TWI629552B - Camera device and image management system - Google Patents

Abstract

The invention provides a photographing device and an image management system that can not be easily perceived by a person and can be photographed as far as possible and can use infrared light to illuminate a target area under low illumination conditions such as at night.

The photographing device 1 includes an image sensor 40, a lens 10 for imaging light from a target area on the image sensor 40, and a light emitting diode 101 for illuminating the target area. Regarding the waveform of the light emission spectrum of the light-emitting diode 101, the wavelength of the light emission intensity of 5% of the peak value is above the upper limit of the visible light band (700 nm or 780 nm), and the spectral sensitivity characteristics of the image sensor 40 and the above-mentioned waveform are obtained. In the case of the integrated value of the product, the emission spectrum of the light-emitting diode 101 is set so as to be roughly integrated with the above-mentioned waveform at the position where the integrated value is the largest.

Description

Camera device and image management system

The present invention relates to a photographing device for photographing a target area and an image management system provided with the same, and is particularly suitable for use when shooting a target area under conditions such as low illumination at night.

An imaging device for monitoring the situation of a street, an intersection, or the like is known. In such a photographing device, the captured image is used, for example, to verify a traffic accident. During the verification, confirm the condition of the vehicle and pedestrians, or the lighting status of the traffic signal. The camera takes pictures of the target area not only during the day but also at night after sunset.

The following Patent Document 1 discloses a photographing device including LED lighting with infrared light. When the illuminance sensor determines that the monitoring area is dark, the photographing device turns on the infrared light LED to irradiate the infrared light to the monitoring area. In addition, Patent Document 1 describes a configuration in which a visible light LED is turned on and off to give a deterrent effect to an intruder when a situation of the intruder is detected.

[Prior technical literature] [Patent Literature]

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

In order to monitor the condition of the target area more effectively, the photographing device is preferably used to illuminate the target area with infrared light as far as possible under conditions of low illumination such as nighttime. The above-mentioned Patent Document 1 discloses a structure that gives an intruder a deterrent effect by turning on and off a visible light LED when a situation of an intruder is detected, but it does not disclose that it can be photographed to a long distance in a low illumination condition. A structure that uses infrared light to illuminate a target area.

When a photographing device is used for monitoring, it is preferable that infrared light irradiated onto a target area is not perceived by a human as much as possible. If infrared light is sensed, the presence of a photographing device is found, allowing other paths to pass. In this way, the monitoring purpose of the photographing device cannot be achieved.

In view of this problem, an object of the present invention is to provide a photographing device and an image management system having the same. The photographing device is difficult to be perceived by humans and can be photographed as much as possible under low illumination conditions such as at night. Use infrared light to illuminate the target area at a long distance.

A first aspect of the present invention relates to a photographing device. The photographing device in this aspect includes an image sensor, a lens for imaging light from a target area on the image sensor, and a light-emitting diode that illuminates the target area. When the waveform of the polar body's light emission spectrum has a wavelength of 5% of the peak light emission and a wavelength of 700 nm or more, the integral value of the product of the spectral sensitivity characteristics of the image sensor and the waveform is obtained. When the above integration value is the largest The light emission spectrum of the light-emitting diode is set in a manner that the waveforms are roughly integrated.

Generally speaking, the upper limit of human visible light band is about 700 nm. According to the photographing device of this aspect, the light emission spectrum of the light emitting diode is set such that the wavelength of the light emission intensity of about 5% of the peak value is at least 700 nm or more, so even if the skirt portion of the light emission spectrum reaches the upper limit of the visible light band, The intensity of this part of the light is also approximately zero or becomes extremely weak. Therefore, even if the light-emitting diode is turned on under low-light conditions such as at night, it is almost impossible for a person in the target area to find light from the light-emitting diode. Therefore, even when the imaging device is used for surveillance purposes, it can prevent people from perceiving the existence of the imaging device due to the lighting of the light-emitting diode.

In addition, according to the photographing device of this aspect, the light emission spectrum of the light emitting diode is set in a manner that is roughly integrated with the waveform having the maximum integral value of the product of the waveform sensitivity of the image sensor, so it can be used in When the sensitivity (sensitivity) of the image sensor is increased to the maximum wavelength band, the self-emitting diode irradiates light to the target area. Therefore, the photographing distance of the photographing device when the light emitting diode is turned on can be extended.

In this way, according to the photographing device of this aspect, under the conditions of low illumination such as at night, it will not be noticed that the light emitting diode is lit, and it can shoot as far as possible and use infrared light to target the area. For lighting.

A second aspect of the present invention relates to a photographing device. The photographing device in this aspect includes an image sensor, a lens for imaging light from a target area on the image sensor, and a light-emitting diode that illuminates the target area; For the waveform, when the wavelength of the light emission intensity of 5% of the peak value is in the range of 780nm or more, when the integrated value of the product of the spectral sensitivity characteristic of the image sensor and the waveform is obtained, The light emission spectrum of the light-emitting diode is set in such a manner that the above-mentioned waveform with the maximum integrated value is roughly integrated.

