JP5495008B2 - EXPOSURE CONTROL DEVICE AND EXPOSURE CONTROL METHOD - Google Patents

Description

  The present invention relates to an exposure amount control apparatus and an exposure amount control method for obtaining preferable exposure for both a visible light system and an infrared light system when photographing with visible light and infrared light is performed simultaneously.

  As described in Patent Document 1 and Patent Document 2, there is known an imaging apparatus that can perform imaging with visible light and imaging with infrared light by one unit, and is used for a monitoring camera or the like. It has been. In such an imaging device, shooting under infrared light that can clearly show a subject even under a slightly dark shooting condition such as in the evening, and shooting with visible light that can obtain color information of the subject. Can be done at the same time.

  In the imaging apparatus, exposure control according to the brightness of the subject is performed during imaging. Exposure control is performed mainly by adjusting the EV value determined by the aperture value and the shutter speed. In general, the sensitivity of the image sensor to visible light and the sensitivity to infrared light are different, and the reflectance of visible light and infrared light of the subject are also different. Often the proper exposure does not match. For this reason, there is a problem that when exposure control is performed so as to give appropriate exposure to one side, the other side may be underexposed or saturated.

  In order for both to capture images with appropriate exposure, it is preferable to perform exposure control independently between the visible light imaging system and the infrared light imaging system. Patent Document 1 describes that an aperture value can be independently controlled in a visible light system and an infrared light system by using a diaphragm mechanism that can control light amounts in different wavelength bands. Japanese Patent Application Laid-Open No. H10-228561 describes that independent diaphragm mechanisms for visible light and infrared light are provided at the subsequent stage of the spectroscopic optical system. In this way, by controlling the aperture value independently for the visible light system and the infrared light system, good imaging results can be obtained for both the visible light system and the infrared light system.

JP 2002-369049 A Japanese Patent Laid-Open No. 2005-4181

  2. Description of the Related Art In recent years, an electronic shutter system that changes the shutter speed by controlling the time to extract charge from the image sensor has been widely adopted in image pickup apparatuses, and the shutter speed is controlled independently between the visible light system and the infrared light system. This can be easily performed without increasing the cost.

  However, in order to control the diaphragm independently between the visible light system and the infrared light system, a diaphragm mechanism capable of controlling the light amounts in different wavelength bands as described in Patent Document 1 is used, or described in Patent Document 2. As described above, it is necessary to provide a plurality of aperture mechanisms, which complicates the configuration and increases the cost of the imaging apparatus. Patent Document 2 also mentions a configuration using only one stop, but does not describe control for obtaining a preferable exposure.

  In recent years, an automatic aperture lens that can electrically control the opening / closing of the aperture from the outside has been widely distributed as an imaging optical system for surveillance cameras. It is considered industrially preferable that such an automatic aperture lens can be used for an imaging apparatus capable of imaging with visible light and infrared light.

  However, in general, an automatic aperture lens cannot acquire information such as the current aperture value, the wide aperture value, and the aperture value when performing exposure control, and often cannot set the aperture value directly. . For this reason, it is more difficult to obtain preferable exposure for both the visible light system and the infrared light system with a simple configuration.

  Therefore, the present invention provides a preferable exposure for both the visible light system and the infrared light system with a simple configuration even when the current aperture value information cannot be acquired when photographing with visible light and infrared light is performed simultaneously. It aims to be obtained.

In order to solve the above-described problem, an exposure amount control apparatus according to the first aspect of the present invention is configured to receive and set visible light separated from incident light incident through a diaphragm unit that cannot obtain aperture value information. An exposure evaluation value is calculated for each of a visible light imaging unit that captures images according to time and an infrared light imaging unit that receives infrared light dispersed from the incident light and images according to a set exposure time. Based on the exposure evaluation value and the exposure time of each of the visible light imaging means and the infrared light imaging means related to the exposure evaluation value, and the change amount of the aperture means, the visible light imaging means, and the infrared light An exposure condition determining means for setting a combination with an exposure time of each of the optical imaging means, and an aperture control for controlling the aperture means in accordance with a change amount of the aperture means according to the set combination. And means, based on the exposure time of the visible light imaging means according to a combination of the set, a visible light system exposure time setting means for setting the exposure time of the visible light imaging means, the according to the combination of the set Infrared light exposure time setting means for setting the exposure time of the infrared light imaging means based on the exposure time of the infrared light imaging means.

  Here, the exposure condition determination unit is configured to change the amount of change of the diaphragm unit and the visible light so that at least one of the visible light imaging unit and the infrared light imaging unit has appropriate exposure based on the calculated exposure evaluation value. A combination with the exposure time of each of the imaging means and the infrared light imaging means can be extracted as a selection target, and any combination can be selected and set from the selection targets.

