat to a predetermined set temperature and the temperature of the thermostat becomes the set temperature, leave it until the temperature of the infrared imaging device 100 is stabilized as described above, and the temperature of the infrared imaging device 100 is sufficient After stabilization, the surface temperature of the shutter 1 is measured and recorded, and at the same time, the temperature measured by the temperature sensor 8 is recorded. As a result, data in which the temperatures measured by the total of 801 sets of temperature sensors 8 correspond to the surface temperature of the shutter 1 in increments of 0.1 ° C. in the range of −20 ° C. to 60 ° C. is generated. This data is data of the estimated temperature table 11.

  The data of the estimated temperature table 11 generated as described above can be used as it is for the infrared imaging device 100 having the same structure as the infrared imaging device 100 used for data generation. That is, if the data of the estimated temperature table 11 is generated once at the time of production, it is not necessary to generate the data again at the time of subsequent mass production, and is common to the respective estimated temperature tables 11 of the mass produced infrared imaging devices 100. Write the data.

  As described above, since data relating the temperature measured by the temperature sensor 8 to the surface temperature of the shutter 1 is recorded in the estimated temperature table 11, the temperature estimation circuit 9 refers to the estimated temperature table 11, The surface temperature of the shutter 1 can be estimated from the temperature measured by the temperature sensor 8. In the offset calibration value acquisition operation, the temperature estimation circuit 9 outputs the surface temperature of the shutter 1 estimated from the temperature measured by the temperature sensor 8 with reference to the estimated temperature table 11 to the temperature correction unit 52 of the correction circuit 5. The temperature correction unit 52 can calculate an offset calibration value with a small error.

  Next, FIG. 6 is a block diagram showing another configuration of the infrared imaging device in Embodiment 1 of the present invention. While the temperature estimation circuit 9 has the estimated temperature table 11 in the infrared imaging device 100 shown in FIG. 5, the infrared imaging device 100 in FIG. 6 is different in that the temperature estimation circuit 9 has the estimated temperature calculation circuit 12. The infrared imaging device 100 shown in FIG. 6 is an example specifically showing the configuration of the temperature estimation circuit 9 in the infrared imaging device shown in FIG.

  The estimated temperature calculation circuit 12 is a circuit in which an approximate expression representing the relationship between the temperature measured by the temperature sensor 8 and the surface temperature of the shutter 1 is realized by a description in a program of a digital arithmetic circuit or a microcomputer. The relationship between the temperature measured by the temperature sensor 8 and the surface temperature of the shutter 1 is obtained by simultaneously recording the temperature measured by the temperature sensor 8 and the surface temperature of the shutter 1 using a thermostat as described above. be able to. An approximate expression may be derived from the relationship between the temperature measured by the temperature sensor 8 and the surface temperature of the shutter 1 thus obtained, and may be realized by a description in a program of a digital arithmetic circuit or a microcomputer.

  As shown in FIG. 6, the infrared imaging device 100 using the estimated temperature calculation circuit 12 compares the temperature measured by the temperature sensor 8 with the surface temperature of the shutter 1 as compared with the case where the estimated temperature table 11 shown in FIG. There is a merit when the relation is expressed by a relatively simple approximate expression. As described above, in the estimated temperature table 11 of FIG. 5, for example, data in increments of 0.1 ° C. is written, so that an offset calibration value can not be obtained with an accuracy less than the increment value of, for example, 0.05 ° C. On the other hand, in the estimated temperature calculation circuit 12 which represents the relationship between the temperature measured by the temperature sensor 8 and the surface temperature of the shutter 1 by an approximate expression, the offset calibration value can be obtained with a smaller resolution. The error of can be made smaller.

  The infrared imaging device 100 described in the first embodiment is particularly suitable for security applications such as surveillance cameras operating for 24 hours, for example. In the surveillance camera which has been operating for almost 24 hours, the temperature change due to the heat generation of the electric circuit inside the infrared imaging device 100 is extremely small, unlike for night vision of the automobile described in Patent Document 1, for example. The surface temperature of the shutter 1 can be estimated with extremely high accuracy from the temperature measured by the temperature sensor 8 provided in the fixed portion made of the non-optical member inside. In particular, when the infrared imaging device 100 is installed indoors, the temperature change of the environment is also small, so the surface temperature of the shutter 1 can be estimated with higher accuracy.

