JPH09134488A - Monitoring camera system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To monitor and output a video signal having always sufficiently enough luminance. SOLUTION: At the arrival of processing timing, a control part 5 enters a luminance signal from a video signal processing part 2 in the OFF state of a light source 7, detects the average luminance of a prescribed frame, compares the detected luminance with a threshold, and when the average luminance is more than the threshold, holds the OFF state of the light source 7. When the average luminance is less than the threshold, the control part 5 instructs an illumination driver 8 to turn on the light source 7. When the processing above is repeated every prescribed period, a video signal having always sufficiently enough luminance is outputted from an image pickup part 1 and the monitoring side can monitor a fine picture.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surveillance camera system.

[0002]

2. Description of the Related Art A black and white camera may be used as a surveillance camera and a color camera may be used.
In any case, the surveillance camera is always operating, and the output video signal is transmitted to a predetermined place such as a surveillance center and displayed on the monitor.

The environment in which the surveillance camera is installed varies, but in the daytime, since the surroundings of the surveillance camera are brightened by outside light or indoor lighting, the luminance of the output video signal is high, and the monitor image is bright. While good monitoring is possible, the surroundings of the surveillance camera are dark at night, and the brightness of the output video signal is low, making it difficult to properly monitor on a monitor. .

Therefore, it is conceivable to provide an illuminating device for illuminating the field of view of the surveillance camera, and to operate the illuminating device when the brightness around the surveillance camera decreases. Moreover, in that case, instead of simply setting the time for lighting the lighting device with a timer, when the surroundings become dark and the image from the surveillance camera becomes difficult to see, the lighting device is automatically turned on. When the surroundings become bright and the image from the surveillance camera has sufficient brightness, it is desirable to turn off the lighting device in terms of energy saving and life of the lighting device. it is obvious.

As a method therefor, it is conceivable to control the turning on and off of the lighting device by detecting the ambient brightness of the surveillance camera by using a light sensitive sensor such as CdS.

However, in this method, whether the sensor is attached to the surveillance camera or the illumination device,
The structure for mounting the sensor is required, which increases the cost.

When CdS is used as a sensor,
Although the CDS is inexpensive, it cannot be said that the accuracy is good, so that there is also a problem that it is difficult to perform good control.

As another method, for example, the average brightness of the video signal output from the surveillance camera is obtained, and when the average brightness is below a predetermined threshold, the lighting device is turned on, and then the average brightness exceeds the threshold. In such a case, it may be possible to turn off the lighting device.

However, if this method is simply performed, the illumination device will repeatedly turn on and off, which causes a problem that the screen becomes very difficult to see. That is, it is assumed that the surroundings have become dark and the average luminance of the video signal from the surveillance camera has become less than or equal to the threshold value. At this time, the illuminating device is turned on, but when the illuminating device is turned on, the average luminance of the video signal exceeds the threshold value, so the illuminating device is turned off. However, at this time, since the surroundings are dark, the average luminance of the video signal becomes equal to or lower than the threshold value, the lighting device is turned on again, and the above-described operation is repeated thereafter, and the lighting device repeats turning on and off.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a surveillance camera system capable of controlling an illuminating device satisfactorily and thus constantly monitoring good images. is there.

[0011]

In order to achieve the above object, a surveillance camera system according to a first aspect of the invention is a surveillance camera system including a lighting device, an image pickup section, and a control section. Then, the control unit monitors the level of the video signal output from the imaging unit with the lighting device inoperative at every predetermined cycle, and when the level of the video signal is equal to or lower than the predetermined luminance, If it is less than the above, the illuminating device is operated, and if the level of the video signal exceeds the predetermined luminance or is equal to or higher than the predetermined luminance, the illuminating device is inactivated.

Here, the surveillance camera may be a monochrome camera or a color camera.

According to this surveillance camera system, the level of the video signal from the surveillance camera is not measured at all times but at a predetermined cycle, and the video signal level is measured with the illumination device turned off. Since it is performed in step 1, the ambient brightness can be measured with high accuracy, and thus the lighting device can be controlled well.

