TW201741756A - Image pickup apparatus and image management system capable of acquiring a captured image with higher contrast under low illuminance conditions such as nighttime - Google Patents

Abstract

This invention provides an image pickup apparatus and an image management system capable of acquiring a captured image with higher contrast under low illuminance conditions such as nighttime. An image pickup apparatus 1 includes an image sensor 40, a lens 10 for forming image by light from a target area on the image sensor 40, and an illumination light source for illuminating a target area. The illumination light source includes a plurality of types of light emitting diodes 101 in which the peak wavelengths of emission intensity peaks are different from each other and each peak wavelength is included in the infrared wavelength band.

Description

Photography device and image management system

The present invention relates to a photographing apparatus for photographing a target area and an image management system therewith, which is particularly suitable for use in photographing a target area in a situation where nighttime illuminance is low.

There is known a photographing device for monitoring the shooting of a street or an intersection. In such a photographing apparatus, the photographed image is used, for example, for verification of a traffic accident or the like. In the verification, the condition of the vehicle and the pedestrian or the lighting condition of the signal is confirmed. The photographing device photographs the target area not only during the day but also during the night after sunset.

Patent Document 1 below discloses an imaging device having LED illumination with infrared light. When the illuminance sensor judges that the monitoring area is dark, the illuminating sensor lights the infrared light LED to illuminate the monitoring area. Further, Patent Document 1 discloses a configuration in which a visible light LED is turned off to give an intruder a deterrent effect when an intruder is detected.

[Previous Technical Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2009-17185

In order to monitor the condition of the target area more effectively, it is preferable that the photographing apparatus obtains the photographed image with a high contrast as much as possible in the case where the illumination is low at night. In the above Patent Document 1, it is disclosed that the visible light LED is turned off when the intruder is detected, and the intruder is given a deterrent effect, but the higher contrast is not disclosed for the case where the illumination is low. Acquire the composition of the photographic image.

In view of the above problems, an object of the present invention is to provide an image pickup apparatus capable of obtaining a photographic image with a relatively high contrast ratio in a situation where the illuminance at night is low, and an image management system including the same.

A first aspect of the invention relates to a photographing apparatus. The photographing apparatus of the present aspect includes an image sensor, a lens that images light from the target area on the image sensor, and an illumination source that illuminates the target area. The illumination light source includes a plurality of light-emitting diodes having an emission intensity such that peak wavelengths of the peaks are different from each other and respective peak wavelengths are included in the infrared wavelength band.

According to the photographing apparatus of the present aspect, several kinds of light having different wavelength bands are irradiated to the target area. Therefore, infrared light of a wide wavelength region can be irradiated to various subjects having spectral reflectivity characteristics inherent to the substance in the infrared region. Therefore, even in the case where the illumination is low at night, the photographic image can be obtained with a relatively high contrast by irradiating the light to the target region from the illumination source.

In the photographic apparatus of the present aspect, preferably the plurality of light-emitting diodes are divided into The luminescence spectrum is set such that the wavelength on the short wavelength side of the 5% of the luminescence intensity of the peak is equal to or higher than the upper limit of the visible light band. If so, even if the portion of the skirt of the luminescence spectrum reaches the upper limit of the visible light band, the intensity of the portion of the light is substantially zero or extremely weak. Therefore, even if the light-emitting diode is lit in a situation where the illumination is low at night, there is almost no case where a person located in the target area finds light from the light-emitting diode. Therefore, even when the photographing apparatus is used for the purpose of monitoring, it is possible to prevent the person from perceiving the presence of the photographing apparatus due to the lighting of the light-emitting diode.

In the photographic device of the present aspect, preferably, the image sensor is a CMOS image sensor of a P-type 矽 substrate. If so, the sensitivity of the infrared band can be improved in terms of the spectral sensitivity characteristics of the image sensor compared to the case where the image sensor is a CMOS image sensor of an N-type 矽 substrate ( Sensitivity). Thereby, the sensitivity of the image sensor to the infrared light from the plurality of light-emitting diodes can be more effectively improved, and as a result, the photographing distance of the photographing device when the light-emitting diode is lit can be prolonged.

In the photographic device of the present aspect, preferably, the image sensor is a color image sensor capable of generating a color image. If this is the case, the target area can be captured by a color image in a situation where the illumination is high during the daytime, and the infrared light from the light-emitting diode can be used to perform the black-and-white image on the target area in a situation where the illumination is low at night. Shooting.

In this case, the photographing apparatus of the present aspect may be configured to have a configuration that detects an illuminance of a target area, a filter that removes infrared light, and a switching mechanism that causes the filter to be relatively The lens is inserted into and removed from the optical path of the image sensor. In this case, when the illuminance detected by the detector does not reach a predetermined threshold, the imaging device retracts the filter from the optical path and causes the illuminating diode When the illuminance detected by the detector is equal to or greater than the threshold value, the filter is inserted into the optical path, and the light-emitting diode is turned off. In this case, the high-quality color image after the influence of the infrared light can be removed to capture the target area in the case where the illumination is high during the daytime, and the light-emitting diode can be used in the case where the illumination is low at night. The infrared light captures the target area in black and white.

A second aspect of the invention relates to an image management system. The image management system of this aspect includes a first aspect of the photographing device and an external device that acquires the photographed image captured by the photographing device from the photographing device by communication.

According to the image management system of the present aspect, the same effects as those of the image pickup apparatus according to the first aspect described above can be achieved.

As described above, according to the present invention, it is possible to provide an image pickup apparatus capable of obtaining a photographic image with a relatively high contrast ratio in a situation where the illuminance at night is low, and an image management system including the same.

