JP2010039529A - Construction site security system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a construction site security system for reducing false alarms. <P>SOLUTION: The construction site security system includes an infrared imaging unit 24 having an infrared light emitting portion 24a blinking infrared light and an infrared imaging portion 24b provided adjacent to an infrared light emitting portion for receiving the infrared light, and an intrusion detecting unit 25 which outputs a detection signal upon detecting the intrusion of an object into a predetermined detection area. When the detection signal from the intrusion detecting unit is received, the infrared light emitting portion emits light intermittently and the infrared imaging portion captures images. As to a plurality of images captured by the infrared imaging portion 24b, a determination is made as to whether or not the object detected is wearing a member 10 including a retroreflective material 11, according to a difference between an image taken when the infrared light emitting portion 24a is turned on and an image taken when the infrared emitting portion is turned off. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a construction site crime prevention system for preventing an intruder from entering a construction site such as a building or a condominium to be stolen.

  In general, in a building or a condominium, a temporary scaffold for work is assembled so as to surround a building in order to smoothly perform exterior work or equipment maintenance work. At that time, in order to maintain safety and aesthetics, the temporary scaffolding is often covered with a seat cover or the like so as not to be directly visible from the outside.

  However, at construction sites with such temporary scaffolds, intruders climb up above the building using this temporary scaffold during daytime work breaks or at night, and easily enter the building. There are many damages such as theft of residents. Moreover, since the temporary scaffold is often covered with a seat cover or the like so that it cannot be seen from the outside as described above, there is also a problem that it is difficult for an intruder to be detected.

In order to prevent the occurrence of damage such as theft at a construction site where such a temporary scaffold is installed, Patent Document 1 discloses a construction site where an intruder is detected by an intrusion detection sensor on a temporary scaffold and an alarm is activated. A security system is disclosed. This system allows a field worker to carry a portable transmitter and determines the presence or absence of the transmitter based on radio waves transmitted from the portable transmitter. When a person having a transmitter is detected by the intrusion detection sensor, it is determined that the detected person is not a suspicious person and an alarm is not generated.
JP-A-2005-31831

  However, there is a possibility that a sensor detects small animals or foreign objects, rainwater, etc. adheres to a sensor provided outdoors, or a sheet provided on a temporary scaffold shakes due to wind, etc. It was. Furthermore, due to the directivity of the transmitter, there was a malfunction that the field worker was judged as an intruder and an alarm was issued even though the portable transmitter was owned.

  In addition, radio waves transmitted from the portable transmitter are transmitted with a spread around the transmitter. Therefore, for example, when an intruder enters the detection area of an intrusion detection sensor adjacent in the vertical direction or the like, it is not a suspicious person by receiving radio waves from a transmitter existing in the detection area of another intrusion detection sensor. There was a problem of being judged.

  This can be improved by adjusting the directivity of the radio wave transmitted from the transmitter, but in actual use, the direction in which the transmitter is mounted on the worker must be fixed, We had trouble of installation. In addition, it is substantially difficult to always set the directivity of the radio wave transmitted from the transmitter to the direction of the intrusion detection sensor, and there is still a problem of misreporting in the above system.

  On the other hand, the current receivable distance of radio waves transmitted from portable transmitters is at most a few meters, and the scaffolding is made of metal, so it is easy to absorb radio waves, and its reach There was a problem that became even shorter. Therefore, since it is necessary to prevent the intrusion detection distance from exceeding the radio wave arrival distance of the transmitter, it is necessary to install a considerable number of receivers according to the radio wave arrival distance of the portable transmitter. It was a burden.

  Therefore, the technical problem to be solved by the present invention is that an intruder enters a building using a temporary scaffolding installed at a construction site such as a building or a condominium, and a resident is stolen. It is an object of the present invention to provide a construction site crime prevention system that can effectively prevent the occurrence of damage, reduce the occurrence of false alarms, improve the detection accuracy, and reduce the cost burden of the installer.

  In order to solve the above technical problem, the present invention provides a construction site crime prevention system having the following configuration.