According to the photographing device of this aspect, since the emission spectrum of the light-emitting diode is set so that the wavelength of the light-emitting intensity of about 5% of the peak value is at least 780 nm or more, as described above, when the upper limit of the visible light band is 700 nm There is no case where the skirt portion of the light emission spectrum substantially reaches the upper limit of the visible light band. Therefore, even when the photographing device is used for surveillance purposes, it is possible to more completely prevent a person from perceiving the presence of the photographing device due to the lighting of the light-emitting diode.

Furthermore, according to the literature and the like, the upper limit of the human visible light band may be set to about 780 nm. According to the photographing device of this aspect, even if the upper limit of the human visible light band is about 780 nm, the light emission spectrum of the light emitting diode is set so that the wavelength of the light emission intensity of about 5% of the peak is at least 780 nm or more, The part of the skirt reaches the upper limit of the visible light band, and the intensity of the light in this part is also substantially zero or becomes extremely weak. Therefore, even if the light-emitting diode is turned on under low-light conditions such as at night, it is possible to prevent a person from perceiving the presence of a photographing device due to the lighting of the light-emitting diode.

Therefore, according to the photographing device of this aspect, under the conditions of low illumination such as at night, it will not be further noticed that the light emitting diode is lit, and it can shoot as far as possible, and can use infrared light to target the area For lighting.

In the photographing apparatuses of the first and second aspects, the wavelength of the peak value of the emission spectrum of the light-emitting diode may also be included in the range of ± 10 nm with respect to the peak wavelength of the waveform with the maximum integrated value. In this case, it is possible to achieve substantially the same effects as described above.

In the first and second aspects of the photographing device, the image sensor is preferably a CMOS image sensor of a P-type silicon substrate. Accordingly, compared with the case where the image sensor is a CMOS image sensor with an N-type silicon substrate, the sensitivity of the infrared band can be improved in terms of the spectral sensitivity characteristics of the image sensor. Thereby, the effect of improving the sensitivity brought by the optimization of the emission spectrum of the light-emitting diode can be exerted more significantly. Therefore, under low light conditions such as at night, the lighting of the light emitting diode will not be noticed, and it can shoot to a longer distance, and can use infrared light to illuminate the target area.

In the first and second aspects of the photographing device, the image sensor is preferably a color image sensor capable of generating a color image. According to this, under high light conditions such as daylight, the target area can be photographed with color images, and under low light conditions such as nighttime, the infrared light from the light emitting diode can be used to shoot the target area in black and white images. .

In this case, the first and second aspects of the photographing device may be configured to include a detector that detects the illuminance of the target area, a filter that removes infrared light, and a switching mechanism that enables The filter inserts and extracts the light path of the light captured by the lens to the image sensor. In this case, when the illuminance detected by the detector does not reach a predetermined threshold, the photographing device retreats the filter from the optical path and lights the light-emitting diode; when detected by the detector, When the illuminance is greater than the threshold, the filter is inserted into the optical path, and the light-emitting diode is turned off. According to this, under high light conditions such as daylight, high-quality color images that can remove the influence of infrared light can be used to shoot the target area. Under low light conditions such as nighttime, infrared light from light emitting diodes can be used The light shoots the target area in a black and white image.

A third aspect of the present invention relates to an image management system. The shadow of this appearance The image management system includes a photographing device in a first aspect or a second aspect, and an external device that acquires a photographed image captured by the photographing device from the photographing device through communication.

According to the image management system of this aspect, it is possible to achieve the same effects as those produced by the above-mentioned first and second aspects of the photographing device.

As described above, according to the present invention, it is possible to provide a photographing device and an image management system having the same. The photographing device can shoot as far as possible to a target area using infrared light under conditions of low illumination such as nighttime. illumination.

The effect and meaning of the present invention should be made clearer by the description of the embodiment shown below. However, the embodiment described below is merely an example for implementing the present invention, and the present invention is not limited in any way by the content described in the following embodiment.

1‧‧‧Photographic device

10‧‧‧ lens

40‧‧‧Image Sensor

50‧‧‧Filter

51‧‧‧Switch mechanism

101‧‧‧light-emitting diode

102‧‧‧illuminance sensor (detector)

FIG. 1 (a) is a diagram showing an appearance configuration of an image management system according to an embodiment. FIG. 1 (b) is a diagram showing an example of a photographed image of the embodiment. FIG. 1 (c) is a view schematically showing a configuration of a front side of a lens barrel of an image recording apparatus according to an embodiment.

FIG. 2 is a diagram showing a configuration of a photographing apparatus according to the embodiment.

FIG. 3 is a diagram showing a configuration of a CMOS image sensor according to an embodiment.

4 (a)-(c) are diagrams explaining the reading control of the CMOS image sensor according to the embodiment.

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

FIG. 6 is a flowchart showing the control of the filter and the light emitting diode of the embodiment.

FIG. 7 (a) is a graph showing the spectral sensitivity characteristics of the image sensor of Comparative Example and Example 1. FIG. FIG. 7 (b) is a graph showing a spectral transmittance characteristic of a color filter disposed in the image sensor of Example 1. FIG. FIG. 7 (c) is a graph showing a spectral transmittance characteristic of a filter for removing the infrared light of Example 1. FIG. FIG. 7 (d) is a graph showing a light emission spectrum of the light emitting diode of Example 1. FIG.