The effects and significance of the present invention will be more apparent from the following description of embodiments. However, the embodiments described below are merely illustrative of the embodiments of the present invention, and the present invention is not limited to the contents described in the following embodiments.

1‧‧‧Photographing device

10‧‧‧ lens

40‧‧‧Image Sensor

50‧‧‧ filter

51‧‧‧Switching mechanism

101‧‧‧Lighting diode (light source)

102‧‧‧illuminance sensor (detector)

Fig. 1(a) is a view showing the appearance of the image management system of the embodiment. Fig. 1(b) is a view showing an example of a photographic image of the embodiment. Figure 1 (c) is a schematic representation of the implementation A diagram of the configuration of the front side of the lens barrel of the image recording apparatus.

Fig. 2 is a view showing the configuration of a photographing apparatus of the embodiment.

Fig. 3 is a view showing the configuration of a CMOS image sensor of the embodiment.

4(a) to 4(c) are diagrams for explaining read control of the CMOS image sensor of the embodiment.

5(a) and 5(b) are diagrams schematically showing the configuration of a switching mechanism of the embodiment.

Fig. 6 is a flow chart showing the control of the filter and the light-emitting diode of the embodiment.

Fig. 7(a) is a view showing the spectral sensitivity characteristics of the image sensor of the comparative example and the first embodiment. Fig. 7(b) is a view showing the spectral transmittance characteristics of the color filters disposed in the image sensor of the first embodiment. Fig. 7(c) is a view showing the spectral transmittance characteristics of the filter for removing the infrared light of the first embodiment. Fig. 7 (d) is a view showing the luminescence spectrum of the light-emitting diode of Example 1.

Fig. 8 is a view showing a method of setting an emission spectrum of the light-emitting diode of the first embodiment.

Fig. 9 is a view showing a method of setting an emission spectrum of the light-emitting diode of the second embodiment.

Fig. 10 is a flow chart showing the control of the filter and the light-emitting diode of the modified example.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Fig. 1(a) is a view showing the appearance of the image management system of the embodiment.

As shown in FIG. 1(a), the image management system includes a photographing device 1 and an external device 2. The photographing device 1 is a monitor camera, and is provided in an object 3 that can image a street or an intersection including a signal. The object to be set 3 is, for example, a wall or a roof structure of a building or the like. Things, utility poles, etc. The photographing device 1 records the captured image at any time on the internal recording medium. The external device 2 is a portable personal computer. In addition, the external device 2 can also be other portable information terminals such as a mobile phone and an input board.

The image recorded on the photographing device 1 is appropriately collected by the external device 2. The photographing device 1 and the external device 2 can communicate via a wireless LAN. The external device 2 establishes a communication path based on the wireless LAN, and downloads an image from the photographing device 1. The communication between the photographing device 1 and the external device 2 is not limited to the wireless LAN, and may be other communication methods such as Bluetooth (registered trademark) (Bluetooth).

Fig. 1(b) is a view showing an example of a photographic image taken by the photographing apparatus 1. Here, the intersection 5 including the traffic signal 4 is set as the target area. For the sake of convenience, only the signal 4 facing the direction of the photographing device 1 is illustrated in Fig. 1(b). The image captured by the photographing device 1 is recovered to the external device 2, and is used, for example, for verification of a traffic accident. In this verification, the status of the vehicle or pedestrian passing through the intersection 5 and the lighting condition of the signal unit 4 are confirmed. In other words, it is confirmed that the traffic signal 4 is lit in any of red, blue, and yellow colors at the time of the accident.

Fig. 1(c) is a view schematically showing the configuration of the front side of the lens barrel of the photographing apparatus 1.

As shown in FIG. 1(c), the photographing apparatus 1 is provided with a plurality of light emitting diodes 101 around the lens 10, and an illuminance sensor 102 for detecting the illuminance of the target area. In the case where the illumination is low at night, the light-emitting diode 101 is lit to illuminate the target area. The light-emitting diode 101 is an illumination source that illuminates a target area by infrared light. The plurality of light-emitting diodes 101 have different peak wavelengths of the peaks of the light-emitting intensity and the respective peak wavelengths are included in The plurality of light-emitting diodes of the infrared wavelength band are composed of a plurality of light-emitting diodes.

Fig. 2 is a view showing the configuration of the photographing apparatus 1.

The photographing apparatus 1 includes a lens 10, a diaphragm 20, a shutter 30, an image sensor 40, a filter 50, a switching mechanism 51, a photographing signal processing circuit 61, a shutter drive circuit 62, a filter drive circuit 63, a diaphragm drive circuit 64, and an LED. The drive circuit 65, the detection signal processing circuit 66, the control unit 67, the memory unit 68, the communication unit 69, and the power supply circuit 70.

The lens 10 extracts light from the target area and images the image of the target area on the light receiving surface of the image sensor 40. The aperture 20 restricts light from the outside in such a manner that an appropriate amount of light is incident on the image sensor 40 in accordance with the intensity of light from the target area. The aperture 20 adjusts the amount of pupil by the aperture driving circuit 64.

The shutter 30 is a liquid crystal shutter. The shutter 30 is, for example, a so-called normaly black type liquid crystal shutter having a transmittance which is maximized in a state where a voltage is applied and a transmittance is lowered when the application of the voltage is blocked. In this case, the shutter 30 transmits light in a state where a voltage is applied, and blocks the light in a state where no voltage is applied. Further, the shutter 30 may be a so-called normaly white type liquid crystal shutter in which the transmittance is maximized in a state where no voltage is applied and the transmittance is lowered when a voltage is applied. Further, the shutter 30 may be a shutter of another type as long as it can be opened and closed at a high speed. The shutter 30 is switched on and off in accordance with a drive signal from the shutter drive circuit 62.

