JP2008187254A - Infrared imaging device and output value calculation method of imaging device - Google Patents

Abstract

An infrared imaging device and an imaging element output value calculation method capable of reducing fixed pattern noise on an image due to a temperature change and reducing the frequency of NUC processing.
A weighting unit calculates a weighted temperature Tc with respect to each of a package temperature Tp and a lens barrel temperature Ts by an expression of Tc = α × Tp + β × Ts, and multiplies the calculated weighted temperature. 26. The multiplying unit 26 multiplies the temperature Tc by the gradient Aij that is the temperature characteristic of the image sensor, and outputs the multiplication result Tc × Aij to the subtracting unit 25. The subtracting unit 25 subtracts Tc × Aij from the output value Uij of the image sensor, corrects the output value Vij of the image sensor, and outputs the corrected output value Vij to the NUC processing unit 28. In this case, the corrected output value Vij is expressed as Vij = Uij−Tc × Aij. Note that i and j indicate the position of the image sensor.
[Selection] Figure 2

Description

  The present invention relates to an infrared imaging device and an image sensor output value calculation method capable of reducing fixed pattern noise in an image due to a temperature change of the infrared imaging device.

  An infrared camera (infrared imaging device) that collects infrared light emitted from an object at night to acquire an image has an image sensor such as an uncooled bolometer arranged in a two-dimensional array. The infrared light (far-infrared light) acquired in step 1 is converted into an electrical signal and output.

  However, there are variations (non-uniformity) in the characteristics of each image sensor, and the ambient temperature changes with the passage of time immediately after using the device, causing an offset or drift in the output of the image sensor, which is fixed to the image. The noise pattern is superimposed and the image quality of the video deteriorates.

  For this reason, in order to stabilize the image quality, the conventional infrared imaging device has a plate-like shutter with a substantially uniform temperature distribution on the surface that can be opened and closed between the condenser lens and the imaging device, and the shutter is closed. In this state, NUC (Non-Uniformity Correction) processing is performed to correct the offset of the output value of the image sensor and to correct the non-uniformity of sensitivity that differs for each image sensor.

Further, as a method of correcting the output value of the image sensor, in order to prevent the invalid incident light component incident on the image sensor from the lens barrel from fluctuating due to the fluctuation of the environmental temperature of the apparatus, the output of the image sensor is prevented in advance. An infrared imaging device has been proposed in which the relationship between the output value of the image sensor with respect to the temperature data of the lens barrel is stored as a correction value, and the correction value is subtracted from the output value of the image sensor (see Patent Document 1).
Japanese Patent No. 2680879

  However, in the conventional infrared imaging device, when the ambient temperature changes, the output value of the imaging device is offset. Therefore, it is necessary to frequently perform NUC processing not only when the device is turned on but also during use. there were. For this reason, every time the NUC process is performed, if the shutter is closed, the video is interrupted, and a necessary video cannot be obtained. In particular, in the case of an infrared imaging device mounted on a vehicle, it is necessary to continuously acquire images for safe driving, and it has been desired to reduce the frequency of NUC processing.

  Further, in the infrared imaging device of Patent Document 1, although the output value of the imaging element can be corrected for the temperature change of the lens barrel, the imaging element is effective even when the temperature change of the lens barrel is not large. In some cases, an offset of the output value occurred. This is because the temperature change of the image sensor is kept almost constant by the action of the mounted Peltier element, but is considered to be affected by the heat from the package housing the image sensor, It has been desired to reduce fixed pattern noise on video.

  The present invention has been made in view of such circumstances, and by adding or subtracting the fluctuation of the output value due to the temperature change of the image sensor surface from the output value of the image sensor, the fixed pattern to the image due to the temperature change. It is an object of the present invention to provide an infrared imaging apparatus and an imaging element output value calculation method that can reduce noise and reduce the frequency of NUC processing.

  An infrared imaging device according to a first aspect of the present invention is an infrared imaging device that includes a plurality of imaging elements and acquires imaging data based on an output value of the imaging element, and detects the temperature of the imaging element surface. Temperature detection means; storage means for storing first fluctuation information indicating fluctuations in the output value of the imaging element with respect to the temperature of the imaging element surface; first fluctuation information stored in the storage means; and the imaging element surface Based on the temperature detected by the temperature detection means, a calculation means for calculating the fluctuation amount of the output value of the imaging element, and an addition / subtraction for adding or subtracting the fluctuation amount calculated by the calculation means from the output value of the imaging element And imaging data is acquired based on the output value added or subtracted by the addition / subtraction means.

