JP5500442B2 - Low light camera - Google Patents

Description

  The present invention relates to a low-illuminance camera suitable for photographing a relatively dark imaging location.

  In recent years, taxis and the like are equipped with small cameras (in-vehicle monitoring cameras) for in-vehicle monitoring. This is because it is useful not only for grasping the situation of troubles with passengers occurring in the car but also for deterrence. Since such troubles often occur not only in the daytime but also at midnight, the in-vehicle monitoring camera is required to be able to acquire an image even in the dark where the room light is not lit. Therefore, a camera equipped with a light-receiving element (sensor) compatible with low illuminance, a camera with an illumination function, or the like is used as an in-vehicle monitoring camera. Among these, in-vehicle surveillance cameras equipped with low-illuminance sensors are relatively expensive, so in-vehicle surveillance cameras with illumination functions are more prevalent. An in-vehicle surveillance camera with an illumination function generally illuminates a subject using light emitting means such as an LED, receives reflected light from the subject with a sensor (light receiving means), and receives light reception intensity data obtained thereby by a predetermined amount. Frame image data is generated at a frame period (frame rate), and moving image data is created based on the frame image data.

  In-vehicle surveillance cameras are often installed in the vicinity of a rearview mirror disposed in front of the driver's seat. In-vehicle surveillance cameras can be used not only for the driver's seat at a distance of several tens of centimeters from the camera, but also for the passenger seat, and for crime prevention against illegal intrusion from the driver's seat and the passenger's seat door (front door of the vehicle body). In other words, it is desirable to be able to image even the situation near the front door of the vehicle body. Therefore, the in-vehicle surveillance camera is desired to have such a wide angle of view that enables this imaging. On the other hand, when using a camera with an illumination function as an in-vehicle monitoring camera, considering the influence on the visibility of the driver, etc., there is a great limitation in using visible light for the illumination. For this reason, as the illumination, a light source (infrared LED or the like) that emits light in a wavelength band outside the visible light (for example, an infrared wavelength band) among the bands having light receiving sensitivity of the sensor is often used. However, light sources with wavelengths outside visible light such as high-power infrared LEDs that can illuminate a wide area included in the imaging range of in-vehicle surveillance cameras that require a wide angle of view are expensive because their applications are limited. Unlike a visible light source such as a visible light LED that has been replaced by a fluorescent lamp as a lighting device, it is difficult to obtain it at low cost. Therefore, in order to provide an in-vehicle surveillance camera with an illumination function for which a wide angle of view is desired at a low price, as a light source there are more inexpensive low-power type light sources with a wavelength outside visible light than those of a high-power type. A configuration has been proposed that can be mounted to illuminate a wide area.

  The in-vehicle surveillance camera is battery-driven using a car battery or the like, and therefore, its power consumption cannot be increased unnecessarily. Therefore, it is important to suppress the light emission amount of the light source used for illumination to the minimum amount necessary for illumination. However, in order to reduce power consumption, the rear seats (2 for cars with more than two rows of seats) are illuminated with the minimum amount of light necessary for recognizing the driver's and passenger's seats close to the vehicle-mounted surveillance camera. The amount of light is insufficient to image the state of the seats in the rows and beyond. Therefore, the image which can recognize the mode of a backseat is not obtained, but the problem that the visibility about a backseat is bad arises. Further, even in a driver's seat or a passenger seat, there is a problem that the amount of light is insufficient in a dark portion such as a relatively dark hand or foot, and the visibility of such a portion is poor.

  Here, in order to improve the visibility of the rear seats and dark places, it is conceivable to increase the sensitivity (amplification factor) of the sensor. However, in this case, the noise included in the sensor output increases, which is rather visually recognized. It can make your sex worse. Therefore, when increasing the visibility of the rear seat or the dark part, it is preferable to increase the light emission intensity of the illumination. However, illuminating the entire imageable range with an amount of light that can recognize the state of the rear seat and the state of the dark part increases the power consumption, so that it is difficult to realize it with a battery-driven in-vehicle monitoring camera.

  The above-mentioned problems are not limited to in-vehicle surveillance cameras with illumination functions. In low-light environments, strong illumination intensity such as subjects in relatively distant places or relatively dark places can be obtained with cameras with illumination functions. In the case of trying to obtain high visibility with low power consumption for an imaging location where high visibility can be obtained under the illumination, there is a problem that may occur in the same way without being limited to its use or place of use.

  The present invention has been made in view of the above problems, and the object of the present invention is high in low power consumption with respect to an imaging location where high visibility is obtained under illumination with strong light emission intensity in a low illumination environment. It is an object to provide a low-illuminance camera capable of obtaining visibility.

In order to achieve the above object, the invention of claim 1 is directed to a light emitting means, a light receiving means having a light receiving sensitivity for at least a part of an emission wavelength band of the light emitting means, and reflection from an object under illumination by the light emitting means. Condensing means for condensing light on the light receiving means, received light intensity data obtained by the light receiving means is acquired at a predetermined frame period to generate frame image data, and moving image data is generated based on the frame image data In the low-illuminance camera having the moving image data creating means to be created, the light emitting means includes a first light emitting portion having a predetermined emission angle and a predetermined emission intensity, and an emission angle that is greater than the emission angle of the first light emitting portion. Having a plurality of light emitting parts including a second light emitting part having a narrow emission intensity and a stronger emission intensity than that of the first light emitting part, and emitting light from the first light emitting part in synchronization with the frame period. Strength Provided is a light emission intensity control means for controlling the light emission intensity of each light emitting part so that the light emission intensity of the second light emitting part and the light emission intensity of the second light emitting part are greater than those of the first light emitting part. The image data creation means is configured such that the frame image data obtained under illumination when the light emission intensity of the first light emitting unit is greater than that of the second light emitting unit and the light emission intensity of the second light emitting unit are greater than those of the first light emitting unit. One piece of moving image data is created using frame image data obtained under illumination when the size of the image is large.
According to a second aspect of the present invention, in the low-illuminance camera according to the first aspect, the emission angle of the first light emitting unit is 120 degrees, and the emission angle of the second light emitting unit is 40 degrees. To do.
According to a third aspect of the present invention, there is provided a light emitting means, a light receiving means having a light receiving sensitivity for at least a part of an emission wavelength band of the light emitting means, and reflected light from a subject under illumination by the light emitting means to the light receiving means. Condensing means for condensing, and received light intensity data obtained by the light receiving means at a predetermined frame period to generate frame image data, and create moving image data based on the frame image data The light emitting means has a plurality of light emitting parts including a first light emitting part and a second light emitting part that irradiate light toward different locations within the imageable range. In synchronization with the frame period, the light emission intensity of the first light emitting unit is greater than that of the second light emitting unit and the light emission intensity of the second light emitting unit is greater than that of the first light emitting unit. The light intensity control means for controlling the light emission intensity of each light emitting part is provided, and the moving image data creating means is obtained under illumination when the light emission intensity of the first light emitting part is larger than that of the second light emitting part. One moving image data is created using the frame image data obtained and the frame image data obtained under illumination when the light emission intensity of the second light emitting unit is larger than that of the first light emitting unit. Is.
According to a fourth aspect of the present invention, in the low-illuminance camera according to the third aspect, the plurality of light emitting portions include an asymmetric distributed light emitting portion having an asymmetric light emission intensity distribution, and under illumination with a predetermined light emission intensity. An object with high emission intensity that provides high visibility is illuminated with the predetermined emission intensity, and an object with low emission intensity that provides high visibility under illumination with an emission intensity smaller than the predetermined emission intensity is provided with the predetermined emission intensity. The light emission intensity distribution of the asymmetrically distributed light emitting part is set so that illumination is performed with a smaller light emission intensity.
According to a fifth aspect of the present invention, in the low-illuminance camera according to any one of the first to fourth aspects, the moving image data creating means includes the at least two light emission modes for at least a part of the imageable range. The unit synthesizes a plurality of received light intensity data for the same imaging location respectively obtained under illumination when the emission intensity is maximum among the plurality of light emitting portions, and obtains one received light intensity data for the same imaging location. The moving image data is generated using the received light intensity data generated.
According to a sixth aspect of the present invention, there is provided the low-illuminance camera according to any one of the first to fifth aspects, wherein the moving image data creating unit is configured to obtain a plurality of imaging locations obtained by dividing the imaging range. The received light intensity data obtained under illumination when the light emission intensity of the first light-emitting part is larger than that of the second light-emitting part and the light-emission intensity of the second light-emitting part are larger than those of the first light-emitting part, respectively. The moving image data is created using received light intensity data obtained under illumination.
Further, the invention of claim 7 is the low-illuminance camera according to claim 6, further comprising a frame memory having a plurality of memory areas capable of storing a plurality of frame image data, Memory corresponding to the plurality of imaging locations with respect to a memory area in which frame image data generated from received light intensity data obtained first among received light intensity data obtained under illumination by at least two light emitting units is stored The processing is performed by replacing the data of the portion with that of the frame image data generated from the received light intensity data obtained under illumination by another light emitting unit that provides high visibility.
The invention of claim 8 is the low-illuminance camera according to any one of claims 1 to 7, wherein the light emitting means has an infrared wavelength band as an emission wavelength band. To do.