The image sensor 40 is a CMOS image sensor. The image sensor 40 is a color image sensor that can generate a color image. The image sensor 40 has a photodiode at a position corresponding to each pixel on the light receiving surface. Moreover, the image sensor is configured to be used for red, blue, and green light at positions corresponding to pixels respectively receiving red, blue, and green light. Filtered color filters. The image sensor 40 is controlled by the photographic signal processing circuit 61 in such a manner that the charge and output of the photodiode are performed for each line. Furthermore, the image sensor 40 can also be a black and white image sensor.

The filter 50 removes light of the infrared wavelength band from the light condensed by the lens 10. The switching mechanism 51 causes the filter 50 to be inserted and removed with respect to the optical path of the light that is captured by the lens 10 to the image sensor 40. The switching mechanism 51 switches the insertion and removal of the filter 50 based on the drive signal from the filter drive circuit 63.

The LED drive circuit 65 turns on or off the light-emitting diode 101 in accordance with control from the control unit 67. The detection signal processing circuit 66 performs processing such as amplification and A/D conversion on the detection signal from the illuminance sensor 102, and outputs the processed signal to the control unit 67.

The control unit 67 includes an arithmetic processing circuit such as a CPU (Central Processing Unit), and controls each unit based on a program held in the storage unit 68. The memory unit 68 holds the program for control, and is also used as a work area when the control unit 67 performs control. The control unit 67 controls the imaging signal processing circuit 61, the shutter drive circuit 62, the filter drive circuit 63, the diaphragm drive circuit 64, and the LED drive circuit 65 by the program held in the memory unit 68.

The communication unit 69 communicates with the external device 2 shown in Fig. 1(a). The power supply circuit 70 is connected to a commercial alternating current power supply, and is supplied with electric power supplied from a commercial alternating current power supply and supplied to each unit in the photographing apparatus 1.

FIG. 3 is a view schematically showing the configuration of the image sensor 40. For the sake of convenience, the configuration of the portion corresponding to nine pixels is shown in FIG. 3, but actually, the same configuration is arranged in the vertical and horizontal directions corresponding to the predetermined number of pixels.

The image sensor 40 has a photodiode at a position corresponding to each pixel. 40a. The photodiode 40a accumulates a charge corresponding to the amount of received light when light is received. The accumulated charge is converted into a voltage by the amplifier 40b and amplified. When the switch 40c is set to ON, the amplified voltage is transmitted to the vertical signal line 40d for each line L. The transmitted voltage is temporarily held by the row circuit 40e disposed in each of the vertical signal lines 40d. When the row selection switch 40f is set to ON, the held voltage is supplied to the horizontal signal line 40g. Next, the voltage supplied to the horizontal signal line 40g is sent to the photographic signal processing circuit 61. In this way, in the image sensor 40, a voltage signal is transmitted for each line L.

Further, the image sensor 40 is controlled such that the charge of the photodiode 40a is accumulated for each line L. That is, the photodiode 40a on one line L is set to a state in which electric charge can be accumulated for a predetermined period of time, and when the period elapses, the electric charge generated by each photodiode 40a on the line L is output. This control system is sequentially performed from the line L of the uppermost stage toward the line L of the lowermost stage. When the line L is in a state in which electric charge can be accumulated, when the photodiode 40a on the line L is irradiated with light, electric charges corresponding to the amount of light of the irradiated light are accumulated in the respective photodiodes 40a on the line. The charge accumulated in the above manner is read for each line L as described above, and is converted into a voltage signal, and is output to the photographic signal processing circuit 61.

Hereinafter, a period in which each line is set to a state in which charges can be accumulated is referred to as a "charge accumulation period".

Returning to Fig. 2, the photographic signal processing circuit 61 sequentially sets the lines on the image sensor 40 to the charge accumulation period, and performs charge reading for each line. The photographic signal processing circuit 61 includes an A/D conversion circuit that converts the voltage signal of each line supplied from the image sensor 40 through the horizontal signal line 40g (see FIG. 3) into a digital signal, and outputs it to the control unit 67. The control unit 67 stores the digital signal (image signal) supplied from the photo signal processing circuit 61 in the memory. Part 68. As a result, the image signal of the bus amount (one frame amount) output from the photo signal processing circuit 61 constitutes one photographic image.

4(a) to 4(c) are diagrams for explaining the reading control of the electric charge of the image sensor 40. Fig. 4(a) is a view schematically showing a control in the case of reading electric charges from respective lines at a normal speed (hereinafter, referred to as "normal mode"), and Fig. 4(b) is schematically shown as The control at the time of high-speed reading of electric charge from each line (hereinafter referred to as "high-speed mode"). Moreover, FIG. 4(c) is a view schematically showing control (hereinafter referred to as "low speed mode") in the case where the electric charge is read from each line at a low speed.

On the left side of FIGS. 4(a) to 4(c), the light receiving surface of the image sensor 40 and each line L are schematically shown. Here, the line L of the uppermost stage is set to L0, and the line of the lowermost stage is set to Ln. Further, on the right side of Figs. 4(a) to 4(c), the control timing for each line is schematically shown.

Referring to Fig. 4(a), in the normal mode, the control of the uppermost line L0 is started at the timing t1 and ends at the timing t2. The control of the line L2 of the next segment is started after the predetermined time has elapsed from the timing t1. In this way, each time the line L changes to the lower stage, the start timing is sequentially delayed by a predetermined time, and the control of each line is sequentially performed. The start timing of the lowermost line Ln is the timing t2 after the delay Δt from the timing t1.