  At this time, when the exposure condition determination unit detects that the aperture state of the aperture unit has reached the aperture limit on the open side, the combination relating to the change amount on the open side of the aperture unit is excluded from the selection target. When it is detected that the aperture state of the aperture means has reached the aperture limit on the aperture side, the combination relating to the amount of change on the aperture side of the aperture means can be excluded from the selection target.

  Further, the exposure condition determination means, when there is a combination in which both the visible light imaging means and the infrared light imaging means have proper exposure in the extracted combination, If any combination is selected and set from among the combinations and the visible light imaging means and the infrared light imaging means are not properly exposed in the extracted combination, the visible light is selected. Among the combinations related to the most open change amount among the combinations in which the imaging unit has proper exposure, and among the combinations related to the most open amount change in the combination in which the infrared light image pickup unit has proper exposure, A combination related to the amount of change on the narrowing side can be selected and set.

In order to solve the above-described problem, an exposure amount control method according to a second aspect of the present invention is configured to receive visible light spectrally separated from incident light incident through a diaphragm unit that cannot obtain aperture value information. An exposure evaluation value is calculated for each of a visible light imaging unit that captures images according to time and an infrared light imaging unit that receives infrared light dispersed from the incident light and images according to a set exposure time. Based on the exposure evaluation value and the exposure time of each of the visible light imaging means and the infrared light imaging means related to the exposure evaluation value, and the change amount of the aperture means, the visible light imaging means, and the infrared light An exposure condition determining step for setting a combination with the exposure time of each optical imaging means, and an aperture for controlling the aperture means according to the amount of change of the aperture means for the set combination. A control step, based on the exposure time the visible light imaging means according to the set combination, a visible light system exposure time setting step of setting an exposure time of the visible light imaging means, according to the combination of the set on the basis of the exposure time of the infrared light imaging means, and having an infrared optical system exposure time setting step of setting an exposure time of said infrared light imaging means.

  Here, in the exposure condition determination step, based on the calculated exposure evaluation value, the amount of change of the diaphragm unit and the visible light in which at least one of the visible light imaging unit and the infrared light imaging unit has appropriate exposure A combination with the exposure time of each of the imaging means and the infrared light imaging means can be extracted as a selection target, and any combination can be selected and set from the selection targets.

  At this time, when the exposure condition determining step detects that the aperture state of the aperture means has reached the aperture limit on the open side, the combination relating to the change amount on the open side of the aperture means is excluded from the selection target. When it is detected that the aperture state of the aperture means has reached the aperture limit on the aperture side, the combination relating to the amount of change on the aperture side of the aperture means can be excluded from the selection target.

  In the exposure condition determination step, when there is a combination in which both the visible light imaging unit and the infrared light imaging unit have appropriate exposure in the extracted combination, the combination of the appropriate exposure is determined. If any combination is selected and set from among the combinations and the visible light imaging means and the infrared light imaging means are not properly exposed in the extracted combination, the visible light is selected. Among the combinations related to the most open change amount among the combinations in which the imaging unit has proper exposure, and among the combinations related to the most open amount change in the combination in which the infrared light image pickup unit has proper exposure, A combination related to the amount of change on the narrowing side can be selected and set.

  According to the present invention, when photographing with visible light and infrared light is performed at the same time, even if the current aperture value information cannot be obtained, the visible light system and the infrared light system have preferable exposure with a simple configuration. It will be obtained.

It is a block diagram which shows the structure of the imaging device which concerns on this embodiment. It is a figure which shows the example of the relative intensity with respect to the wavelength for every light source. It is a figure which shows the example of the relative sensitivity with respect to the wavelength of CCD. It is a figure which shows EV value table. It is a flowchart explaining the flow of the exposure control processing of this embodiment. It is a figure explaining extraction of the combination candidate of an aperture and shutter speed. It is a figure explaining correction | amendment of the combination candidate of an aperture stop and shutter speed. It is a flowchart explaining the 1st method of a combination setting. It is a flowchart explaining the 2nd method of a combination setting. It is a figure which shows the example of the setting result by the 1st method of a combination setting. It is a figure which shows the example of the setting result by the 2nd method of combination setting.

  Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration of an imaging apparatus to which the present invention is applied. This image pickup apparatus is capable of simultaneously shooting with visible light and shooting with infrared light, and the image pickup device for receiving visible light and the image pickup device for receiving infrared light are independently provided. And one common aperture mechanism. In this imaging apparatus, the configuration is simplified by preventing the increase in cost by providing a common aperture mechanism for the visible light system and the infrared light system instead of providing them separately.