In the invention according to claim 1, under illumination by the first light-emitting portion, than under illumination by the second light emitting portion, it is possible to obtain an image having high visibility in a wide range for a short distance object near the camera. On the other hand, under illumination by the second light emitting part, than under illumination by the first light emitting portion, a narrow range, the dark area subject existing distant far subject and dark portion portion from a camera to obtain a high visibility images it can. Thus, according to the first aspect of the invention, the first light emitting unit secures high visibility in a wide range for a short-distance subject, and the second subject for a long-distance subject and a dark subject in a predetermined narrow range. High visibility can be ensured by the light emitting portion. In addition, in the invention according to claim 1, each of the first light-emitting part and the second light-emitting part has a light emission intensity greater than that of the second light-emitting part and a light emission intensity of the second light-emitting part larger than that of the first light-emitting part. Since the emission intensity of the light emitting unit is controlled , the second light emitting unit has a lower power consumption than the case where the second light emitting unit always emits light with a light emission intensity higher than that of the first light emitting unit , and has the same visibility for a long-distance subject and a dark subject. The moving image data can be obtained.
Here, if the emission angle of the second light emitting unit, which has a higher emission intensity than the first light emitting unit, is set to an emission angle equivalent to that of the first light emitting unit, it not only increases power consumption but also wastes power as follows. It will also be consumed. That is, when the emission angle of the second light emitting unit is increased to be equal to that of the first light emitting unit, strong light hits a near-distance subject close to the camera, and the near-distance subject is so-called whiteout (too bright and the light receiving sensitivity upper limit of the sensor May be in a state of exceeding white and whitening). Light that is strong enough to cause overexposure in a short-distance subject is not useful because it does not improve the visibility of the short-distance subject.
In the invention according to claim 1, since the emission angle of the second light emitting unit is narrower than that of the first light emitting unit , and the illumination range thereof is limited to a range narrower than that of the first light emitting unit , whiteout occurs in a short-distance subject. It is possible to suppress wasteful power consumption. In particular, if setting is made so that there is no short-distance subject between the long-distance subject far from the camera and the second light-emitting unit, whiteout will not occur in the short-distance subject, so there is an effect of reducing wasteful power consumption. high.

In the invention which concerns on Claim 3, when the light emission intensity | strength of a 1st light emission part is larger than a 2nd light emission part among the several light emission parts which irradiate light toward the mutually different imaging location within an imaging possible range, The light emission intensity of each light emitting part is controlled so that the time when the light emission intensity of the second light emitting part is greater than that of the first light emitting part occurs . Accordingly, a plurality of different imaging locations within the imageable range can be sequentially illuminated with a relatively large light emission intensity that provides high visibility for a long-distance subject and a dark subject. As a result, high visibility for long-distance subjects and dark subjects is achieved with less power consumption than when constantly illuminating the entire imageable range with a relatively large light emission intensity that provides high visibility for long-distance subjects and dark subjects. Can be obtained.

In the first and third aspects of the invention, the frame image data obtained under illumination when the light emission intensity of the first light-emitting part is larger than the second light-emitting part and the light emission intensity of the second light-emitting part are the first light-emitting part. using frame image data that is obtained under the illumination is greater than the light emitting portion, to create a single frame image data used in the moving image data, the frame rate of the moving image data is obtained by the light receiving means It falls below the frame rate of the predetermined frame period for acquiring the received light intensity data. Even in this case, the smoothness of the image is reduced, but the visibility of a long-distance subject and a dark subject is not reduced.

  In Patent Document 1, a spectroscopic optical system that splits an optical image of a subject incident from a lens in two directions, two solid-state imaging devices that convert each of the optical images split in two directions into electric signals, and Electronic shutter control means for sequentially controlling the exposure of the two solid-state imaging devices within a time corresponding to ½ frame for each frame period and at intervals not overlapping with each other, and sequential exposure by the electronic shutter control means A color camera having a light emission synchronization signal output means for outputting a light emission synchronization signal in synchronization with the control, and a wavelength band in synchronization with the exposure control of the solid-state imaging device that receives the light emission synchronization signal of the color camera A lighting device that emits light by sequentially switching light of a plurality of different colors is disclosed. This illuminating device synchronizes with the exposure control of the solid-state imaging device and sequentially emits light of a plurality of colors having different wavelength bands, and the emission intensity and the illumination location are the same. Therefore, even if this illuminating device is used, it is impossible to obtain high visibility with low power consumption for an imaging location where high visibility is obtained under illumination with strong light emission intensity.

  As described above, according to the present invention, it is possible to obtain an excellent effect that high visibility can be obtained with low power consumption with respect to an imaging portion where high visibility is obtained under illumination with strong light emission intensity in a low illumination environment. .