Further, since the lighting device is turned on only when necessary, it is effective as an energy saving measure, and the life of the lighting device can be maximized.

A surveillance camera system according to a second aspect of the present invention includes a lighting device that emits infrared light having a predetermined wavelength, a color image pickup section having a night-vision function, a video signal processing section, and a control section. In the system, the control unit monitors the level of the video signal output from the video signal processing unit with the lighting device inoperative at predetermined intervals, and the level of the video signal is equal to or lower than a predetermined brightness. In the case where the brightness is lower than a predetermined brightness, the lighting device is operated and a black-and-white video signal is output to the video signal processing unit, and the level of the video signal exceeds the predetermined brightness or is higher than the predetermined brightness. In this case, the lighting device is made inoperative and a process of outputting a color video signal to the video signal processing unit is performed.

In this surveillance camera system, an illumination device that emits infrared light is used. A color camera having a night-vision function is used as the surveillance camera. Having a night-vision function means that the color camera as a whole including the color filter and other filters and the image sensor has sensitivity to infrared light emitted from the lighting device.

Then, as in the first aspect, the level of the video signal is measured in a predetermined cycle with the lighting device turned off, and when the video signal level is below or below the threshold value, the lighting device is turned on. Although it is turned on, in this case, since infrared light is illuminated, when a color image captured in this state is displayed on a monitor, a specific color is emphasized or an image lacking a specific color is displayed, which causes an error. It is a natural image and difficult to see.

Therefore, in this surveillance camera system, a black and white video signal is output when the illumination device is turned on. According to this, the image that can be monitored by the monitor is naturally a black and white image, but since it is illuminated with infrared light, the brightness is sufficient and it can be monitored well.

Further, similarly to the surveillance camera system according to claim 1, since the lighting device is turned on only when necessary, it is effective as an energy saving measure, and the life of the lighting device can be maximized. Naturally, it also has advantages.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the configuration of an embodiment of a surveillance camera system according to the present invention. In the figure, 1 is an imaging unit, 2 is a video processing unit, 3 is a timing signal generation unit,
Reference numeral 4 is an image pickup unit driver, 5 is a control unit, 6 is a lighting device, 7 is a light source, and 8 is a lighting driver.

The timing signal generating section 3 generates a horizontal synchronizing signal, a vertical synchronizing signal and other various timing signals necessary for driving the image pickup section 1.
The timing signal generated here is supplied to the imaging unit driver 4. The vertical synchronization signal is also supplied to the control unit 5. Since the timing signal generating circuit is well known, its detailed configuration is omitted.

The imaging section driver 4 drives the imaging section 1 based on the timing signal supplied from the timing signal generating section 3. Since the configuration of the image pickup unit driver 4 is also well known, detailed description thereof will be omitted.

The image pickup section 1 is composed of a CCD and its peripheral circuits, and is driven by a signal from the image pickup section driver 4,
Output video signal. The image pickup unit 1 uses a monochrome video signal,
That is, a so-called monochrome camera that outputs a luminance signal may be used,
A so-called color camera that outputs a color video signal may be used, but here it is assumed that a monochrome video signal is output for easy understanding.

The video signal output from the image pickup section 1 is input to the video processing section 2. The video processing unit 2 performs a predetermined process on the video signal, such as a process of adding the horizontal synchronization signal and the vertical synchronization signal input from the timing signal generation unit 3 to the video signal from the imaging unit 1 and outputs the processed video signal. The video signal output from the video processing unit 2 is transferred to and displayed on a monitor arranged in a surveillance center or the like.

The control section 5 is composed of a CPU and its peripheral circuits, and controls the illumination device 6 as described later.

The lighting device 6 comprises a light source 7 and a lighting driver 8. LED that emits infrared light as the light source 7
It is also possible to use a large number of lamps arranged, or it is possible to use a fluorescent lamp or an incandescent lamp.

In the above structure, the control unit 5 takes in the vertical synchronizing signal from the timing signal generating unit 3 and uses it as a clock, and performs the following processing at every predetermined cycle. Note that this cycle can be arbitrarily set in units of minutes or hours.

