JP2005043376A - Infrared picture imaging device and car equipped with it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an infrared picture imaging device mountable for cars which can inhibit temperature variation in optical system. <P>SOLUTION: In this infrared picture imaging device 200 provided on a car 220, its periphery structure 320 is filled with engine cooling water supplied from a radiator 330 of the car 220 to be circulated. Since cooling water temperature stays in nearly constant after warm-up is completed, the periphery structure 320 allows temperature of the operative infrared picture imaging device 200 to be stabilized. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention belongs to a technique related to temperature calibration in an infrared imaging apparatus and a technique for displaying an infrared image more easily.

  The infrared imaging device can remotely measure the temperature of a subject, and is used as a monitoring camera or the like for detecting a person or a car.

  FIG. 8 is a diagram showing an example of the configuration of a conventional infrared imaging device (described in Patent Document 1). The configuration of FIG. 8 is intended to calibrate the relationship between the output signal and temperature.

  In FIG. 8, the temperature characteristic correction means 1050 stores in advance the characteristics (subject temperature vs. luminance table) of the infrared detector 1010 as shown in FIG. Each graph curve 1210, 1220, 1230, and 1240 in FIG. 9 represents the relationship between the subject temperature T and the output voltage Ei of the infrared detector 1010, and the temperatures T1, T2, T3, and T4 in the vicinity of the infrared detector 1010 are shown. It is a parameter.

  The temperature measuring means 1080 measures a temperature Tx in the vicinity of the infrared detector 1010. The temperature characteristic correction unit 1050 obtains the subject temperature T from the output signal Ei of the infrared detector 1010 using the temperature Tx and the characteristic shown in FIG. If T2 <Tx <T3, the temperature characteristic correction unit 1050 creates a characteristic curve 1250 by interpolating the graph curves 1220 and 1230 corresponding to the temperatures T2 and T3, and infrared detection is performed using the characteristic curve 1250. The output signal Ei of the container 1010 is converted into the subject temperature T.

  FIG. 10 is a diagram showing another example of the configuration of a conventional infrared imaging device (described in Patent Document 2).

  In FIG. 10, optical systems 1310 and 1320 form an infrared image of a subject 1330 on an infrared detector 1340. The reference heat source A 1350 and the reference heat source B 1360 are heat sources each composed of a Peltier element, and the temperatures thereof are variable and are controlled by the controllers 1440 and 1450, respectively.

  The infrared imaging device shown in FIG. 10 images the target object during the effective scanning period, and images the reference heat source A 1350 and the reference heat source B 1360 during the invalid scanning period. The average value calculating means 1370 calculates the average value of the output of the infrared detector 1340 during the effective scanning period. The reference heat source A output calculating means 1380 calculates the average value of the output of the infrared detector 1340 when imaging the reference heat source A 1350 in the invalid scanning period, while the reference heat source output calculating means 1390 is infrared when imaging the reference heat source B 1360 in the invalid scanning period. An average value of the outputs of the detector 1340 is calculated, and the intermediate value output means 1400 outputs an intermediate value of these calculation results. The subtractor 1410 subtracts the output of the intermediate value output means 1400 from the output of the average value calculation means 1370, and the adder 1420 adds a predetermined temperature difference ΔT to the subtraction result and supplies it to the reference heat source A controller 1440, while subtracting it. The unit 1430 subtracts the temperature difference ΔT from the subtraction result and supplies it to the reference heat source B controller 1450. Controllers 1440 and 1450 perform feedback control so that the subtraction result of subtractor 1410 is zero, that is, the output of average value calculation means 1370 and the output of intermediate value output means 1400 are equal.

  By such control, even if the imaging scene changes, the temperatures of the reference heat source A 1350 and the reference heat source B 1360 change according to the average value of the temperatures of the captured images, and are always in a predetermined temperature range (average value ± ΔT). Be controlled. The correction unit 1460 obtains a correction coefficient for correcting the output variation based on the output of the infrared detector 1340 when the reference heat source A 1350 and the reference heat source B 1360 are imaged during the invalid scanning period. Thereby, temperature calibration according to the temperature range to be measured is realized.

  FIG. 11 is a diagram showing another example of the configuration of a conventional infrared imaging device (described in Patent Document 3). The configuration of FIG. 11 is intended to eliminate two-dimensional output variations.