  As shown in the figure, the imaging apparatus 10 includes a photographing optical system 11 having a lens and a diaphragm mechanism 12 that adjusts the amount of incident light, a spectroscopic optical system 13 that separates incident light into visible light and infrared light, and separation. The visible light imaging unit 14 that can receive the visible light and can adjust the shutter speed, the infrared light imaging unit 15 that can receive the separated infrared light and the shutter speed can be adjusted, and the visible light imaging unit 14 Performs processing on the visible light signal output from the infrared light, performs processing on the infrared light signal output from the visible light signal processing unit 16 that generates the visible light video signal, and the infrared light imaging unit 15, and transmits infrared light. An infrared light signal processing unit 17 that generates a video signal, an exposure control unit 18 that controls exposure determined by a shutter speed and an aperture, and an aperture drive unit 19 that drives the aperture mechanism 12 are provided.

  The photographing optical system 11 employs an automatic aperture lens. With the automatic aperture lens, the current aperture value of the aperture mechanism 12 cannot be acquired. That is, it is not possible to acquire information about whether the current aperture value is, for example, F5.6 or F11. For this reason, the aperture drive unit 19 performs an operation to relatively open and close the aperture mechanism 12 according to the control voltage.

  Specifically, when a voltage higher than the currently applied control voltage is applied, the diaphragm mechanism 12 is driven to close more than the current voltage, and a voltage lower than the currently applied control voltage is applied. Then, the aperture mechanism 12 is driven so as to open more than the present. At this time, the relationship between the control voltage and the aperture value varies depending on the shape of the aperture mechanism 12, the presence or absence of the ND filter, and the like, and does not always have a linear characteristic. Further, when the aperture reaches the limit on the open side or the aperture side, no further opening / closing is performed even if the control voltage is changed low or high.

  In the present embodiment, the aperture drive unit 19 that drives the photographing optical system 11 and the aperture mechanism 12 is a general DC iris, and in addition to the current aperture value, information such as the maximum aperture value and the minimum aperture value is electrically stored. Shall not be obtained.

  Many DC irises are designed such that the control voltage applied to the aperture drive unit 19 is 0.5 V when the aperture is open and 4.5 V when the aperture is minimum. There is also a DC iris that has a minimum aperture at 3.3V. For this reason, there are cases where it can be determined whether or not the aperture has reached the limit based on the control voltage.

  In addition, the aperture value and the minimum aperture value can be acquired by using a calibration system or the like. However, the present invention is applicable to cases where the aperture value and the minimum aperture value can be acquired or cannot be acquired. can do.

  The spectroscopic optical system 13 can use a dichroic mirror, a color separation prism, or the like. In the present embodiment, the light is dispersed with a wavelength of 700 nm as a boundary.

  The visible light imaging unit 14 and the infrared light imaging unit 15 include a light receiving element such as a CCD or CMOS and a peripheral circuit. The visible light imaging unit 14 has sensitivity in at least a visible light region, and the infrared light imaging unit 15. Is sensitive to at least the infrared region. In addition, the visible light imaging unit 14 and the infrared light imaging unit 15 can use, for example, an electronic shutter system that changes the shutter speed by controlling the time for taking out charges from the imaging device.

  The visible light signal processing unit 16 and the infrared light signal processing unit 17 generate a video signal by performing general signal processing such as γ correction, luminance signal processing, color signal processing, and encoding.

  The exposure control unit 18 controls the aperture of the aperture mechanism 12 based on the exposure condition determination unit 20 that determines appropriate exposure conditions for each of the visible light imaging unit 14 and the infrared light imaging unit 15 and the appropriate exposure conditions for each. A diaphragm control unit 23 that performs the visible light imaging unit 14, a visible light system shutter speed setting unit 21 that sets the shutter speed, and an infrared light system shutter speed setting unit 22 that sets the shutter speed in the infrared light imaging unit 15. It has.

  The exposure condition determination unit 20 can determine the exposure condition using an existing photometry method, for example, overall average photometry. Of course, center-weighted metering, multi-segment metering, or the like may be used. In the entire surface average metering, the average luminance of the entire screen is calculated, and a ratio with a predetermined luminance value at the time of proper exposure is calculated, and a logarithmic value with this value 2 as the base is used as the exposure evaluation value. Here, the luminance value at the time of proper exposure can be 50 IRE for an analog value, and 118/255 for a digital 8-bit.