It is a front view which shows the outline | summary of the in-vehicle surveillance camera in Embodiment 1. FIG. It is a plain diagram which shows the outline | summary of the monitoring camera in the same vehicle. (A)-(c) is explanatory drawing for demonstrating the irradiation distance of the emitted light from LED of the illumination unit in the same vehicle surveillance camera, and its radiation | emission angle. It is explanatory drawing which shows the illumination area | region by an illumination unit in case the vehicle by which the same monitoring camera is mounted is a 2 row vehicle. It is explanatory drawing which shows the illumination area | region by an illumination unit about the example in which the vehicle by which the same monitoring camera is mounted is a 3-row seat car. It is a functional block diagram which shows the illumination unit and camera unit in the same surveillance camera. It is explanatory drawing which shows the circuit structure of the light emission driver of the illumination unit. It is a block diagram which shows the control part provided in the camera unit. It is explanatory drawing explaining an example of the process sequence of the image process part with respect to the frame memory in the same control part. It is explanatory drawing which shows an example of the edit process which edits and processes two frame image data, and produces one new frame image data. It is explanatory drawing which shows the other example of the edit process which edits and processes two frame image data, and produces one new frame image data. 10 is an explanatory diagram illustrating a processing sequence of an image processing unit in Modification 1. FIG. It is a front view which shows the state which attached the in-vehicle monitoring camera which concerns on Embodiment 2 to the room mirror. It is explanatory drawing which shows the illumination range of the illumination unit in Embodiment 2. FIG. (A) is explanatory drawing which shows the light emission intensity distribution of general LED. (B) is explanatory drawing which shows the light emission intensity distribution of LED used in the modification 2. FIG.

Embodiment 1
Hereinafter, an embodiment (hereinafter, this embodiment is referred to as “Embodiment 1”) in which the present invention is applied to an in-vehicle surveillance camera that is a low-illuminance camera will be described.
The in-vehicle monitoring camera according to the first embodiment is mounted on a vehicle such as a taxi to obtain a moving image obtained by capturing an image of the inside of the vehicle, and has the following characteristics.
In other words, conventional in-vehicle surveillance cameras illuminate the interior of a dark car with no light at night, etc., with a constant amount of light. In general, illumination with a relatively weak emission intensity is required to reduce power consumption. To do. Therefore, although visibility is obtained at an imaging location near the camera such as a driver's seat or a passenger seat, sufficient visibility may not be obtained at an imaging location such as a rear seat that is far from the camera. On the other hand, lighting with strong light emission intensity to obtain the visibility of the imaging location far from the camera not only increases the power consumption, but also causes the whiteout to occur in the imaging location close to the camera and deteriorates the visibility coming out. The in-vehicle monitoring camera according to the first embodiment emits light by alternately emitting illumination with a wide emission angle and low emission intensity, a first light emitting unit, and a second light emitting unit with a narrow emission angle and high emission intensity. Using the received light intensity data obtained under the illumination of each part, cut and paste the imaging location where effective visibility is obtained, and create moving image data with high visibility in both perspective using the frame image obtained thereby I have to.

FIG. 1 is a front view illustrating an outline of the in-vehicle monitoring camera according to the first embodiment.
FIG. 2 is a plan view showing an outline of the in-vehicle monitoring camera according to the first embodiment.
The in-vehicle surveillance camera 1 includes a wide-angle lens 2, a camera unit 3, a camera cable 4, illumination units 5A and 5B, illumination cables 6A and 6B, an inter-unit cable 8, and the like. The wide-angle lens 2 has an angle of view in the range of 90 degrees or more and 180 degrees or less, preferably about 135 degrees so that the wide angle of view required for the in-vehicle surveillance camera can be obtained. The camera cable 4 is an electric wire that combines a power line and a video line. The illumination cables 6A and 6B are electric wires for the power lines of the LEDs 7A and 7B. The inter-unit cable 8 is a cable for transmitting timing signals (synchronization signals) between the camera unit 3 and the illumination units 5A and 5B, and is connected inside the housing of the in-vehicle monitoring camera 1. The timing signal may be externally connected via the camera cable 4 and the illumination cables 6A and 6B.

  The illumination units 5A and 5B as the light emitting means are disposed in the vicinity of the wide-angle lens 2, and in the first embodiment, it is preferable to use a light source having a wavelength band outside visible light. In the first embodiment, infrared light emitting diodes (LEDs) 7A and 7B are used as the light source. The LEDs 7A and 7B, which are light emitting units, have an exit lens disposed on the light exit surface of the LED element, and are configured to radiate light radially within a desired exit angle range.

FIGS. 3A to 3C are explanatory diagrams for explaining the irradiation distance and the emission angle of the emitted light from the LEDs 7A and 7B.
The LED elements using the LEDs 7A and 7B of the first embodiment all have the same light emission intensity, but have different exit lenses. For this reason, the wide-angle LED 7A in which an emission lens having a wide emission angle is used has a low emission intensity and a short irradiation distance, as shown in FIG. On the other hand, as shown in FIG. 3B, the narrow-angle LED 7B using an emission lens with a narrow emission angle has a high emission intensity and a long irradiation distance. In this embodiment, the wide-angle LED 7A is used for illuminating a short-distance subject such as a driver's seat or a passenger seat, and the narrow-angle LED 7B is used for illuminating a long-distance subject such as a rear seat. Note that the arrangement of the wide-angle LED 7A and the narrow-angle LED 7B is not limited to that of the first embodiment as long as they are arranged close to each other.

  FIG. 3C illustrates an illumination area when the wide-angle LED 7A and the narrow-angle LED 7B emit light simultaneously. In this case, the short-distance center part (near between the driver's seat and the passenger seat) where both illumination areas overlap is extremely bright and wasted. Further, when the wide-angle LED 7A and the narrow-angle LED 7B are caused to emit light at the same time, the power consumption is doubled as compared with the case where either one is caused to emit light. Therefore, in this embodiment, as will be described later, the wide-angle LED 7A and the narrow-angle LED 7B are alternately strengthened in synchronization with the frame period.

  The LEDs 7 </ b> A and 7 </ b> B need to be configured so that the illumination light does not directly enter the incident range of the wide-angle lens 2. In the first embodiment, an example in which six LEDs 7A and 7B are mounted will be described. However, depending on the installation environment of the in-vehicle surveillance camera 1, etc., if the light emission intensity is too strong, the number is reduced, and it seems to be too weak. Try to increase the number.

FIG. 4 is an explanatory diagram showing illumination areas by the illumination units 5A and 5B when the vehicle on which the in-vehicle surveillance camera 1 is mounted is a two-row seat automobile.
In addition, in FIG. 4, the code | symbol A-D has shown the passenger | crew, and is an example of a sedan type motor vehicle. The actual occupant position varies slightly depending on the vehicle.
As shown in FIG. 4, the illumination ranges of the illumination units 5A and 5B in the present embodiment are approximately x = 50 cm, d1 = 30 cm, and d2 = 150 cm. When the emission angle of the wide-angle LED 7A in this case is calculated, 2 × arctan (50/30) ≈118 degrees, which is approximately 120 degrees. On the other hand, when calculating the emission angle of the narrow-angle LED 7B, 2 × arctan (50/150) ≈37 degrees, which is approximately 40 degrees. The optimum emission angle of each LED 7A, 7B varies depending on the size of the vehicle and the seat configuration. In general, if the LED having this emission angle is combined, the driver's seat and front passenger seat can be sufficiently illuminated by the wide-angle LED 7A. The rear seat can be sufficiently illuminated by the narrow-angle LED 7B.