In the uppermost line L0, charges are accumulated from the timing t1 to the timing t2. For example, the entire period Δt between the timing t1 and the timing t2 is set as the charge accumulation period. The charge accumulation period is also set similarly for the other line L. The reading of the charge of the uppermost line L0 is performed at the timing t2 after the period Δt elapses from the timing t1.

The line L1 of the second stage starts accumulating charges at a timing delayed by a predetermined time from the timing t1, and performs charge reading at a timing delayed by a predetermined time from the timing t2. in this way As a result, each time the line L changes, the start timing of the charge accumulation is successively delayed by a predetermined time, and the execution timing of the charge reading is also sequentially delayed by a predetermined time. The start timing of the charge accumulation of the lowermost line Ln is the timing t2 after the delay Δt from the timing t1, and the execution timing of the charge reading becomes the timing t3 after the delay Δt from the timing t2.

As described above, in the normal mode, the end timing of the charge accumulation on the uppermost line L0 becomes the start timing of the charge accumulation on the lowermost line Ln. Therefore, in the normal mode, there is no coincidence period during charge accumulation of all lines.

Referring to Fig. 4(b), in the high speed mode, the reading speed of the electric charge of each line L is increased, whereby the amount of shift between the control start timings between the lines L is shortened compared with the normal mode. In the example of Fig. 4(b), the offset of the control start timing between the lines L is reduced by half compared with the normal mode. Therefore, the start timing of the control of the lowermost line Ln is delayed by Δt/2 from the start timing t1 of the control of the uppermost line L0.

The reading speed of the electric charge of each line L is increased by reducing the number of bits when the charge signal of each line is sampled (A/D conversion) is smaller than the number of bits in the normal mode. This processing is performed based on the control by the control unit 67 of Fig. 2 and by the photographic signal processing circuit 61. In the high speed mode, since the number of sample bits is reduced as described above, the image quality of the photographic image is slightly deteriorated compared with the normal mode. However, this deterioration is not a problem in that the visibility is not particularly problematic in applications such as surveillance cameras. Alternatively, the number of equivalent sample bits can be retained by the improvement and speeding up of the image sensor 40 and the photographic signal processing circuit 61.

As described above, by setting the control mode of the image sensor 40 to the high speed mode, as shown in FIG. 4(b), overlapping accumulation of mutually coincident charge accumulation periods occurs. period. Further, by performing the exposure by opening the shutter 30 during the overlap accumulation, the light from the target region is irradiated to the respective lines L at the same timing, and the photodiodes 40a on all the lines L are accumulated at the same timing and exposure amount. Charge. Therefore, it is possible to suppress deformation of the photographic image of the subject moving at a high speed. That is, the Rolling Shutter phenomenon can be suppressed, and the Global Shutter function using the image sensor 40 can be realized.

In the present embodiment, the control mode of the image sensor 40 is set to the high speed mode. Further, the shutter 30 is opened during the overlap accumulation, and the light from the target area is guided to the image sensor 40.

Furthermore, the overlap accumulation period can also be generated by setting the control mode of the image sensor 40 to the low speed mode. As shown in FIG. 4(c), in the low speed mode, the shooting period of each line is set to twice the normal mode, that is, 2 Δt. In this case, the shutter 30 is also opened during the overlap accumulation. Thereby, similarly to the case of the high speed mode, it is possible to suppress deformation of the photographic image of the subject moving at a high speed.

5(a) and 5(b) are diagrams schematically showing the configuration of the switching mechanism 51.

The switching mechanism 51 includes a base 510, a moving plate 520, a motor 530, and a rod 540.

The base plate 510 has two guide members 511 each having an L-shaped cross section at the left and right end portions. The two guide members 511 are respectively engaged with the moving plate 520 so as to be in contact with the upper surface and the side surface of the moving plate 520. The left and right ends. Thereby, the moving plate 520 is supported by the base 510 so as to be movable in the longitudinal direction. A through opening 512 is formed in the base 510.

The moving plate 520 is composed of a thin plate-shaped member. The movable plate 520 is formed with two openings 521 and 522 arranged in the longitudinal direction. A filter 50 shown in Fig. 2 is attached to the opening 521. In order to make the optical path length uniform, a transparent plate such as a glass plate is attached to the opening 522. Figure 5 (a) In the state, the opening 521 is located at the through opening 512 of the substrate 510. A flange portion 520a that protrudes in the right direction is formed in the moving plate 520. An elongated hole 523 extending in the lateral direction is formed in the flange portion 520a.

One end of the rod 540 is fixed to the drive shaft 531 of the motor 530. When the motor 530 is driven, the lever 540 rotates clockwise or counterclockwise in Figures 5(a), (b). A pin 541 is formed on the other end of the rod 540, and the pin 541 is inserted into the long hole 523 from the back side of the flange portion 520a. Motor 530 is a stepper motor.

The through hole 512 formed in the substrate 510 serves as an optical path for the light collected by the lens 10 shown in FIG. Therefore, in the state of Fig. 5 (a), the filter 50 is inserted into the optical path. When the motor 530 is driven to rotate the lever 540 in the counterclockwise direction, the pin 541 pushes the long hole 523 to slide the moving plate 520. When the moving plate 520 is slid to the position of FIG. 5(b), the opening 522 is located at the position of the through opening 512. As a result, the filter 50 is deflected from the optical path to open the optical path.

The filter drive circuit 63 of Fig. 2 drives the motor 530 under the control of the control unit 67 to position the moving plate 520 at either the position of Fig. 5 (a) and the position of Fig. 5 (b). Thereby, the filter 50 is inserted and removed with respect to the optical path of the light collected by the lens 10.