  For example, when the average luminance value is digital 59/255, the exposure evaluation value is −1 by the above calculation method. This value is equivalent to the EV value to be corrected so as to obtain an appropriate exposure with respect to the EV value obtained from the aperture value and the shutter speed at the time of photometry. However, in this embodiment, since the aperture value at the time of metering cannot be obtained, the absolute value of the proper EV value cannot be obtained, and only the correction value (= exposure evaluation value) for the proper EV value can be obtained. become.

  Further, the exposure condition determination unit 20 includes an evaluation value storage unit 20a that stores the previous exposure evaluation value in order to determine that the aperture state of the aperture mechanism 12 has reached the limit. That is, when the exposure evaluation value when the control voltage applied to the aperture drive unit 19 is changed from the previous exposure evaluation value while the shutter speed is constant, the aperture state of the aperture mechanism 12 reaches the limit. Can be determined. Note that the evaluation value storage unit 20a is not necessary when it can be determined from the control voltage value that the aperture state of the aperture mechanism 12 has reached the limit.

  Here, as can be seen from the graph of the relative intensity example with respect to the wavelength for each light source shown in FIG. 2, the intensity distribution of the visible light and the infrared light greatly varies depending on the type of the light source. In addition, FIG. 2 has shown the relative intensity example with respect to a wavelength about each of sunlight (FIG. 2 (a)), a fluorescent lamp (FIG.2 (b)), and an incandescent lamp fluorescent lamp (FIG.2 (c)).

  Further, as can be seen from the graph of the relative sensitivity example with respect to the wavelength of the CCD shown in FIG. 3, the sensitivity distribution with respect to the wavelength greatly varies depending on the kind of the CCD. FIG. 3 shows an example of relative sensitivity with respect to wavelength for different types of CCD 1 (FIG. 3A) and CCD 2 (FIG. 3B).

  From the above characteristics, in the case of simultaneously recording visible light and infrared light, when exposure control is performed so as to give appropriate exposure to one, the other may be underexposed or saturated. In particular, if it becomes overexposed and becomes saturated, it becomes a so-called whiteout state and cannot be saved by subsequent image processing. This tendency of underexposure and saturation varies depending on the type of light source and the sensitivity of the image sensor as shown in FIGS. 2 and 3, and therefore cannot be controlled uniformly. Therefore, in the present embodiment, the following exposure control is performed.

  First, the exposure possible range of the imaging device 10 will be described. FIG. 4A is a known EV value table, and the exposure possible range of the imaging apparatus 10 is assumed to be the shaded portion of FIG. 4B. That is, the possible aperture values are the open side aperture value F2.0 and the aperture side aperture value F22. Also, the shutter speed on the high speed side was set to 1/4000 seconds, and the shutter speed on the low speed side was set to 1/60 seconds. The imaging device 10 performs exposure control with a combination of these possible aperture values and shutter speeds. However, as described above, the aperture value cannot be acquired.

  Next, exposure control processing in the present embodiment will be described with reference to the flowchart of FIG. First, at the time of imaging, the exposure condition determination unit 20 calculates exposure evaluation values of the visible light imaging unit 14 and the infrared light imaging unit 15 (S101). The exposure evaluation value can be calculated by the above-described procedure. That is, photometry is performed with the current aperture mechanism 12 and the current shutter speed of the visible light imaging unit 14 to calculate the exposure evaluation value of the visible light imaging unit 14. Further, photometry is performed with the current aperture of the aperture mechanism 12 and the current shutter speed of the infrared light imaging unit 15 to calculate the exposure evaluation value of the infrared light imaging unit 15.

  Next, based on the calculated exposure evaluation value, the exposure condition determination unit 20 combines a combination of an aperture and a shutter speed that give appropriate exposure and a combination of the surroundings for each of the visible light system and the infrared light system. A candidate is extracted (S102). Here, the aperture is expressed as a relative value with respect to the current aperture, and the shutter speed is expressed as an absolute value.

  For example, when the exposure evaluation value is calculated, the visible light system shutter speed is 1/1000, the exposure evaluation value is ± 0, the infrared light system shutter speed is 1/1000, and the exposure evaluation value is −2. The extraction of combination candidates in the case of FIG. 6 will be described with reference to FIG. In this case, the difference between the visible light system and the infrared light system is 2 EV.

  First, the visible light system will be described. In the visible light system, the exposure evaluation value is ± 0 at a shutter speed of 1/1000. Therefore, if the aperture is not changed, a proper exposure can be obtained with the shutter speed remaining at 1/1000. If the aperture is opened by 1 EV from the present, the shutter speed is 1/2000 and a proper exposure can be obtained. Similarly, if the aperture is opened by 2 EV, the shutter speed is 1/4000 and a proper exposure is obtained. However, if the aperture is opened by 3 EV, the shutter speed is 1/8000 and appropriate exposure is obtained. However, since the upper limit of the shutter speed is 1/4000, appropriate exposure cannot be obtained and the exposure evaluation value is +1.