Now, the control unit 5 counts the vertical synchronizing signals from the timing signal generating unit 3, and when the timing of processing comes, it takes in the video signal of the period of the next predetermined number of frames from that timing, Find the average value for that period. Here, the light source 7 determines how many frames are averaged.
It may be set according to the type. That is, L as the light source 7
When using a fast responding one such as ED, the average value of one frame period may be obtained, and when using a slow responding one such as a fluorescent lamp or an incandescent lamp as the light source 7, several frames are used. The average value of the period may be calculated.

The process of obtaining the average value of the video signal is performed with the light source 7 turned off. That is, when the processing timing arrives, the control unit 5 starts the processing for obtaining the average value of the video signal as described above, determines whether the light source 7 is turned on, and if it is turned on, Lighting driver 8
Is instructed to turn off, and when it is turned off, that state is maintained. As a result, the actual brightness around the image capturing unit 1 can be measured.

Then, when the average value of the video signal is obtained, the control unit 5 compares the obtained average value with a preset threshold value, and when the average value of the video signal is less than or equal to the threshold value or less than the threshold value, The lighting driver 8 is instructed to turn on.
As a result, the light source 7 is turned on, so that the image pickup unit 1 outputs a video signal having sufficient brightness.

However, when the average value of the video signal exceeds the threshold value or is equal to or more than the threshold value, the control section 5 does not give any instruction to the illumination driver 8. As a result, the light source 7 remains in the off state.

The above operation will be described below with reference to the timing chart shown in FIG. In FIG. 2, V _D is a vertical synchronizing signal, T _FL is one frame period, T
_FE indicates the period of one field.

Now, assuming that a large number of LEDs are arranged as the light source 7 and the average value of the period of one frame of the video signal is obtained, the control unit 5 controls the timing signal generation unit 3 from the timing signal generation unit 3 as shown in FIG. If the vertical synchronization signal V _D that has been captured is counted and the processing timing comes at time t ₀ in FIG. 2, the video signal is captured at this time and the average value of the video signals during the period of the next one frame from t _0. Is started, and it is determined whether or not the light source 7 is turned on, and if the light source 7 is turned on, the lighting driver 8 is instructed to turn off.

Then, at t ₁ when the period of one frame for obtaining the average value ends, the obtained average value is compared with the threshold value. If the average value of the video signal is below the threshold value now, The control unit 5 instructs the lighting driver 8 to turn on. Therefore, in this case, the light source 7 is turned on at least from t _{1 of} FIG. 2 to the timing of the next processing.

However, if the average value of the video signal exceeds the threshold value, the control section 5 does not give any instruction to the illumination driver 8, and in this case, at least t _{1 in} FIG.
After that, the light source 7 is turned off until the timing of the next process.

By performing the above operation, the image pickup unit 1 always outputs a video signal having sufficient brightness, and therefore the monitor can perform good monitoring. Moreover, since the light source 7 is turned on only when necessary, unnecessary energy is not used for illumination.

Next, a second embodiment according to the present invention will be described. In the above-described embodiment, the image pickup unit 1 outputs the black-and-white image signal, but here, the light source 7 that emits infrared light is used, and the image pickup unit 1 that outputs the color image signal is used.

FIG. 3 is a diagram showing the configuration of the second embodiment of the surveillance camera system according to the present invention. In the figure, 11 is a color image pickup section, 12 is a color image processing section, 13 is a timing signal generation section, 14 is an imaging unit driver, 15 is a control unit,
Reference numeral 16 is a lighting device, 17 is a light source, and 18 is a lighting driver.

The timing signal generator 13 generates a horizontal synchronizing signal, a vertical synchronizing signal, a carrier color signal, and other various timing signals necessary for driving the color image pickup section 11, and is generated here. The timing signal is supplied to the imaging unit driver 14. The vertical synchronization signal is also supplied to the control unit 15. Since the timing signal generating circuit is well known, its detailed configuration is omitted.

The imaging section driver 14 drives the color imaging section 11 based on the timing signal supplied from the timing signal generating section 13. The configuration of the image pickup unit driver 14 is also well known, and a detailed description thereof will be omitted.

