ES2240909T3 - A SECURITY SYSTEM, PARTICULARLY FOR PROPERTY SURVEILLANCE, AND A SENSOR. - Google Patents

Abstract

A security system (SEC-ST), particularly for property surveillance, to be associated with at least one element (5) of a protective structure (1) that can be subjected to flexural forces, the system comprising: minus a deviation sensor (6) to detect deviations of the element (5) as a result of the forces, the sensor comprising: - a substantially plate-shaped piezoelectric transducer (10) for converting mechanical stresses into electrical signals, - a container ( 40) for the transducer (10), in which the transducer is attached to at least two points arranged substantially opposite each other with respect to a center of the transducer, whose container (40) can be fixed to the element (5) of the structure of protection, the container (11, 12) being such that it deviates elastically as a result of the bending forces and to transmit the deviations of the element to the transducer (10) which in turn deflects in a path qu e corresponds to the deviations of the element (5) and the container to give rise to the corresponding electrical deviation signals, and - electronic processing means (8) connected to the sensor (6) to receive and process the electrical detection signals.

Description

A security system, particularly for property surveillance, and a sensor.

The present invention relates to systems of security, particularly for property surveillance. The The present invention also relates to a sensor that is used in said security systems.

For some time, as you know, there is a need to monitor property boundaries and the immediate signaling of any intrusion by a unknown in an area that must be protected or, similarly, from an attempt to escape from there, by the appropriate issuance of warnings

Security systems known as the buried barrier systems are known and widely used; these systems use sensors of various types that are intended to be located on the ground or under the floor covering or the pavement and along the limit of the property that must be protected, to detect the steps due to the crossing of the limit.

Among these systems, the systems according to pressure or seismic sensors, for example, also called "buried tube" systems or facilities of "microphone - cable".

There are also complex and expensive facilities that use buried coaxial cables or optical fibers to detect steps in the boundary that delimits the area under surveillance.

It has been discovered that security systems based on sensors located in the field may be subject to interference or inactivation due to environmental conditions adverse effects such as heavy rain, snow, or presence of ice In other cases, ground vibrations caused by the passage of vehicles around the areas which must be protected can cause the incorrect activation of these systems, giving rise to inappropriate signals.

Moreover, the use of the installation of buried sensors, makes maintenance operations and of repair in case of damage are particularly complex and faces.

Among the security systems that are currently in use, there are some who do not use buried sensors but that use microwave barriers or infrared rays. These systems they are not suitable for surveillance in open spaces because they are particularly sensitive to atmospheric phenomena, for example, to fog or even the passage of small animals.

The objective of the present invention is provide a security system that does not have the disadvantages of the systems described above of the prior art.

This goal is achieved with a system of security as described in the first claim. An object Additional of the present invention is a sensor that is used in security systems, as described in the claim 12.

The other features and advantages of the invention will be better understood from the following description detailed of the preferred embodiments thereof, which they are given by way of non-limiting example referring to the attached drawings, in which:

Figure 1 is a schematic plan view of a property delimited by a protection structure of limits,

Figure 2 shows, schematically, a system of particular security according to the invention,

Figure 3 shows an enlarged detail of the security system of figure 2,

Figure 4 shows an embodiment particular of a sensor, schematically and in lateral section, according to the invention, with separate parts, and

Figure 5 shows, schematically, some Stages of operation of the sensor in Figure 4.

A preferred embodiment of a SEC-ST security system according to the invention referring to figures 1, 2 and 3. In particular, this system is provided for monitoring a structure of protection 1 of an area 2 in which a dwelling is located 3.

The protection structure 1 is, for example, an outdoor fence, composed of a plurality of trellises 4, typically metal lattices, supported by posts 5 or by other suitable support or support elements. The elements of support have the function of fixing the fence firmly to the masonry structures such as, for example, small walls, or to the ground

Regarding this, point out that the teachings of the present invention apply to protective structures of another type other than the fence in particular to the one that makes Reference this description.