  On the contrary, if the aperture is closed by 1 EV from the present time, the shutter speed is 1/500 and appropriate exposure can be obtained. Similarly, if the aperture is closed by 2 EV, the shutter speed is 1/250 and appropriate exposure is obtained. If the aperture is closed by 3 EV, the shutter speed is 1/125 and appropriate exposure is obtained, and if the aperture is closed by 4 EV, A proper exposure can be obtained at a shutter speed of 1/60.

  Next, an infrared light system will be described. In the infrared light system, the exposure evaluation value is −2 at a shutter speed of 1/1000. Therefore, if the aperture is not changed, a proper exposure can be obtained at 1/250, which is two steps slower than the shutter speed. If the aperture is opened by 1 EV from the present time, the shutter speed is 1/500 and appropriate exposure can be obtained. Similarly, when the aperture is opened by 2 EV, a proper exposure is obtained at a shutter speed of 1/1000, and when the aperture is opened by 3 EV, an appropriate exposure is obtained at a shutter speed of 1/2000.

  On the contrary, if the aperture is closed by 1 EV from the present time, the shutter speed is 1/125 and a proper exposure can be obtained. Similarly, if the aperture is closed by 2 EV, the shutter speed is 1/60 and appropriate exposure is obtained. However, if the aperture is closed by 3 EV, the shutter speed is 1/30 and a proper exposure is obtained, but the lower limit of the shutter speed is 1/60, so the proper exposure cannot be obtained and the exposure evaluation value is -1. . Similarly, if the aperture is closed by 4 EV, the shutter speed is 1/60 and the exposure evaluation value is −2.

  As another example, when the exposure evaluation value is calculated, the visible light system shutter speed is 1/1000, the exposure evaluation value is +1, the infrared light system shutter speed is 1/500, and the exposure evaluation value is The extraction of the combination candidate when it is −5 will be described with reference to FIG. In this case, the difference between the visible light system and the infrared light system is 6 EV.

  First, the visible light system will be described. In the visible light system, the shutter speed is 1/1000 and the exposure evaluation value is +1. Therefore, if the aperture is not changed, a proper exposure can be obtained at 1/2000, where the shutter speed is increased by one step. If the aperture is opened by 1 EV from the present, the shutter speed is 1/4000 and a proper exposure can be obtained. However, since the upper limit of the shutter speed is 1/4000, if the aperture is opened by 2 EV, the exposure evaluation value becomes +1. If the aperture is opened by 3 EV, the exposure evaluation value becomes +2, and if the aperture is opened by 4 EV. The exposure evaluation value is +3, and when the aperture is opened by 5 EV, the exposure evaluation value is +4.

  On the contrary, if the aperture is closed by 1 EV from the present time, the shutter speed is 1/1000 and a proper exposure can be obtained. Similarly, if the aperture is closed by 2 EV, the shutter speed is 1/500 and appropriate exposure can be obtained.

  Next, an infrared light system will be described. In the infrared light system, the shutter speed is 1/1000 and the exposure evaluation value is −5. Therefore, if the aperture is not changed, appropriate exposure can be obtained at 1/15 with the shutter speed reduced by 5 steps. However, since the lower limit of the shutter speed is 1/60, the exposure evaluation value is −2. If the aperture is opened by 1 EV from the present time, the exposure evaluation value is -1 at a shutter speed of 1/60. If the aperture is opened by 2 EV from the present time, a proper exposure can be obtained at a shutter speed of 1/60. Similarly, when the aperture is opened by 3 EV, the shutter speed is 1/125 and proper exposure is obtained. When the aperture is opened by 4 EV, the shutter speed is 1/250 and appropriate exposure is obtained, and when the aperture is opened by 5 EV, Proper exposure is obtained at a shutter speed of 1/500.

  Conversely, if the aperture is closed by 1 EV from the present, the exposure evaluation value is -3 at the shutter speed 1/60, and if the aperture is closed by 2 EV, the exposure evaluation value is -4 at the shutter speed 1/60.

  As described above, when the combination of the aperture and shutter speed giving the appropriate exposure and the peripheral combination are extracted as combination candidates, the exposure condition determination unit 20 brings the aperture mechanism 12 into the aperture limit state on the open side or the aperture side. It is determined whether or not there is (S103).