According to the first aspect of the present invention, there is provided an intrusion detection device that is installed at a specific location of the temporary scaffold where there is a risk of entering the building by the temporary scaffold, and transmits an intrusion confirmation signal when the intruder is detected. ,
A mounting member to be mounted on a field worker with a retroreflective material on the outer surface;
A construction site crime prevention system comprising:
The intrusion detection device is
An infrared imaging unit including an infrared light emitting unit capable of flashing and emitting infrared light, and an infrared imaging unit provided adjacent to the infrared light emitting unit and receiving infrared rays;
An intrusion detection unit that detects an intrusion of an object in a predetermined detection area and outputs a detection signal;
An operation control unit that, when receiving a detection signal from the intrusion detection unit, intermittently emits an infrared light emitting unit of the infrared imaging unit and starts imaging of the infrared imaging unit continuously for a predetermined period;
For a plurality of images captured by the infrared imaging unit, the brightness of a lit image captured at a timing when the infrared light emitting unit is lit and an unlit image captured at a timing when the infrared light emitting unit is turned off A determination unit that determines whether the object detected by the intrusion detection unit is wearing the mounting member based on the difference;
A construction site crime prevention system is provided.

  According to the second aspect of the present invention, the determination unit calculates a difference value between luminance values of a plurality of images captured by the infrared imaging unit as a pair of a continuous lighting image and a non-lighting image, The construction site crime prevention system according to the first aspect is characterized in that when the absolute value of the sum of the difference values is smaller than a threshold value, it is determined that the mounting member is not mounted.

  According to a third aspect of the present invention, the determination unit divides a plurality of images captured by the infrared imaging unit into a plurality of image regions, and calculates a difference value for each of the divided regions. A construction site crime prevention system according to the second aspect is provided.

According to the fourth aspect of the present invention, it is further provided with a camera capable of always overwriting and continuously overwriting and storing a predetermined number of images of a predetermined area within a unit time,
The operation control unit is configured such that when the determination unit determines that the object detected by the intrusion detection unit is not wearing the mounting member, a predetermined number of images are captured during a predetermined period before and after receiving the stored detection signal. A construction site crime prevention system according to any one of the first to third aspects is provided.

  According to the present invention, since the mounting member includes the retroreflective material, the light incident on the retroreflective material is reflected in the incident direction. In addition, since the light emitting unit and the imaging unit provided in the infrared imaging unit are provided adjacent to each other, the light incident on the retroreflecting material from the light emitting unit is reflected toward the imaging unit and is captured by the imaging unit. Will be. Here, since the light emitting unit flashes and emits light, the luminance value of the region of the retroreflecting material varies in the lighting image and the non-lighting image. On the other hand, for example, when infrared rays contained in sunlight or the like are reflected on the subject, the luminance value of the image captured by the imaging unit does not change according to the blinking timing from the light emitting unit. Therefore, based on the image from the infrared imaging unit, it can be determined whether or not the object detected by the intrusion detection unit is mounting the mounting member.

  Therefore, for example, if an installation member is attached to an operator, it can be determined whether the person detected by the intrusion detection unit is an intruder or an operator. Therefore, the intruder can be confirmed with higher accuracy, and false reports to the field supervisor or the resident representative can be reduced. In addition, the retroreflective material used for the mounting member is configured to be very thin, so it does not interfere with the worker, and can be determined only when it is within the imaging range of the infrared imaging unit. Compared with confirmation of invasion by radio waves, the accuracy can be improved.

  According to the fourth aspect of the present invention, it is possible to more reliably detect a suspicious person based on an image captured by a camera.

  Hereinafter, a construction site crime prevention system according to an embodiment of the present invention will be described with reference to the drawings.

(First embodiment)
Drawing 1 is a figure showing the schematic structure of the building which is the construction site where the construction site crime prevention system concerning the embodiment of the present invention is used. This construction site crime prevention system is in a state in which a temporary scaffold 110 is provided around the outer wall of the building 100, and the purpose is to prevent an intruder from entering the building through the temporary scaffold 110. As shown in FIGS. 1 and 2, the temporary scaffolding 110 is assembled in a multi-story structure along the periphery of the building 100. That is, the pillars 114 are erected around the building, and the treads 111, 112, 113 are assembled between the pillars 114 so as to have a multilayer floor structure from the ground floor. Stairs 115 are provided between the treads 111, 112, 113 of each level, and are configured to be movable on each floor.

  Drawing 2 is a mimetic diagram showing an example of attachment arrangement of an intrusion detection device of a construction site crime prevention system of this embodiment. As shown in FIG. 2, in the construction site crime prevention system, a plurality of intrusion detection devices 20 a, 20 b, 20 c, 20 d, and 20 e are provided on the column 114 of the temporary scaffold 110. Hereinafter, the intrusion detection device is denoted by reference numeral 20 when it is not necessary to distinguish between individual intrusion detection devices.