Actually, the security system of the invention can be provided for single-sided surveillance of a property that has to be protected, or the structure of protection 1 may comprise a wire net boundary fence adequate, supported by stakes, or protective panels made of suitable material.

In another variant, the protection structure 1 can comprise one or more bars or trellises installed in the openings in the walls of the house 3, for example, in doors or windows

SEC-ST security system of the invention is particularly suitable for detecting and signaling intrusions or attempted intrusions on protected property 2.

In the described embodiment, the system SEC-ST safety comprises one or more sensors 6, 7 control and supply lines for sensors, media 8 electronic processing, and signaling means of warning, being the last of conventional type and not shown in the drawings

As shown in Figure 3, the sensors 6 are embedded in posts 5 of the lattices 4, which are fixed firmly to a base B. Each sensor 6 comprises a transducer piezoelectric in the form of respective plate and can generate signals electrical lines that can be made available on lines 7, for detect deviations (or, in other words, deformations) of posts 5 due, according to the described embodiment, intent of intrusions.

A preferred embodiment of the sensors 6 will be described in more detail below.

As shown schematically in Figure 2, the particular security system of the embodiment described divides the perimeter of the protection structure 1, under a logical point of view, in one or more sections 9, including each at least one sensor 6.

In the described embodiment, the perimeter of fence 1 is divided into eight sections 9, each of which defines a region under surveillance, which is associated with three sensors 6.

The sensors 6 within the same section 9 are properly connect, by means of lines 7, to the means of electronic processing 8 which are formed, for example, by an electronic analysis and control card 8 of type conventional.

Lines 7 are, for example, wires conventional electric that allow the signals generated by the sensors 6 transfer to the analysis card electronics 8.

The electronic analysis card 8, which is preferably digital, it has the function of receiving the signals electrical emitted by sensors 6 and process them. This card 8 is also provided with suitable stages to amplify and Filter the received signals. Card 8 is also responsible for activate the warning signaling means. The card electronics 8 can also advantageously perform functions for the control and monitoring of the security system status.

Anyone who attempts an intrusion into the property 2 trying to climb fence 1, scaling it directly or with the help of a ladder, you are forced to make contact physical with the fence.

Posts 5 that support the fence are submitted in addition to a flexural force (or tension) due to contact with the intruder and his weight, which leads to an increase in oscillations Deviations (that is, deformations mechanical) of fence 1 or, more precisely, of posts 5, is detect by one or more sensors 6 of one or more sections 9, which transmit one or more electrical detection signals to the card analysis 8.

Card 8 receives these signals and after filter them and amplify them properly set, according to your nature, if an intrusion attempt is in progress, activating therefore the warning means.

These warning means produce a signal local warning (for example, an image that can be exposed in a monitor of a control station, sirens or lights intermittent) or send the warning signal to a station remote control, for example, by means of a device telephone dialing or a radio bridge. The logical division in sections 9, allows card 8 to locate any region of the fence under surveillance that is affected by the intrusion.

It should be noted that atmospheric conditions extremes such as, for example, strong wind, can cause oscillations or deviations from the structure of fence 1, but the electrical signal generated by sensors 6 in these situations it has different characteristics from those related to the intrusion and can therefore be ignored correctly by the control station For example, card 8 can analyze the frequency of the received signals, evaluating if they belong to a typical intrusion frequency band (typically up to 20 Hz) or An attempted robbery.

It should be noted that sensor 6 can detect oscillations of the protection structure elements 1 to very high frequencies. Card 8 advantageously has the task of filtering the electrical signals generated by the sensors 6 so that only signals with actual processing are processed / analyzed typical frequencies of intrusion attempts.