  An infrared imaging device according to a second aspect of the present invention is an infrared imaging device that includes a plurality of imaging elements and acquires imaging data based on an output value of the imaging element. A lens barrel temperature detecting means for detecting the temperature of the cylinder, a storage means for storing second fluctuation information indicating a fluctuation in the output value of the imaging element with respect to the temperature of the lens barrel, and a second memory stored in the memory means Based on variation information and the temperature detected by the lens barrel temperature detection unit, a calculation unit that calculates a variation of the output value of the image sensor, and a variation calculated by the calculation unit from the output value of the image sensor And an addition / subtraction means for adding or subtracting the image data, and the imaging data is acquired based on the output value added or subtracted by the addition / subtraction means.

  An infrared imaging device according to a third aspect of the invention is an infrared imaging device that includes a plurality of imaging elements and acquires imaging data based on output values of the imaging elements, and that detects the temperature of the imaging element surface. A temperature detection unit; a lens barrel that holds a condenser lens; a lens barrel temperature detection unit that detects a temperature of the lens barrel; and a first that indicates fluctuations in the output value of the image sensor with respect to the temperature of the surface of the image sensor. First storage means for storing fluctuation information, second storage means for storing second fluctuation information indicating fluctuations in the output value of the imaging device with respect to the temperature of the lens barrel, and first storage means stored in the first storage means Based on the fluctuation information of 1 and the temperature detected by the imaging element surface temperature detection means, a first calculation means for calculating the fluctuation amount of the output value of the imaging element, and a second storage stored in the second storage means Fluctuation information and the lens barrel temperature detecting means Based on the detected temperature, second calculation means for calculating a fluctuation amount of the output value of the imaging element, and a first calculation part for adding or subtracting the fluctuation amount calculated by the first calculation means from the output value of the imaging element. 1 addition / subtraction means, and second addition / subtraction means for adding or subtracting the fluctuation calculated by the second calculation means from the output value of the image sensor, and adding or subtracting by the first addition / subtraction means and the second addition / subtraction means The imaging data is obtained on the basis of the output value thus obtained.

  An infrared imaging device according to a fourth invention, according to any one of the first invention to the third invention, weighting means for weighting the temperature detected by the imaging device surface temperature detection means and / or the lens barrel temperature detection means, And a fluctuation amount calculating means for calculating a fluctuation amount of the output value of the image sensor based on the temperature weighted by the weighting means.

  An output value calculation method for an image sensor according to a fifth aspect of the present invention is the output value calculation method for calculating output values of a plurality of image sensors provided in an infrared imaging device, wherein the output of the image sensor with respect to the temperature of the surface of the image sensor First variation information indicating variation in value is stored in advance, the temperature of the surface of the image sensor is detected, and based on the stored first variation information and the detected temperature, the variation of the output value of the image sensor is calculated. The output value of the image sensor is calculated by calculating and adding or subtracting the variation from the output value of the image sensor.

  An output value calculation method for an image sensor according to a sixth aspect of the present invention is the output value calculation method for calculating the output values of a plurality of image sensors provided in an infrared imaging device, wherein the output value is calculated with respect to the temperature of the lens barrel holding the condenser lens. Second variation information indicating variation in the output value of the image sensor is stored in advance, the temperature of the lens barrel is detected, and the output value of the image sensor is determined based on the stored second variation information and the detected temperature. The variation is calculated, and the output value of the image sensor is calculated by adding or subtracting the variation from the output value of the image sensor.

  According to a seventh aspect of the present invention, there is provided an output value calculation method for an image sensor, wherein the output value of the image sensor is calculated with respect to the temperature of the surface of the image sensor. First variation information indicating variation in value and second variation information indicating variation in the output value of the image sensor with respect to the temperature of the lens barrel holding the condenser lens are stored in advance, and the temperature of the image sensor surface and the temperature The temperature of the lens barrel is detected, and based on the stored first variation information and second variation information and each detected temperature, the variation of the output value of the image sensor is calculated, and the output value of the image sensor is calculated. The output value of the image sensor is calculated by adding or subtracting the variation.