  As described above, when the infrared imaging device 100 shown in the first embodiment of the present invention images infrared light emitted from the surface of the shutter 1 and performs offset calibration with the surface temperature of the shutter 1, The surface temperature is estimated from the temperature measured by the temperature sensor 8 provided at a place different from the shutter 1 and the estimated temperature is used as the surface temperature of the shutter 1, so the weight of the shutter 1 does not increase and the shutter speed is high. The effect of being able to open and close 1 can be obtained. In addition, since the offset calibration value is calculated by averaging the pixel values of the screen captured by closing the shutter 1 for at least one frame period, the time for acquiring the offset calibration value can be shortened, and the speed can be increased. The effect of being suitable for the shutter to open and close is acquired.

Second Embodiment
FIG. 7 is a block diagram showing an infrared imaging device according to Embodiment 2 of the present invention. 7, the same reference numerals as those in FIG. 5 denote the same or corresponding components, and the description thereof will be omitted. The configuration of the temperature estimation circuit 9 including the delay circuit 13 is different from the first embodiment of the present invention. The configuration is the same as that of the first embodiment of the present invention except for the temperature estimation circuit 9, and the same operation is performed, so the description thereof is omitted.

  The infrared imaging device 100 according to the present invention is more suitable for applications where the temperature change of the environment or the temperature change inside the infrared imaging device is larger than the infrared imaging device described in the first embodiment. The temperature sensor 8 is provided at a place where the temperature change is larger than that of the shutter 1. For example, when the infrared imaging device 100 is frequently started and stopped, and the temperature change due to the heat generation of the electric circuit in the infrared imaging device 100 can not be ignored, the temperature sensor 8 may be used as shown in FIG. Preferably, it is provided on a substrate. Further, for example, when the infrared imaging device 100 is installed in a place where the environmental temperature change is large such as outdoors, the temperature sensor 8 may be provided inside the housing 20 as shown in FIG. 4.

  As shown in FIG. 7, the temperature estimation circuit 9 of the infrared imaging device 100 has a delay circuit 13, and the temperature measured by the temperature sensor 8 is input to the delay circuit 13. The delay circuit 13 may be, for example, a low pass filter configured by a digital circuit, or may be another form of delay circuit. The delay circuit 13 delays the temperature measured by the temperature sensor 8 for a predetermined time. For example, the delay circuit delays the temperature measured by the temperature sensor 8 by a predetermined frame unit time and outputs the temperature to the estimated temperature table 11. The time for delaying the delay circuit 13 (hereinafter referred to as delay time) is determined based on the time constant of heat conduction from the location where the temperature sensor 8 is installed to the shutter 1. As described in the first embodiment, the temperature sensor 8 is disposed in the fixed portion formed of a non-optical member inside the infrared imaging device 100, but the material of the member on which the temperature sensor 8 is disposed, the temperature sensor 8 The time constant of heat conduction from the temperature sensor 8 to the shutter 1 changes depending on the material of the member of the heat transfer path from the installed place to the shutter 1. Therefore, the delay time of the delay circuit 13 may be determined based on the time constant calculated from the physical property values of the members of the heat transfer path from the location where the temperature sensor 8 of the infrared imaging device 100 is installed to the shutter 1 The time constant of heat conduction from the place where the temperature sensor 8 of the apparatus 100 is installed to the shutter 1 may be measured and determined. When the time constant of heat conduction from the place where the temperature sensor 8 is installed to the shutter 1 is small, the delay time of the delay circuit 13 becomes short, and the time constant of heat conduction from the place where the temperature sensor 8 is installed to the shutter 1 Is larger, the delay time of the delay circuit 13 becomes longer.

  As described above, the infrared imaging device 100 according to the second embodiment of the present invention is suitable for use where the temperature change at the location where the temperature sensor 8 is installed is larger than the temperature change of the shutter 1. For example, in applications where the power supply of the infrared imaging device 100 is frequently switched, the temperature change of the electric circuit of the infrared imaging device 100 is large, and the shutter 1 whose temperature changes due to heat conduction from the electric circuit The temperature changes late based on the heat conduction time constant of the heat transfer path up to the point. Therefore, by setting the temperature sensor 8 near the electric circuit and setting the delay time of the delay circuit 13 based on the heat conduction time constant, the temperature change of the shutter 1 and the temperature sensor 8 output from the delay circuit 13 Since the measured temperature change is closer, the temperature estimation circuit 9 can estimate the temperature of the shutter 1 with higher accuracy using the estimated temperature table 11. The same applies to the case where the infrared imaging device 100 is installed at a place where the environmental temperature change is large and the temperature sensor 8 is installed on the inner wall of the housing 20.