  When it can be determined that the aperture mechanism 12 is at the aperture limit by the control voltage applied to the aperture drive unit 19, it is determined whether the aperture mechanism is in the aperture limit state based on the control voltage. For example, if the characteristic information of the photographic optical system 11 is known, the control voltage is 0.5V or 4.5V if the photographic optical system 11 is open when the control voltage is 0.5V and the minimum aperture is 4.5V. The aperture limit can be determined depending on whether there is any.

  When the characteristic information of the photographing optical system 11 is not obtained and it is not possible to determine that the diaphragm mechanism 12 is at the diaphragm limit by the control voltage, the latest exposure evaluation value stored in the evaluation value storage unit 20a and the latest calculation are calculated. By comparing with the exposure evaluation value, it can be determined whether or not the aperture mechanism 12 is in the aperture limit state on the open side or the aperture side.

  Specifically, if the exposure evaluation value does not change despite the aperture mechanism 12 being controlled to the open side, it can be determined that the aperture limit on the open side has been reached. On the contrary, if the exposure evaluation value does not change even though the aperture mechanism 12 is controlled to the aperture side, it can be determined that the aperture limit on the aperture side has been reached. This determination is effective when the previous exposure evaluation value is stored in the evaluation value storage unit 20a. For this reason, this determination is not performed at the start of control.

  If the aperture limit has been reached, the extracted combination candidates are corrected by excluding combinations that cannot be obtained (S104). For example, in the case of the example shown in FIG. 6A, when the aperture reaches the limit on the open side, the combination on the open side is selected from the candidates as shown in the shaded portion in FIG. Exclude correction. On the other hand, when the aperture reaches the limit on the narrowing side, as shown in the shaded portion in FIG. 7B, correction for removing the combination on the narrowing side from the candidates is performed. If the aperture limit has not been reached, these corrections are not necessary.

  Then, the exposure condition determination unit 20 selects and sets one combination from the remaining combination candidates (S105). In the present embodiment, a first method and a second method will be described as a combination setting method.

  First, the first method of combination setting will be described with reference to the flowchart of FIG. In the first combination setting method, it is determined whether there is an appropriate exposure combination candidate with an exposure evaluation value ± 0 in both the visible light system and the infrared light system (S201).

  As a result, when there is a combination of appropriate exposures in both systems (S201: Yes), either combination is set from among the combinations of appropriate exposures in both systems (S202). Here, which combination of the proper exposures is adopted for both systems can be determined according to the situation, the monitoring purpose of the imaging apparatus 10 and the like.

  For example, when the monitoring target is in a wide depth range, the combination on the narrowing-down side can be set in the combination of appropriate exposure in both systems so that the depth of field is deep. Further, when the movement of the monitoring object is fast, in order to prevent subject blurring, it is possible to set a combination on the open side among the combinations of appropriate exposures for both systems. Since these combinations have an exposure evaluation value ± 0 for both the visible light system and the infrared light system, appropriate exposure can be obtained for both the visible light system and the infrared light system with a simple configuration.

  On the other hand, when there is no combination of proper exposures in both systems (S201: No), the larger one of the minimum relative F values (open side) of the proper exposure of each of the visible light system and the infrared light system (the narrowing side) A combination including the relative F value is set (S203). In this combination, either one of the systems is exposed properly, and the other system is exposed as brightly as possible to prevent saturation. Therefore, it is possible to obtain preferable exposure for both the visible light system and the infrared light system with a simple configuration. it can.

  For example, a case where the first method is applied with the combination candidates as shown in FIG. 10A will be described. In the example of this figure, in the combination candidates from 2EV open to 2EV close, both systems have appropriate exposure. Therefore, any combination from 2EV open to 2EV close can be set.

  Further, the case where the first method is applied with the combination candidates as shown in FIG. 10B will be described. In the example of this figure, there is no combination candidate for proper exposure in both systems. In the visible light system, the minimum relative F value for proper exposure is 1 EV. On the other hand, the minimum relative F value for proper exposure in an infrared light system is 5 EV or less. For this reason, a combination including 1 EV opening on the narrowing side (the one with a larger relative F value) is set.

  Next, the second method for setting the combination will be described with reference to the flowchart of FIG. Also in the second combination setting method, it is determined whether there is a combination candidate of appropriate exposure with an exposure evaluation value ± 0 in both the visible light system and the infrared light system (S301).