FIG. 5 is an explanatory diagram showing an illumination area in an example in which the vehicle on which the in-vehicle monitoring camera 1 is mounted is a three-row seat car.
As shown in FIG. 5, the illumination range in this example is approximately x = 50 cm, d1 = 30 cm, d2 = 100 cm, and d3 = 170 cm. In this case, when the emission angle of the LED for a short-distance subject such as a driver's seat or a passenger seat is calculated, 2 × arctan (50/30) ≈118 degrees, which is approximately 120 degrees. Further, when calculating the emission angle of the LED for the medium distance subject such as the seat in the second row, 2 × arctan (50/100) ≈53 degrees, which is approximately 55 degrees. Further, when calculating the emission angle of the LED for a long-distance subject such as a seat in the third row, 2 × arctan (50/170) ≈33 degrees, which is approximately 35 degrees.

FIG. 6 is a functional block diagram showing the lighting units 5A and 5B and the camera unit 3. As shown in FIG.
In the camera unit 3, the reflected light from the subject under illumination by the LEDs 7 </ b> A and 7 </ b> B is collected by the wide-angle lens 2 as the light collecting means and guided to the light receiving surface of the light receiving sensor 9 as the light receiving means. The wide-angle lens 2 is composed of a plurality of lenses composed of, for example, 6 elements in 4 groups combining materials such as glass and plastic. As the light receiving sensor 9, a sensor composed of a CCD, a CMOS, or the like is known, but in general, a CCD can be suitably used because it has a higher sensitivity of low illuminance. However, CMOS is also being actively promoted to increase sensitivity, and CMOS may be used. Since the resolution of the light receiving sensor 9 is used for in-vehicle monitoring in the first embodiment, for example, it is set to about VGA (640 × 480 dots) and the frame rate is 30 fps (frame per second) or less. In the low-illuminance camera as in the first embodiment, for example, the exposure time may be increased in order to cope with weak light, and in this case, the frame rate tends to decrease. Further, as a function of the light receiving sensor 9 or a function of the control device of the light receiving sensor 9, there is known a function for performing luminance correction processing for making a moving image easy to see by brightening a dark part and darkening an excessively bright part. Yes. This is to change the amplification factor of the luminance level so as to keep the average luminance of the moving image constant. In many cases, the average luminance is calculated over a plurality of frames and is gradually corrected.

The control unit 10 as moving image data creating means sequentially takes the output data (received light intensity data) of the light receiving sensor 9, creates moving image data converted into a standard video signal transmission format such as NTSC, and the camera cable 4 Output to.
The illumination units 5A and 5B are connected to drive power sources (not shown) of the LEDs 7A and 7B via the illumination cables 6A and 6B. Of course, a power source common to the camera unit 3 may be used. As the light source of the illumination units 5A and 5B, a light bulb, a fluorescent lamp, and the like are conceivable, but the LEDs 7A and 7B are employed in the first embodiment because of low power consumption and infrared wavelength selectivity.
The light emitting driver 11 generates a current source based on a driving power source (not shown), and operates so as to alternately turn ON / OFF the light emission intensity of the LEDs 7A and 7B. Depending on the amount of light required for each of the wide-angle LED 7A and the narrow-angle LED 7B, if one LED cannot cope with the light, it is possible to share the illumination with a plurality of LEDs. In this case, it is important to arrange the illumination so that there are no locally bright spots.

FIG. 7 is an explanatory diagram showing a circuit configuration of the light emitting driver 11 of the illumination units 5A and 5B.
In the first embodiment, constant current sources 13A and 13B based on the illumination drive power supply 12 are arranged to cause the LEDs 7A and 7B to emit light. If the emission intensity is changed independently for the wide-angle LED 7A and the narrow-angle LED 7B, the current values of these constant current sources 13A and 13B may be changed. Between the constant current sources 13A and 13B and the LEDs 7A and 7B, switch units 14A and 14B that are turned ON / OFF by the input timing signals A and B are arranged, respectively. By controlling the timing signals A and B input to the switch sections 14A and 14B, it is possible to select whether to supply a current to either the wide-angle LED 7A or the narrow-angle LED 7B. Here, the configuration in which the LEDs 7A and 7B that supply current are selected by controlling the timing signals A and B input to the switch units 14A and 14B has been described, but the constant current sources 13A and 13B are connected to one D It is composed of voltage setting and voltage / current conversion resistors such as the / A converter, and the timing signal is a parallel digital signal, so that the set voltage of the D / A converter is sequentially changed to change the emission intensity of the LEDs 7A and 7B. You can also. In addition, it can respond to many illuminations by increasing the circuit and timing signal of illumination.

FIG. 8 is a block diagram showing the control unit 10 provided in the camera unit 3.
The control unit 10 receives the output data from the light receiving sensor 9 and performs processing, the frame memory 16 that stores frame image data obtained by the processing in the image processing unit 15, and the frame memory 16 NTSC conversion unit 17 that converts the moving image data composed of the frame image data into the NTSC standard, which is a standard data format for displaying on an external monitor, and obtains the entire captured image or part of luminance information. And a luminance determining unit 18 for determining brightness.

  The image processing unit 15 sequentially stores frame image data based on output data from the light receiving sensor 9 in the frame memory 16 at a speed of 30 fps or 60 fps. When there is sufficient brightness (brightness) such as daytime and the illumination of the LEDs 7A and 7B is not necessary, the data does not need to be processed, so the frame image data is transferred to the NTSC converter 17 at an appropriate speed. In this case, since it is not necessary to use the LEDs 7A and 7B, it is not necessary to output the timing signals A and B. Whether it is daytime or nighttime may be determined by an external setting, but if the camera automatically determines the average brightness of the frame image data and the dark time continues longer than the preset brightness, it will be nighttime. You may make it judge. Further, a comparison result of whether or not the luminance by the luminance determination unit 18 exceeds a preset level may be used.

  When it is necessary to take an image in a low illumination environment such as at night, the imaging range is illuminated by driving the LEDs 7A and 7B. In this case, the image processing unit 15 functions as a light emission intensity control unit, and first instructs the light emitting driver 11 to turn on the timing signal A and turn off the timing signal B. As a result, the LED 7A performs illumination in the illumination range LA having a low emission intensity (that is, a short illumination distance) and a wide emission angle as shown in FIG. 4, and frame image data based on output data from the light receiving sensor 9 is framed. The first frame image data is stored in a predetermined memory area of the memory 16. Next, a command to turn off the timing signal A and turn on the timing signal B is instructed to the light emitting driver 11. As a result, the LED 7B performs illumination in an illumination range LB having a high emission intensity (ie, a long illumination distance) and a narrow emission angle as shown in FIG. 4, and frame image data based on output data from the light receiving sensor 9 is framed. The second frame image data is stored in a predetermined memory area of the memory 16. Here, the “illumination distance” means the distance between the light emitting surface of the light source and the farthest place among places where the minimum necessary light quantity can be obtained.