FIG. 8 is a diagram showing a method of setting a light emitting spectrum of the light emitting diode of Example 1. FIG.

FIG. 9 is a diagram showing a method of setting a light emitting spectrum of the light emitting diode of Example 2. FIG.

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

FIG. 1 (a) is a diagram showing an appearance configuration of an image management system according to an embodiment.

As shown in FIG. 1 (a), the video management system includes a photographing device 1 and an external device 2. The photographing device 1 is a surveillance camera, and is installed on an object 3 capable of photographing a street or an intersection including a traffic signal. The installation object 3 is, for example, a structure such as an outer wall or a roof of a building, a telephone pole, or the like. The photographing device 1 records the captured images in an internal recording medium at any time. The external device 2 is a portable personal computer. In addition, the external device 2 may be other portable information terminals such as a mobile phone, an input board, and the like.

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

FIG. 1 (b) is a diagram showing an example of a photographed image captured by the photographing device 1. Here, the intersection 5 including the traffic signal 4 is set as a target area. For the sake of convenience, only the signal device 4 facing the direction of the photographing device 1 is illustrated in FIG. 1 (b). After the image captured by the photographing device 1 is recovered to the external device 2, it is used for verification of a traffic accident, for example. In this verification, the condition of the vehicle or pedestrian passing through the intersection 5 and the lighting condition of the traffic signal 4 are confirmed. That is, it was confirmed which of the red, blue, and yellow lights the traffic light 4 was in 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 device 1. FIG.

As shown in FIG. 1 (c), the photographing device 1 is provided with a plurality of light emitting diodes 101 and an illuminance sensor 102 for detecting the illuminance of a target area around the lens 10. Under low light conditions such as at night, the light-emitting diode 101 is lit to illuminate the target area. The light emitting diode 101 irradiates infrared light to a target area. As described below, the light-emitting diode 101 adjusts the light-emitting spectrum in such a manner that the irradiated infrared light is not easily perceivable by humans and can be photographed as far as possible and can use infrared light to illuminate a target area.

FIG. 2 is a diagram showing the configuration of the photographing apparatus 1. As shown in FIG.

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

Lens 10 captures light from the target area and makes the image of the target area appear on the image The light receiving surface of the sensor 40 is imaged. The diaphragm 20 restricts light from the outside so that an appropriate amount of light is incident on the image sensor 40 according to the intensity of the light from the target area. The aperture 20 is adjusted by an aperture driving circuit 64.

Shutter 30 is an LCD shutter. The shutter 30 is, for example, a liquid crystal shutter having a characteristic of a so-called normaly black method in which the transmittance is maximized when a voltage is applied and the transmittance decreases when the application of the voltage is blocked. In this case, the shutter 30 transmits light when a voltage is applied, and blocks light when a voltage is not applied. In addition, the shutter 30 may be a liquid crystal shutter having a characteristic of a so-called normaly white method in which the transmittance is maximum when no voltage is applied and the transmittance decreases when a voltage is applied. In addition, as long as the shutter 30 can be opened and closed at a high speed, it may be a shutter of another method. The shutter 30 is switched on and off according to a driving signal from the shutter driving circuit 62.

The image sensor 40 is a CMOS image sensor. The image sensor 40 is a color image sensor capable of generating a color image. The image sensor 40 has a photodiode at a position corresponding to each pixel on the light receiving surface. In addition, the image sensor is provided at a position corresponding to a pixel respectively receiving red, blue, and green light, and a color filter is configured to filter the red, blue, and green light. The image sensor 40 is controlled by a photographing signal processing circuit 61 so as to accumulate and output electric charges to the photodiode for each line. Furthermore, the image sensor 40 may be a black-and-white image sensor.

The filter 50 removes light in the infrared wavelength band from the light collected by the lens 10. The switching mechanism 51 causes the filter 50 to insert and remove the optical path of the light captured by the lens 10 to the image sensor 40. The switching mechanism 51 switches the insertion and removal of the filter 50 according to a driving signal from the filter driving circuit 63.

The LED driving circuit 65 turns on or off the light emitting diode 101 according to the 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 memory unit 68. The memory section 68 holds a program for control, and is also used as a work area when controlled by the control section 67. The control section 67 controls the photographing signal processing circuit 61, the shutter driving circuit 62, the filter driving circuit 63, the aperture driving circuit 64, and the LED driving circuit 65 by a program held in the memory section 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 AC power source, and adjusts electric power supplied from the commercial AC power source to be supplied to each unit in the imaging device 1.

FIG. 3 is a diagram schematically showing the configuration of the image sensor 40. For convenience, the configuration corresponding to 9 pixels is shown in FIG. 3, but in fact, the same configuration is arranged corresponding to a predetermined number of pixels in the vertical and horizontal directions.

The image sensor 40 has a photodiode 40a at a position corresponding to each pixel. When the photodiode 40a receives light, it accumulates a charge corresponding to the amount of received light. 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 arranged on each vertical signal line 40d. When the row selection switch 40f is set to ON, the held voltage is transmitted to the horizontal signal line 40g. Next, the voltage transmitted to the horizontal signal line 40g is transmitted to the photographing signal processing circuit 61. In this way, in the image sensor 40, a voltage signal is sent for each line L.