  As a result, when there is a combination candidate of appropriate exposure for both systems (S301: Yes), a combination including an aperture value having the largest relative F value (narrowing side) is selected from the combinations of appropriate exposure for both systems. (S302). In the second method of setting the aperture value, the influence of lens aberration can be reduced by narrowing as much as possible within the range of appropriate exposure. In particular, the influence of lens aberration on the infrared light side having a small refractive index can be suppressed, and an image with high sharpness can be obtained.

  On the other hand, when there is no combination candidate for appropriate exposure in both systems (S301: No), the minimum F value (open side) of the appropriate exposure for each of the visible light system and the infrared light system is the same as in the first method. Among them, the combination including the larger relative F value (narrowing side) is set (S303). In this combination, either one of the systems is exposed properly, and the other system is exposed as brightly as possible to prevent saturation. Therefore, it is possible to obtain preferable exposure for both the visible light system and the infrared light system with a simple configuration. it can.

  For example, a case where the second method is applied in a combination as shown in FIG. In the example of this figure, in the combination candidates from 2EV open to 2EV close, both systems have appropriate exposure. For this reason, 2EV close on the most narrow side is set.

  Further, a case where the second method is applied in a combination as shown in FIG. In the example of this figure, there is no combination candidate for proper exposure in both systems. In the visible light system, the minimum relative F value for proper exposure is 1 EV. On the other hand, the minimum relative F value for proper exposure in an infrared light system is 5 EV or less. For this reason, a combination including 1 EV opening on the narrowing side (the one with a larger relative F value) is set.

  Returning to the description of the flowchart of FIG. 5, when the combination is set by the above-described procedure, the shutter speed corresponding to the combination set for each of the visible light system and the infrared light system is set (S106).

  Further, the diaphragm is driven in the direction corresponding to the set combination (S107). Here, when the characteristic information of the photographic optical system 11 is known or can be specified and the aperture value can be controlled based on the relative aperture value, the aperture value corresponding to the set combination is directly changed. On the other hand, when the characteristic information of the photographic optical system 11 cannot be obtained, the diaphragm drive unit 19 is driven with a predetermined control voltage such as 0.1 V, for example.

  Then, the visible light system and the infrared light system are simultaneously imaged with the set shutter speed and the aperture after the change (S108). Then, the exposure evaluation values of the visible light imaging unit 14 and the infrared light imaging unit 15 at this time are calculated (S109). As a result, when the calculated exposure evaluation values of both systems converge to the exposure evaluation value of the combination set according to the above procedure (S110: Yes), both the visible light system and the infrared light system The preferred exposure has been obtained and the control ends.

  On the other hand, when the calculated exposure evaluation values of both systems have not converged to the set combination exposure evaluation values (S110: No), the latest exposure evaluation values are stored in the evaluation value storage unit 20a ( Steps S111) and subsequent steps (S102) are repeated until the exposure evaluation value converges. However, if it is possible to determine whether or not the aperture limit is reached based on the control voltage, it is not necessary to store the exposure evaluation value in the evaluation value storage unit 20a.

  If the exposure evaluation value has not converged, instead of extracting and resetting the combination candidates every time the process is repeated, the exposure evaluation value is changed by changing the aperture step by step while keeping the set combination fixed. You may make it converge. In this case, when it is detected that the aperture has reached the limit during the convergence, the combination candidates are re-extracted with the latest exposure evaluation value and reset.

  As described above, the imaging apparatus 10 including the single aperture mechanism 12 sets the aperture and shutter speed that give appropriate exposure to both the visible light imaging unit 14 and the infrared light imaging unit 15 as much as possible. If the aperture and shutter speed that give the right exposure to both sides cannot be obtained, give the appropriate exposure to one of them, and prevent the other from becoming saturated and make the exposure as bright as possible. Even if the value information cannot be acquired, it is possible to obtain preferable exposure for both the visible light system and the infrared light system with a simple configuration.

DESCRIPTION OF SYMBOLS 10 ... Imaging device 11 ... Imaging optical system 12 ... Aperture mechanism 13 ... Spectral optical system 14 ... Visible light imaging part 15 ... Infrared light imaging part 16 ... Visible light system signal processing part 17 ... Infrared light system signal processing part 18 ... Exposure control unit 19 ... Aperture drive unit 20 ... Exposure condition determination unit 20a ... Evaluation value storage unit 21 ... Visible light system shutter speed setting unit 22 ... Infrared light system shutter speed setting unit 23 ... Aperture control unit

Claims (8)