  In FIG. 11, a first blocking unit 1510 is provided for shading correction, and a second blocking unit 1530 is provided for correcting output variation between pixels. At the time of imaging, the first and second blocking means 1510 and 1530 are opened, and infrared light incident through the optical system 1520 forms an image on the infrared detector 1540.

The first blocking means 1510 is set to a closed state about once every 30 seconds by the control means 1560 and blocks infrared rays. In this state, the inter-pixel variation correcting unit 1550 determines a shading correction value from the output of the infrared detector 1540. On the other hand, the second blocking means 1530 is also set to a closed state about once every 30 seconds by the control means 1560 to block infrared rays. In this state, the inter-pixel variation correcting unit 1550 determines a sensitivity correction value from the output of the infrared detector 1540.
JP-A-5-302855 Japanese Patent Laid-Open No. 10-111172 Japanese Patent Laid-Open No. 10-142065

  In order to obtain the temperature information of the subject with high accuracy using the infrared imaging device, it is necessary to perform two types of image correction. One is so-called temperature calibration, that is, calibration of the relationship between an output signal (luminance signal) and temperature, and the other is correction of two-dimensional output variation in an image.

  The cause of the necessity of temperature calibration includes a change in characteristics caused by a temperature change of the infrared detector itself and a change caused by a temperature change in the amount of infrared radiation from an optical system such as a lens or a lens barrel. For example, when an infrared imaging device is used outdoors, the temperature changes drastically. Therefore, even after the temperature calibration is performed, the correspondence between the temperature and the brightness is shifted from the actual one, making it difficult to see the image. End up. In addition, when it is raining, even if the same subject is imaged, the luminance level is greatly reduced due to the temperature drop.

  There are two main causes of two-dimensional output variations. One is the sensitivity variation between the pixels of the infrared detector. Due to this sensitivity variation, the infrared image becomes an image having a rough surface. The other is called lens shading. This is a phenomenon in which the amount of light received at the center of the infrared detector is uniformly higher than that at the periphery due to the nature of the optical system.

  In the conventional example of FIG. 8, the temperature near the infrared detector 1010 is measured, and the subject temperature vs. luminance table is referred to based on this temperature. However, for example, when an infrared imaging device is installed outdoors and imaging is performed, the temperature of the optical system 1020 is greatly different from the temperature in the vicinity of the infrared detector 1010, and the optical system 1020 is used during table creation and during actual imaging. The amount of infrared radiation from will vary greatly. For this reason, there has been a problem that highly accurate temperature compensation cannot always be realized.

  In the conventional example of FIG. 10, a heat source serving as a temperature calibration standard is provided between the optical systems. For this reason, for example, when an infrared imaging device is installed outdoors and imaging is performed, the temperature fluctuation of the optical system becomes severe, but calibration cannot be performed in consideration of the influence of the temperature fluctuation of the optical system. In particular, there was a problem that the infrared radiation from the optical system 1310 outside the heat source fluctuated greatly, which caused the apparent measurement temperature of the subject to fluctuate.

  In addition, in the conventional example of FIG. 11, although two blocking means are provided and the structure is complicated, it has only a two-dimensional output variation correction function, and the output signal and temperature The relationship cannot be calibrated. Further, the timing for performing the correction is fixed, and it is inappropriate for use as a surveillance camera because there is a time during which imaging cannot be performed.

  As described above, the conventional infrared image capturing apparatus cannot always realize highly accurate image correction. In particular, it becomes a big problem when used in a rapidly changing environment such as when mounted on a vehicle.

  It is an object of the present invention to realize an image correction with a simple structure and higher accuracy than the conventional one as an infrared image pickup apparatus.

  The present invention relates to an infrared imaging device for mounting on a vehicle, an infrared detector, an optical system that forms an infrared image emitted from a subject on the infrared detector, and a temperature in the vicinity of the infrared detector and the optical system. And a heat insulation structure that is stabilized by using the mechanism of the vehicle.

  According to the present invention, when the infrared imaging device is mounted on a vehicle, the temperature in the vicinity of the infrared detector and the optical system is stabilized by the heat retaining structure using the mechanism of the vehicle. This suppresses fluctuations in image quality.