The image sensor 40 is controlled so as to accumulate the electric charge of the photodiode 40a for each line L. That is, the photodiodes 40a on one line L are set to a state capable of accumulating electric charges in a predetermined period, and when this period elapses, the electric charges generated by the respective photodiodes 40a on the line L are output. This control is performed sequentially from the line L in the uppermost stage to the line L in the lowermost stage. When the line L is in a state capable of accumulating charges, if the photodiodes 40a on the line L are irradiated with light, charges corresponding to the light amount of the irradiated light are accumulated in the respective photodiodes 40a on the line. The charges accumulated in the above manner are read for each line L as described above, and are converted into a voltage signal and output to the photographing 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 photographing signal processing circuit 61 sequentially sets each line on the image sensor 40 as a charge accumulation period, and reads the charge for each line. The photographing signal processing circuit 61 includes an A / D conversion circuit, and converts a voltage signal of each line supplied from the image sensor 40 through a horizontal signal line 40g (see FIG. 3) into a digital signal and outputs the digital signal to the control unit 67. The control unit 67 stores a digital signal (image signal) supplied from the photographing signal processing circuit 61 in the storage unit 68. In this way, one photographic image is constituted by the image signal of the bus amount (one frame amount) output from the photographic signal processing circuit 61.

FIGS. 4 (a) to 4 (c) are diagrams explaining the reading control of the electric charge of the image sensor 40. FIG. Fig. 4 (a) is a diagram schematically showing a control (hereinafter, referred to as "normal mode") in a case where electric charges are read from each line at an ordinary speed, and Fig. 4 (b) is a diagram schematically showing A diagram of control (hereinafter, referred to as "high-speed mode") in the case where electric charges are read from each line at a high speed. In addition, FIG. 4 (c) schematically shows a situation in which charge is read from each line at a low speed. Time control (hereinafter referred to as "low speed mode").

On the left side of Figs. 4 (a) to (c), the light receiving surface of the image sensor 40 and each line L are schematically shown. Here, the uppermost line L is set to L0, and the lowermost line is set to Ln. In addition, on the right side of Figs. 4 (a) to (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 starts at timing t1 and ends at timing t2. The control of the line L2 of the next stage is started after a predetermined time delay from the timing t1. In this way, each time the line L changes to the lower stage, control of each line is sequentially performed while delaying the start timing sequentially by a predetermined time. The start timing of the lowest line Ln becomes the timing t2 after the delay Δt from the timing t1.

In the line L0 in the uppermost stage, a charge is 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 a charge accumulation period. The charge accumulation period is similarly set for the other lines L. At the timing t2 after the period Δt has elapsed from the timing t1, the reading of the charge of the line L0 in the uppermost stage is performed.

Regarding the line L1 in the second stage, charges are accumulated at a timing delayed from the timing t1 by a predetermined time, and reading of charges is performed at a timing delayed from the timing t2 by a predetermined time. In this way, whenever the line L changes, the start timing of charge accumulation is sequentially delayed by a predetermined time, and the execution timing of charge reading is also sequentially delayed by a predetermined time. The start timing of the charge accumulation of the lowermost line Ln becomes 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 charge accumulation for the line L0 at the uppermost stage becomes the start timing of charge accumulation for the line Ln at the lowermost stage. Therefore, in the normal mode, the charge accumulation periods of all lines do not overlap.

Referring to FIG. 4 (b), in the high-speed mode, the reading speed of the charges on each line L is increased, whereby the shift amount of the control start timing between the lines L is shortened compared with the normal mode. In the example of FIG. 4 (b), the shift amount of the control start timing between the lines L is reduced to 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 read speed of the charges on each line L is increased by reducing the number of bits when the charge signal of each line is sampled (A / D converted) as compared to the number of bits in the normal mode. This processing is performed based on the control performed by the control unit 67 in FIG. 2 and performed by the imaging signal processing circuit 61. In the high-speed mode, since the number of specimen bits is reduced as described above, the image quality of photographic images is slightly deteriorated compared to the normal mode. However, this deterioration is such that the visibility is not a particular problem in applications such as surveillance cameras. Alternatively, the same number of specimen bits can be retained by improving and speeding up the image sensor 40 and the imaging 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), the charge accumulation periods of all the lines have overlapping accumulation periods that overlap each other. In addition, by opening the shutter 30 for exposure during the overlap accumulation period, each line L is irradiated with light from the target area at the same timing, and the photodiodes 40a on all lines L accumulate charges at the same timing and exposure amount. . Therefore, it is possible to suppress deformation of a photographed image of a subject moving at a high speed. That is, the rolling shutter phenomenon can be suppressed, and a global shutter function using the image sensor 40 can be realized.

In this embodiment, the control mode of the image sensor 40 is set to a high-speed mode. Then, the shutter 30 is opened during the overlap accumulation period to guide the light from the target area to the shadow. Like the sensor 40.

In addition, an overlapping accumulation period may be generated by setting the control mode of the image sensor 40 to a 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, 2Δt. In this case, the shutter 30 is also opened during the overlap accumulation period. Accordingly, as in the case of the high-speed mode, it is possible to suppress the distortion of the photographed image of the subject moving at 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 lever 540.