  FIG. 8 is a block diagram showing another configuration of the infrared imaging device in the second embodiment of the present invention. In the infrared imaging device 100 of FIG. 7, the temperature estimation circuit 9 having the estimated temperature table 11 includes the delay circuit 13. However, in the infrared imaging device 100 of FIG. 8, the temperature estimation circuit 9 having the estimated temperature calculation circuit 12 is The difference is that the delay circuit 13 is provided. Even when the temperature estimation circuit 9 includes the estimated temperature calculation circuit 12 as shown in FIG. 8, the operation of the delay circuit 13 is the same as that of the infrared imaging device 100 shown in FIG. 7 and the delay time of the delay circuit 13 is also It can be determined in the same manner as the infrared imaging device 100 shown in FIG.

  As described above, in the infrared imaging device 100 shown in the second embodiment of the present invention, the temperature change inside the infrared imaging device 100 is large, and the environmental temperature change in the place where the infrared imaging device 100 is installed is Even when used for a large application, the surface temperature of the shutter 1 can be accurately estimated, and the error of the offset calibration value calculated by the temperature correction unit 52 can be reduced.

Third Embodiment
FIG. 9 is a block diagram showing an infrared imaging apparatus according to Embodiment 3 of the present invention. FIG. 10 is a schematic cross-sectional view showing the infrared imaging device in Embodiment 3 of the present invention. In FIGS. 9 and 10, the same reference numerals as those in FIGS. 1, 2, 3 and 4 indicate the same or corresponding configurations, and the description thereof will be omitted. The second embodiment differs from the first embodiment in the configuration in which two temperature sensors are provided, and the temperature estimation circuit estimates the surface temperature of the shutter 1 from the temperatures measured by the two temperature sensors. The other configuration and operation are the same as those of the infrared imaging device described in the first embodiment, and thus the description thereof is omitted.

  As shown in FIG. 9, the infrared imaging device 100 according to the third embodiment includes a first temperature sensor 8a and a second temperature sensor 8b. As shown in FIG. 10, the first temperature sensor 8a is provided, for example, next to the infrared sensor 3 on the substrate 25, and the second temperature sensor 8b is provided, for example, on the inner wall of the housing 20. The place where the first temperature sensor 8a and the second temperature sensor 8b are provided is not limited to the place shown in FIG. 10, but as described in the first embodiment, it is inside the casing 20 of the infrared imaging device 100. It may be provided in a fixed portion made of a non-optical member, and in particular, it is desirable to be provided in a fixed portion made of a non-optical member located at a distance smaller than the width of the shutter 1 from the center of the shutter 1. Further, as shown in FIG. 10, it is desirable that the first temperature sensor 8 a and the second temperature sensor 8 b be provided with the shutter 1 interposed therebetween. That is, when the first temperature sensor 8a is provided on the inner side (the infrared sensor 3 side) than the shutter support portion 22, the second temperature sensor 8b is provided on the outer side (the opening window 23 side) than the shutter support portion 22. Is desirable.

  The main factors of the temperature change of the infrared imaging device 100 are the temperature change of the environment where the infrared imaging device 100 is installed and the temperature change inside the infrared imaging device 100 centering on the heat generation of the electric circuit including the infrared sensor 3 It is. Therefore, as shown in FIG. 10, by providing the first temperature sensor 8a inside the shutter support 22 and the second temperature sensor 8b outside the shutter support 22, the temperature of the infrared imaging device 100 changes. Also, the temperature estimation circuit 9 can accurately estimate the surface temperature of the shutter 1.

  The temperature measured by the first temperature sensor 8a and the temperature measured by the second temperature sensor 8b are input to the temperature estimation circuit 9, and the temperature estimation circuit 9 measures the temperature measured by the first temperature sensor 8a and the second temperature sensor 8b. The surface temperature of the shutter 1 is estimated based on the selected temperature. For example, the temperature estimation circuit 9 may estimate the surface temperature of the shutter 1 by averaging the temperature measured by the first temperature sensor 8 a and the temperature measured by the second temperature sensor 8 b. Here, the average may be a simple average of the temperature measured by the first temperature sensor 8a and the temperature measured by the second temperature sensor 8b, or the temperature measured by the first temperature sensor 8a and the second temperature sensor 8b May be a weighted average weighted to one of the temperatures measured. For example, the distance between the first temperature sensor 8 a and the shutter 1 is closer than the distance between the second temperature sensor 8 b and the shutter 1, and the temperature measured by the first temperature sensor 8 a is the shutter 1. If the temperature is closer to the surface temperature, the temperature measured by the first temperature sensor 8a may be weighted and averaged.