The color image pickup section 11 is composed of a single-plate CCD having a color filter and its peripheral circuits, and is driven by a signal from the image pickup section driver 14 to output a dot-sequential color video signal.

The color image pickup section 11 has a night vision function. That is, assuming that a large number of LEDs that emit infrared light having a wavelength of 945 nm are used as the light source 17, the color imaging unit 11 as a whole has sensitivity to infrared light of 945 nm. Specifically, the spectral sensitivity characteristic of the CCD is as shown in FIG.
If G and B filters are used, the R, G, and B filters have the spectral characteristics shown in FIGS. 5A, B, and C, respectively, and if an infrared cut filter is provided, the infrared cut filter is used. Has a spectral characteristic of transmitting infrared light having a wavelength of 945 nm as shown in FIG.

As a result, it is clear that a good night-vision image signal can be obtained from the color image pickup section 11 when the light source 17 is turned on.

The dot-sequential color video signal output from the color image pickup section 11 is input to the color video processing section 12. The color image processing unit 12 uses a dot-sequential color image signal from the color image pickup unit 11 and a timing signal from the timing signal generation unit 13 to generate a predetermined format, for example, a composite color image signal in compliance with the NTSC system (hereinafter, simply referred to as color A video signal) is generated and output, and the color video signal output from the color video processing unit 12 is transferred to and displayed on a monitor arranged in a surveillance center or the like.

FIG. 7 shows an example of the configuration of the color image processing section 12. In the figure, 21 is a color separation circuit, 22 is a matrix, and 2
3 is a balanced modulator, 24 and 25 are adders, and 26 is a switch.

The dot-sequential color video signal from the color image pickup section 11 is separated into three primary color signals of R, G and B by a color separation circuit. I and Q are generated. The color signals I and Q are balanced-modulated by the carrier color signal supplied from the timing signal unit 13 in the balanced modulator 23, and the switch 26
Is added to the luminance signal Y by the adder 24 via. The black burst signal supplied from the timing signal generator 13 is further added to the output of the adder 24 to form a color video signal conforming to the NTSC system, and the color video signal is output.

The luminance signal Y output from the matrix 22 is branched and supplied to the control unit 15. Control unit 1
The reference numeral 5 performs a process for obtaining an average value of luminance using the luminance signal Y, which will be described later. Also, the switch 26
Is opened and closed by a control signal from the control unit 15, which will be described later.

The control unit 15 is composed of a CPU and its peripheral circuits, and controls the illumination device 16 as will be described later.
Also, the color image processing unit 12 is controlled.

The lighting device 16 comprises a light source 17 and a lighting driver 18. The light source 17 has a wavelength of
An LED with a large number of LEDs that emit infrared light of 945 nm is used.

In the above configuration, the control unit 15 takes in the vertical synchronizing signal from the timing signal generating unit 13 and uses it as a clock, and performs the following processing at every predetermined cycle.
Note that this cycle can be arbitrarily set in units of minutes or hours.

Now, when the timing of the processing has arrived by counting the vertical synchronizing signals from the timing signal generator 13, the controller 15 outputs the luminance signal Y in the color image of the period of the next predetermined frame from the timing. It is read from the processing unit 12 and the average value of the period is obtained. Here, although it is possible to arbitrarily set how many frames the average value is to be obtained, the light source 17 using the above-mentioned LED that emits infrared light is used.
Responds quickly, the average value for one frame period may be obtained.

The process of obtaining the average value of the luminance signal Y is performed with the light source 17 turned off. That is, when the processing timing arrives, the control unit 15 starts the processing for obtaining the average value of the luminance signal Y as described above, determines whether or not the light source 17 is turned on, and if it is turned on, Instructs the lighting driver 18 to turn off the light, and if the light is off, keeps that state. As a result, the actual brightness around the color imaging unit 11 can be measured.

When the average value of the luminance signal Y is calculated,
The control unit 15 compares the obtained average value with a preset threshold value, and instructs the lighting driver 18 to turn on when the average value of the luminance signal Y is less than or equal to the threshold value or less than the threshold value.