  In the first invention, the third invention, the fifth invention, and the seventh invention, the first variation information indicating the variation of the output value of the image sensor with respect to the temperature of the surface of the image sensor is stored in advance. The temperature of the imaging element surface is detected, and the fluctuation amount of the output value of the imaging element is calculated based on the stored first fluctuation information and the detected temperature. The fluctuation amount is added or subtracted from the output value of the image sensor. That is, if the fluctuation is positive with respect to the output value of the image sensor at the detected temperature, the fluctuation is subtracted from the output value, and the fluctuation is negative with respect to the output value of the image sensor at the detected temperature. If it is a value, the output value of the image sensor is corrected by adding the fluctuation amount to the output value (that is, subtracting the negative value). The correction process can be performed at predetermined time intervals.

  Thereby, even when the detected temperature changes, the output value of the image sensor can be maintained at a substantially constant value without being affected by the temperature change. The imaging data is acquired based on the output value obtained by adding or subtracting the variation. Thereby, the offset of the output value of the image sensor due to the temperature change on the surface of the image sensor does not occur, and the fixed pattern noise on the video can be reduced. Further, for example, if the NUC process is performed only once when the power is turned on, the NUC process is repeatedly performed during use, and it is not necessary to correct the offset of the output value of the image sensor, thereby reducing the frequency of the NUC process.

  In the second invention, the third invention, the sixth invention, and the seventh invention, the second variation information indicating the variation of the output value of the image sensor with respect to the temperature of the lens barrel holding the condenser lens is stored in advance. Yes. The temperature of the lens barrel is detected, and the fluctuation amount of the output value of the image sensor is calculated based on the stored second fluctuation information and the detected temperature. The fluctuation amount is added or subtracted from the output value of the image sensor. That is, if the fluctuation is positive with respect to the output value of the image sensor at the detected temperature, the fluctuation is subtracted from the output value, and the fluctuation is negative with respect to the output value of the image sensor at the detected temperature. If it is a value, the output value of the image sensor is corrected by adding the fluctuation amount to the output value (that is, subtracting the negative value). The correction process can be performed at predetermined time intervals.

  Thereby, even when the detected temperature changes, the output value of the image sensor can be maintained at a substantially constant value without being affected by the temperature change. The imaging data is acquired based on the output value obtained by adding or subtracting the variation. Thereby, the offset of the output value of the image sensor due to the temperature change of the lens barrel does not occur, and the fixed pattern noise to the video can be reduced. Further, for example, if the NUC process is performed only once when the power is turned on, the NUC process is repeatedly performed during use, and it is not necessary to correct the offset of the output value of the image sensor, thereby reducing the frequency of the NUC process.

  In the fourth invention, the temperature detected by the image sensor surface temperature detecting means and / or the lens barrel temperature detecting means is weighted, and the fluctuation amount of the output value of the image sensor is calculated based on the weighted temperature. . For example, α is a weighting coefficient for the temperature Tp of the imaging element surface, β is a weighting coefficient for the temperature Ts of the lens barrel (α + β = 1), and the weighted temperature Tc is calculated as Tc = α × Tp + β × Ts. When calculating the variation of the output value of the image sensor, the variation of the output value of the image sensor according to the temperature change from the temperature α × Tp of the surface of the image sensor is calculated, and the temperature from the temperature β × Ts of the lens barrel A fluctuation amount of the output value of the image sensor according to the change is calculated. By adding both fluctuations, the fluctuation of the output value of the image sensor can be calculated. Alternatively, fluctuation information indicating fluctuations in the output value of the image sensor with respect to the pre-weighted temperature Tc can be stored in advance.

  Depending on how the device is mounted, the relationship between the surface of the image sensor containing the image sensor and the lens barrel, or the distance, the contact area between the two, etc. differ. The degree of influence of heat generated may be different. Even in such a case, it is possible to appropriately calculate the variation of the output value according to the degree of the influence of the temperature of the imaging element surface and the lens barrel. For example, if the influence of the temperature change of the lens barrel is negligible, β can be set to 0 and α can be set to 1. Also, the weighting coefficient can be changed as appropriate according to the mounting status of the apparatus. As a result, the output value of the image sensor can be calculated in consideration of the influence of the ambient temperature regardless of whether the device is mounted, and the degree of freedom in device design can be greatly improved.