The base 510 is provided with two guides 511 having an L-shaped cross section at the left and right ends. The two guides 511 are respectively engaged with the moving plate 520 so as to be in contact with the upper and side surfaces of the moving plate 520. Left and right ends. Thereby, the moving plate 520 is supported on the base 510 so as to be movable in the long-side direction. A through opening 512 is formed in the base 510.

The moving plate 520 is made of a thin plate-like member. Two openings 521 and 522 are formed in the moving plate 520 along 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. In the state of FIG. 5 (a), the opening 521 is located at the through opening 512 of the base 510. A flange portion 520a is formed on the moving plate 520 so as to protrude to the right. A long hole 523 extending in the lateral direction is formed in the flange portion 520a.

One end of the lever 540 is fixed to the driving shaft 531 of the motor 530. When the motor 530 is driven, the lever 540 rotates in a clockwise direction or a counterclockwise direction in FIGS. 5 (a) and (b). A pin 541 is formed on the upper surface of the other end portion of the lever 540, and the pin 541 is inserted into the long hole 523 from the back side of the flange portion 520a. The motor 530 is a stepping motor.

The through opening 512 formed in the base 510 becomes an optical path of light condensed by the lens 10 shown in FIG. 2. 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 counterclockwise, the pin 541 pushes the long hole 523 and causes the moving plate 520 to slide. 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. In this way, the filter 50 deviates from the optical path and opens the optical path.

The filter driving circuit 63 of FIG. 2 controls the control unit 67 to drive the motor 530 so that the moving plate 520 is located at any one of the positions shown in FIG. 5 (a) and FIG. 5 (b). As a result, the filter 50 is inserted into and removed from the optical path of the light collected by the lens 10.

FIG. 6 is a flowchart 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 the illuminance detected by the illuminance sensor 102 is smaller than a predetermined threshold (S11).

When the sunlight is weak and the illumination of the target area is low at night or in the evening, the determination in step S11 becomes YES. When the determination of step S11 is YES, the control unit 67 lights up the light emitting diode 101 (S12), and further controls the switching mechanism 51 to cause the filter 50 to retreat from the optical path of the light collected by the lens 10 ( S13).

On the other hand, when the sunlight is strong during the day and the illumination intensity of the target area is high, the determination in step S11 becomes NO. When the determination in step S11 is NO, the control unit 67 turns off the light-emitting diode 101 (S14), and further controls the switching mechanism 51 to insert the filter 50 into the light path of the light focused by the lens 10 (S15 ). The control unit 67 repeatedly performs the processing of steps S11 to S15 until the end of the photographing operation (S16: YES).

However, in this embodiment, the light emitting diode 101 is irradiated with infrared light that is not easily perceivable by a person, and can be photographed as far as possible and can use infrared light to Adjust the light emission spectrum by illuminating the target area. In more detail, regarding the waveform of the light emission spectrum of the light emitting diode 101, the wavelength of the light emission intensity of 5% of the peak value is above the upper limit of the human visible light band, and the spectral sensitivity characteristics of the image sensor 40 and In the case of the integrated value of the product of the waveform of the light emitting spectrum of the light emitting diode 101, the light emitting spectrum of the light emitting diode 101 is set so as to be roughly integrated with the waveform of the position where the integrated value is the largest.

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 graph 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 silicon substrate is used. As a comparative example, the spectral sensitivity characteristics of an image sensor using an N-type silicon substrate are also shown in FIG. 7 (a). As shown in FIG. 7 (a), if a P-type silicon substrate is used as the substrate of the image sensor 40 as in Example 1, it can be improved compared with the case where a N-type silicon substrate is used (comparative example). Sensitivity in the near-infrared band, so the peak of sensitivity can be shifted to the side of the infrared wavelength band.

FIG. 7 (b) is a diagram showing a spectral transmission characteristic of a color filter disposed in the image sensor 40 of Example 1. FIG. R, G, and B in FIG. 7 (b) represent the spectral transmittance characteristics of the color filter corresponding to the pixels receiving red, green, and blue light, respectively. As shown in FIG. 7 (b), the color filters of each color are set so that the transmittance increases in the wavelength band of the color. In addition, the color filters of each color maintain the transmittance high when the wavelength exceeds the vicinity of 820 nm.

FIG. 7 (c) is a graph showing the spectral transmittance characteristics of the filter 50 of Example 1. FIG. Case of the figure. As shown in FIG. 7 (c), when the wavelength of the filter 50 exceeds the vicinity of 630 nm, the transmittance decreases sharply, and at the wavelength of 700 nm, the transmittance is approximately zero. When the wavelength exceeds 700 nm, the transmittance of the filter 50 is maintained at substantially zero.

FIG. 7 (d) is a graph showing a light emission spectrum of the light emitting diode 101 of Example 1. FIG.