  3A and 3B are schematic diagrams illustrating an external configuration of the intrusion detection device. 3A is a view when the intrusion detection device is attached to the horizontal member 116, and FIG. 3B is a view when the intrusion detection device is attached to the column 114. The intrusion detection device 20 is fixed to a horizontal member 116 and a column 114 that fix the tread plates 112 and 113 by a fixing bracket 22 provided in the housing 21. The housing 21 includes a camera unit 23, an infrared imaging unit 24, and a person detection unit 25 as a mechanism for detecting an intruder intrusion and notifying it. The infrared imaging unit 24 includes an infrared light emitting unit 24a configured by arranging a plurality of light emitting elements in a circular shape, and an infrared imaging unit 24b that is provided at the center of the infrared light emitting unit 24a and receives infrared rays. Note that, for example, a speaker (not shown) or a light emitting unit may be provided so as to generate a threatening light by a threatening sound or visible light for an intruder. A mechanism for notifying an intruder when an intruder is detected will be described later.

  The person detection unit 25 provided in the intrusion detection device 20 is, for example, a human body detection infrared sensor called a so-called passive infrared system, and the ambient and temperature are detected by the infrared detection element of the detection window 25a of the person detection unit 25. It detects infrared changes that occur when people or animals with differences move.

  The detection window 25a of the person detection unit 25 may adjust the angles of the detection ranges 25b, 25c, and 25d according to the detection range of the intrusion detection device 20, as shown in FIG. 4A. That is, the angle of the detection range can be adjusted according to how far away the person H is detected. For example, when the angle is made closer to the horizontal direction, it is possible to detect a person present at a distant place. The detection range of the intrusion detection device 20 can be adjusted according to the accuracy of person detection by the infrared imaging unit.

  As shown in FIG. 4B, when the intrusion detection device 20 is attached to the support column 114 or the horizontal member 116, the installation height of the intrusion detection device 20 and the direction of the detection range are adjusted to detect the small animal D or the like. Can be prevented. In this case, the attachment position P of the person detection unit 25 with respect to the scaffolding plate 111 is preferably about 900 to 1200 mm.

  FIG. 5 shows an overall configuration of network connection constituting the construction site crime prevention system according to the present embodiment. The system according to the present embodiment has a configuration in which a construction site crime prevention system installed on the site 1 is connected to the monitoring center 2 and the recording center 3 via the Internet NT. For example, when the monitoring center 2 receives data indicating that a suspicious person has been invaded by a crime prevention system installed at the site, the monitoring server 2 and the camera 23 of the intrusion detection device for managing the abnormalities at each site. And a monitoring server 7 that displays an image captured by the monitor 7 on the monitor 7. The recording center 3 includes a recording server 8 that stores images captured by the camera 23 of the intrusion detection device. The monitoring center makes a comprehensive judgment from the live image of the camera unit 23 and the image stored in the recording center that an emergency such as an intrusion abnormality is required and an emergency such as a false alarm is not required. Take action.

  FIG. 6 shows the configuration of an apparatus installed on the site. The intrusion detection device 20 determines whether the person detected by the person detection unit 25 has the mounting member 10 to be supplied to a related person such as a worker who performs the construction work, so that the intruder or the related person It is a device which distinguishes.

  The operation control unit 26 performs operation control of the infrared imaging unit 24 and the person detection unit 25. The determination unit 27 determines whether or not the person detected by the person detection unit 25 has the mounting member 10. The mounting member 10 is composed of clothes, a helmet, and the like, and includes a retroreflecting material 11. The specific control of the operation control unit 26 and the determination unit 27 will be described in detail later. However, when the presence of a person is detected by the person detection unit 25, a detection signal is transmitted via the operation control unit 26 to the determination unit 27. Is output. When the person detection unit 25 confirms the presence of the person, the determination unit 27 compares the timing of infrared emission of the light emitting unit 24a of the infrared imaging unit 24 with the captured image from the infrared imaging unit 24b, and It is determined whether or not has the mounting member 10.

  When the determination unit 27 determines that the detected person has the mounting member 10, even if the person detection unit 25 detects the person, the person is not a suspicious person, and the intrusion confirmation of the suspicious person intrusion is confirmed. It does not send a signal.