  And it is preferable that the said heat retention structure circulates the engine cooling water of the said vehicle in the vicinity of the said infrared detector and an optical system.

  Moreover, this invention is provided with the infrared image imaging device as a vehicle, and the heat retention structure which stabilizes the temperature of the vicinity of the said infrared image imaging device using the mechanism of the said vehicle.

  And it is preferable that the said heat retention structure circulates the engine cooling water of the said vehicle in the vicinity of the said infrared imaging device.

(First embodiment)
FIG. 1 is a block diagram showing a configuration of an infrared image capturing apparatus according to the first embodiment of the present invention. In FIG. 1, 10 is an infrared detector such as a microbolometer that detects infrared rays, 20 is an optical system that has a lens and forms an infrared image emitted from a subject 70 on the infrared detector 10, and 30 is an infrared detector. 10 is a correction means for correcting 10 outputs. The blocking means 40 is configured to be openable and closable, and blocks infrared rays incident on the optical system 20 from the subject 70 when in the closed state. The temperature measuring unit 50 measures the surface temperature of the blocking unit 40. The control unit 60 controls the open / close state of the blocking unit 40 and the optical system 20, the correction unit 30, and the temperature measurement unit 50.

  Here, it is assumed that the infrared detector 10 is a two-dimensional area sensor having two-dimensionally arranged pixels. The temperature setting means 52 will be described later.

  Hereinafter, the operation of the infrared imaging apparatus configured as shown in FIG. 1 will be described.

  First, when the subject 70 is imaged, the blocking unit 40 is set to an open state under the control of the control unit 60. For this reason, the infrared rays radiated from the subject 70 are imaged as an infrared image on the infrared detector 10 by the optical system 20. The infrared detector 10 outputs a signal corresponding to the amount of infrared light received by each pixel. The output of the infrared detector 10 is corrected by the correction means 30. The correction unit 30 corrects sensitivity variations between pixels, DC offset variations between pixels, lens shading effects, and the influence of infrared radiation from the optical system 20.

  Next, a calibration method in the correction unit 30 will be described.

FIG. 2 is a diagram showing a model for explaining the calibration method according to the present embodiment. In the model of FIG. 2, the following values are defined for the pixel coordinates (x, y) of the infrared detector 10.
Radiation of subject 70: L0 (x, y, T0)
Radiation of optical system 20: L1 (x, y, T1)
Lens shading: S (x, y)
Output of the infrared detector 10: e (x, y) = a (x, y) Ltotal + b (x, y)
a (x, y): sensitivity of pixel (x, y) b (x, y): DC offset of pixel (x, y) Here, in the model of FIG.
e (x, y, T0)
= A (x, y). (S (x, y) .L0 (x, y, T0) + L1 (x, y, T1))
+ B (x, y) (1)

1) Determination of First Correction Coefficient Each of flat objects 70 uniformly distributed at temperatures Ta and Tb is imaged, and the difference in the output of infrared detector 10 at this time is obtained.
e (x, y, Ta) -e (x, y, Tb)
= A (x, y) .S (x, y). (L0 (x, y, Ta) -L0 (x, y, Tb))
... (2)
Further, in a narrow temperature range of normal temperature (for example, 0 to 60 ° C.), the infrared radiation L0 can be approximated by a linear function of the temperature T0 as in the following equation.
L0 (x, y, T0) = c · T0 + d (3)
c and d are constants. Substituting equation (3) into equation (2) and dividing both sides by the temperature difference (Ta−Tb) is defined as a first correction coefficient G (x, y). That is,
G (x, y) = (e (x, y, Ta) −e (x, y, Tb)) / (Ta−Tb)
= A (x, y) · S (x, y) · c (4)
Then, the obtained first correction coefficient G (x, y) is stored in the correction means 30.

  As can be seen from Equation (4), the first correction coefficient G (x, y) is proportional to the sensitivity (gain) for each pixel and the lens shading. By using the first correction coefficient G (x, y), it is possible to correct the influence of the lens shading effect and pixel sensitivity variations.

  Note that variations in pixel sensitivity are mainly caused by variations in processing dimensions at the time of manufacturing each pixel, and hardly change after the device is manufactured. Therefore, it is not necessary to periodically determine the first correction coefficient G (x, y) when the apparatus is used. In particular, when the fixed-focus optical system 20 is used, it may be determined once when the apparatus is manufactured. Good.