In this regard, the structure of the sensors 6 and the electronic card 8 make the SEC-ST security system of the invention particularly suitable for detecting intrusions, whereby the corresponding oscillations of an element of the protection structure 1 such as , for example, post 5 has frequencies of less than 20 Hz. According to a particularly advantageous embodiment, the SEC-ST security system is suitable for detecting intrusions that cause oscillations at frequencies of less than 10 Hz. In particular, the SEC-ST security system allows the detection of intrusions that cause oscillations at very low frequencies, that is, less than
5 Hz

The system according to the present invention can also advantageously detect attempts to force / break the protection structure 1. Even if the use of tools various types, such as, for example, arc saws or shears, they do not cause the real deviations of structure 1, cause vibrations however that can be picked up with sensor 6. These Vibrations typically have frequencies between 500 Hz and 10 kHz. For this reason, in a preferred embodiment, the card electronics 8 analyzes the electrical signals generated by the sensors 6 in a suitable frequency frame to detect Breaking attempts (500 Hz - 10 kHz) as well as in the band specified for intrusion attempts (frequencies below of 20 Hz).

To distinguish an attempted intrusion / break from other causes of oscillations of the protection structure 1, the electronic card 8 can establish a correlation properly between the electrical signals that come from a sensor or a section and those that come from the sensors or sections adjoining

It will be described now, referring to the Figure 4, a preferred embodiment of a sensor 6 which is used in the type of security system described previously.

The sensor 6, according to the present invention, substantially comprises a piezoelectric transducer in the form of plate 10, arranged in a container 40 comprising a base 12 and a cover 11.

The piezoelectric plate-shaped transducer 10 is, for example, disk-shaped, and comprises a plate 21 of conductive material, for example, brass or copper, covered by a thin layer of piezoelectric ceramic 22. In the form of embodiment of figure 4, the plate 21 has a large diameter and a thickness greater than the ceramic layer covering 22.

The respective conductive wires 24, 23 are extend from transducer 10, more precisely, from the plate 21 and from layer 22, and arise from the container 40 of the sensor 6. These conductive wires 23 and 24 can be properly connected to line 7 of the security system described above.

Under the piezoelectric properties of the ceramic layer 22, the transducer 10 allows deformations, vibrations, and mechanical stresses to which it is subjected to become detectable electrical signals (for example signals pulse) on wires 23 and 24.

Piezoelectric transducers are known in plate form of the type described above and, for example, a Transducer of this type is produced and marketed by Murata Manufacturing Co., Ltd.

The container 40 of the sensor 6 can be fixed to the post 5 of protection structure 1 and be so elastically deformed as a result of the bending forces at which submit to post 5 to transmit post deviations to transducer 10 so that deviations can give rise to electrical detection signals

In particular, base 12 and cover 11 which can be fixed to it are made of plastic materials suitable such as, for example, ABS (acrylonitrile butadiene styrene), Teflon, Plexiglas, nylon, or PVC (chloride polyvinyl).

The base 12 comprises, a first cavity or upper chamber 13, for example, a cylindrical chamber to accommodate the piezoelectric transducer 10. The base 12 also comprises a second cavity or lower chamber 14, for example, a chamber cylindrical, which opens in the upper chamber 13. In the form of preferred embodiment of Figure 4, the lower chamber 14 is coaxial with upper chamber 13 but has a smaller diameter.

The upper chamber and the lower chamber 14 define a stepped wall 15 provided with an annular support edge 19 for the piezoelectric transducer 10.

In a mounted sensor configuration 6, the piezo transducer 10 is intended to rest on the edge cancel 19 and, in the absence of bending forces or stresses mechanical, the transducer 10 extends in a support area imaginary.

On the other hand, the sensor 6 comprises a cylinder rigid hollow 18 provided with an annular edge 19 '. The cylinder is interposes between the cover 11 and the base 12. The annular edge 19 ' It is intended to rest and lean on peripheral regions in front of the piezo transducer 10 facing the cover 11. According to the embodiment of Figure 4, the cylinder 18 is intended to rest on the peripheral regions of the plate 21 of the piezoelectric transducer 10 so that it does not touch the layer of ceramic 22.