  FIG. 11 is a block diagram showing the configuration of another infrared imaging device according to Embodiment 3 of the present invention. The difference from the block diagram showing the configuration of the infrared imaging device 100 shown in FIG. 8 is that the temperature estimation circuit 9 has an estimated temperature table 11. The infrared imaging device 100 shown in FIG. 11 is an example specifically showing the configuration of the temperature estimation circuit 9 in the infrared imaging device shown in FIG.

  The estimated temperature table 11 of the infrared imaging device 100 of FIG. 11 has a data structure different from the estimated temperature table of the infrared imaging device shown in FIG. 5 of the first embodiment. That is, since the infrared imaging device shown in FIG. 5 of the first embodiment has one temperature sensor, the temperature measured by the temperature sensor and the surface temperature of the shutter 1 are one-to-one correlated. It has an estimated temperature table of the array. On the other hand, since the infrared imaging device 100 shown in FIG. 11 of the third embodiment has two temperature sensors, the first temperature sensor 8a and the second temperature sensor 8b, the shutter estimated by the temperature estimation circuit 9 The estimated temperature table 11 has a surface temperature of 1 as an element of a two-dimensional array. That is, when the surface temperature of the shutter 1 is TS, the temperature measured by the first temperature sensor 8a is T1, the temperature measured by the second temperature sensor 8b is T2, and the estimated temperature table 11 is a two-dimensional array EST, TS = EST (T1, T2). The temperature estimation circuit 9 estimates the surface temperature of the shutter 1 with reference to the estimated temperature table 11 from the temperature measured by the first temperature sensor 8a and the temperature measured by the second temperature sensor 8b. The surface temperature is output to the temperature correction unit 52 of the correction circuit 5. As a result, as described in the first embodiment, the temperature correction unit 52 can calculate the offset calibration value using the surface temperature of the shutter 1.

  The data of the estimated temperature table 11 is written to the estimated temperature table 11 in the temperature estimation circuit 9 in the adjustment process at the time of production. The data generation method of the estimated temperature table 11 will be described below.

  With the infrared imaging device 100 closed, the infrared imaging device 100 is installed in a constant temperature bath, and the surface temperature of the shutter 1 of the infrared imaging device 100, the temperature measured by the first temperature sensor 8a, and the second temperature sensor 8b At the same time, the recorded temperature is recorded by a data logger or the like. As described in the first embodiment, the surface temperature of the shutter 1 may be measured by a contact temperature sensor such as a thermocouple or a noncontact temperature sensor such as a radiation thermometer. In addition, a wire is provided for extracting the temperature measured by the first temperature sensor 8a and the temperature measured by the second temperature sensor 8b from the inside to the outside of the infrared imaging device 100, and the temperature data output from this wire is recorded by the data logger. You may

  A method of operating a thermostatic chamber for generating data relating the surface temperature of the shutter 1, the temperature measured by the first temperature sensor 8a, and the temperature measured by the second temperature sensor 8b is different from that of the first embodiment. . In the data generation method of the first embodiment, the temperature data is recorded after the temperatures of the infrared imaging device and the thermostatic chamber are sufficiently stabilized, but the data written to the estimated temperature table 11 of the third embodiment is Temperature data on the way of the constant temperature bath and the temperature of the infrared imaging device 100 are also recorded.

  As described above, the infrared imaging device 100 according to the third embodiment is configured to estimate the surface temperature of the shutter 1 using the temperature measured by the first temperature sensor 8 a and the temperature measured by the second temperature sensor 8 b. I have to. That is, for one temperature measured by the first temperature sensor 8a, the plurality of temperatures measured by the second temperature sensor 8b and the surface temperature of the shutter 1 corresponding to the respective temperatures measured by the second temperature sensor 8b are Similarly, for one temperature measured by the second temperature sensor 8b, the plurality of temperatures measured by the first temperature sensor 8a correspond to the respective temperatures measured by the second temperature sensor 8b. There is a surface temperature of the shutter 1. That is, the surface temperature data of the shutter 1 associated with the temperature measured by the first temperature sensor 8a and the temperature measured by the second temperature sensor 8b are in a two-dimensional array.