2) Determination of the second correction coefficient When the infrared imaging device is started up or after long-time shooting, the roughness of the image is caused by the temperature change of the optical system 20 or the subtle output variation between the pixels of the infrared detector 10 due to the temperature fluctuation. And the average luminance level fluctuates. Therefore, when such a phenomenon occurs, the control means 60 is manually activated to determine a second correction coefficient for correcting output variations between pixels.

First, the blocking means 40 is changed from the open state to the closed state by a control signal from the control means 60 to block the incidence of infrared rays on the optical system 20. Then, the average temperature Tc of the blocking means 40 is measured by the temperature measuring means 50. At this time, it is preferable that the optical system 20 is set in an out-of-focus state. Moreover, it is preferable that the interruption | blocking means 40 is a flat thing with which temperature distributed uniformly. When the focal point of the optical system 20 is focused several meters or more ahead, the image of the blocking means 40 disposed immediately in front of the optical system 20 is formed on the infrared detector 10 in a defocused state. here,
H (x, y) = Ke (x, y, Tc) / G (x, y) (5)
A second correction coefficient H (x, y) expressed by the following is obtained and stored in the correction means 30. K is a constant. That is, the second correction coefficient H (x, y) is obtained so that the output of all pixels is uniform when the temperature Tc blocking means 40 is imaged.

The second correction coefficient H (x, y) is a correction coefficient for correcting variations in DC offset between pixels and variations in the amount of infrared radiation from the optical system 20 (variations in DC components). Now, by dividing both sides of equation (1) by both sides of equation (4), the influence of lens shading and pixel sensitivity variations can be eliminated. All that remains is the effect of variations in the DC component.
e (x, y, T0) / G (x, y)
= L0 (x, y, T0) / c
+ L1 (x, y, T1) /c.S (x, y) + b (x, y) / G (x, y) (6)
In Equation (6), the first term on the right side represents the radiation of the subject 70, and the second and third terms represent DC components that vary from pixel to pixel. Of the terms representing the DC component, the term of the radiation L1 of the optical system 20 changes due to environmental fluctuations. This term changes according to the temperature T1 of the optical system 20. Therefore, it is desirable that the second correction coefficient H (x, y) is updated every time the temperature T1 of the optical system 20 changes.

3) Correction of imaging signal During imaging, the imaging signal is corrected as follows. The control means 60 opens the blocking means 40 and starts imaging the subject 70. At this time, the corrected output signal E (x, y, T0) is obtained as follows.
E (x, y, T0)
= E (x, y, T0) / G (x, y) + H (x, y) (7)
At this time,
dE / dT0 = c ² (8)
That is, the temperature of the object 70 c ² by a correction output E rises every time the up once. Since E = K when T0 = Tc,
E (x, y, T0)
= C ² · (T0−Tc) + K (9)
To organize T0,
T0 = (E (x, y, T0) −K) / c ² + Tc (10)
c ² is a constant that does not vary depending on the environment.

  The correction output signal E (x, y, T0) is such that the temperature of the optical system 20 is constant both when the second correction coefficient H (x, y) is determined and when the subject is imaged. As long as outside radiation does not fluctuate, the relationship of Expression (10) is established. That is, the corrected output signal E (x, y, T0) is a signal representing a two-dimensional temperature distribution of the subject 70 in which output variations between pixels are corrected. The correcting unit 30 converts the corrected output signal E (x, y, T0) into a video signal having a dynamic range suitable for display and outputs the video signal.

  After that, the temperature of the optical system 20 changes due to external temperature fluctuations, heat dissipation of the internal electric circuit, and the like, resulting in a rough image or an error between the actual temperature and the temperature calculated from the imaging signal. If it becomes larger, the second correction coefficient H (x, y) may be updated again by driving the control means 60. Therefore, it is desirable to start imaging the subject after the second correction coefficient H (x, y) is updated and before the temperature of the optical system 20 is substantially changed.