Once cover 11 has been fixed to the base 12, holds the hollow cylinder 18 so that the transducer piezoelectric 10 is firmly and strongly embedded around its periphery, between the support edge 19 and the annular edge 19 'of the cylinder 18. In a different embodiment, cylinder 18 it could be, for example, part of cover 11.

It should be noted that the cylindrical body 18 and the annular edge 19 constitutes only a preferred embodiment of the rigid clamping means that can be used to ensure the piezoelectric transducer to the upper cavity 13 of the container 40. Rigid clamping means can rest on the entire periphery of the plate-shaped transducer 10 or only in some regions, preferably peripheral regions, of transducer

The cylindrical body 18 and the annular edge 19 u other fastening means equivalent to these allow the transducer 10 be fixed to container 40 advantageously so such that the transducer can deviate in two opposite directions in relation to the support area. The ability to deviate in opposite directions in relation to the support area is particularly advantageous since it allows transducer 20 to detect the bending forces that result from the intrusion and that have opposite directions and generate electrical signal detection as a result of deviations from post 5 in directions opposite.

On the other hand, the sensor 6 is provided advantageously of contact means interposed between the container 40 and transducer 10 to exert a force on the minus one region of transducer 10 during the effect of forces of flexion.

These means of contact may comprise, preferably, a first protuberance 17, for example a cylindrical protuberance that extends from a wall of the cover 11 and is intended to contact a first front of the plate-shaped transducer 10. In Figure 4, the first cylindrical protuberance 17 contacts the layer of ceramic 22 in a central region of the same, in the mounted sensor configuration. The sensor 6 also comprises advantageously a second protuberance 16, for example a cylindrical protuberance extending from a base wall of the lower chamber 14 and is intended to come into contact with a second front of the plate-shaped transducer 10, section of the First. In Figure 4, the second cylindrical protuberance 16 is contacts plate 21 in a central region of the same.

According to a particular embodiment, the sensor 6 also comprises a protective material 20 arranged in the upper chamber 13. In particular, this material is a resin 20 which almost completely fills the upper chamber 13. For example, the Resin 20 is a known type of epoxy resin in two parts. This commercialized a resin that can be used in particular in the sensor 6, for example, by CAFARELLI RESINS Co. S.n.c., Montescudaio, Pisa, Italy.

This resin 20 performs a sealing action, which prevents the formation of rust on a front of the transducer piezoelectric 10 due to possible moisture infiltration from the exterior or internal condensation caused by variations thermal.

The resin advantageously has a function additional consisting of the transmission of bending forces resulting from deformation of container 40 to transducer 10, Without absorbing them.

In the security system described above SEC-ST, sensor 6 is advantageously embedded substantially in a region of maximum deformation of the element of protection structure 1, for example, in the form of described embodiment, around the base B of the post 5. The sensor 6 can be firmly fixed to the post 5 by means of fixing 25 such as, for example, screws.

The operation of sensor 6, when used in SEC-ST security system will be described referring to figure 5.

Attempts to climb or disassemble the structure of protection, etc., produce flexural forces, possibly in opposite directions, indicated by arrows 27 and 28 in figure 5, as to cause the deviation and / or oscillation of one or more posts 5.

The support area line 26 (in the case specific, a support plane) defined by the transducer in Plate form 10 in the absence of mechanical stresses, is shown in Figure 5. This line of the support plane 26 is parallel to the axis longitudinal V-V 'of post 5 separating the plane of Figure 5 in a flat half R, on the right hand side, and a flat half L, on the left hand side

As a result of deviations from post 5, container 40 also deforms and deflects. Container 40 also transmits the deviations from post 5 to the transducer piezoelectric 10, which in turn deviates.

It should be noted that, under the action of holding the cylinder 18 and the support edge 19 shown in the Figure 4, the piezoelectric transducer 10 deviates in relation to with the support plane 26 both under the effect of force 27 and under the effect of force 28 in the opposite direction.