FIG. 6 is a flow chart showing the control of the filter 50 and the light-emitting diode 101.

When the photographing operation is started, the control unit 67 determines whether or not the illuminance detected by the illuminance sensor 102 is smaller than a predetermined threshold (S11).

When the sunshine is weak at night or in the evening and the illumination of the target area is low, the determination in step S11 is YES. When the determination in step S11 is YES, the control unit 67 turns on all of the light-emitting diodes 101 (S12), and further controls the switching mechanism 51 to evacuate the filter 50 from the light path of the light collected by the lens 10. (S13).

On the other hand, when the daylight is strong during the day and the illuminance of the target area is high, the determination in step S11 is NO. When the determination in step S11 is NO, the control unit 67 turns off all of the light-emitting diodes 101 (S14), and further controls the switching mechanism 51 to insert the filter 50 into the light path of the light collected by the lens 10 ( S15). The control unit 67 repeats the processing of steps S11 to S15 until the shooting operation is completed (S16: YES).

However, in the present embodiment, the luminescence spectrum of the illuminating diode 101 is adjusted so that the photographic image having a high contrast can be obtained by the infrared light irradiated to the target region. More specifically, the plurality of light-emitting diodes 101 shown in FIG. 1(c) are a combination of three types of light-emitting diodes in which the peak wavelengths of the peaks are different from each other and the peak wavelengths are included in the infrared wavelength band. Composition.

Hereinafter, a setting example of the light emission spectrum of the light-emitting diode 101 will be described.

<Example 1>

Fig. 7(a) is a view showing the spectral sensitivity characteristics of the image sensor 40 of the comparative example and the first embodiment.

In the first embodiment, as the image sensor 40, a CMOS image sensor using a P-type germanium substrate is used. The spectral sensitivity characteristics of the image sensor using the N-type germanium substrate are shown together as a comparative example in Fig. 7(a). As shown in FIG. 7(a), when the P-type germanium substrate is used as the substrate of the image sensor 40 as in the first embodiment, it can be improved as compared with the case of using the N-type germanium substrate (comparative example). The sensitivity of the near-infrared band allows the peak of sensitivity to move toward the infrared wavelength band side.

Fig. 7(b) is a view showing the spectral transmission characteristic of the color filter disposed in the image sensor 40 of the first embodiment. Figure 7 (b) R, G, and B respectively indicate spectral transmittance characteristics of color filters corresponding to pixels that receive red, green, and blue light. As shown in FIG. 7(b), the color filters of the respective colors are set such that the transmittance in the wavelength band of the color is increased. Further, when the color filters of the respective colors are in the vicinity of a wavelength exceeding 820 nm, the transmittance is maintained high.

Fig. 7(c) is a view showing an example of the spectral transmittance characteristics of the filter 50 of the first embodiment. As shown in Fig. 7(c), when the wavelength of the filter 50 exceeds 630 nm, the transmittance is drastically lowered, and the transmittance is substantially zero at a wavelength of around 700 nm. When the wavelength exceeds about 700 nm, the transmittance of the filter 50 is maintained substantially at zero.

Fig. 7 (d) is a view showing the luminescence spectra of the three types of light-emitting diodes 101 of the first embodiment.

The luminescence spectra S1 to S3 of the three types of light-emitting diodes 101 are shown in Fig. 7(d), respectively. Further, the upper limit A1 of the visible light band of the person is shown. In general, the upper limit of the human visible light band is about 700 nm. Therefore, in the first embodiment, the upper limit A1 of the human visible light band is set to 700 nm. As shown in FIG. 7(d), each of the luminescence spectra S1 to S3 is set so as not to reach the upper limit A1 of the human visible light band.

Fig. 8 is a view showing an enlarged light emission spectrum of the three types of light-emitting diodes 101 of the first embodiment.

In Fig. 8, P1 to P3 are wavelengths (wavelength wavelengths) at which the luminescence spectra S1 to S3 are positions of the peaks, respectively. The peak wavelengths P1 to P3 of the three types of light-emitting diodes 101 are different from each other, and the respective peak wavelengths P1 to P3 are included in the infrared wavelength band (the wavelength band of 700 nm or more).

As described above, by arranging the three types of light-emitting diodes 101 having different wavelength bands in the imaging device 1, the wavelength of light irradiated to the target region can be widened. Thereby, even for red The spectral reflectivity characteristic of external light varies depending on the substance constituting the subject, and light suitable for the wavelength of each substance is also easily irradiated to each substance. For example, when the image capturing system is composed of a substance having a high reflectance at a wavelength of 810 nm, it can be obtained from the light of the light-emitting diode 101 of the light-emitting spectrum S1 of the three types of light-emitting diodes 101. The higher reflected light of the subject. Thereby, even in the case where the illuminance at night is low, the light of the different wavelength bands can be irradiated to the target region from the three types of the light-emitting diodes 101, and the photographic image can be obtained with a high contrast.

Further, all of the three types of light-emitting diodes 101 are set such that the portion of the skirt on the short-wavelength side of the light-emitting spectrum does not reach the upper limit A1 of the human visible light band. Therefore, even if the light-emitting diode 101 is lit in a situation where the illumination is low at night, the light from the light-emitting diode 101 is hardly found by a person located in the target area. Therefore, even when the photographing apparatus 1 is used for the purpose of monitoring, it is possible to prevent the person from perceiving the presence of the photographing apparatus 1 due to the lighting of the light-emitting diode 101.