  In the present invention, the offset of the output value of the image sensor due to the temperature change on the surface of the image sensor does not occur, and the fixed pattern noise on the video can be reduced. Further, for example, if the NUC process is performed only once when the power is turned on, the NUC process is repeatedly performed during use, and it is not necessary to correct the offset of the output value of the image sensor, thereby reducing the frequency of the NUC process.

  Hereinafter, the present invention will be described with reference to the drawings illustrating embodiments thereof. FIG. 1 is a block diagram showing a configuration of an infrared imaging device 100 according to an embodiment of the present invention. The infrared imaging device 100 includes a condenser lens 1, a lens barrel 2 that holds the condenser lens 1, a temperature sensor 4 that detects the temperature of the lens barrel 2, a plate-like shutter 3 that has a substantially uniform temperature distribution on the surface, The imaging unit 10 includes an imaging unit 10, a signal processing unit 20, an image memory 30, a communication interface unit 40, and the like. The imaging unit 10 includes a plurality of imaging elements 12 arranged in a two-dimensional array on the substrate 11, and imaging elements 12 includes a package 13 that houses the temperature 12, a temperature sensor 5 that detects the temperature of the package 13, and the like. Note that a plurality of imaging elements may be arranged in a one-dimensional array.

  The condensing lens 1 collects infrared light incident from the outside and irradiates the surface of the image sensor 12 with incident light, and is held in a cylindrical lens barrel 2. A temperature sensor 4 such as a thermocouple or a thermistor is attached to an appropriate location inside the lens barrel 2, and the temperature Ts of the lens barrel 2 is detected and output to the signal processing unit 20.

  The imaging element 12 is, for example, a bolometer type far infrared sensor, converts far infrared light having a wavelength of 7 to 14 μm into a luminance signal, and outputs the converted luminance signal to the signal processing unit 20. The image pickup device 12 is housed in, for example, a metal package 13, and the package 13 has a transmission portion through which incident light is transmitted, and a temperature such as a thermocouple or thermistor is provided at an appropriate location of the package 13. A sensor 5 is attached, and the temperature Tp of the package 13 (the surface of the image sensor 12) is detected and output to the signal processing unit 20. Note that the image sensor 12 may detect near-infrared light having a wavelength of about 0.8 to 3 μm.

  For example, a Peltier effect in which heat is transferred from one metal to the other metal by flowing a current through a joint portion (PN junction portion) of two kinds of metals is used for the substrate 11 on which the imaging element 12 is arranged. Thus, the temperature of the image sensor 12 can be kept constant. Note that the Peltier element is not essential, and the temperature can be stabilized by another method instead of the Peltier element.

  The shutter 3 is provided so as to be openable and closable between the condensing lens 1 and the image sensor 12, and the far-infrared light from the condensing lens 1 is blocked by closing the shutter 3 during calibration such as NUC processing. In addition, a uniform temperature distribution is supplied to the image sensor 12. As a result, offset correction due to variations in individual sensitivity of the image sensor 12 can be performed. Note that the configuration of the shutter 3 is not limited to a mechanical type, and may be another configuration.

  The signal processing unit 20 is configured by an LSI, converts the luminance signal input from the image capturing unit 10 into a digital signal, corrects variations in the image sensor 12, and calculates an output value (luminance signal) of the image sensor 12. Processing, defect element correction processing, gain control processing, and the like are performed, and the processed video data is stored in the image memory 30. Note that it is not essential to temporarily store the video data in the image memory 30, and the video data can be output to the outside via the communication interface unit 40. Details of the signal processing unit 20 will be described later.

  The communication interface unit 40 outputs video data to the outside via a video cable 6 compatible with an analog video system such as NTSC or a digital video system.

  FIG. 2 is a block diagram showing the configuration of the signal processing unit 20. The signal processing unit 20 includes A / D conversion units 21, 22, 23, a weighting unit 24, a subtraction unit 25, a multiplication unit 26, a storage unit 27, a NUC (Non-Uniformity Correction) processing unit 28, a timing generator 29, and the like. I have.

  The output value (luminance signal) of the image sensor 12 input from the image capturing unit 10 is converted into a digital signal by the A / D conversion unit 21, and the A / D conversion unit 21 subtracts the converted digital signal Uij. To 25. Here, i and j indicate the position in the x direction and the position in the y direction when the image sensor 12 is a two-dimensional array (x, y). Therefore, Uij is an output value of the image sensor 12 at the position (x, y) in the two-dimensional array.