In FIG. 7 (d), it is assumed that the upper limit of the human visible light band is 780 nm. The upper limit of the visible light band is indicated by A1 in FIG. 7 (d). In this case, as shown by the solid line in FIG. 7 (d), the light emission spectrum of the light emitting diode 101, the wavelength of the light emission intensity at 5% of the peak value is above the upper limit A1 of the visible light band of the human, so that the light is emitted. The spectrum waveform is shifted in the wavelength direction (horizontal axis direction), and when the integrated value of the product of the spectral sensitivity characteristic of the image sensor 40 and the waveform of the light emission spectrum is obtained, the position where the sum of the integrated values is the largest Waveforms are roughly integrated. Here, as shown in FIG. 7 (a), since the peak of the spectral sensitivity of the image sensor 40 is near 650 nm, the emission spectrum of the light-emitting diode 101 is at the upper limit of the wavelength corresponding to 5% of the peak and the upper limit of the visible light band. Set in the same way as A1. In this case, the emission spectrum is the wavelength of the peak, which is around 830 nm.

Furthermore, as described above, when the image sensor 40 is a color CMOS image sensor, the transmittance of the color filters of each color is set as shown in FIG. 7 (d), for example. Therefore, if the emission spectrum of the light-emitting diode 101 is set as the solid line of FIG. 7 (d), the transmittance of the blue and green color filters is shorter on the short wavelength side than the peak of the emission spectrum. The maximum value. Therefore, light with a wavelength shorter than the short-wavelength side of the peak of the emission spectrum is filtered by the blue and green color filters and may not be effectively used.

To avoid this, the spectral transmittance characteristics of color filters are preferably The light emission spectrum of the light-emitting diode 101 is adjusted in such a manner that the light-wavelength spectrum is maintained at a high level over the entire wavelength band. That is, it is preferable to set the boundary of the short-wavelength side of the range W1 to the emission spectrum of the light-emitting diode 101 in such a manner that the range W1 shown in FIG. 7 (b) includes the full wavelength band of the light-emitting diode 101. Near the lower wavelength (for example, around 750nm). 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 shooting a target area in an environment with high illuminance such as daytime, it is possible to suppress infrared light other than visible light from entering the pixels of the image sensor 40.

Furthermore, when the spectral transmittance of the color filter is not adjusted as described above, that is, when the spectral transmittance of the color filter is maintained as the characteristic of FIG. 7 (b), only the image sensing In addition to the spectral sensitivity characteristics of the filter 40, the emission spectrum of the light emitting diode 101 may be set in consideration of the spectral transmittance characteristics of the color filter. That is, in a range where the wavelength of the light emission intensity of 5% of the peak value is above the upper limit of the human visible light band, the spectral sensitivity characteristic of the image sensor 40, the waveform of the light emission spectrum of the light emitting diode 101, and the color filter of each color are obtained. In the case of the integrated value of the product of the spectral transmittance characteristics of the light sheet, the emission spectrum of the light-emitting diode 101 may be set so as to be roughly integrated with the waveform with the largest integrated value. The emission spectrum in this case is set as shown by the dotted line in FIG. 7 (d).

Furthermore, since the black-and-white CMOS image sensor does not include a color filter, when the black-and-white CMOS image sensor is used as the image sensor 40, the above limitation disappears. Therefore, when a black-and-white CMOS image sensor is used as the image sensor 40, the light emission spectrum of the light-emitting diode 101 is set in such a way that the integral value of the product of the spectral sensitivity characteristic of the image sensor 40 is the largest. Just fine.

FIG. 8 is a diagram showing a method of setting a light emission spectrum of the light emitting diode 101 of Example 1. FIG.

In FIG. 8, as described above, the emission spectrum of the light-emitting diode 101 when the upper limit of the visible light band of S1 is 780 nm (upper limit A1). In this case, the wavelength P1 of the peak of the emission spectrum is around 830 nm.

In FIG. 8, S2 is the light emission spectrum of the light emitting diode 101 when the upper limit of the visible light band is 700 nm (the upper limit A2), and P2 is the wavelength of the light emission position S2.

In this case, the emission spectrum of the light-emitting diode 101 is also shifted in the wavelength direction (horizontal axis direction) in a range above the upper limit A2 of the human visible light band at a wavelength of 5% of the peak light emission intensity. When the integrated value of the product of the spectral sensitivity characteristic of the image sensor 40 and the waveform of the light emission spectrum is obtained, it is set in a manner that is roughly integrated with the waveform at the position where the integrated value is the largest. As shown in FIG. 7 (a), since the peak of the spectral sensitivity of the image sensor 40 is near 650 nm, the emission spectrum of the light emitting diode 101 is consistent with the upper limit A2 of the visible light band at a wavelength corresponding to 5% of the peak Mode setting. In this case, the emission spectrum is that the wavelength of the peak is around 750 nm.

<Example 2>

FIG. 9 is a diagram showing a method for setting a light-emitting spectrum of the light-emitting diode 101 according to the second embodiment. For the sake of convenience, the spectral sensitivity characteristic and the light emission spectrum S1 and the peak wavelength P1 of the embodiment 1 shown in FIG. 8 are shown in FIG. 9.

In Example 2, the position of the peak of the spectral sensitivity characteristic of the image sensor 40 is near 880 nm, which is shifted toward the longer wavelength side than in Example 1.