Figure 5 schematically shows the piezo transducer 10 in two deflected configurations or different deformed (highlighted for clarity) indicated like 10-R and 10-L, which correspond to the effects of forces 27 and 28, respectively.

Under the effect of force 27 (which causes a deflection of post 5 towards the flat medium R), the transducer piezoelectric deviates enough to have a concavity that go to the middle plane R on the right hand side (configuration 10-R). Conversely, under the effect of tension 28 (which causes post 5 to yield to the flat half L), the piezo transducer yields enough to have a concavity that faces the middle plane L on the left (L configuration).

On the other hand, when the transducer piezo is in the 10-R configuration (10-L), the second (first) bulge 16 (17) exerts a force on the central region of the plate (layer of ceramic) 21 (22).

This force exerted on the transducer piezoelectric 10 greatly increases the magnitude of the mechanical stress suffered by the transducer compared to the simple deformation due to deviation. On the other hand, each bulge 16 or 17 produces an improvement and even distribution of the external bending forces inside the transducer 10, making the deformation of the transducer more uniform piezoelectric 10.

Deviation and / or deformation as a whole suffered by the transducer 10 carries, by the piezoelectric effect, to the generation of one or more electrical detection signals that are found in conductive wires 23 and 24. In particular, the piezoelectric transducer 10 generates voltage pulses of opposite polarities depending on whether the deviation took place in a direction or in the other. For example, the piezoelectric transducer 10 generates electrical voltage pulses no greater than approximately 500 mV.

It should be noted that it is not strictly necessary for the piezoelectric transducer 10 be attached to the container 40 around its entire periphery but it would in fact be enough subject it to at least two substantially opposite arranged points from each other with respect to the center of the transducer in the form of plate 10 and in a diameter substantially parallel to the axis longitudinal V-V 'of post 5.

The described invention allows the production of particularly reliable security systems to detect and signal intrusion attempts.

The security system of the invention is almost insensitive to external environmental conditions. In particular, the system has been arranged to be completely insensitive to storms, which represents a critical aspect of Many known limit protection systems.

On the other hand, the embedding of these systems can take place in structures to monitor that are already installed and does not require burying sensors or other device detection. A sensor can therefore also be replaced. quickly and easily.

It should be noted that, in addition to detecting if it climbs by the fences, the system of the invention is also effective, in a more general sense, in signaling attempts to break, exhaust, or disassembly carried out in the structures of protection.

Naturally, to meet the requirements specific, a person skilled in the art can apply to security system described above and to the sensor many modifications and variations all of which, however, are included within the scope of protection of the invention as defined in the appended claims.

Claims (24)