  Moreover, you may provide the temperature setting means 52 for setting the temperature of the interruption | blocking means 40. FIG. This temperature setting means 52 can be easily realized by a combination of a heater and a temperature detector, for example. If the temperature setting means 52 is used, the temperature Tc of the cutoff means 40 when obtaining the second correction coefficient H (x, y) can be set to a desired value. The temperature Tc of the blocking means 40 at this time is preferably set in the vicinity of the temperature of a specific imaging target (for example, “person”).

  Also, the blocking means 40 may be used when setting the first correction coefficient G (x, y). In this case, using the temperature setting means 52, the blocking means 40 may be set to the first temperature Ta and closed to take an image, and then set to the second temperature Tb and closed to take an image.

  FIG. 3 is a diagram showing a modification of the infrared image capturing apparatus according to the first embodiment of the present invention. In the configuration of FIG. 3, two blocking means 110 and 120 are provided as means for blocking infrared rays incident on the optical system 20. The temperature measuring unit 130 is configured to be able to measure the temperatures of the first and second blocking units 110 and 120, respectively.

  In the configuration of FIG. 3, the first and second blocking means 110 and 120 can be used for setting the first correction coefficient G (x, y). That is, first, the infrared detector 10 when the first blocking means 110 is closed while the second blocking means 120 is opened and the first blocking means 110 having a uniform first temperature Ta is imaged. Memorize the output. Next, when the first blocking means 110 is opened and the second blocking means is closed, the infrared detector 10 when the second blocking means 120 having a uniform second temperature Tb is imaged. Memorize the output. Then, the first correction coefficient G (x, y) may be obtained by the method described above using the stored output signal.

  It should be noted that the temperature calibration may be performed using the blocking means 40 by a method different from the correction method described in the present embodiment. By using the blocking means 40 that blocks the infrared rays incident on the optical system 20, it is possible to realize correction that takes into account the influence of the radiation of the optical system 20.

  Further, the temperature measurement means 50 may not be provided. When the temperature measuring unit 50 is not provided, the temperature Tc of the blocking unit 40 when determining the second correction coefficient H (x, y) is unknown, and therefore the temperature T0 of the subject 70 using the equation (9). Cannot be asked. However, relative temperature vs. luminance characteristics can be determined more accurately than in the past. That is, in Expression (6), the characteristic variation between pixels due to the shading of the optical system 20 is corrected by the first term on the right side, and the variation in the radiation from the optical system 20 is corrected by the second term on the right side. In this way, the shading effect and the variation in radiation from the optical system 20 can be individually corrected, so that a more accurate relative temperature-luminance characteristic can be obtained.

(Second Embodiment)
FIG. 4 is a diagram showing a schematic configuration of a vehicle equipped with an infrared imaging device according to the second embodiment of the present invention. In FIG. 4, the same reference numerals as those in FIG. An infrared imaging device 200 mounted on a vehicle 220 as a moving body shown in FIG. 4A has substantially the same configuration as that according to the first embodiment as shown in FIG. 4B. The infrared imaging device 200 is mounted so as to image the front of the vehicle 220 in the traveling direction, and is provided to detect a subject 240 (a person or other vehicle) ahead of the traveling direction. Then, the output signal of the vehicle speed sensor 230 as a means for detecting the speed of the vehicle 220 is supplied to the control means 210 of the infrared image capturing apparatus 200.

  When the infrared imaging device 200 is mounted on the vehicle 220, the temperature of the optical system 20 is likely to fluctuate because it is affected by weather, air temperature, traveling speed, and the like. Therefore, it is necessary to frequently update the second correction coefficient H (x, y) shown in the first embodiment. On the other hand, since the normal imaging operation cannot be performed while the correction coefficient is being updated, it is not preferable to frequently update the correction coefficient while the vehicle 220 is traveling.

  Therefore, in the present embodiment, the correction coefficient is updated only during the period in which the vehicle 220 is stopped or traveling at a very low speed, using the output signal of the vehicle speed sensor 230. Thus, calibration is performed only when there is almost no possibility of colliding with an obstacle, and temperature calibration can be realized without impairing the significance of providing the infrared imaging device.

  Specifically, calibration is performed in the same manner as in the first embodiment. That is, the first correction coefficient G (x, y) is obtained when the infrared imaging device 200 is manufactured. Then, when it is detected from the output signal of the vehicle speed sensor 230 that the vehicle 220 has stopped or the speed has become a predetermined value or less, the blocking means 40 is closed and the second correction coefficient H (x, y). Update.