S3 is the emission spectrum of the light-emitting diode 101 when the upper limit of the visible light band is 780 nm (the upper limit A1). In this case, the light emission spectrum S3 of the light emitting diode 101 is also in a range where the wavelength of the light emission intensity of 5% of the peak is above the upper limit A2 of the visible light band of the human, so that the waveform of the light emission spectrum is in the wavelength direction (horizontal axis direction) ) Offset, and when the integrated value of the product of the spectral sensitivity characteristic of the image sensor 40 and the waveform of the light emission spectrum is obtained, it is set so as to be roughly integrated with the waveform at the position where the integrated value is the largest. As shown in FIG. 9, since the peak of the spectral sensitivity of the image sensor 40 is near 880 nm, the emission spectrum of the light-emitting diode 101 is set such that the wavelength at which the emission spectrum becomes a peak is near 880 nm. In this case, the emission spectrum of the light-emitting diode 101 is substantially zero at the upper limit A1 of the visible light band.

As described above, in Example 2, compared with Example 1, the emission spectrum of the light-emitting diode 101 is set closer to the longer wavelength side. In the second embodiment, compared with the first embodiment, the integrated value of the product of the spectral sensitivity characteristic of the image sensor 40 and the waveform of the light emission spectrum is increased, so that the situation when the light emitting diode 101 is turned on can be further improved. The sensitivity of the image sensor 40. Thereby, compared with Embodiment 1, the photographing distance of the photographing device 1 can be further extended.

When the upper limit of the human visible light band is A2, the emission spectrum of the light-emitting diode 101 is also set in the same manner as in FIG. 9. In this case, the emission spectrum of the light emitting diode 101 is also at the upper limit A2 of the visible light band, and the light emission intensity becomes substantially zero.

<Effects of Implementation Mode>

According to this embodiment, the following effects are achieved.

The light emission of the light-emitting diode 101 is set in such a way that the wavelength of the luminous intensity of about 5% of the peak value is at least the upper limit (780nm or 700nm) of the human visible light band. Spectrum, so even if the part of the skirt of the luminescence spectrum reaches the upper limit of the visible light band, the intensity of the light in that part is approximately zero or becomes extremely weak. Therefore, even if the light-emitting diode 101 is lit under low-illumination conditions such as at night, it is almost impossible for a person located in the target area to find light from the light-emitting diode 101. Therefore, even when the photographing device 1 is used for monitoring purposes, it is possible to prevent people from perceiving the presence of the photographing device 1 due to the lighting of the light emitting diode 101.

In addition, the light emission spectrum of the light emitting diode 101 is set in such a manner as to be roughly integrated with a waveform whose integral value of the product of the waveform sensitivity characteristics of the image sensor 40 and the light emitting spectrum of the light emitting diode 101 is maximized. The self-luminous diode 101 can irradiate light to a target region in a wavelength band that can increase the sensitivity of the image sensor 40 to the maximum limit. Therefore, the photographing distance of the photographing device 1 when the light emitting diode 101 is turned on can be extended.

As described above, according to the photographing device 1 of this embodiment, under conditions of low illumination such as at night, the lighting of the light-emitting diode 101 is not noticed, and it is possible to shoot as far as possible and use infrared rays. The light illuminates the target area.

In addition, the light emission spectrum of the light emitting diode 101 is in a range above the upper limit of the human visible light band at a wavelength of 5% of the peak light emission intensity, and the spectral sensitivity characteristics of the image sensor 40 and the waveform of the light emission spectrum are obtained. In the case of the integrated value of the product, it may not necessarily be integrated with the waveform of the position with the maximum integrated value. For example, it may be offset from the position in the range of ± 10 nm in the wavelength axis direction (horizontal axis direction). Waveform integration mode setting. In this case, even if the skirt part of the light emission spectrum reaches the upper limit of the visible light band, the intensity of the light in this part is substantially zero or becomes extremely weak, so even when the illumination is low at night, such as night, The polar body 101 can also suppress a person located in the target area from finding light from the light emitting diode 101. In addition, it can emit light in a wavelength band that can increase the sensitivity of the image sensor 40 to the maximum limit. The diode 101 irradiates light to a target area, so that the photographing distance of the photographing device 1 when the light-emitting diode 101 is lit can be extended.

Furthermore, in the case where the above-mentioned shift is ± 20nm, the intensity of the light in the skirt portion of the emission spectrum which reaches the upper limit of the visible light band may be slightly increased, but in this case, the intensity of the light in the portion is also suppressed To the extent that it is not easily noticed. Therefore, even if the emission spectrum of the light-emitting diode 101 is set as described above, the light from the light-emitting diode 101 is not easy to be found by people who are located in the target area, especially when it is far away from the outer wall of the building or the roof, or a telephone pole When the photographing device 1 is installed at a position such as a target area or a position deviating from the line of sight of a walking person for surveillance purposes, the light intensity of the skirt portion is hardly a problem. And can achieve the desired purpose.