  The temperature of the lens barrel 2 input from the temperature sensor 4 is converted into a digital signal by the A / D conversion unit 22, and the A / D conversion unit 22 outputs the converted digital signal Ts to the weighting unit 24. The temperature of the package 13 input from the temperature sensor 5 is converted into a digital signal by the A / D converter 23, and the A / D converter 23 outputs the converted digital signal Tp to the weighting unit 24.

  The weighting unit 24 assigns weighting coefficients α and β (α + β = 1) to the temperature Tp of the package 13 and the temperature Ts of the lens barrel 2 input from the A / D conversion units 23 and 22, respectively. The calculated temperature Tc is calculated by the equation Tc = α × Tp + β × Ts, and the calculated weighted temperature is output to the multiplication unit 26.

  The weighting coefficients α and β can be appropriately set according to the mounting status of the apparatus, the arrangement status of components, and the like. This is because the arrangement relationship between the package 13 containing the image sensor 12 and the lens barrel 2, the distance, or the contact area between the two differs depending on the mounting of the apparatus, and the degree of the influence of heat generated from the package 13, This is because the degree of influence of heat generated from the lens barrel 2 may be different. Even in such a case, the weighting coefficients α and β can be appropriately set according to the degree of the influence of the temperature of the package 13 and the lens barrel 2. For example, if the influence of the temperature change of the lens barrel 2 can be ignored, β can be set to 0 and α can be set to 1. Also, the weighting coefficient can be changed as appropriate according to the mounting status of the apparatus. As a result, the output value of the image sensor 12 can be calculated in consideration of the influence of the ambient temperature regardless of whether the device is mounted, and the degree of freedom in device design can be greatly improved. Note that the magnitude relationship between the weighting coefficients α and β is considered to be approximately α> β. This is because the package 13 is closer to the image sensor 12 than the lens barrel 2.

  FIG. 3 is an explanatory diagram showing the output of the image sensor 12 with respect to the temperature of the package 13 and the lens barrel 2. The substantially straight line indicated by “package” is a linear approximation of the change in the output of the image sensor 12 when the temperature Tp of the package 13 is changed with the temperature of the subject being constant, by the least square method or the like. A substantially straight line indicated by “lens barrel” is obtained by linearly approximating a change in the output of the image pickup element 12 when the temperature Ts of the lens barrel 2 is similarly changed by the least square method or the like. That is, the substantially straight lines indicated by “package” and “lens barrel” indicate how the output of the image sensor 12 varies due to temperature variation of the package, the lens barrel, and the like.

  Further, in FIG. 3, a straight line indicated by a broken line indicates a change in output of the image sensor 12 with respect to a temperature Tc obtained by weighting the temperature Tp of the package 13 and the temperature Ts of the lens barrel 2 with a ratio of 7: 4. That is, in this case, α = 7/11 and β = 4/11. As shown in FIG. 3, it can be seen that the output of the image sensor 12 with respect to the temperature Tc has a substantially linear characteristic by weighting. The weighting of the ambient temperature (for example, the package 13 and the lens barrel 2) varies depending on the size and material of the package 13 or the lens barrel 2, the contact area between the two, the mounting position of the temperature sensors 4 and 5, and the like. It can be determined accordingly. Further, the values of α and β may be the same value.

  FIG. 4 is an explanatory diagram showing the output of the image sensor with respect to the temperature obtained by weighting the package temperature and the lens barrel temperature. In FIG. 4, the horizontal axis represents the temperature Tc obtained by weighting the package temperature and the lens barrel temperature, and the vertical axis represents the output of the image sensor 12. In FIG. 4, Aij is linearly approximated by the method shown in FIG. 3, and represents the fluctuation of the output of the image sensor 12 with respect to the weighted change in temperature Tc, that is, the slope of the straight line. Here, i and j indicate the position in the x direction and the position in the y direction when the image sensor 12 is a two-dimensional array (x, y). Therefore, Aij is an inclination obtained by linearly approximating the temperature characteristic of the image sensor 12 at the position (x, y) in the two-dimensional array. Aij may differ for each image sensor 12 due to variations in sensitivity of the image sensors 12 and the like. That is, the output variation of the image sensor 12 due to the weighted temperature Tc variation has a characteristic represented by a straight line with a slope Aij, and a substantially linear characteristic can be obtained.