FIG. 9 is an explanatory diagram illustrating an example of a processing sequence of the image processing unit 15 for the frame memory 16.
This explanatory diagram shows data accessed to each memory area of the frame memory 16 frame by frame from t1 to t8 with the time axis on the horizontal axis. Arrows in the figure indicate data movement.
In this processing sequence, a frame memory 16 having at least five memory areas (memory 1 to 5) for storing one frame image data is used. As such a frame memory 16, a single physical memory having a storage area divided into five may be used, or five physical memories may be individually prepared. However, as described later, since it is necessary to perform a plurality of processes within one frame period, sufficient high speed is required for the data read speed and write speed.

Hereinafter, the flow of this processing sequence will be specifically described.
First, at time t1, the frame image data D1 for one frame is stored in the memory 1, and at the same time, the processed frame image data P1 stored in the memory 2 is output to the NTSC converter 17.
At time t2, the frame image data D2 for the next one frame is stored in the memory 2, and at the same time, the processed frame image data P2 that has already been processed is output from the memory 5 to the NTSC converter 17.
At time t3, the frame image data D3 for the next one frame is stored in the memory 4, and at the same time, the processed frame image data P2 is repeatedly output from the memory 5 similarly to the time t2. At the same time, the frame image data D1 stored in the memory 1 and the frame image data D2 stored in the memory 2 are combined and edited, and the processed frame image data D12 is stored in the memory 3.

  Here, although editing processing of the processed frame image data D12 will be described later, it does not mean that the entire frame image data D2 is overwritten on the image of the frame image data D1, but the image frame is divided into some regions. This means that the data of the above are replaced with each other, and the luminance and color difference data of both images are averaged. In the first embodiment, one frame is divided into at least a frame portion corresponding to a subject portion close to the camera (short-distance region) and a frame portion corresponding to a subject portion far from the camera (long-distance region). .

At time t4, the frame image data D4 for the next one frame is stored in the memory 5, and at the same time, the processed frame image data D12 is output from the memory 3 to the NTSC converter 17.
At time t5, the frame image data D5 for the next one frame is stored in the memory 2, and at the same time, the processed frame image data D12 is repeatedly output from the memory 3 in the same manner as at time t4. At the same time, the frame image data D3 stored in the memory 4 and the frame image data D4 stored in the memory 5 are combined and edited, and the processed frame image data D34 is stored in the memory 1.
At time t6, the frame image data D6 for the next one frame is stored in the memory 3, and at the same time, the processed frame image data D34 is output from the memory 1 to the NTSC converter 17.
At time t7, the frame image data D7 for the next one frame is stored in the memory 5, and at the same time, the processed frame image data D34 is repeatedly output from the memory 1 in the same manner as at time t6. At the same time, the frame image data D5 stored in the memory 2 and the frame image data D6 stored in the memory 3 are combined and edited, and the processed frame image data D56 is stored in the memory 4.
At time t8, the frame image data D8 for the next one frame is stored in the memory 1, and at the same time, the processed frame image data D56 is output from the memory 4 to the NTSC converter 17.

The processing sequence as described above is repeated after time t9. With such a processing sequence, it is possible to obtain moving image data in which the frame is updated at a half speed of the frame speed at which the output data from the light receiving sensor 9 is sequentially acquired.
As in the example shown in FIG. 5, when there are three or more subjects, such as a short-distance subject, a medium-distance subject, and a long-distance subject, the number of memory areas in the frame memory 16 is increased. What is necessary is just to process in order, without deleting the frame image data of a process.
Here, the case where image processing is performed for each frame in non-interlace has been described, but in the case of interlace, processing may be performed for each field. In that case, it is possible to replace only the frame described above with a field, but it is desirable to treat two fields as one because a line shift occurs.

  In the first embodiment, in synchronization with the processing timing (frame period) of the above processing sequence, the image processing unit 15 causes the LEDs 7A and 7B to turn on the timing signal A and turn off the timing signal B at time t1. To control the emission intensity. As a result, the frame image data D1 is obtained under relatively weak illumination. Subsequently, at time t2, the timing signal A is turned off and the timing signal B is turned on. As a result, the frame image data D2 is obtained under relatively strong illumination. The processed frame image data D12 uses the frame image data D1 and D2 obtained with these two types of illumination intensities, and actively uses the frame image data D1 for a short-distance region that is a partial region of the frame. The long-distance area, which is the other area of the frame, is edited by actively adopting the frame image data D2. By performing such editing processing, it is possible to obtain frame image data D12 in which both near and far are imaged under appropriate illumination conditions. If turning off an LED causes a problem that the rise time at the next ON is delayed, the LED may emit weak light instead of turning off the LED. Further, it is important that the luminance correction of the light receiving sensor 9 does not follow the ON / OFF of the LEDs 7A and 7B.

FIG. 10 is an explanatory diagram illustrating an example of an editing process in which two frame image data D1 and D2 are edited and processed to create one new frame image data D12.
In the first embodiment, the in-vehicle monitoring camera 1 is installed in the vicinity of a rearview mirror disposed in front of the driver's seat of an automobile, and is arranged so as to take an image of the inside of the vehicle from the rear side. Even if there is no room mirror, it is the same if it is installed near the top of the windshield. In general, an automobile has a gap between a driver seat and a passenger seat, and a rear seat can be photographed from the gap. Therefore, in the first embodiment, one frame is divided into three, the central area is set as a long distance area including the rear seat, and the both side areas are set as the short distance area including the driver seat and the passenger seat.

  As described above, the frame image data D1 is obtained under relatively weak illumination by the wide-angle LED 7A, whereas the frame image data D2 is obtained under relatively strong illumination by the narrow-angle LED 7B. . In the first embodiment, priority is given to the visibility of the driver seat and the passenger seat, and the editing process is performed based on the frame image data D1. Since the frame image data D1 has a wide angle but a short illumination distance, as shown in FIG. 10, the passenger C in the rear seat is dark and hardly recognized. Conversely, the frame image data D2 has a narrow angle but a long illumination distance, so that the passenger C in the rear seat can be recognized well, but the driver A in the driver's seat and the passenger B in the passenger seat are out of the illumination range and are dark. Almost unrecognizable. For this reason, in the first embodiment, a region (far-distance region) surrounded by a broken line shown in FIG. 10 is cut out from the frame image data D2, and only the cut-out long-distance region is overwritten on the frame image data D1. Thus, frame image data D12 is obtained. Furthermore, it is preferable to perform image quality improvement processing such as performing overall brightness adjustment or blurring of the boundary on the frame image data D12 obtained in this way. By performing the editing process as described above, frame image data D12 with high visibility is obtained for all of driver A in the driver's seat, passenger B in the passenger seat, and passenger C in the rear seat. The editing process for the other frame image data D3 to D8 is performed in the same manner.