Further, as described above, when the image sensor 40 is a color CMOS image sensor, for example, as shown in FIG. 7(b), the transmittance of the color filters of the respective colors is set. Therefore, when the light-emission spectra S1 to S3 of the three types of light-emitting diodes 101 are respectively set as shown in FIG. 7(d), the color filters of the blue and green colors are shorter than the short-wavelength side of the peak of the light-emitting spectrum S2. The transmittance of the sheet is below the maximum. Therefore, light having a wavelength shorter than the short-wavelength side of the peak of the emission spectrum S2 is filtered by the blue and green color filters, causing a situation in which it is not effectively utilized.

In order to avoid this, the spectral transmittance of the color filter is preferably adjusted so as to maintain a high level in the entire wavelength band of the light-emitting spectra S1 to S3 of the three types of light-emitting diodes 101. That is, it is preferable that the range of the light-emitting diode 101 is included in the range W1 shown in FIG. 7(b). The boundary of the short-wavelength side of the range W1 is set to the vicinity of the wavelength of the lower limit of the light-emission spectrum S2 of the light-emitting diode 101 (for example, in the vicinity of 750 nm). Even if the spectral transmittance of the color filter is set as described above, as shown in FIG. 7(c), since the spectral transmittance of the filter 50 converges to zero near 700 nm, the wavelength is longer than the long wavelength side of the red wavelength band. The near-infrared light is also removed by the filter 50. Therefore, when the target area is imaged in an environment with high illumination in the daytime, it is possible to suppress infrared light other than visible light from entering each pixel of the image sensor 40.

Furthermore, since the black and white CMOS image sensor does not include a color filter, the above limitation disappears when a black and white CMOS image sensor is used as the image sensor 40. Therefore, when a black-and-white CMOS image sensor is used as the image sensor 40, the light-emitting spectrum S1 to S3 of the light-emitting diode 101 is set so as to be close to the peak wavelength of the spectral sensitivity characteristic of the image sensor 40. can. Also in this case, it is preferable that the luminescence spectra S1 to S3 are set such that the portion of the skirt on the short-wavelength side does not reach the upper limit A1 of the visible light band as much as possible.

<Example 2>

The upper limit of the human visible light band is generally about 700 nm. However, according to the literature, there is a case where the upper limit of the human visible light band is about 780 nm. In the second embodiment, the upper limit of the visible light band of the human is set to about 780 nm, and the light-emission spectra S1 to S3 of the three types of the light-emitting diodes 101 are set.

In this case, the luminescence spectra S1 to S3 of the three types of light-emitting diodes 101 are changed as shown in FIG. In Fig. 9, A2 is the upper limit of the human visible light band, that is, 780 nm. P1 to P3 are wavelengths (wavelength wavelengths) at which the luminescence spectra S1 to S3 are peaks.

In this case as well, as in the case of FIG. 8, the irradiation to the target area can be performed. The width of the wavelength of the light is widened, and even if the spectral reflectance characteristic of the infrared light differs depending on the substance constituting the subject, light suitable for the wavelength of each substance is easily irradiated to each substance.

Further, in the case of Fig. 9, the portion of the skirt on the short-wavelength side of the luminescence spectrum S2 substantially reaches the upper limit A2 of the human visible light band. However, since the intensity of the light-emitting diode 101 of the upper limit A2 of the visible light band is about 5% of the peak value, the intensity of the light reaching the portion of the skirt portion of the upper limit A2 is substantially zero or extremely weak. Therefore, even if the light-emitting diode 101 of the light-emitting spectrum S2 is turned on in a situation where the illumination is low at night, the light from the light-emitting diode 101 is hardly found by a person located in the target area. Therefore, even when the photographing apparatus 1 is used for the purpose of monitoring, it is possible to prevent the person from perceiving the presence of the photographing apparatus 1 due to the lighting of the light-emitting diode 101.

<Effects of Embodiments>

According to this embodiment, the following effects are achieved.

Three types of light having different wavelength bands are irradiated from the three types of light-emitting diodes 101 to the target area. Therefore, even if the spectral reflectance characteristics of the infrared light differ depending on the substance constituting the subject, light of a wavelength having a high reflectance in each substance is easily irradiated to each substance. Therefore, even in a situation where the illuminance at night is low, the target region is irradiated with light from the illumination light source (the three types of light-emitting diodes 101), and a photographic image having good visibility and high contrast can be obtained.

The three kinds of light-emitting diodes 101 are set such that the wavelength on the short-wavelength side of the 5% of the peak intensity is at least the upper limit (A1 or A2) of the visible light band, and the light-emission spectra S1 to S3 are set. Therefore, even if the portion of the skirt of the luminescence spectrum S1 to S3 reaches the upper limit (A1 or A2) of the visible light band, the intensity of the light in this portion is substantially zero or extremely weak. Therefore, even if the light-emitting diode 101 is lit in a situation where the illumination is low at night, the target area is hardly generated. The person finds the light from the light-emitting diode 101. Therefore, even when the photographing apparatus 1 is used for the purpose of monitoring, it is possible to prevent the person from perceiving the presence of the photographing apparatus 1 due to the lighting of the light-emitting diode 101.

In the present embodiment, since the CMOS image sensor using the P-type germanium substrate is used as the image sensor 40, as shown in FIGS. 7(a) and 8, the image sensor 40 is an N-type germanium substrate. In the case of the CMOS image sensor, the sensitivity of the near-infrared region of the image sensor 40 becomes higher, and the peak of the spectral sensitivity characteristic shifts to the longer long wavelength side. Therefore, the sensitivity of the image sensor 40 to the infrared light from the three types of the light-emitting diodes 101 can be improved, and the photographing distance of the photographing apparatus 1 when the three kinds of the light-emitting diodes 101 are turned on can be changed long.