  The storage unit 27 stores temperature characteristics (output with respect to the weighted temperature Tc) Aij of the image sensor 12.

  The multiplication unit 26 multiplies the temperature Tc input from the weighting unit 24 and the gradient Aij read from the storage unit 27, and outputs the multiplication result Tc × Aij to the subtraction unit 25.

  The subtractor 25 subtracts the value Tc × Aij input from the multiplier 26 from the output value Uij of the image sensor 12 input from the A / D converter 21 to correct the output value Vij of the image sensor 12 to be corrected. The subsequent output value Vij is output to the NUC processing unit 28. The output value correction process of the image sensor 12 is performed every time a predetermined time (for example, several tens of milliseconds) elapses, and the NUC processing unit 28 stores the latest output value Vij. In the NUC process, the latest output value Vij is used. The corrected output value Vij of the image sensor 12 is expressed as Vij = Uij−Tc × Aij. Here, i and j indicate the position in the x direction and the position in the y direction when the image sensor 12 is a two-dimensional array (x, y). Therefore, Vij is an output value after correction of the image sensor 12 at the position (x, y) in the two-dimensional array. That is, by subtracting Tc × Aij from the output value Uij of the image sensor 12, the variation Tc × Aij included in the output value Uij of the image sensor 12 at the weighted temperature Tc can be subtracted.

  FIG. 5 is an explanatory diagram illustrating an example of temperature characteristics of the output value Vij of the image sensor 12 after correction. In FIG. 5, the horizontal axis represents the temperature Tc obtained by weighting the package temperature and the lens barrel temperature, and the vertical axis represents the output of the image sensor 12. As shown in FIG. 5, the output Uij before correction of the image sensor 12 fluctuates due to fluctuations in the weighted temperature Tc. For example, when the weighted temperature obtained by detecting the temperature with the temperature sensors 4 and 5 is Tc1, the corrected output value Vij of the image sensor 12 is obtained by subtracting Tc1 × Aij from the uncorrected output value Uij. Value. When the weighted temperature obtained by detecting the temperature with the temperature sensors 4 and 5 is Tc2, the corrected output value Vij of the image sensor 12 is obtained by subtracting Tc2 × Aij from the uncorrected output value Uij. Value. As a result, even if the output value of the image sensor 12 varies due to the temperature around the image sensor, only the variation in the output value due to the temperature variation can be removed. As the value Vij, only the temperature component of the subject can be extracted.

  The output value correction process of the image sensor 12 is performed based on the formula Vij = Uij−Tc × Aij, but when the weighted temperature Tc is higher than 0 ° C. (reference temperature), the output value Uij of the image sensor 12 Is subtracted by a value corresponding to Tc × Aij, and when the weighted temperature Tc is lower than 0 ° C., the output value Uij of the image sensor 12 is subtracted by a value corresponding to (−Tc × Aij). Processing, that is, addition processing (negative subtraction processing) is performed by a value corresponding to Tc × Aij.

  Note that the output value correction processing of the image sensor 12 is not limited to the above formula, and other formulas can also be used. For example, the corrected output value Vij of the image sensor 12 can be calculated by Vij = Uij− (Tc−25) × Aij. When the infrared imaging device is used in a relatively high temperature environment such as summer, the weighted temperature Tc is also a relatively high value. In this case, the variation Tc × Aij to be removed due to the temperature variation may become too large to be corrected. Therefore, by setting the reference temperature of the weighted temperature Tc from 0 ° C. to, for example, 25 ° C. (corresponding to approximately the center point of −40 to 85 ° C., which is an example of the operating temperature range of the infrared imaging device), the temperature is increased. Even if it fluctuates to the side, sufficient correction can be performed.

  The NUC processing unit 28 corrects the output value Vij (luminance signal) of the image sensor 12 input from the subtracting unit 25. In this case, the NUC processing unit 28 can use the latest value of the corrected output value Vij of the image sensor 12. The NUC processing unit 28 equalizes the output value Vij due to the variation for each image sensor 12 by averaging or the like. Note that the processing in the NUC processing unit 28 does not need to be repeated again during use, for example, by closing the shutter 3 after turning on the power and correcting the non-uniformity of the image sensor 12. This is because the output value of the image sensor 12 due to the ambient temperature is corrected as shown in FIG. 5, and a constant output value can be calculated regardless of the ambient temperature change.