  Even with other correction methods, it is preferable to control the timing of calibration using the output signal of the vehicle speed sensor 230, as in the present embodiment. Moreover, you may apply to mobile bodies other than a vehicle, for example, a train, a ship, an aircraft, etc.

(Third embodiment)
FIG. 5 is a diagram showing a schematic configuration of a vehicle equipped with an infrared imaging device according to the third embodiment of the present invention. In FIG. 5, the same reference numerals as those in FIG. The infrared imaging device 200 uses the configuration shown in FIG.

  In FIG. 5, the infrared imaging device 200 mounted on the vehicle 220 causes the control unit 210 to output in addition to the output signal of the vehicle speed sensor 230, the output signal of the unit 310 that identifies the signal of the traffic light in the traveling direction, The output signal of the means 340 for determining the presence or absence of a person as a detection target in the direction is received. The traffic light identifying means 310 detects the position of the traffic light from the camera image and discriminates the color of the lit light. In addition, the person detection determination unit 340 extracts an image in a predetermined temperature range from the infrared image, and determines the presence or absence of a person from the size and shape thereof.

  In the present embodiment, in addition to the vehicle speed sensor 230, the traffic signal identification means 310 and the person detection determination means 340 are used for controlling the calibration timing. Thereby, the operation | movement when operation | movement of the infrared imaging device 200 is required can be ensured reliably. For example, the vehicle speed sensor 230 detects that the traveling speed of the vehicle 220 is zero, the traffic light identifying means 310 identifies that the signal of the traffic light ahead indicates the vehicle 220 to “stop”, and Only when the person detection determination unit 340 has not detected a person, the infrared imaging apparatus 200 updates the correction coefficient. Thereby, it is possible to perform calibration only when there is almost no possibility of collision with an obstacle even more reliably than in the second embodiment.

  In addition, the infrared imaging device 200 has a peripheral structure 320 filled with engine coolant supplied from the radiator 330 of the vehicle 220 and circulated. Since the temperature of the cooling water becomes substantially constant after the warm-up operation of the vehicle 220 is completed, the temperature during operation of the infrared imaging apparatus 200 is stabilized by the surrounding structure 320 as the heat retaining structure. For this reason, the temperature fluctuation of the optical system is reduced, and the fluctuation of the image quality is reduced.

  Note that one or two of the vehicle sensor 230, the traffic signal identification unit 310, and the person detection unit 340 may be used for controlling the calibration timing, or another sensor may be further used.

  Further, the surrounding structure 320 may be configured integrally with the infrared image capturing apparatus 200, or may be configured to be provided on the vehicle 220 side so that the infrared image capturing apparatus 200 is fitted therein. Moreover, you may implement | achieve a heat retention structure using the other mechanism of the vehicle 220. FIG.

(Fourth embodiment)
FIG. 6 is a diagram showing a configuration of a vehicle equipped with an infrared imaging device according to the fourth embodiment of the present invention. In FIG. 6, the same reference numerals as those in FIGS. 1 and 4 are assigned to components common to those in FIGS. 1 and 4. In FIG. 6, 410 and 420 are mirrors that reflect infrared rays having a wavelength to be imaged, 430 is a mirror driving device that controls the direction of the mirror 420, 440 is a radiator of the vehicle 220, and 450 is a temperature that measures the temperature of the radiator 440. It is a measuring means. The angle and position of the mirror 410 are fixed. In the configuration shown in FIG. 6, no blocking means is provided.

  In the infrared imaging apparatus shown in FIG. 6, calibration is performed when the speed of the vehicle 220 detected by the vehicle speed sensor 230 is equal to or lower than a predetermined value, as in the second embodiment. Here, in the present embodiment, it is assumed that the radiator 440 is imaged as a temperature standard during calibration.

  The mirror driving device 430 blocks the direction of the mirror 420 at the time of calibration, the infrared rays incident on the optical system 20 from the outside of the vehicle 220, and the infrared rays emitted from the radiator 440 and reflected by the mirror 410 are incident on the optical system 20. Set as follows. In this state, for example, the same calibration as in the first embodiment is performed. The temperature of the radiator 440 is kept substantially constant while the vehicle 220 is traveling, and therefore, the radiator 440 can be used as a temperature standard during calibration.