Moreover, since the image sensor 40 is a color image sensor capable of generating a color image, the color image can be used to capture the target area in a situation where the illumination is high during the daytime, and the illumination is low at night. The infrared light from the light-emitting diode 101 can be used to photograph the target area in a black-and-white image.

In addition, when the illuminance detected by the illuminance sensor 102 does not reach a predetermined threshold value, the filter 50 is evacuated from the optical path of the lens 10, and the light-emitting diode 101 is turned on. When the illuminance detected by the illuminance sensor 102 is equal to or greater than the threshold value, the filter 50 is inserted into the optical path of the lens 10, and the light-emitting diode 101 is turned off. Therefore, in the case where the illumination is high during the daytime, The high-quality color image after the influence of the infrared light can be removed by the filter 50 to capture the target area. In the case where the illumination is low at night, the infrared light from the LED 101 can be used to black and white the image to the target area. Take a picture.

<Modification>

In the above embodiment 1, as shown in FIG. 7(d) and FIG. 8, three kinds of light-emitting diodes 101 are emitted. The light spectrums S1 to S3 are set so as not to reach the upper limit A1 of the human visible light band. However, for example, the portion of the skirt on the short wavelength side of the light emission spectrum S2 may reach the upper limit A1 of the visible light band, and the light emission spectrum S1 may be used. ~S3 moves to the short wavelength side. However, in this case as well, the light-emitting spectrum S2 is preferably set such that the wavelength on the short-wavelength side of the light-emitting intensity of 5% of the peak is equal to or higher than the upper limit A1 of the visible light band. Thereby, since the intensity of the light reaching the upper limit A1 of the visible light band is substantially zero or extremely weak, even if the light-emitting diode 101 is lit in a situation where the illumination is low at night, the target region is hardly generated. The person finds the light from the light-emitting diode 101. Therefore, even when the photographing apparatus 1 is used for the purpose of monitoring, it is possible to suppress the person from perceiving that the photographing apparatus 1 is present due to the lighting of the light-emitting diode 101.

Further, in the second embodiment, as shown in FIG. 9, the portion of the skirt portion on the short-wavelength side of the luminescence spectrum S2 reaches the upper limit A2 of the human visible light band, but the skirt portion on the short-wavelength side of the luminescence spectrum S2 may be used. The luminescence spectrum S1 to S3 are shifted to the long wavelength side in such a manner that the upper limit A2 of the visible light band is not reached.

Further, the intensity of light irradiated to the target region from the three types of the light-emitting diodes 101 may not necessarily be the same as each other, and the intensity of light irradiated from the light-emitting diode 101 to the target region may be set higher than that of other types of light. The intensity of the light that the diode 101 illuminates to the target area.

For example, the light-emitting diode 101 (the light-emitting diode 101 which is the light-emitting spectrum S2 in the case of FIGS. 8 and 9) may be irradiated to the light-emitting diode 101 having a peak wavelength close to the spectral sensitivity characteristic of the image sensor 40. The intensity of the light in the target region is set to be higher than that of the light emitted from the other two light-emitting diodes 101 (the light-emitting diodes 101 of the light-emitting spectra S1 and S3 in the case of FIGS. 8 and 9). strength. Thereby, the intensity of the illumination light in the wavelength band in which the spectral sensitivity of the image sensor 40 is high is increased, so that the luminous intensity of all the light-emitting diodes 101 is uniform. In comparison with the case, the photographing effective distance of the photographing apparatus 1 can be made longer.

Alternatively, the light-emitting diode 101 having the peak wavelength away from the spectral sensitivity characteristic of the image sensor 40 (the light-emitting diode 101 of the light-emitting spectrum S3 in the case of FIGS. 8 and 9) may be irradiated to The intensity of light in the target region is set to be higher than that of the light emitted from the other two light-emitting diodes 101 (the light-emitting diodes 101 of the light-emitting spectra S1 and S2 in the case of FIGS. 8 and 9). strength. Thereby, the intensity of the illumination light in the wavelength band having a low spectral sensitivity of the image sensor 40 is increased, and thus the wavelength band of the luminescence spectrum S3 is compared with the case where the luminescence intensity of all the illuminating diodes 101 is uniformly the same. A subject having a characteristic spectral reflectance characteristic can easily obtain an image with good visibility and high contrast. In this way, optimum illumination light can be easily obtained for various subjects.

In the above-described embodiment, the three kinds of the light-emitting diodes 101 are provided in the imaging device 1. However, the types (wavelength bands) of the light-emitting diodes 101 are not limited to three types, and two or more types may be used. The more the type (wavelength band) of the light-emitting diode 101 is increased, the wider the wavelength of the light that is irradiated to the target region is, and the spectral reflectance characteristics of various substances constituting the subject can be broadly recognized, and the spectrum is easily obtained. Highly visible and contrasting images.

Furthermore, the number of the plurality of light-emitting diodes 101 does not have to be the same between the types, and the number of the light-emitting diodes 101 may be larger than the number of the other types of the light-emitting diodes 101. By changing the number of the light-emitting diodes 101 for each wavelength band as described above, the intensity of light for one wavelength band of the target region and the intensity of light for other wavelength bands can be made different from each other.

Further, the spectral sensitivity characteristics of the image sensor 40 are not necessarily limited to those shown in FIGS. 7(a), 8 and 9, and may be other characteristics. Also, the spectrum of the color filter is transparent. The luminescence characteristics and the spectral transmittance characteristics of the filter 50 are not necessarily limited to those shown in Figs. 7(b) and 7(c), and may be other characteristics.