  The timing generator 29 outputs a synchronization signal such as a horizontal synchronization signal and a vertical synchronization signal to each unit in the signal processing unit 20 to synchronize execution of processing of each unit.

  As described above, in the present invention, fluctuations in the output value of the image sensor 12 due to changes in the ambient temperature of the package 13 (the surface of the image sensor 12), the lens barrel 2, etc. can be deleted. The offset of the output value of the image sensor 12 due to temperature fluctuation does not occur, and fixed pattern noise on the video can be reduced. Further, for example, if the NUC process is performed only once when the power is turned on, it is not necessary to perform the NUC process repeatedly during use to correct the offset of the output value of the image sensor 12, and the frequency of the NUC process can be reduced.

  Further, by weighting the temperature of the package 13 and the temperature of the lens barrel 2, the arrangement relationship, distance, contact area, etc. between the package 13 and the lens barrel 2 differ depending on the mounting of the apparatus, and thus the light is emitted from the package 13. The degree of influence of heat and the degree of influence of heat generated from the lens barrel 2 may be different, and the heat generated from both may be related to each other. Even in such a case, it is possible to appropriately calculate the variation of the output value according to the degree of the influence of the temperature of the package 13 and the lens barrel 2. As a result, the output value of the image sensor 12 can be calculated in consideration of the influence of the ambient temperature regardless of whether the device is mounted, and the degree of freedom in device design can be greatly improved.

  In the above-described embodiment, the temperature sensor 4 is provided in the lens barrel 2. However, when the influence of heat from the lens barrel 2 can be ignored (for example, the package 13 and the lens barrel 2 are separated, and a certain amount of For example, when there is a separation dimension, the temperature sensor 4 may not be provided. In this case, the characteristic (slope of the straight line) indicated by “package” in FIG. 3 is stored, and the output value of the image sensor 12 can be corrected in the same manner as in the above-described embodiment. Conversely, it is also possible to adopt a configuration in which only the temperature sensor 4 is provided and the temperature sensor 5 is not provided.

  The configuration of the signal processing unit 20 of the above-described embodiment is an example, and the configuration is not limited to this. If the configuration represented by the expression Vij = Uij−Tc × Aij can be realized, Any configuration may be used. For example, the output characteristic of the image sensor 12 with respect to the temperature change of the package 13 as shown in FIG. 3 and the output characteristic of the image sensor 12 with respect to the temperature change of the lens barrel 2 are individually stored in the storage unit 27, and the temperature Tp, Each Ts is multiplied by weighting factors α and β, the multiplied temperature α × Tp is multiplied by the negative slope of the output characteristic of the image sensor 12 with respect to the temperature change of the package 13, and the temperature β × Ts is It is also possible to correct the output value of the image sensor 12 by multiplying the negative slope of the output characteristic of the image sensor 12 with respect to the temperature change of the lens barrel 2 and adding the both.

  The present invention is not limited to the examples.

It is a block diagram which shows the structure of the infrared imaging device which concerns on embodiment of this invention. It is a block diagram which shows the structure of a signal processing part. It is explanatory drawing which shows the output of the image pick-up element with respect to the temperature of a package and a lens-barrel. It is explanatory drawing which shows the output of the image pick-up element with respect to the temperature which weighted package temperature and lens-barrel temperature. It is explanatory drawing which shows the example of the temperature characteristic of the output value of the image sensor after correction | amendment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Condensing lens 2 Lens barrel 3 Shutter 4, 5 Temperature sensor 10 Image pick-up part 12 Image pick-up element 13 Package 20 Signal processing part 21, 22, 23 A / D conversion part 24 Weighting part 25 Subtraction part 26 Multiplication part 27 Storage part 28 NUC processing unit 29 Timing generator 30 Image memory

Claims (7)