1. A security system (SEC-ST), particularly for the surveillance of property, to be associated with at least one element (5) of a protective structure (1) that can be subjected to forces of flexion, comprising the system: - at least one deflection sensor (6) for detect deviations of the element (5) as a result of the forces, including the sensor: - a substantially piezoelectric transducer in the form of a plate (10) to convert mechanical stresses into electrical signals, - a container (40) for the transducer (10), in which the transducer is attached to at least two arranged points substantially opposite each other with respect to a center of the transducer, whose container (40) can be fixed to the element (5) of the protective structure, the container (11, 12) being such that deviate elastically as a result of bending forces and to transmit the deviations of the element to the transducer (10) which deviates in turn on a path that corresponds to deviations of the element (5) and the container to give rise to corresponding electrical deviation signals, and - electronic processing means (8) connected to the sensor (6) to receive and process the signals of electrical detection 2. A system (SEC-ST) according to the claim 1 wherein, in the absence of bending forces, the transducer (10) rests on a support plane (26), and in the that the sensor (6) further comprises rigid clamping means (18, 19) to fix the transducer (10) to the container (40) in such a way that the transducer can deviate in two opposite directions in relationship with the support plane (26). 3. A system (SEC-ST) according to the claim 2 wherein the clamping means (18, 19) are such as to fix the transducer (10) in a cavity (13) in the inside the container (40). 4. A system (SEC-ST) according to the claim 1 wherein the sensor (6) is intended to be embedded substantially in a region of maximum deformation of the element (5). 5. A system (SEC-ST) according to the claim 1, comprising a plurality of sensors (6) subdivided into sections (9) each corresponding to a region respective under surveillance. 6. A system (SEC-ST) according to the claim 1, further comprising signaling means of warning connected to the processing means (8), causing the processing means the activation of the means of warning signaling according to the detection signals electric 7. A system (SEC-ST) according to the claim 1 wherein the processing means (8) they comprise an amplification stage and a filtration stage for electrical detection signals. 8. A system (SEC-ST) according to the claim 7 such that it detects the oscillations of the element (5) with frequencies of less than 20 Hz. 9. A system (SEC-ST) according to the claim 8 such that it detects the oscillations of the element (5) with frequencies of less than 5 Hz. 10. A system (SEC-ST) according to the claim 7 such that it detects the vibrations of the element (5) with frequencies between 500 Hz and 10 kHz. 11. A system (SEC-ST) according to the claim 1 wherein the protective structure (1) is at less than one type that belongs to the group that comprises: a plurality of metal lattices, a wire network supported by Support posts, a fence to limit. 12. A deflection sensor (6) used in the security systems (SEC-ST) to detect deviations of an element (5) from a protection structure (1) which can undergo bending forces, comprising the sensor: - a substantially piezoelectric transducer in the form of a plate (10) such that it converts the mechanical tension into electrical signals, and - a container (40) for the transducer (10), in the one that holds the transducer to at least two arranged points substantially opposite each other with respect to a center of the transducer, container (40) that can be attached to the element (5) of the  protective structure, the container (11, 12) being such that deflect elastically as a result of the bending forces and to transmit the deviations of the element to the transducer (10) which deviates in turn so that it corresponds to deviations of the element (5) and the container (40) to give rise to the corresponding electrical detection signals. 13. A sensor (6) according to claim 12 in which, in the absence of bending forces, the transducer (10) rests on a support plane (26), comprising the sensor (6) also rigid clamping means (18, 19) to fix the transducer  (10) to the container (40) so that the transducer can deviate in two opposite directions in relation to the plane of support (26). 14. A sensor (6) according to claim 13 in that the rigid clamping means (18, 19) rely on the peripheral regions of the transducer (10). 15. A sensor (6) according to claim 13 in that the rigid clamping means (18, 19) affect all the periphery of the transducer (10). 16. A sensor (6) according to claim 12 in which the container (40) comprises a base (12) and a cover (11) that can be fixed to the base. 17. A sensor (6) according to claim 16 in which the base (12) comprises a cavity (13) to accommodate the transducer (10). 18. A sensor (6) according to claim 17 in which the base (12) comprises another cavity (14) that opens in the cavity (13). 19. A sensor (6) according to claim 12, which further comprises contact means (16; 17) interposed between the container (40) and the transducer (10) to exert a force on the less a region of the transducer during the effect of the forces of flexion. 20. A sensor (6) according to claim 19 in which the contact means comprise a first protuberance (17) to contact a first front of the transducer (10) 21. A sensor (6) according to claim 20 in which the contact means comprise a second protuberance (16) to contact a second transducer front (10), away from the first front. 22. A sensor (6) according to claim 12, which it also comprises a layer of protective material (20) arranged in minus one front of the transducer (10). 23. A sensor (6) according to claims 13, 14 and 15, wherein the fastening means comprise: - a tubular body (18) interposed between the cover (11) and base (12) and provided with an edge (19 ') that supports the peripheral regions of a first front of the transducer (10), - a support edge (19) for the regions peripherals of a second side of the transducer, away from the first front, the edge (19) being formed in the base (12). 24. A sensor (6) according to claim 12 in which the transducer (10) comprises a metal plate (21), a layer of piezoelectric ceramic material (22), and wires electrically conductive (23, 24) connected to the board and to the layer, respectively, to make available the signals of electrical detection