  Such temperature data of a two-dimensional array can be acquired by keeping the temperature of the environment measured by one of the temperature sensors constant and changing the temperature of the environment measured by the other temperature sensor. For example, in the case of the infrared imaging device 100 shown in FIG. 10, when the power is turned on, the electric circuit of the infrared imaging device 100 generates heat, so the temperature of the place where the first temperature sensor 8a is installed is transient. To rise. A plurality of temperature data can be measured by measuring this transiently rising temperature with the first temperature sensor 8a as needed. Further, when the set temperature of the thermostatic chamber is changed or the wind is applied from the outside of the infrared imaging device 100, the temperature of the housing 20 is transiently changed. A plurality of temperature data can be measured by measuring the transiently changing temperature with the second temperature sensor 8b as needed.

  The data acquisition method of the estimated temperature table 11 will be described more specifically. As in the first embodiment, the temperature setting of the thermostatic chamber is set in steps of 0.1 ° C from -20 ° C to 60 ° C, and after the temperature of the thermostatic chamber is stabilized, the infrared imaging device 100 is turned on to perform infrared imaging The surface temperature of the shutter 1, the temperature measured by the first temperature sensor 8a, and the temperature measured by the second temperature sensor 8b are recorded while the temperature of the device 100 rises due to heat generation from the electric circuit. Thus, for example, in the case of the infrared imaging device 100 in which the first temperature sensor 8a is provided on the substrate and the second temperature sensor 8b is provided inside the housing 20 as shown in FIG. 10, the second temperature sensor 8b is For one measured temperature, data of the temperatures measured by the plurality of first temperature sensors 8a and the surface temperature of the shutter 1 for each temperature can be obtained.

  Also, after a sufficient time has passed since the infrared imaging device 100 was turned on, the set temperature of the thermostat changes from -20 ° C to 60 ° C, and the temperature of the thermostat changes from -20 ° C to 60 ° C. The surface temperature of the shutter 1, the temperature measured by the first temperature sensor 8a, and the temperature measured by the second temperature sensor 8b may be recorded to generate data. Furthermore, while changing the wind speed to the infrared imaging device 100 and applying a wind, the surface temperature of the shutter 1, the temperature measured by the first temperature sensor 8a, and the temperature measured by the second temperature sensor 8b are recorded and data are recorded. May generate. By recording the surface temperature of the shutter 1, the temperature measured by the first temperature sensor 8a, and the temperature measured by the second temperature sensor 8b while changing the conditions as described above, the estimated temperature table 11 of the two-dimensional array is obtained. Data can be generated.

  When the number of temperatures measured by the first temperature sensor 8a is n1 and the number of temperatures measured by the second temperature sensor 8b is n2, the two-dimensional array of data of the estimated temperature table 11 is a two-dimensional array. Although there may be data of the surface temperature of the n1 × n2 shutters 1, in the above method, when the temperature to be measured by one of the temperature sensors is determined, the temperature of the place where the other temperature sensor is installed reaches Because there is an impossible temperature, n1 × n2 data can not be obtained. However, such an unreachable temperature is a temperature that can not be reached even when the infrared imaging device 100 is actually used, so data is generated only at the temperature obtained by the above method. Good.

  As described above, in the infrared imaging device 100 shown in FIG. 11, since the temperature estimation circuit 9 has the estimated temperature table 11 formed of a two-dimensional array, the temperature change inside the infrared imaging device 100, the infrared imaging device Even when the temperature change of the environment where 100 is installed is large, the temperature estimation circuit 9 refers to the estimated temperature table 11 using the temperatures measured by the first temperature sensor 8a and the second temperature sensor 8b. The surface temperature of the shutter 1 can be estimated. As a result, since the surface temperature of the shutter 1 estimated by the temperature estimation circuit 9 is output to the temperature correction unit 52 of the correction circuit 5, the temperature correction unit 52 can calculate an offset calibration value with a small error.