By turning on the light source 17 in this way, the luminance signal Y generated by the matrix 22 of the color image processing unit 12 has sufficient luminance, but the color may be unnatural. Are known. That is, when the subject is illuminated with monochromatic infrared light of 945 nm, the color balance is significantly lost, unlike when illuminated with visible light.
When observed on a monitor, a specific color is emphasized, or a specific color is missing, resulting in an unnatural image that is difficult to see.

Therefore, when the control unit 15 turns on the light source 17, the switch 26 of the color image processing unit 12 is turned on as shown in FIG.
The opening control is performed as indicated by the broken line. As a result, since only the luminance signal Y is output from the color image processing unit 12, it is possible to observe a black and white image with good luminance on the monitor.

However, if the average value of the luminance signal Y exceeds the threshold value or is equal to or more than the threshold value, the control section 15 does not give any instruction to the illumination driver 18. At this time, the control unit 15 causes the switch 26 of the color image processing unit 12 to operate.
Is controlled as shown by the solid line in FIG.

By performing this control, the light source 17
Keeps turned off, and in this case, the color video signal output from the color video processing unit 12 has sufficient brightness and color balance, so that a good color image is observed on the monitor. be able to.

By performing the above operation, the color image pickup section 11 outputs a bright color video signal when the light source 17 is turned off, and is sufficient when the light source 17 is turned on. Since the brightness signal Y having brightness is output, the monitor can always perform good monitoring. Further, since the light source 17 is turned on only when necessary, it does not use unnecessary energy for illumination.

Although the embodiments of the present invention have been described above, it is obvious to those skilled in the art that the present invention is not limited to the above-mentioned embodiments and various modifications can be made.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of a surveillance camera system according to the present invention.

FIG. 2 is a timing chart for explaining the operation of the surveillance camera system shown in FIG.

FIG. 3 is a diagram showing a configuration of another embodiment of the surveillance camera system according to the present invention.

4 is a CCD used in the color image pickup unit 11 shown in FIG.
It is a figure which shows the example of the spectral sensitivity characteristic of.

5 is a diagram showing an example of spectral characteristics of a color filter used in the color imaging unit 11 shown in FIG.

6 is a diagram showing an example of spectral sensitivity characteristics of an infrared cut filter used in the color image pickup section 11 shown in FIG.

7 is a diagram showing a configuration example of the color image processing unit 12 shown in FIG.

[Explanation of symbols]

1 ... Imaging unit, 2 ... Image processing unit, 3 ... Timing signal generating unit, 4 ... Imaging unit driver, 5 ... Control unit, 6 ... Illumination device,
7 ... Light source, 8 ... Lighting driver, 11 ... Color imaging unit, 1
2 ... Color image processing unit, 13 ... Timing signal generating unit,
14 ... Imaging unit driver, 15 ... Control unit, 16 ... Illumination device, 17 ... Light source, 18 ... Illumination driver, 21 ... Color separation circuit, 22 ... Matrix, 23 ... Balanced modulator, 24, 25
… Adder, 26… Switch.

Claims (2)

[Claims] 1. A surveillance camera system comprising a lighting device, an image pickup section, and a control section, wherein the control section sets an image output from the image pickup section as a non-operation of the lighting apparatus at each predetermined cycle. The signal level is monitored, and if the level of the video signal is below a predetermined brightness or lower than the predetermined brightness, the lighting device is operated, and if the level of the video signal exceeds the predetermined brightness or a predetermined level is reached. A surveillance camera system characterized by performing processing for disabling a lighting device when the brightness is equal to or higher than the brightness. 2. A surveillance camera system comprising: a lighting device which emits infrared light having a predetermined wavelength; a color image pickup section having a night-vision function; a video signal processing section; and a control section, the control section comprising: When the level of the video signal output from the video signal processing unit is monitored with the lighting device inoperative at every predetermined cycle, and the level of the video signal is less than or equal to the predetermined brightness, or less than the predetermined brightness The illuminating device is operated and a black-and-white video signal is output to the video signal processing section, and the illuminating device is not operated when the level of the video signal exceeds or exceeds a predetermined brightness. In addition to the above, the surveillance camera system is characterized by performing processing for outputting a color video signal to the video signal processing unit.