In an infrared imaging device that includes a plurality of imaging elements and acquires imaging data based on output values of the imaging elements,
Image sensor surface temperature detecting means for detecting the temperature of the image sensor surface;
Storage means for storing first fluctuation information indicating fluctuations in the output value of the imaging element with respect to the temperature of the surface of the imaging element;
Calculation means for calculating the fluctuation amount of the output value of the image sensor based on the first fluctuation information stored in the storage means and the temperature detected by the image sensor surface temperature detection means;
Adding / subtracting means for adding or subtracting the variation calculated by the calculation means from the output value of the image sensor;
An infrared imaging apparatus configured to acquire imaging data based on an output value added or subtracted by the addition / subtraction means. In an infrared imaging device that includes a plurality of imaging elements and acquires imaging data based on output values of the imaging elements,
A lens barrel for holding a condenser lens;
A lens barrel temperature detecting means for detecting the temperature of the lens barrel;
Storage means for storing second variation information indicating variations in the output value of the imaging element with respect to the temperature of the lens barrel;
Calculation means for calculating a fluctuation amount of the output value of the image sensor based on the second fluctuation information stored in the storage means and the temperature detected by the lens barrel temperature detection means;
Adding / subtracting means for adding or subtracting the variation calculated by the calculation means from the output value of the image sensor;
An infrared imaging apparatus configured to acquire imaging data based on an output value added or subtracted by the addition / subtraction means. In an infrared imaging device that includes a plurality of imaging elements and acquires imaging data based on output values of the imaging elements,
Image sensor surface temperature detecting means for detecting the temperature of the image sensor surface;
A lens barrel for holding a condenser lens;
A lens barrel temperature detecting means for detecting the temperature of the lens barrel;
First storage means for storing first fluctuation information indicating fluctuations in the output value of the imaging element with respect to the temperature of the imaging element surface;
Second storage means for storing second fluctuation information indicating fluctuations in the output value of the imaging element with respect to the temperature of the lens barrel;
First calculation means for calculating a fluctuation amount of the output value of the image sensor based on the first fluctuation information stored in the first storage means and the temperature detected by the image sensor surface temperature detection means;
Second calculation means for calculating a fluctuation amount of the output value of the image sensor based on the second fluctuation information stored in the second storage means and the temperature detected by the lens barrel temperature detection means;
First addition / subtraction means for adding or subtracting the variation calculated by the first calculation means from the output value of the image sensor;
Second addition / subtraction means for adding or subtracting the variation calculated by the second calculation means from the output value of the image sensor;
An infrared imaging apparatus configured to acquire imaging data based on an output value added or subtracted by the first addition / subtraction means and the second addition / subtraction means. Weighting means for weighting the temperature detected by the image sensor surface temperature detecting means and / or the lens barrel temperature detecting means;
4. The red component according to claim 1, further comprising: a fluctuation component calculating unit that calculates a fluctuation component of the output value of the image sensor based on the temperature weighted by the weighting unit. 5. Outside imaging device. In an output value calculation method for calculating output values of a plurality of image sensors provided in an infrared imaging device,
Preliminarily storing first variation information indicating variations in the output value of the image sensor with respect to the temperature of the image sensor surface;
Detecting the temperature of the image sensor surface;
Based on the stored first variation information and the detected temperature, the variation of the output value of the image sensor is calculated,
An output value calculation method for an image pickup device, wherein the output value of the image pickup device is calculated by adding or subtracting the variation from the output value of the image pickup device. In an output value calculation method for calculating output values of a plurality of image sensors provided in an infrared imaging device,
Preliminarily storing second variation information indicating variation in the output value of the imaging element with respect to the temperature of the lens barrel holding the condenser lens;
Detecting the temperature of the lens barrel,
Based on the stored second variation information and the detected temperature, the variation of the output value of the image sensor is calculated,
An output value calculation method for an image pickup device, wherein the output value of the image pickup device is calculated by adding or subtracting the variation from the output value of the image pickup device. In an output value calculation method for calculating output values of a plurality of image sensors provided in an infrared imaging device,
First variation information indicating variation in the output value of the image sensor with respect to the temperature of the surface of the image sensor and second variation information indicating variation in the output value of the image sensor with respect to the temperature of the lens barrel holding the condenser lens. Remember in advance,
Detect the temperature of the image sensor surface and the temperature of the lens barrel,
Based on the stored first variation information and second variation information and each detected temperature, the variation of the output value of the image sensor is calculated,
An output value calculation method for an image pickup device, wherein the output value of the image pickup device is calculated by adding or subtracting the variation from the output value of the image pickup device.

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