In the first embodiment, since one frame image data is created from two frame image data, the frame rate is reduced to half that of the frame rate (frame speed) of the light receiving sensor 9. Since the NTSC format needs to output video at a prescribed rate, the first embodiment outputs the same frame image data twice in succession.
In addition, when performing editing processing with a higher function, the luminance level is read from the frame image data before editing processing, and the frame image data with the lower illuminance is adopted for the area judged to be whiteout, On the other hand, it is also effective to install an automatic discrimination algorithm such as adopting frame image data with higher illuminance for an area having a luminance below a certain level. Basically, in security applications such as in-vehicle monitoring, it is not necessary to capture high-speed motion, so there is no particular problem even if the frame rate drops to half. Moreover, since what is output is a moving image, it does not cause a major problem with respect to discontinuities at fine boundaries, and therefore image processing can be simplified.

  In the first embodiment, an example in which one frame is divided into three in the horizontal direction as illustrated in FIG. 10 has been described. However, the division method may be, for example, which subject in the imaging region of the camera should be improved in visibility. It is set as appropriate according to the design matters. For example, although the location of the foot of the passenger C in the rear seat does not need high visibility, when it is desired to obtain high visibility for the location of the driver A in the driver seat and the passenger B in the passenger seat, for example, FIG. As shown, the upper part of the central area in one frame may be set as the long distance area, and the remaining area may be set as the short distance area.

  Further, it is not impossible to obtain the same effect as in the first embodiment by changing the luminance correction of the light receiving sensor 9 or the amplification factor of the light receiving sensor 9 for each frame without changing the illumination intensity. Considering that the amount of light reaching the passenger C is small, the S / N ratio of the first embodiment that changes the illumination intensity is more advantageous and can be said to be a better method.

[Modification 1]
Next, a modified example of the processing sequence of the image processing unit 15 in the first embodiment (hereinafter, this modified example is referred to as “modified example 1”) will be described.
FIG. 12 is an explanatory diagram illustrating a processing sequence of the image processing unit 15 in the first modification.
In the first modification, setting of area division of one frame is as simple as the dividing method shown in FIGS. 10 and 11, for example, and editing processing of two frame image data replaces one with the other data. This is an example suitable for simple processing such as

  The frame memory 16 in the first modification is divided into two memory areas. As such a frame memory 16, a storage area of a single physical memory divided into two may be used, or two physical memories may be prepared separately. However, since it is necessary to perform a plurality of processes within one frame period, the point that sufficient high speed is required for the data read speed and write speed is the same as in the first embodiment.

Hereinafter, the flow of the processing sequence in the first modification will be specifically described.
First, at time t1, the frame image data D1 for one frame is stored in the memory 1, and at the same time, the processed frame image data P1 is output from the memory 2 to the NTSC converter 17.
At time t2, the memory 1 in which the frame image data D1 is stored is overwritten only with the data of the area portion cut out from the frame image data D2 for the next one frame. For example, in the example shown in FIG. 10, the data of the central area, which is a long-distance area, is cut out from the frame image data D2, and the memory 1 is accessed to overwrite only the data on the frame image data D1. At the same time, similarly to the time t1, the processed frame image data P1 is repeatedly output from the memory 2.
At time t3, the frame image data D3 for the next one frame is stored in the memory 2, and at the same time, the processed frame image data D12 created at time t2 is output from the memory 1 to the NTSC converter 17.
At time t4, the operation is similar to that at time t2. Specifically, the frame image data D4 for the next one frame is partially overwritten in the memory 2 in which the frame image data D3 is stored, and at the same time, the processed frame image data D12 is repeatedly output from the memory 1.
At time t5, the frame image data D5 for the next frame is stored in the memory 1, and at the same time, the processed frame image data D34 created at time t4 is output.
At time t6, the operation is similar to that at time t4. Specifically, the frame image data D6 for the next one frame is partially overwritten on the memory 1 in which the frame image data D5 is stored, and at the same time, the processed frame image data D34 is repeatedly output from the memory 2.
The processing sequence as described above is repeated after time t7. With such a processing sequence, it is possible to obtain moving image data in which the frame is updated at a half speed of the frame speed at which the output data from the light receiving sensor 9 is sequentially acquired.

  The technique capable of reducing the memory capacity required for editing as in the first modification is suitable when the area to be overwritten is fixed, as in the example of dividing into three in the horizontal direction as shown in FIG. . On the other hand, region division that cuts out an arbitrary region is effective for image recognition in which the luminance level is read and video data in a specific region is replaced. In this case, it is preferable to use the method shown in FIG. The optimal value of the area setting varies depending on the distance from the camera to the occupant, the size and spacing of the seats, and may be adjusted when installed in the vehicle. It may be a set value.

[Embodiment 2]
Next, another embodiment (hereinafter, this embodiment is referred to as “embodiment 2”) in which the present invention is applied to an in-vehicle monitoring camera that is a low-illuminance camera will be described.
Since the basic configuration of the in-vehicle surveillance camera according to the second embodiment is the same as that of the first embodiment, only the differences from the first embodiment will be described in the following description.

FIG. 13 is a front view illustrating a state in which the in-vehicle monitoring camera according to the second embodiment is attached to the room mirror 20.
In the second embodiment, the room mirror 20 is attached to the windshield of the automobile by a mirror attachment portion 21. In the in-vehicle surveillance camera of the second embodiment, the two illumination units 25A and 25B are configured separately from the camera unit 23, the camera unit 23 is in the center of the room mirror 20, and the two illumination units 25A and 25B are in the room mirror. They are arranged slightly apart on the left and right sides of 20. Specifically, as shown in FIG. 10, a stay 22 is installed on the attachment portion 21 of the room mirror 20, and two illumination units 25 </ b> A and 25 </ b> B are attached to the stay 22.

FIG. 14 is an explanatory diagram showing illumination ranges of the illumination units 25A and 25B in the second embodiment.
As shown in FIG. 14, the illumination unit 25A attached to the right side of the drawing among the lighting units 25A and 25B has its LED emitting surface directed so as to emit light toward the left side of the drawing in the vehicle. ing. On the other hand, the illumination unit 25B attached to the left side in the drawing has its LED emission surface directed so as to irradiate light toward the right side in the drawing in the vehicle. Thus, it is preferable to arrange the two illumination units 25A and 25B so that the irradiation directions of the two illumination units 25A and 25B intersect each other. With such an arrangement, it is possible to reduce the subject area hidden behind the seat in the vehicle, and an image with high visibility can be obtained over a wider range. In addition, each of the illumination units 25A and 25B is set with an illumination distance, an emission angle, an irradiation direction, and the like so that both the front seat and the rear seat are within the irradiation range.