  FIG. 12 is a block diagram showing another configuration of the infrared imaging device of the third embodiment of the present invention. The infrared imaging device 100 of FIG. 12 is different in the configuration in which the temperature estimation circuit includes the estimated temperature calculation circuit 12 instead of the estimated temperature table. The infrared imaging device 100 shown in FIG. 12 is an example specifically showing the configuration of the temperature estimation circuit 9 in the infrared imaging device shown in FIG.

  The estimated temperature calculation circuit 12 converts an approximate expression representing the relationship between the temperature measured by the first temperature sensor 8a and the temperature measured by the second temperature sensor 8b and the surface temperature of the shutter 1 into the program of the digital arithmetic circuit or microcomputer. Is a circuit realized by the description of Since the variables of the approximate expression are two, the temperature measured by the first temperature sensor 8a and the temperature measured by the second temperature sensor 8b, the approximate expression is an approximate expression representing a surface. The data acquisition method for deriving the approximate expression may be the same as the data generation method of the estimated temperature table 11 of the infrared imaging device 100 of FIG. 11 described above.

  The infrared imaging device 100 using the estimated temperature calculation circuit 12 as shown in FIG. 12 has temperatures measured by the first temperature sensor 8a and the second temperature sensor 8b as compared with the case where the estimated temperature table 11 shown in FIG. 11 is used. Since the offset calibration value can be obtained with a smaller resolution when the relationship between the surface temperature of the shutter 1 and the surface temperature of the shutter 1 is expressed by a relatively simple approximate expression such as an ellipse, the error of the offset calibration value is smaller. It has the merit of being able to

  As described above, according to the infrared imaging device 100 of the third embodiment, the temperature estimation circuit 9 is a shutter using two temperatures, the temperature measured by the first temperature sensor 8a and the temperature measured by the second temperature sensor 8b. Since the surface temperature of 1 is estimated, the start and stop of the infrared imaging device 100 are frequently performed, and the temperature change of the inside of the infrared imaging device 100 is large, and the temperature change of the environment where the infrared imaging device 100 is installed The temperature estimation circuit 9 can accurately estimate the surface temperature of the shutter 1 even in a large application. As a result, since the surface temperature of the shutter 1 with a small error is input to the temperature correction circuit 52, an effect that the error of the offset calibration value calculated by the temperature correction circuit 52 can be reduced can be obtained.

Fourth Embodiment
FIG. 13 is a block diagram showing the configuration of the infrared imaging device in the fourth embodiment of the present invention. The infrared imaging device 100 of FIG. 13 is the same as the infrared imaging device of FIG. 11 shown in the third embodiment, except that the temperature estimation circuit 9 corresponds to the first temperature sensor 8a and the second temperature sensor 8b. The structure provided with 13a and the 2nd delay circuit 13b differs. The infrared imaging device 100 of FIG. 13 corresponds to the infrared imaging device of FIG. 7 shown in the second embodiment, in which two temperature sensors, the first temperature sensor 8a and the second temperature sensor 8b, are used. The configuration differs in that the temperature estimation circuit 9 includes two delay circuits, a first delay circuit 13a and a second delay circuit 13b respectively corresponding to the first temperature sensor 8a and the second temperature sensor 8b. The other configurations and operations are the same as those of the infrared imaging device described in the first to third embodiments, and thus the description thereof is omitted.

  The infrared imaging device 100 of the present invention is suitable for applications where the temperature change of the environment or the temperature change inside the infrared imaging device is larger or the temperature change is quicker than the infrared imaging device described in the third embodiment. .

  In the fourth embodiment, the temperature estimation circuit 9 includes the first delay circuit 13a and the second delay circuit 13b respectively corresponding to the first temperature sensor 8a and the second temperature sensor 8b. When one of the first temperature sensor 8a and the second temperature sensor 8b is provided in a place where the temperature change is smaller than the other, only one of the first delay circuit 13a or the second delay circuit 13b is provided. It is also good.