In addition, since a CMOS image sensor using a P-type silicon substrate is used as the image sensor 40, as shown in FIG. 7 (a), the case where the image sensor 40 is a CMOS image sensor having an N-type silicon substrate Compared with that, the peak of the spectral sensitivity characteristic of the image sensor 40 can be set to the longer wavelength side of the infrared band. As shown in FIG. 9, the peak of the spectral sensitivity characteristic of the image sensor 40 can be further set at Long wavelength side. Thereby, the maximum value of the integral value of the product of the spectral sensitivity characteristic of the image sensor 40 and the waveform of the light emission spectrum of the light emitting diode 101 can be further improved. Therefore, under conditions of low illumination such as at night, the lighting of the light-emitting diode 101 is not noticed, and further shooting can be performed to a long distance, and the target area can be illuminated with infrared light.

In addition, since the image sensor 40 is a color image sensor that can produce color images, the target area can be photographed with color images under conditions of high illumination such as daytime, and under conditions of low illumination such as nighttime. The infrared light from the light emitting diode 101 can be used to shoot the target area in a black and white image.

In addition, because it has a structure that when the illuminance detected by the illuminance sensor 102 does not reach a predetermined threshold, the filter 50 is retracted from the optical path of the lens 10 and the light-emitting diode 101 is lit. When the illuminance detected by the illuminance sensor 102 is greater than or equal to the threshold, the filter 50 is inserted into the optical path of the lens 10 and the light-emitting diode 101 is turned off. Therefore, under conditions of high illuminance such as daytime, The target area can be photographed with a high-quality color image after removing the influence of infrared light by the filter 50. Under low light conditions such as at night, infrared light from the light emitting diode 101 can be used to target the target area in black and white. Take a shot.

<Example of change>

The waveform of the emission spectrum of the light-emitting diode 101 is not necessarily limited to those shown in FIG. 7 (d), FIG. 8 and FIG. 9, for example, it may be narrower or wider than the waveforms shown in these figures. Wider waveform. By setting the waveform of the emission spectrum of the light-emitting diode 101 to be wide, the wavelength width of the infrared light radiated from the light-emitting diode 101 to the target region can be enlarged. With this, even if the reflectance of infrared light varies depending on the materials constituting the subject, light of a wavelength with a higher reflectance among the materials is easily irradiated to the materials. Therefore, even at low illumination conditions, such as at night, the light can be irradiated to the target area by the self-illuminating light source, and the photographic image can be obtained with a high contrast.

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. In addition, the spectral transmittance of the color filter and the spectral transmittance of the filter 50 are not necessarily limited to those shown in FIGS. 7 (b) and 7 (c), and may have other characteristics.

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

In addition, 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 arranged in the photographing device 1 in other numbers and arrangements.

In addition, in the above embodiment, the photographing device 1 transmits signals to the external device 2 through wireless communication, but the photographing device 1 may transmit signals to the external device 2 through wired communication. Alternatively, the photographic image may be recorded in advance on a memory card installed in the photographing device 1, and the memory card may be removed from the photographing device 1 and installed in the external device 2, thereby capturing the photographic image to the external device 2.

In addition, in the above-mentioned embodiment, the photographing device 1 is a structure, a telephone pole, or the like installed on an outer wall or a roof of a building or the like. For example, the photographing device 1 may be provided on a traffic sign, or the constitution of the photographing device 1 may be integrally included in a street lamp or the like.

In addition, the embodiment of the present invention can be appropriately modified in various ways within the scope of the technical idea shown in the scope of the patent application.

Claims (7)

A photographing device, comprising: an image sensor; a lens that images light from a target area on the image sensor; and a light emitting diode that illuminates the target area; and the light emitting diode The waveform of the light emission spectrum of the body is calculated by integrating the product of the spectral sensitivity characteristic of the image sensor and the waveform in a range where the wavelength of the light emission intensity of 5% of the peak is 700 nm or more. The light emission spectrum of the light-emitting diode is set in such a manner that the waveform with the largest value is roughly integrated. A photographing device, comprising: an image sensor; a lens that images light from a target area on the image sensor; and a light emitting diode that illuminates the target area; and the light emitting diode When the waveform of the light emission spectrum of the body is in the range of 5% of the peak light emission intensity and the wavelength is 780 nm or more, when the integral value of the product of the spectral sensitivity characteristic of the image sensor and the waveform is obtained, the above integration is used. The light emission spectrum of the light-emitting diode is set in such a manner that the waveform whose value becomes the maximum is roughly integrated. For example, the photographing device of the scope of patent application No. 1 or 2, wherein the wavelength of the peak value of the light emission spectrum of the light-emitting diode relative to the peak wavelength of the waveform at the position where the integral value is maximum is included in the range of ± 10 nm Inside. For example, a photographing device according to item 1 or 2 of the patent scope, wherein the image sensor is a CMOS image sensor of a P-type silicon substrate. For example, a photographing device according to item 1 or 2 of the patent application scope, wherein the image sensor is a color image sensor capable of generating a color image. For example, the photographing device of the fifth scope of the patent application includes: a detector that detects the illuminance of the target area; a filter that removes infrared light; and a switching mechanism that causes the filter pair to be captured by the lens To 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 retracted from the optical path and the light-emitting diode is lit; When the illuminance detected by the detector is greater than the threshold, the filter is inserted into the optical path, and the light-emitting diode is turned off. An image management system includes: a photographing device such as any of items 1 to 6 of the scope of patent application; and an external device that obtains a photographic image captured by the photographing device from the photographing device through communication.