  In the first embodiment described above, one lighting unit 5A is in charge of the front seat (short-distance subject) and the other lighting unit 5B is in charge of the rear seat (long-distance subject). 2, one lighting unit 25 </ b> A is responsible for lighting the front seat and the rear seat located on the left side in the figure in the vehicle, and the other lighting unit 25 </ b> B is used for lighting the front seat and the rear seat located on the right side in the figure in the vehicle. It is different in the point in charge. For this reason, as the illumination units 25A and 25B of the second embodiment, LEDs of a relatively narrow angle type are used.

  In the second embodiment, the frame image data D1 is obtained under illumination by the illumination unit 5A, and the frame image data D2 is obtained under illumination by the illumination unit 5B. In the second embodiment, the editing process is performed based on the frame image data D1. Specifically, in the second embodiment, one frame is divided into left and right at the center in the horizontal direction, a right half area corresponding to the illumination range of the illumination unit 5B is cut out from the frame image data D2, and the cut out right half area is cut out. Only the frame image data D1 is overwritten, thereby obtaining the frame image data D12. By performing such editing and processing, frame image data D12 with high visibility is obtained for all of driver A in the driver's seat, passenger B in the passenger seat, and passengers C and D in the rear seat. Note that the ON / OFF control of the lighting units 5A and 5B and the access method to the frame memory 16 in the editing process according to the second embodiment are the same as those in the first embodiment, and a description thereof will be omitted.

[Modification 2]
Next, a modified example of the illumination units 25A and 25B in the second embodiment (hereinafter, this modified example is referred to as “modified example 2”) will be described.
FIG. 15A is an explanatory diagram showing a light emission intensity distribution of a general LED, and FIG. 15B is an explanatory diagram showing a light emission intensity distribution of an LED used in the second modification.
In the second embodiment, each of the lighting units 25A and 25B is in charge of illuminating both the front seat and the rear seat, and therefore there are two subjects having different distances in the illumination area. Therefore, when the emission intensity distribution is normally distributed as in the general LED shown in FIG. 15A, the front seat (short-distance subject) is closer than the far rear seat (far-distance subject). Is illuminated with slightly stronger light. Therefore, illumination unevenness occurs between the long-distance subject and the short-distance subject, and the visibility is different.

As shown in FIG. 15B, the illumination units 25A and 25B used in the second modification example use LEDs having an asymmetric emission intensity distribution. Specifically, the LED used in each of the lighting units 25A and 25B has a peak value shifted toward the region where the light emission intensity distribution illuminates the rear seat (far-distance subject). Such an LED having an asymmetric emission intensity distribution can be realized by using an aspheric lens as its exit lens. In addition, the broken-line arrow shown to Fig.15 (a) and (b) shows c of each illumination unit 25A, 25B. In the second modification, each of the lighting units 25A and 25B may be set approximately at the center of the front seat and the rear seat.
In the second modification, there is no problem with a general light emission intensity distribution in the vertical direction. However, if uneven illumination occurs between distant subjects in the vertical direction, the light emission intensity distribution is asymmetric in the vertical direction. A thing may be used.

As described above, the in-vehicle monitoring camera 1 which is a low-illuminance camera according to Embodiment 1 (including Modification 1) includes at least the light emission wavelength bands of the illumination units 5A and 5B as the light emitting means and the illumination units 5A and 5B. A light receiving sensor 9 as a light receiving means having a light receiving sensitivity for a part, a wide-angle lens 2 as a light collecting means for condensing reflected light from the subject onto the light receiving sensor 9 under illumination by the illumination units 5A and 5B, and a light receiving sensor Is generated at a predetermined frame period (frame rate) to generate frame image data D1, D2,..., And moving image data is generated based on the frame image data. And a control unit 10 as creation means. The illumination units 5A and 5B of the in-vehicle surveillance camera 1 include a wide-angle LED 7A as a first light-emitting unit with a wide emission angle and a short illumination distance, and a narrow-angle LED 7B as a second light-emitting unit with a short emission angle and a long illumination distance. have. Then, in synchronism with the frame period, the control unit 10 as light emission intensity control means for controlling the light emission intensity of each LED 7A, 7B so that the LEDs emitting light with the maximum light emission intensity are sequentially switched between the LEDs 7A, 7B. The control unit 10 creates one moving image data using the frame image data obtained under the illumination emitted by the LEDs 7A and 7B. As a result, in a low-light environment such as a dark car at night, high visibility can be obtained with low power consumption for an imaging location (long-distance region) where high visibility is obtained under illumination with strong light emission intensity. . Moreover, in the first embodiment (including Modification 1), it is possible to obtain a highly visible image for both a near subject portion such as a driver seat and a passenger seat and a far subject portion such as a rear seat.
In this case, the exit angle of the wide-angle LED 7A is preferably 120 degrees, and the exit angle of the narrow-angle LED 7B is preferably 40 degrees.
In addition, the in-vehicle monitoring camera 1 according to the second embodiment (including the modified example 2) includes a plurality of light emitting units (LEDs) in which the illumination units 25A and 25B irradiate light toward different locations within the imageable range. )have. And it has the control part 10 as a light emission intensity control means which controls the light emission intensity of each LED7A and 7B so that LED which light-emits with maximum light emission intensity may switch sequentially among these LEDs synchronizing with a frame period. The control unit 10 creates one moving image data using the frame image data obtained under the illumination emitted by the LEDs 7A and 7B. As a result, in a low-light environment such as a dark car at night, high visibility can be obtained with low power consumption for an imaging location (long-distance region) where high visibility is obtained under illumination with strong light emission intensity. .
Further, as in the second modification, the LEDs of the illumination units 25A and 25B used in the second embodiment are asymmetrically distributed light emitting portions having asymmetric emission intensity distribution, and high visibility is obtained under illumination with strong emission intensity. Each LED is used to illuminate the rear seat, which is a subject with high emission intensity, with strong emission intensity, and to illuminate the front seat, which is a subject with weak emission intensity, which provides high visibility under illumination with weak emission intensity, with low emission intensity. If the emission intensity distribution is set, the illumination unevenness between the front seat and the rear seat is reduced, and a moving image with higher image quality can be obtained.
Further, in the first embodiment, the control unit 10 has the same imaging location (under the central region shown in FIG. 10 or FIG. 11) obtained under each illumination of the wide-angle LED 7A and the narrow-angle LED 7B for at least a part of the imageable range. One new received light intensity data D12 for the same imaging location is generated from a plurality of received light intensity data D1 and D2 for the upper part of the center area shown), and is generated into moving image data using the received light intensity data D12. Thereby, it is possible to obtain an image with high visibility in which the plurality of received light intensity data D1 and D2 are complemented to each other at the same imaging location.
On the other hand, as in Modification 1, the control unit 10 receives light intensity data D1, D2 obtained under illumination of the wide-angle LED 7A and the narrow-angle LED 7B, respectively, for a plurality of imaging locations obtained by dividing the imaging range. You may make it produce moving image data using. In this case, the moving image data creation process can be simplified.
Moreover, in the said modification 1, the frame memory 16 which has several memory area (memory 1-5) which can each store several frame image data is provided, and the control part 10 is obtained under illumination of wide-angle LED7A. Narrow-angle LED 7B with which high visibility can be obtained from the data in the memory area corresponding to the central area shown in FIG. 10 or the upper central area shown in FIG. The frame image data D2 generated from the received light intensity data obtained under the illumination is replaced with the frame image data D2. Thereby, the required memory capacity can be reduced.
Further, if the LEDs 7A and 7B have an infrared wavelength band as a light emission wavelength band, even when the present invention is applied to an in-vehicle surveillance camera, the influence on the driver's visibility can be reduced.