  As shown in FIG. 13, the temperature estimation circuit 9 of the infrared imaging device 100 has a first delay circuit 13a and a second delay circuit 13b, and the temperature measured by the first temperature sensor 8a corresponds to the first delay circuit 13a. The temperature measured by the second temperature sensor 8b is input to the second delay circuit 13b. As described in the second embodiment, the first delay circuit 13a and the second delay circuit 13b may be, for example, low-pass filters configured by digital circuits, or may be delay circuits of another form. Further, as described in the second embodiment, the delay time of the first delay circuit 13a and the second delay circuit 13b is a time constant of heat conduction of each heat transfer path from the place where each temperature sensor is installed to the shutter 1 It should be decided according to

  The temperature measured by the first temperature sensor 8 a and the temperature measured by the second temperature sensor 8 b are delayed for a predetermined time by the first delay circuit 13 a and the second delay circuit 13 b, and are input to the estimated temperature table 11. For example, the first delay circuit 13a delays the temperature measured by the first temperature sensor 8a by a predetermined frame unit time and outputs it to the estimated temperature table 11, and the second delay circuit 13b outputs the second temperature sensor 8b. The measured temperature is output to the estimated temperature table 11 by delaying the measured temperature by a time different from or in the same predetermined frame unit as the first delay circuit 13 a. As a result, as described in the second embodiment, the infrared imaging device 100 according to the third embodiment of the present invention is used even when the temperature change in the place where each temperature sensor is installed is large. Since the delay time of each delay circuit is set according to the heat conduction time constant of the heat transfer path between the location where each temperature sensor is installed and the shutter 1, the surface temperature of the shutter 1 is estimated with higher accuracy. can do. As a result, the error of the surface temperature of the shutter 1 estimated by the temperature estimation circuit 9 becomes smaller, and the error of the offset calibration value calculated by the temperature correction unit 52 of the correction circuit 5 becomes smaller.

  FIG. 14 is a block diagram showing another configuration of the infrared imaging device in the fourth embodiment of the present invention. In the infrared imaging device 100 of FIG. 13, the temperature estimation circuit 9 having the estimated temperature table 11 includes the first delay circuit 13 a and the second delay circuit 13 b. However, the infrared imaging device 100 of FIG. The difference is that the temperature estimation circuit 9 having T.12 includes the first delay circuit 13a and the second delay circuit 13b. Even when the temperature estimation circuit 9 has the estimated temperature calculation circuit 12 as shown in FIG. 14, the operations of the first delay circuit 13a and the second delay circuit 13b are the same as those of the infrared imaging device 100 shown in FIG.

  As described above, the infrared imaging device 100 shown in the fourth embodiment of the present invention has a large change in the temperature inside the infrared imaging device 100 and a large change in the environmental temperature in the place where the infrared imaging device 100 is installed. Even when used in applications, it is possible to accurately estimate the surface temperature of the shutter 1 and obtain an offset calibration value with a small error.

Reference Signs List 1 shutter 2 lens 3 infrared sensor 4 A / D converter 5 correction circuit, 51 signal correction unit, 52 temperature correction unit 8 temperature sensor, 8a first temperature sensor, 8b second temperature sensor 9 temperature estimation circuit 11 estimated temperature table 12 Estimated temperature calculation circuit 13 delay circuit 13a first delay circuit 13b second delay circuit 20 housing 21 lens barrel 22 shutter support portion

Claims (11)