  The camera unit 23 always operates based on the control from the operation control unit 26, continuously captures a certain number of images within a unit time, and overwrites and saves the captured images in the storage area of the camera. When an intrusion confirmation signal indicating a suspicious person intrusion is received, information such as an image from which camera at which site and information such as a recording time are added to the captured images stored in the storage area before and after reception, and the Internet NT To the monitoring center and the recording center. The camera unit 23 may continuously capture images regardless of whether or not the person detection unit 25 detects the presence of a person, or may start imaging when the person detection unit 25 detects a person. .

  FIG. 7 is a flowchart showing intrusion detection processing executed by the intrusion detection device of the construction site security system according to the present embodiment.

  First, the camera unit 23 of the intrusion detection device 20 always captures a predetermined imaging area every predetermined time, and overwrites and saves a predetermined amount of images in the internal storage area with the captured image data. .

  When the person detection unit 25 detects a person (# 1), the information is transmitted to the operation control unit 26. The operation control unit 26 receives this information and starts the operation of the infrared imaging unit 24 (# 2).

  The infrared imaging unit 24 causes the infrared light emitting unit 24a to blink and emit light, and also causes the infrared imaging unit 24b to capture an image based on the reflected light from the infrared subject emitted from the infrared light emitting unit 24a. The light emission time of the infrared light emitting unit 24a and the image pickup time of the infrared imaging unit 24b are not particularly limited, but are preferably within several seconds.

  The infrared imaging unit 24 transmits information related to the timing of blinking emission of the infrared light emitting unit 24a and an image captured by the infrared imaging unit 24b to the operation control unit 26, and the subject captured by the determination unit based on this information is a mounting member. 10 is determined (# 3).

  In the present embodiment, the principle by which it can be determined whether or not the subject includes the mounting member 10 based on the information related to the timing of the flashing emission of the infrared light emitting unit 24a and the image captured by the infrared imaging unit 24b will be described. . FIG. 8 is an explanatory diagram of the imaging principle of the infrared imaging unit in the present embodiment.

  The infrared imaging unit 24b of the infrared imaging unit 24 receives infrared rays reflected from the subject (including both the retroreflecting material 11 of the mounting member 10 and the normal object 15) and captures an infrared image. Here, the subjects 11 and 15 are irradiated with infrared rays S1 and S2 included in sunlight in addition to the infrared rays L1 and L2 emitted from the infrared light emitting unit 24a. Therefore, infrared rays reflected from the subject imaged by the infrared imaging unit 24b include those based on sunlight and infrared rays emitted from the infrared light emitting unit 24a.

  Here, among the subjects, the infrared rays S1 and L1 irradiated on the normal object 15 diffuse and diverge at the object, and a part of the reflected light reaches the infrared imaging unit 24b and is imaged. On the other hand, the infrared rays S2 and L2 irradiated on the retroreflecting material 11 of the mounting member 10 are reflected in the direction irradiated on the object surface. Therefore, the infrared ray S2 applied to the retroreflecting material 11 from the sun S is reflected in the direction of the sun and does not reach the infrared imaging unit 24b. Further, the infrared ray L2 applied to the retroreflecting material 11 from the infrared light emitting unit 24a is reflected in the direction of the infrared light emitting unit 24a. Since the infrared light emitting unit 24a and the infrared imaging unit 24b are provided close to each other, the reflected light reaches the infrared imaging unit 24b and is imaged.

  In other words, the infrared image captured by the infrared imaging unit 24b is captured by infrared rays from the infrared light emitting unit 24a in addition to sunlight in a state where the infrared light emitting unit 24a is lit, and is further reflected on the retroreflecting material 11. The reached infrared rays reach the infrared imaging unit 24b. On the other hand, in a state in which the infrared light emitting unit 24a is turned off, the sunlight that is captured based on sunlight and reaches the retroreflecting material 11 does not reach the infrared imaging unit 24b. Therefore, as shown in FIGS. 9A and 9B, the lighting image captured at the timing when the infrared light emitting portion emits light, the portion of the retroreflecting material 11 becomes bright and the infrared light emitting portion is turned off. In the captured unlit image, the part of the retroreflecting material 11 is captured darkly.