  On the other hand, during normal imaging, the mirror driving device 430 blocks the infrared ray emitted from the radiator 440 and reflected by the mirror 410 in the direction of the mirror 420, and the infrared ray from the outside of the vehicle 220 is incident on the optical system 20. Set as follows.

  As described above, according to the present embodiment, the temperature characteristics of the infrared imaging device mounted on the vehicle can be calibrated without providing a special temperature standard such as the blocking means provided in the first embodiment. .

  In the present embodiment, the radiator 440 is used as the temperature standard, but other parts of the vehicle where the temperature is constant may be used as the temperature standard.

  In this embodiment, the mechanism for changing the setting of the imaging direction is realized by the mirror 420 and the mirror driving device 430. However, other mechanisms, for example, the orientation of the imaging device main body including the infrared detector 10 and the optical system 20 are changed. You may use a mechanism that changes. Further, the mechanism for changing the setting of the imaging direction may be configured integrally with the infrared imaging device or provided on the vehicle side.

(Fifth embodiment)
FIG. 7 is a diagram showing the configuration of an infrared image adjustment apparatus according to the fifth embodiment of the present invention. In FIG. 7, the infrared imaging device 500 has the configuration shown in FIG. 1, and the first correction coefficient G (x, y) and the second correction coefficient H (x, y) are performed according to the procedure shown in the first embodiment. ) Is already required. That is, the correspondence between the luminance signal output from the infrared image capturing apparatus 500 and the temperature of the subject is known.

  The infrared image adjustment device 590 adjusts the display temperature range of the infrared image. In the infrared image adjusting device 590, 510 is an image memory for storing infrared image data, 520 is a maximum temperature detecting unit for detecting the maximum temperature Th from the infrared image data stored in the image memory 510, and 530 is an image memory. A minimum temperature detection unit that detects the minimum temperature Tl from the infrared image data stored in 510. Reference numeral 540 denotes a memory for storing the upper limit Toh and the lower limit Tol of the measurement target temperature range based on the temperature of a specific imaging target, and 550 compares the maximum temperature Th with the upper limit Toh of the temperature range, and selectively outputs the larger one. The first comparison unit 560 is a second comparison unit that compares the lowest temperature Tl with the lower limit Tol of the temperature range and selectively outputs the smaller one.

  The image memory 510, the maximum temperature detection unit 520, and the minimum temperature detection unit 530 constitute a first means, and the temperature range upper and lower limit memory 540 constitutes a second means, and the first and second comparisons The parts 550 and 560 constitute a third means. The infrared image adjustment device 590 outputs the selection outputs of the first and second comparison units 550 and 560 as the upper limit temperature Tah and the lower limit temperature Tal of the display temperature range, respectively.

  The video signal generation unit 570 receives the output of the infrared imaging device 500 and generates a video signal for causing the video display device 580 to display an infrared image. At this time, using the upper limit temperature Tah and the lower limit temperature Tal output from the infrared image adjustment device 590, the dynamic range of the video signal is adjusted so that the upper limit temperature Tah matches the white level and the lower limit temperature Tal matches the black level. To do.

  Now, it is assumed that imaging is performed using the infrared imaging apparatus 500 for the purpose of detecting “people” outdoors in winter. In this case, for example, the upper limit Toh of the measurement target temperature range is set to 35 ° C., and the lower limit Tol is set to 30 ° C.

  When the control circuit 600 activates the infrared image adjustment device 590, the image data for one frame output from the infrared image capturing device 500 is accumulated in the image memory 510. The highest temperature detection unit 520 detects the temperature Th indicated by the highest luminance pixel in the target frame image, and the lowest temperature detection unit 530 detects the temperature Tl indicated by the lowest luminance pixel in the target frame image.

Outside of winter, the temperature of buildings and road asphalts is lower than the human body surface temperature.
Tl <Th <Tol <Toh
The relationship holds. Accordingly, the first comparison unit 550 outputs the upper limit temperature Toh stored in the temperature range upper / lower limit memory 540 as the upper limit temperature Tah of the display temperature range instead of the maximum temperature Th detected by the maximum temperature detection unit 520. On the other hand, the second comparison unit 560 outputs the minimum temperature Tl detected by the minimum temperature detection unit 530 as the lower limit temperature Tal of the display temperature range.