A housing having a window through which infrared light is incident from the outside;
A shutter support provided inside the housing;
A movable portion that is supported by the shutter support portion and is an openable shutter that shields infrared rays incident from the window in a closed state;
An infrared sensor, provided inside the housing, for detecting infrared light incident from the window when the shutter is open, and detecting infrared light emitted by the shutter when the shutter is closed;
A first temperature sensor provided on a fixed part inside the housing and measuring the temperature of the provided place;
A temperature estimation circuit for estimating the temperature of the shutter based on the measurement result of the first temperature sensor;
Based on the difference between the estimated shutter temperature estimated by the temperature estimation circuit when the output signal of the infrared sensor is converted to the object temperature and the shutter is closed, and the shutter imaging temperature obtained by converting the output signal of the infrared sensor A correction circuit which calculates an offset calibration value and calibrates the object temperature based on the offset calibration value;
Bei to give a,
When the measurement result of the first temperature sensor is input, the temperature estimation circuit determines the temperature based on an estimated temperature table in which the temperature of the place where the first temperature sensor is provided is associated with the temperature of the shutter in advance. An infrared imaging device for estimating the temperature of the shutter . A housing having a window through which infrared light is incident from the outside;
A shutter support provided inside the housing;
A movable portion that is supported by the shutter support portion and is an openable shutter that shields infrared rays incident from the window in a closed state;
An infrared sensor, provided inside the housing, for detecting infrared light incident from the window when the shutter is open, and detecting infrared light emitted by the shutter when the shutter is closed;
A first temperature sensor provided on a fixed part inside the housing and measuring the temperature of the provided place;
A temperature estimation circuit for estimating the temperature of the shutter based on the measurement result of the first temperature sensor;
Based on the difference between the estimated shutter temperature estimated by the temperature estimation circuit when the output signal of the infrared sensor is converted to the object temperature and the shutter is closed, and the shutter imaging temperature obtained by converting the output signal of the infrared sensor A correction circuit which calculates an offset calibration value and calibrates the object temperature based on the offset calibration value;
Equipped with
The temperature estimation circuit, when the measurement result of the first temperature sensor is input, the shutter based on an approximate expression representing the relationship between the temperature of the place where the first temperature sensor is provided and the temperature of the shutter. An infrared imaging device comprising an estimated temperature calculation circuit for estimating the temperature of The inside of the housing includes a substrate provided with at least one of the infrared sensor, the temperature estimation circuit, and the correction circuit.
The fixed portion first temperature sensor is provided, the substrate, an infrared imaging apparatus according to claim 1 or 2 which is either the inner wall of the shutter supporting portion or the housing. A lens provided between the window and the infrared sensor, and a lens barrel supporting the lens;
The fixed portion first temperature sensor is provided an infrared imaging device according to claim 1 or 2 which is the barrel. The infrared sensor is configured by arranging infrared detection elements in a two-dimensional plane, and each of the infrared detection elements outputs a signal.
The infrared imaging device according to any one of claims 1 to 4 , wherein the offset calibration value is calculated by averaging each signal output from the infrared detection element. The infrared imaging device according to claim 5 , wherein the offset calibration value is calculated based on a signal output from the infrared detection element in one frame period. The infrared imaging device according to any one of claims 1 to 6 , wherein the first temperature sensor is provided at a position closer to the center than the position separated from the center of the shutter by the same distance as the width of the shutter. A housing having a window through which infrared light is incident from the outside;
A shutter support provided inside the housing;
A movable portion that is supported by the shutter support portion and is an openable shutter that shields infrared rays incident from the window in a closed state;
An infrared sensor, provided inside the housing, for detecting infrared light incident from the window when the shutter is open, and detecting infrared light emitted by the shutter when the shutter is closed;
A first temperature sensor provided on a fixed portion inside the housing;
A temperature estimation circuit for estimating the temperature of the shutter based on the measurement result of the first temperature sensor;
Based on the difference between the estimated shutter temperature estimated by the temperature estimation circuit when the output signal of the infrared sensor is converted to the object temperature and the shutter is closed, and the shutter imaging temperature obtained by converting the output signal of the infrared sensor A correction circuit which calculates an offset calibration value and calibrates the object temperature based on the offset calibration value;
Equipped with
A first delay circuit that delays the measurement result of the first temperature sensor based on a heat conduction time constant of a heat transfer path between a location where the first temperature sensor is provided and the shutter. Infrared imaging device equipped with The infrared imaging device according to any one of claims 1 to 8 , further comprising a second temperature sensor provided in a fixing portion inside the casing. The infrared imaging device according to claim 9 , wherein the first temperature sensor is provided closer to the infrared sensor than the shutter support portion, and the second temperature sensor is provided closer to the window than the shutter support portion. A housing having a window through which infrared light is incident from the outside;
A shutter support provided inside the housing;
A movable portion that is supported by the shutter support portion and is an openable shutter that shields infrared rays incident from the window in a closed state;
An infrared sensor, provided inside the housing, for detecting infrared light incident from the window when the shutter is open, and detecting infrared light emitted by the shutter when the shutter is closed;
A first temperature sensor provided on a fixed portion inside the housing;
A temperature estimation circuit for estimating the temperature of the shutter based on the measurement result of the first temperature sensor;
Based on the difference between the estimated shutter temperature estimated by the temperature estimation circuit when the output signal of the infrared sensor is converted to the object temperature and the shutter is closed, and the shutter imaging temperature obtained by converting the output signal of the infrared sensor A correction circuit which calculates an offset calibration value and calibrates the object temperature based on the offset calibration value;
Equipped with
It further comprises a second temperature sensor provided on a fixed part inside the housing,
A second delay circuit for delaying a measurement result of the second temperature sensor based on a heat conduction time constant of a heat transfer path between a location where the second temperature sensor is provided and the shutter; An infrared imaging device further comprising

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