Further, the configuration of the switching mechanism 51 is not necessarily limited to the configuration shown in FIGS. 5(a) and 5(b), and may be, for example, a configuration in which the moving plate 520 is moved using a gear. Further, the filter 50 may be omitted.

Further, the number and arrangement of the light-emitting diodes 101 are not necessarily limited to those shown in FIG. 1(c), and the light-emitting diodes 101 may be disposed in the photographing device 1 in other numbers and arrangements.

Further, in the above embodiment, the photographing apparatus 1 transmits to the external apparatus 2 by wireless communication, but the photographing apparatus 1 can also transmit to the external apparatus 2 by wired communication. Alternatively, the captured image may be recorded in advance on the memory card attached to the photographing device 1, and the memory card may be removed from the photographing device 1 and then attached to the external device 2, whereby the captured image may be captured to the external device 2.

Further, in the above-described embodiment, the photographing apparatus 1 is installed on a wall such as a building or a roof structure, a utility pole, or the like, but the installation location of the photographing apparatus 1 is not limited thereto. For example, the photographing device 1 may be installed in a traffic sign, or the configuration of the photographing device 1 may be integrally included in a street lamp or the like.

Further, in the above-described embodiment, all of the light-emitting diodes 101 are turned on in step S12 of Fig. 6. However, depending on the state of use of the image pickup apparatus 1 such as the location where the image pickup apparatus 1 is installed, it can be assumed that All of the three types of light-emitting diodes 101 are turned on, and only a predetermined type of light-emitting diode 101 is turned on, and it is possible to suppress power consumption and obtain a photographed image suitable for monitoring. For example, when photographing a location that is relatively close to the installation position and that does not require illumination light intensity, there may be a light-emitting diode 101 that illuminates only the wavelength band having a higher sensitivity of the image sensor 40. Having all the LEDs 101 illuminated can make a more suitable photographic image for monitoring image. In view of this, the user can also appropriately set which of the light-emitting diodes 101 is lit.

In this case, the flowchart of FIG. 6 can be changed, for example, as shown in FIG. In the flowchart of Fig. 10, step S12 is removed as compared with Fig. 6, and steps S21 to S23 are added instead. In step S21, it is determined whether or not the user sets the type of the light-emitting diode 101 to be lit. If the determination in step S21 is NO, all of the light-emitting diodes 101 are turned on (S22). If the determination in the step S21 is YES, only the set light-emitting diode 101 is turned on (S23).

Furthermore, the total intensity of the light-emitting diodes 101 that are lit in step S23 may be set differently from the total intensity of all of the light-emitting diodes 101 that are turned on in step S22.

As described in this modification, by allowing the user to appropriately set the light-emitting diode 101 to be lit, it is possible to illuminate the optimum type of wavelength light depending on the state of use of the image pickup apparatus 1 such as the location where the image pickup apparatus 1 is installed. Go to the target area to get a more suitable photographic image for surveillance.

Further, the embodiments of the present invention can be variously modified as appropriate within the scope of the technical idea shown in the claims.

1‧‧‧Photographing device

10‧‧‧ lens

20‧‧‧ aperture

30‧‧ ‧Shutter

40‧‧‧Image Sensor

50‧‧‧ filter

51‧‧‧Switching mechanism

61‧‧‧Photo signal processing circuit

62‧‧‧Shutter drive circuit

63‧‧‧Filter drive circuit

64‧‧‧Aperture drive circuit

65‧‧‧LED drive circuit

66‧‧‧Detection signal processing circuit

67‧‧‧Control Department

68‧‧‧Memory Department

69‧‧‧Communication Department

70‧‧‧Power circuit

101‧‧‧Lighting diode

102‧‧‧illuminance sensor

Claims (8)

A photographic device, comprising: an image sensor; a lens for imaging light from a target area to image the image sensor; and an illumination source for illuminating the target area; the illumination source having an illumination intensity A plurality of light-emitting diodes in which the peak wavelengths of the peaks are different from each other and the respective peak wavelengths are included in the infrared wavelength band. An imaging apparatus is characterized in that the plurality of light-emitting diodes each set an emission spectrum such that a wavelength on a short-wavelength side of an emission intensity of 5% of the peak value is equal to or higher than an upper limit of a visible light band. The photographic device of claim 1 or 2, wherein the image sensor is a CMOS image sensor of a P-type 矽 substrate. The photographic device of claim 1 or 2, wherein the image sensor is a color image sensor capable of generating a color image. The photographic device of claim 3, wherein the image sensor is a color image sensor capable of generating a color image. A photographing apparatus according to claim 4, comprising: a detector that detects illumination of a target area; a filter that removes infrared light; and a switching mechanism that causes the filter to be relatively captured by the lens to Inserting and removing the optical path of the light of the image sensor; when the illuminance detected by the detector does not reach a predetermined threshold, The filter is evacuated from the optical path, and the light-emitting diode is turned on. When the illuminance detected by the detector is equal to or higher than the threshold, the filter is inserted into the optical path, and the light is emitted. The diode is extinguished. A photographing apparatus according to claim 5, comprising: a detector that detects illumination of a target area; a filter that removes infrared light; and a switching mechanism that causes the filter to be relatively captured by the lens Inserting and removing the optical path of the light to the image sensor; and when the illuminance detected by the detector does not reach a predetermined threshold, the filter is retracted from the optical path, and the light emitting diode is caused When the illuminance detected by the detector is equal to or greater than the threshold value, the filter is inserted into the optical path, and the light-emitting diode is turned off. An image management system comprising: the photographing apparatus according to any one of claims 1 to 7; and an external device that obtains a photographed image taken by the photographing apparatus from the photographing apparatus by communication.