  The construction site crime prevention system according to the present embodiment uses this principle, and determines whether or not the retroreflecting material 11 is included in the subject by comparing the luminance values of the lit image and the unlit image. Specifically, as shown in FIG. 10, when the infrared light emitting unit 24a is turned on at timings t1 and t3 and is turned off at timings t2 and t4, the retroreflecting material 11 of the mounting member 10 is A bright image is captured only in the frames F1 and F3 captured at the timings t1 and t3. On the other hand, other objects are imaged with low brightness values for all the frames F1 to F4.

  Next, the process flow of the determination process performed by the determination unit 27 will be described. FIG. 11 is a flowchart of the determination process performed by the determination unit. First, the determination unit 27 receives timing information and an infrared image transmitted from the infrared imaging unit 24 (# 31). Next, the infrared image is divided into a plurality of segments (# 32).

  FIG. 12 is a diagram for explaining a state in which an infrared image is divided into segments. The segments A1, A2, A3,... Obtained by dividing the infrared image may all be the same size or may have different sizes. For example, as shown in FIG. 13, in the construction site crime prevention system according to the present embodiment, since the shooting range is provided along the longitudinal direction of the scaffolding plate 112, persons m1, m2, and m3 are located at the center portion of the image. There is a high possibility of being imaged. For this reason, the size of the segment in the central portion may be reduced so that it can be determined with high accuracy.

  Further, regarding the division of the infrared image, as shown in FIG. 12, other objects may be photographed in the segment An in which the retroreflective material 11 is imaged, or the retroreflective material 11 includes a plurality of retroreflective materials 11. Each segment may be divided so as to span the region.

Next, a difference in luminance value is obtained for each segment. Specifically, the sum of the luminance values of each pixel is calculated for the i-th segment, and the difference between the luminance values is obtained. In the difference calculation, as shown in FIG. 14, the difference value of the luminance value is calculated for each pair of the continuously lit image and the unlit image (# 34). That is, the difference F ₁₂ between the brightness values of the corresponding segments is obtained for the lit image and the unlit image of the continuous frame. Similarly, the difference value is calculated as F ₃₄ and F ₅₆ , and the total luminance value F _t obtained by summing the difference values is calculated (# 35).

By calculating the total luminance value F _t which is the sum of differences of luminance values of the lighting picture unlit image, it is possible to reduce the error generated such as when the object due wind and position movement. At construction sites, the amount of light in the surrounding environment randomly increases or decreases in a short time due to sheet fluctuations. By summing up a plurality of times, an error that varies randomly is canceled out. In addition, the increase or decrease in the amount of light due to the periodically flashing infrared light increases if added according to the period. Therefore, by determining the total luminance value F _t, only the portion that is reflected is retroreflective material 11 and thus appearing as a calculation result.

The above process is performed for all the segments, and if the total luminance value F _t of any segment exceeds the threshold value, it is determined that the retroreflecting material 11 is reflected in the image. Note that the threshold value may be constant at all times, or may be changed according to time, season, or the place where the intrusion detection device 20 is provided. For example, unlike the proportion is sunny by month, since less is the amount of infrared rays from the sun in a cloudy day, the effect of infrared rays emitted from the infrared light emitting portion 24a has on the total luminance value F _t increases. In addition, intruders often infiltrate workers during the evening shopping, and the balcony is often provided on the south side of the building, so in the evening, about the intrusion detection device located on the south side, The threshold for determining that the retroreflective material 11 is included can be increased, and the level at which it is determined to be an operator by possessing the retroreflective material 11 can be adjusted to be strict.

  Returning to FIG. 7, when it is determined that the person does not wear the mounting member 10 as a result of detection by the person detection unit 25, the operation control unit 26 transmits an intrusion confirmation signal indicating intrusion of a suspicious person.

  As the processing of the intrusion detection apparatus 20 after the suspicious person is confirmed, the camera unit 23 continuously returns to the imaging process by overwriting and saving the predetermined unit image in the storage area together with the continuous imaging.

  Based on the image data transmitted from the camera unit 23 and the accompanying information, the management server 5 displays information indicating which intruder detection apparatus 20 has entered the suspicious person and a captured image of the suspicious person. In the monitoring center, after confirming the live image of the monitor 7 of the monitoring server and the image at the time of intrusion detection stored in the recording server, an emergency such as an intrusion abnormality and an emergency such as a false alarm are not required. Make comprehensive judgments and report and respond according to predetermined criteria.

  As described above, according to the construction site crime prevention system according to the present embodiment, the intrusion detection device 20 can determine whether or not the person is a suspicious person with a simple configuration.

  In addition, this invention is not limited to the said embodiment, It can implement in another various aspect.

It is a figure which shows schematic structure of the building which is a construction site where the construction site crime prevention system concerning embodiment of this invention is used. It is a schematic diagram which shows the example of attachment arrangement | positioning of the intrusion detection apparatus of the construction site crime prevention system of this embodiment. It is a schematic diagram which shows the external appearance structure and attachment example of an intrusion detection apparatus. It is a schematic diagram which shows the other example of external appearance structure and attachment of an intrusion detection apparatus. It is a figure which shows an example of the relationship between the detection area | region of a person detection part of an intrusion detection apparatus and an intrusion detection apparatus, and a person. It is a figure which shows the other example of the relationship between the detection area of the person detection part of an intrusion detection apparatus and an intrusion detection apparatus, and a person. It is a figure which shows the whole network connection structure which comprises the construction site crime prevention system concerning 1st Embodiment of this invention. It is a figure which shows the structure of the apparatus installed in the field. It is a flowchart which shows the intrusion detection process performed by the intrusion detection apparatus of the construction site crime prevention system concerning this embodiment. It is explanatory drawing about the imaging principle of the infrared imaging unit in this embodiment. It is a figure which shows the example of the lighting image imaged by the infrared imaging part. It is a figure which shows the example of the light extinction image imaged by the infrared imaging part. It is a figure explaining the principle of the judgment process by a judgment part. It is a flowchart of the judgment process which a judgment part performs. It is a figure which shows the example of the segment division | segmentation of the image imaged by the infrared imaging part. It is a figure which shows an example of the image imaged by the construction site crime prevention system of FIG. It is a figure explaining the calculation method of the total luminance value of the judgment process by a judgment part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Mounting member 11 Retroreflective material 20,20a, 20b, 20c, 20d, 20e Intrusion detection apparatus 23 Camera part 24 Infrared imaging unit 24a Infrared light emission part 24b Infrared imaging part 25 Person detection part 25a Detection window 26 Operation control part 27 Judgment Part 100 Building 110 Temporary scaffolding 111, 112, 113 Footboard 114 Column 116 Horizontal material

Claims (4)

An intrusion detection device that transmits an intrusion confirmation signal when it is installed at a specific location of the temporary scaffold that is likely to enter a building by a temporary scaffold and detects the intruder,
A mounting member to be mounted on a field worker with a retroreflective material on the outer surface;
A construction site crime prevention system comprising:
The intrusion detection device is
An infrared imaging unit comprising: an infrared light emitting unit capable of flashing and emitting infrared light; and an infrared imaging unit provided adjacent to the infrared light emitting unit and receiving infrared light;
An intrusion detection unit that detects an intrusion of an object in a predetermined detection area and outputs a detection signal;
An operation control unit that, when receiving a detection signal from the intrusion detection unit, intermittently emits an infrared light emitting unit of the infrared imaging unit and starts imaging of the infrared imaging unit continuously for a predetermined period;
For a plurality of images captured by the infrared imaging unit, the brightness of a lit image captured at a timing when the infrared light emitting unit is lit and an unlit image captured at a timing when the infrared light emitting unit is turned off A determination unit that determines whether the object detected by the intrusion detection unit is wearing the mounting member based on the difference;
Construction site crime prevention system characterized by comprising   The determination unit calculates a difference value of luminance values for a plurality of images captured by the infrared imaging unit as a pair of a continuous lighting image and a non-lighting image, and the absolute value of the sum of the difference values is greater than a threshold value. The construction site crime prevention system according to claim 1, wherein when it is smaller, it is determined that the mounting member is not mounted.   The construction site according to claim 2, wherein the determination unit divides a plurality of images captured by the infrared imaging unit into a plurality of image regions, and calculates a difference value for each of the divided regions. Security system. Furthermore, it is equipped with a camera that operates constantly and can continuously save images by overtaking a predetermined number of images in a predetermined area within a unit time,
The operation control unit is configured such that when the determination unit determines that the object detected by the intrusion detection unit is not wearing the mounting member, a predetermined number of images are captured during a predetermined period before and after receiving the stored detection signal. The construction site crime prevention system according to any one of claims 1 to 3, characterized in that:

Images