  As a result, the temperature range of the person who is the imaging object is always included in the dynamic range of the video signal. Therefore, even if a person appears or disappears in the captured image, the dynamic range of the video signal does not fluctuate, and a sharp fluctuation in video brightness caused by AGC (Auto Gain Control) occurs. Does not occur. For this reason, for example, detailed classification processing using pattern recognition can be easily executed.

Similarly, if you detect "people" outdoors during the summer days,
Tol <Toh <Tl <Th
The relationship holds. Therefore, the first comparison unit 550 outputs the maximum temperature Th detected by the maximum temperature detection unit 520 as the upper limit temperature Tah of the display temperature range, while the second comparison unit 560 is detected by the minimum temperature detection unit 530. Instead of the lowest temperature Tl, the lower limit temperature Tol stored in the temperature range upper / lower limit memory 540 is output as the lower limit temperature Tal of the display temperature range. As a result, the temperature range of the person who is the object to be imaged is always included in the dynamic range of the video signal, and there is no sudden fluctuation in the brightness of the video.

  When the dynamic range of the image becomes insufficient or the image is saturated due to the temperature fluctuation of the background being imaged, the video signal adjustment device 590 is newly activated by the control circuit 600 to display the display temperature range. May be reset. Alternatively, the display temperature range may be set for each frame image similarly to AGC.

  As described above, according to the present embodiment, a predetermined temperature range based on the temperature of a specific imaging target is included in the display temperature range in advance, so that even when the imaging target suddenly enters the imaging range, it is stable. It is possible to display the infrared image.

  The infrared image adjustment device 590 according to the present embodiment may be provided integrally with the infrared image capturing device 500, or may be provided integrally with the video signal generation unit 570 and the video display device 580.

  In the present embodiment, the maximum temperature and the minimum temperature of the infrared image are first detected, but instead, the upper and lower limits of the temperature range suitable for displaying the infrared image may be detected. For example, a pixel having a brightness that is significantly different from other pixels may be excluded from the temperature detection target.

  Further, instead of setting the measurement target temperature range, one predetermined temperature may be set, and this predetermined temperature may be included in the display temperature range. In this case, if Toh = Tol in this embodiment, it can be easily realized.

1 is a block diagram illustrating a configuration of an infrared imaging device according to a first embodiment of the present invention. It is a figure which shows the model for demonstrating the calibration method in the 1st Embodiment of this invention. It is a figure which shows the modification of the structure of FIG. It is a figure which shows the structure of the vehicle carrying the infrared imaging device which concerns on the 2nd Embodiment of this invention. It is a figure which shows the structure of the vehicle carrying the infrared imaging device which concerns on the 3rd Embodiment of this invention. It is a figure which shows the structure of the vehicle carrying the infrared imaging device which concerns on the 4th Embodiment of this invention. It is a figure which shows the structure of the infrared image adjustment apparatus which concerns on the 5th Embodiment of this invention. It is a figure which shows the structure of the conventional infrared imaging device. It is a figure which shows the to-be-photographed object temperature versus brightness | luminance table which the temperature characteristic correction | amendment means in FIG. 8 has. It is a figure which shows the structure of the conventional infrared imaging device. It is a figure which shows the structure of the conventional infrared imaging device.

Claims (4)

An infrared imaging device for mounting on a vehicle,
An infrared detector;
An optical system that forms an infrared image emitted from a subject on the infrared detector;
An infrared imaging apparatus comprising: a heat retaining structure that stabilizes the temperature in the vicinity of the infrared detector and the optical system using a mechanism of the vehicle. The infrared imaging device according to claim 1,
The thermal insulation structure is characterized in that the engine cooling water of the vehicle is circulated in the vicinity of the infrared detector and the optical system. A vehicle,
An infrared imaging device;
A vehicle comprising: a heat retaining structure that stabilizes the temperature in the vicinity of the infrared imaging device using a mechanism of the vehicle. The vehicle according to claim 3, wherein
The vehicle, wherein the heat retaining structure circulates engine coolant of the vehicle in the vicinity of the infrared imaging device.

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