  In the above description, one frame image data D12 is generated using the two frame image data D1 and D2 obtained under illumination emitted by each of the lighting units 5A, 5B, 25A, and 25B, and the frame rate is set. Although the description has been given of the case of creating the moving image data with dropped, the method of creating the moving image data is not limited to this. For example, the two frame image data D1 and D2 respectively obtained under illumination emitted by each of the lighting units 5A, 5B, 25A, and 25B are used as they are, or some sort is applied to the two frame image data D1 and D2. Moving image data that does not reduce the frame rate may be created using an image that has been subjected to image correction processing. In this case, for example, in the case of the first embodiment, the two frame image data D1 and D2 are moving images that are switched at a high speed. Therefore, the afterimage causes a close subject portion such as a driver seat or a passenger seat and a rear seat. Since both the distant subject portions are perceived by the viewer with high visibility, the same effect can be obtained. For example, in the case of the second embodiment, since the two frame image data D1 and D2 are moving images that are switched at high speed, an image obtained by illuminating the entire imageable range with a comparatively strong light emission intensity by the afterimage. Since it is perceived by the viewer, the same effect can be obtained.

1 In-car surveillance camera 2 Wide-angle lens 3,23 Camera unit 4 Camera cable 5A, 5B, 25A, 25B Lighting unit 6A, 6B Lighting cable 7A, 7B LED
8 Unit-to-unit cable 9 Light receiving sensor 10 Control unit 11 Light emitting driver 12 Illumination drive power supply 13A, 13B Constant current source 14A, 14B Switch unit 15 Image processing unit 16 Frame memory 17 NTSC conversion unit 18 Brightness determination unit 20 Room mirror

Japanese Patent Laid-Open No. 2007-215088

Claims (8)

A light emitting means;
A light receiving means having light receiving sensitivity for at least a part of the emission wavelength band of the light emitting means;
Condensing means for condensing the reflected light from the subject onto the light receiving means under illumination by the light emitting means;
A low-illuminance camera having moving image data creating means for obtaining received light intensity data obtained by the light receiving means at a predetermined frame period, generating frame image data, and creating moving image data based on the frame image data In
The light emitting means includes a first light emitting unit having a predetermined output angle and a predetermined output intensity, an output angle narrower than an output angle of the first light emitting unit, and an output intensity higher than the output intensity of the first light emitting unit. A plurality of light emitting parts including a strong second light emitting part;
In synchronization with the frame period, each of the first light-emitting part and the second light-emitting part has a light-emitting intensity greater than that of the second light-emitting part and a light-emitting intensity of the second light-emitting part larger than that of the first light-emitting part. A light emission intensity control means for controlling the light emission intensity of the light emitting unit is provided,
The moving image data creation means is configured such that the frame image data obtained under illumination when the light emission intensity of the first light emitting unit is larger than that of the second light emitting unit and the light emission intensity of the second light emitting unit are the first light emission. A low-illuminance camera characterized in that one moving image data is created using frame image data obtained under illumination when larger than a portion. The camera for low light intensity according to claim 1,
The low-illuminance camera, wherein the emission angle of the first light emitting unit is 120 degrees, and the emission angle of the second light emitting unit is 40 degrees. A light emitting means;
A light receiving means having light receiving sensitivity for at least a part of the emission wavelength band of the light emitting means;
Condensing means for condensing the reflected light from the subject onto the light receiving means under illumination by the light emitting means;
A low-illuminance camera having moving image data creating means for obtaining received light intensity data obtained by the light receiving means at a predetermined frame period, generating frame image data, and creating moving image data based on the frame image data In
The light-emitting means has a plurality of light-emitting parts including a first light-emitting part and a second light-emitting part that irradiate light toward different locations within the imageable range,
In synchronization with the frame period, each of the first light-emitting part and the second light-emitting part has a light-emitting intensity greater than that of the second light-emitting part and a light-emitting intensity of the second light-emitting part larger than that of the first light-emitting part. A light emission intensity control means for controlling the light emission intensity of the light emitting unit is provided,
The moving image data creation means is configured such that the frame image data obtained under illumination when the light emission intensity of the first light emitting unit is larger than that of the second light emitting unit and the light emission intensity of the second light emitting unit are the first light emission. A low-illuminance camera characterized in that one moving image data is created using frame image data obtained under illumination when larger than a portion. In the low light corresponding camera of Claim 3,
The plurality of light emitting portions include an asymmetric distributed light emitting portion having an asymmetric light emission intensity distribution,
Strong light emission intensity that provides high visibility under illumination with a predetermined light emission intensity A weak light emission that illuminates a subject with the predetermined light emission intensity and provides high visibility under illumination with a light emission intensity smaller than the predetermined light emission intensity A low-illuminance camera characterized in that the light emission intensity distribution of the asymmetrical distribution light-emitting unit is set so as to illuminate a high intensity subject with a light emission intensity smaller than the predetermined light emission intensity. The low-illuminance camera according to any one of claims 1 to 4,
The moving image data creation means is configured to obtain at least a part of an imageable range for the same imaging location obtained under illumination when the at least two light emitting units have a maximum light emission intensity among the plurality of light emitting units. A plurality of received light intensity data are combined to generate one received light intensity data for the same imaging location, and the moving image data is created using the received received light intensity data. camera. In the low illumination corresponding camera of any one of Claims 1 thru | or 5 ,
The moving image data creation means receives light received under illumination when the light emission intensity of the first light emitting unit is larger than that of the second light emitting unit for a plurality of imaging locations obtained by dividing the imageable range. A low-illuminance camera characterized in that the moving image data is created using intensity data and received light intensity data obtained under illumination when the emission intensity of the second light emitting part is greater than that of the first light emitting part. The low-illuminance camera according to claim 6,
A frame memory having a plurality of memory areas each capable of storing a plurality of frame image data;
The moving image data creation means, for the memory area storing the frame image data generated from the received light intensity data obtained first among the received light intensity data respectively obtained under illumination by the at least two light emitting units, A process of replacing the data of the memory portion corresponding to the plurality of imaging locations with the one of the frame image data generated from the received light intensity data obtained under illumination by another light emitting unit capable of obtaining high visibility, A low light camera. In the low illumination corresponding camera of any one of Claims 1 thru | or 7,
The low-illuminance camera, wherein the light emitting means has an infrared wavelength band as a light emission wavelength band.