Visible light imaging means for receiving visible light spectrally separated from incident light incident through an aperture means that cannot obtain aperture value information and imaging in accordance with a set exposure time, and infrared light spectrally separated from the incident light An exposure evaluation value is calculated for each of the infrared light imaging means that receives light and images according to the set exposure time, the calculated exposure evaluation value, and the visible light imaging means and the infrared light related to the exposure evaluation value An exposure condition determination unit that sets a combination of the amount of change of the aperture unit and the exposure time of each of the visible light imaging unit and the infrared light imaging unit based on the exposure time of each of the imaging unit;
Aperture control means for controlling the aperture means according to the amount of change of the aperture means according to the set combination;
Based on the exposure time of the visible light imaging means according to a combination of the set, a visible light system exposure time setting means for setting the exposure time of the visible light imaging means,
Infrared light exposure time setting means for setting the exposure time of the infrared light imaging means based on the exposure time of the infrared light imaging means related to the set combination. Quantity control device. The exposure amount control apparatus according to claim 1,
The exposure condition determining unit is configured to determine, based on the calculated exposure evaluation value, the amount of change of the aperture unit that causes at least one of the visible light imaging unit and the infrared light imaging unit to have proper exposure, the visible light imaging unit, and An exposure amount control apparatus characterized by extracting a combination with an exposure time of each of the infrared light imaging means as a selection target, and selecting and setting any combination from the selection targets. The exposure amount control apparatus according to claim 2,
The exposure condition determining means includes
When it is detected that the aperture state of the aperture means has reached the aperture limit on the open side, the combination relating to the amount of change on the open side of the aperture means is excluded from the selection target,
When it is detected that the aperture state of the aperture means has reached the aperture limit on the aperture side, the exposure amount control apparatus is characterized by excluding a combination related to the amount of change on the aperture side of the aperture means from the selection target. . The exposure amount control apparatus according to claim 2,
The exposure condition determining means, when there is a combination in which both the visible light imaging means and the infrared light imaging means have proper exposure in the extracted combinations, Select and set any combination,
When there is no combination in which the visible light imaging unit and the infrared light imaging unit both have proper exposure among the extracted combinations, the combination that makes the visible light imaging unit have proper exposure is the most open. The combination related to the amount of change on the narrower side is selected and set from among the combinations related to the amount of change on the side and the combination related to the amount of change on the most open side among the combinations in which the infrared light imaging means has the proper exposure. An exposure amount control apparatus. Visible light imaging means for receiving visible light spectrally separated from incident light incident through an aperture means that cannot obtain aperture value information and imaging in accordance with a set exposure time, and infrared light spectrally separated from the incident light An exposure evaluation value is calculated for each of the infrared light imaging means that receives light and images according to the set exposure time, the calculated exposure evaluation value, and the visible light imaging means and the infrared light related to the exposure evaluation value An exposure condition determination step for setting a combination of the amount of change of the diaphragm unit and the exposure time of each of the visible light imaging unit and the infrared light imaging unit based on the exposure time of each of the imaging unit;
An aperture control step for controlling the aperture means in accordance with the amount of change of the aperture means according to the set combination;
Based on the exposure time of the visible light imaging means according to a combination of the set, a visible light system exposure time setting step of setting an exposure time of the visible light imaging means,
Based on the exposure time of the infrared light imaging means according to a combination of the set, an exposure amount and having an infrared optical system exposure time setting step of setting an exposure time of said infrared light imaging means Control method. The exposure amount control method according to claim 5,
In the exposure condition determination step, based on the calculated exposure evaluation value, the amount of change of the aperture unit that causes at least one of the visible light imaging unit and the infrared light imaging unit to have proper exposure, the visible light imaging unit, An exposure amount control method comprising: extracting a combination with an exposure time of each of the infrared light imaging means as a selection target, and selecting and setting any combination from the selection targets. The exposure amount control method according to claim 6,
The exposure condition determination step includes
When it is detected that the aperture state of the aperture means has reached the aperture limit on the open side, the combination relating to the amount of change on the open side of the aperture means is excluded from the selection target,
When it is detected that the aperture state of the aperture means has reached the aperture limit on the aperture side, the exposure amount control method is characterized in that a combination related to the amount of change on the aperture side of the aperture means is excluded from the selection target. . The exposure amount control method according to claim 6,
In the exposure condition determination step, when there is a combination in which both the visible light imaging unit and the infrared light imaging unit have appropriate exposure in the extracted combination, the exposure condition determination step includes Select and set any combination,
When there is no combination in which the visible light imaging unit and the infrared light imaging unit both have proper exposure among the extracted combinations, the combination that makes the visible light imaging unit have proper exposure is the most open. The combination related to the amount of change on the narrower side is selected and set from among the combinations related to the amount of change on the side and the combination related to the amount of change on the most open side among the combinations in which the infrared light imaging means has the proper exposure. An exposure amount control method comprising: