JP2000036083A - Entering object monitoring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the entering object monitoring device of simple constitution capable of easily and surely detecting the entering of a suspicious object to a warehouse or the like without incuring the problem of malfunctions. SOLUTION: This device is provided with an optical system 3 for scanning a prescribed monitoring area 1 by using a laser beam and detecting reflected light at respective scanning positions, an integrator 21 for integrating the intensity of the reflected light over one scanning period of the monitoring area and comparators 22 and 23 for discriminating the integrated value of the reflected light intensity by using a threshold set with the average value of the integrated value of normal reflected light intensity in the monitoring area as a standard and judging the entering of an object in the monitoring area.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intruding object monitoring apparatus capable of easily and surely detecting an intruding object entering a warehouse or the like.

[0002]

2. Related Background Art Recently, various security systems have attracted attention, and one of them is a device for monitoring entry of a suspicious object into a specific monitoring area. Conventionally, this type of device is configured to obtain an image of a monitoring area exclusively using a TV camera and directly monitor the image. Recently, however, infrared light obtained from a light emitting diode is radiated into the monitoring area, and the image is monitored. Various attempts have been made to determine the entry of a suspicious object in the monitoring area from a change in the amount of reflected light.

[0003]

However, even when the monitoring area is outdoors or indoors, in an environment where sunlight enters through a window or the like, a large amount of infrared light is contained in sunlight and moreover, At day and night, the amount of infrared light greatly changes depending on climatic conditions. Because of this,
There is a problem that it is difficult to detect the entry of a suspicious object from the above-mentioned change in the amount of reflected light without being affected by these factors. By the way, it is considered to detect the intensity of external light such as sunlight and use it to correct the amount of reflected light detected from within the monitoring area.However, the device configuration becomes considerably large and expensive. Can not deny. In addition, when other illumination light sources are present, it cannot be denied that they are affected by them.

The present invention has been made in view of such circumstances, and has as its object to simply and reliably detect the entry of a suspicious object in a predetermined monitoring area without being affected by sunlight or the like. It is an object of the present invention to provide an inexpensive and practically usable intrusion monitoring device which can perform the monitoring.

[0005]

In order to achieve the above object, an intruding object monitoring apparatus according to the present invention scans a predetermined monitoring area using a laser beam of a specific wavelength, and scans the specific wavelength at each scanning position. An optical system that detects the reflected light of the monitor area, the integrated value of the intensity of the reflected light is obtained over the entire monitoring area, the steady reflected light intensity of the entire monitoring area is discriminated as a threshold, and the It is characterized by comprising means for determining the entry of an object.

Preferably, the scanning of the laser beam is performed by using a mirror made of a silicon micro optical scanner provided at a position above the monitoring area, for example, on a ceiling. The optical system is characterized in that the optical system is configured to scan the laser light two-dimensionally or three-dimensionally over the monitoring area by changing the reflection direction of the laser light to be irradiated.

Further, according to a preferred aspect of the present invention, the constant reflected light intensity used as the threshold value is set over the entire monitoring area under the condition that no object enters, that is, It is characterized in that an integrated value of the reflected light intensity obtained over one scanning period is periodically obtained, and the average value is set as a reference.

That is, according to the present invention, instead of monitoring the intensity of the reflected light from each part of the predetermined monitoring area, the entire reflected light of the monitoring area scanned by using the laser light of a specific wavelength is used. We focus on strength. Specifically, focusing on the fact that the overall reflected light intensity captured as an integrated value of the reflected light intensity is substantially constant regardless of the difference in the intensity of the locally reflected light at each scanning position of the monitoring area, The method is characterized in that an entry of a suspicious object into the monitoring area is detected according to an integrated value of the intensity of the reflected light.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an ingress monitoring apparatus according to an embodiment of the present invention.

FIG. 1 shows a schematic configuration of an intruding object monitoring apparatus according to an embodiment, and FIG. 2 shows a use form thereof. The intruding object monitoring device optically monitors entry of a suspicious object into a predetermined monitoring area 1 such as a warehouse or an office, and is provided, for example, on a ceiling 2 at a position above the monitoring area 1. An optical system 3 that scans the monitoring area 1 using laser light of a specific wavelength and detects reflected light of the specific wavelength at each scanning position is provided. The optical system 3 scans the laser light with a laser light source 4 such as a laser diode (LD) that oscillates and outputs the laser light of the specific wavelength and scans the laser light by changing the reflection angle with respect to the laser light. A scanning mechanism 5 comprising a galvanomirror (GM) for continuously changing the irradiation position of the laser light to the laser beam; and a photodiode PD for detecting the reflected light of the laser light in the monitoring area 1 in conjunction with the scanning. It comprises a photodetector 6. Incidentally, the photodetector 6 is, for example, a beam splitter 7 provided between the laser light source 4 and the scanning mechanism 5 to reflect the laser beam irradiated on the monitoring area 1 in the reverse direction along the irradiation optical path of the laser light. It is provided so that only light is received and the amount of reflected light (intensity) is detected.

Incidentally, the galvanomirror constituting the scanning mechanism 5 comprises, for example, a silicon micro optical scanner (SMOS) as shown in FIG. In this SMOS, for example, as disclosed in Japanese Patent Application Laid-Open No. 7-175005, a silicon substrate 5a is etched to form a movable portion made of a thin plate that can be displaced in an arbitrary direction and angle at the center thereof. The total reflection mirror 5b is formed on the upper surface of the movable part.

Specifically, the SMOS forms a first movable body 5e made of a frame-shaped thin plate via a first torsion bar 5d inside a rectangular frame portion 5c.
A second movable body 5g having a flat plate shape is formed inside the movable body 5e through a second torsion bar 5f orthogonal to the first torsion bar 5d, and the upper surface of the second movable body 5g is formed on the upper surface of the second movable body 5g. It has a structure in which a total reflection mirror 5b is formed. An electromagnet is formed between a planar coil (not shown) formed on each of the upper surfaces of the first movable body 5e and the second movable body 5g to form an electromagnet, and a permanent magnet 5h incorporated in the frame 5c. Using the magnetic force to be applied, the second movable body 5
g, and thus the total reflection mirror 5b is displaced in an arbitrary direction and at an arbitrary angle, thereby deflecting the laser light (beam light) applied to the total reflection mirror 5b from a predetermined direction to perform scanning. Play a role.

This apparatus, which is provided with such an optical system 5 and scans the monitoring area 1 by using a laser beam and receives the reflected light, specifically, has a control unit as shown in FIG. The galvanomirror (scanning mechanism) under the control of 11
5 is provided with a mirror drive unit 12 that changes the reflection direction of the laser light emitted from the laser light source (LD) 4. The reflected light is received by the photodetector (PD) 6 via the galvanometer mirror 5 in conjunction with the scanning of the laser beam by the galvanometer mirror 5, and a signal indicating the intensity of the reflected light is transmitted to the preamplifier 13. Through what you get.

The monitoring unit for detecting the entry of the suspicious object into the monitoring area 1 from the intensity of the reflected light is synchronized with the drive control of the mirror drive circuit 12 by the control unit 11 (start of laser beam scanning). The integrator 21 integrates the reflected light intensity signal continuously obtained from the photodetector 6 via the preamplifier 13 over one scanning period, and is synchronized with the scanning of the laser beam (end of scanning). The integrated value of the intensity of the reflected light obtained from the integrator 21 is determined by a predetermined discrimination threshold Th.
First and second comparators 22, 23 for comparing with 1, Th2
And an OR circuit 24 for logically ORing the outputs of the comparators 22 and 23, and an alarm circuit 25 for receiving an output from the OR circuit 24 and issuing an alarm.

Incidentally, the discrimination thresholds Th1 and Th2 are determined by the output of the integrator 21 by the average value circuit 26 over a plurality of scanning periods in a steady environment in which no suspicious object or the like enters the monitoring area 1, for example. An upper limit value setting circuit (UL; upper limiter) 27 and a lower limit value setting circuit (LL; lower limiter) 28 based on the average value of the overall reflected light intensity obtained by averaging the (integrated value of the reflected light intensity). It is set as a level for discriminating abnormal reflected light intensity that deviates from the steady-state variation range of the average reflected light intensity variation value. That is, the integrator 21 obtains the integral value Pint of the intensity P of the reflected light over one scanning period when the monitoring area 1 is scanned using the laser light under a steady environment, and the average value is obtained. The circuit 26 calculates an average value Pave of the integral values Pint at a plurality of scan times. The upper limit value setting circuit 27 and the lower limit value setting circuit 28 set the respective discrimination thresholds Th1 and Th2 as Th1 = Pave + .DELTA.P Th1 = Pave-.DELTA.P based on the average value Pave.
The above-mentioned ΔP is a level for preventing a malfunction in consideration of a fluctuation range of the integrated value Pint of the reflected light intensity due to a noise component or the like.

Incidentally, the detection of the average value Pave of the integral value Pint of the reflected light intensity by the average value circuit 26 is carried out, for example, as an initial operation when the monitoring device is operated, and is set in advance. It may be executed every cycle. Further, it is of course possible to obtain the integrated value Pint of the reflected light intensity before the abnormality is detected by the comparators 22 and 23 retroactively up to a predetermined number of scans, while sequentially updating them as the average value Pave. It is. In short, what is necessary is just to obtain the integral value of the steady reflected light intensity over one scanning period in the monitoring area 1.

The intruding object monitoring apparatus constructed as described above basically emits a laser beam of a specific wavelength in the monitoring area 1.
, And the amount of reflected light (the intensity of the reflected light) is determined by the optical path length that changes depending on the object that has entered between the laser light irradiation position in the monitoring area 1 and the laser light source 4 (the galvanometer mirror 5) and the reflectance of the object. ) Is changed, and the approach of the object is detected. In particular, in the apparatus having the above configuration, instead of focusing on the intensity change of the reflected light at each scanning position, attention is paid to the total amount (integral value) of the reflected light intensity in the entire scanning area, and as shown in FIG. The integrated value of the reflected light intensity P is obtained every scanning cycle in synchronization with the scanning of the laser light. Then, the integrated value Pint is set to a discrimination threshold value Th1, T based on the average value Pave under a steady condition.
By comparison with h2, the entry of a suspicious object into the monitoring area 1 is detected. Therefore, even when there is a large variation in the intensity of the reflected light of the laser beam in each part of the monitoring area 1, the change in the intensity of the reflected light over the entire monitoring area 1 indicated as an integrated value is reflected on the monitoring area 1. Intrusion of a suspicious object can be reliably detected.

That is, the intensity of the reflected light at each part of the monitoring area 1 where the laser light is scanned greatly changes depending on the type of the reflected object. Therefore, when trying to discriminate the entry of the suspicious object from the intensity of the reflected light at each scanning position based on the intensity of the entire reflected light in the monitoring area 1, the intensity change of the reflected light due to the suspicious object entering the specific scanning position is performed. However, there is a risk that the intensity of the reflected light at the individual scanning positions in the monitoring area 1 will be buried within the range of variation. However, in the present apparatus, the change in the reflected light intensity due to the entry of the suspicious object into the monitoring region 1 is captured as the sum of the intensity of the reflected light detected in the entire monitoring region 1 (scanning region).
It is possible to reliably detect the entry of the suspicious object into the monitoring area 1 irrespective of the local difference in the intensity of the reflected light at each scanning position or its change. In particular, since the object entering the monitoring area 1 usually has a certain size, even if the change in the intensity of the reflected light at each scanning position due to the entry of the object is small, the reflection due to the presence of the object is small. Since the change in light intensity is added by the above-described integration processing, this can be regarded as a large change. Therefore, it is possible to reliably detect the entry of the suspicious object in distinction from the change in the reflected light intensity due to the noise component.

Further, in the present apparatus, a laser beam of a specific wavelength emitted from the laser light source 4 is used, and only the reflected light of the wavelength component (invisible component) is detected. Even if such a situation occurs, it is possible to detect the entry of the suspicious object with high reliability without being substantially affected. In this case, a wavelength selection filter (not shown) is appropriately provided on the light receiving surface of the photodetector 6.
It is also effective to attach.

Further, in the apparatus according to the above-described embodiment, since the laser beam is scanned by using the galvanomirror (scanning mechanism) 5 made of SMOS, the configuration is simple and the size can be easily reduced. This is suitable for assembling on the ceiling 2 of the monitoring area 1 or the like.
In addition, by utilizing the resonance of the movable portion in the SMOS described above, there is an advantage that scanning of laser light can be performed at high speed while suppressing power consumption.

The present invention is not limited to the above embodiment. For example, the above-described discrimination thresholds Th1 and Th2
Is determined based on the integrated value of the intensity of the reflected light integrated over the first one scanning period detected in a state where no suspicious object enters, and then the reflected light obtained in the next one scanning period The above criteria may be sequentially learned and updated by using the integral value of. Also, regarding the scanning of the monitoring area 1 by the laser beam, it goes without saying that the monitoring area 1 may be three-dimensionally scanned two-dimensionally, as well as two-dimensionally scanning a specific monitoring line. Furthermore, it is of course possible to use a polygon mirror or a mechanical galvanometer mirror for the laser beam scanning method, and it is also possible to scan the laser beam by changing the direction of the laser light source 4 itself. In addition, instead of the silicon micro optical scanner (SMOS) described above, a mirror supported via a torsion spring is subjected to bending vibration and torsional vibration using a piezoelectric vibrator to be driven in resonance. -It is also possible to use a scanner or the like.

Further, the monitoring area 1 is divided into a plurality of areas, the integrated value of the reflected light intensity is calculated for each of the divided areas, and the integrated value of the reflected light intensity is compared with the discrimination threshold value set for each of the areas to prevent the entry of the suspicious object. It is also possible to monitor. In addition, the present invention can be variously modified and implemented without departing from the gist thereof.

[0023]

As described above, according to the present invention, the monitoring area is scanned by using the laser beam, and the monitoring of the entry of the suspicious object into the monitoring area based on the intensity of the reflected light is performed for one scanning period. As the integrated value of the reflected light intensity integrated over
Since the intensity of the reflected light is evaluated, even if the intensity of the reflected light at each scanning position of the laser light slightly changes due to the entering object, this can be reliably detected. In addition, it is possible to easily and reliably detect the entry of the suspicious object with high sensitivity without fear of malfunction, regardless of the difference in the intensity of the reflected light at each scanning position in the monitoring area.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an intruding object monitoring device according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a usage form of the intruding object monitoring device shown in FIG. 1;

FIG. 3 is a diagram showing a configuration example of a silicon micro optical scanner (SMOS) as a scanning mechanism (galvanometer) used for scanning with laser light.

FIG. 4 is a diagram showing the concept of integration of reflected light intensity over one scanning period in the apparatus shown in FIG. 1 and comparison and determination of the integrated value.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Monitoring area 2 Ceiling 3 Optical system 4 Laser light source (LD) 5 Scanning mechanism (galvanometer) 6 Photodetector (PD) 7 Beam splitter 11 Control part 12 Mirror drive part 13 Preamplifier 21 Integrator 22 Comparator 23 Comparator 24 OR circuit 25 Alarm circuit 26 Average value circuit 27 Upper limit value setting circuit (UL; Upper limiter) 28 Lower limit value setting circuit (LL; Lower limiter)

Continued on the front page F-term (reference) 2G065 AA04 AA15 AB02 AB09 AB22 AB26 AB28 BA09 BB11 BB14 BB26 BB45 BB49 BC03 BC04 BC14 BC15 BC19 BD06 CA05 DA01 DA15 5C084 AA02 AA07 AA08 AA14 AA15 AA20 BB05 BB06 DD DD EE10 GG07 GG09 GG12 GG22 GG33 GG37 GG39 GG52 GG56 GG57 GG63 GG68 GG73 GG78

Claims (3)

[Claims] 1. An optical system for scanning a predetermined monitoring area using a laser beam and detecting reflected light at each scanning position, and an optical system for detecting a reflected light obtained from the monitoring area in synchronization with the scanning of the laser light. Integrating means for obtaining an integrated value of the intensity; and an integrated value of the intensity of the reflected light, discriminating the steady reflected light intensity in the entire monitoring area as a threshold value, and a means for determining the entry of an object in the monitoring area. An intruding object monitoring device comprising: 2. The scanning of the laser light is performed by changing the irradiation direction of the laser light using a mirror made of a silicon micro optical scanner provided above the monitoring area. Claim 1
An intruding object monitoring device according to item 1. 3. The stationary reflected light intensity used as the threshold value is obtained based on an integrated value of the reflected light intensity obtained from the specific scanning area under the condition that no object enters. The intruding object monitoring device according to claim 1.