FR2962836A1 - Intrusion detection device for e.g. fence, has detection circuit electrically connected to arm and detection cable to detect contact between detection member and cable, where member is in contact with cable when arm is in alarm position - Google Patents

Abstract

The device has an element (1) comprising a mobile arm (11) mounted elastically on a base (10) e.g. vertical tube, by a spring blade. A detection unit has an electric detection cable (14) fixed with respect to the base extending transversely relative to the arm and cooperating with a detection member (112) e.g. tab, of the arm such that the member is in contact with the cable when the arm is in an alarm position. The unit has a detection circuit (17) electrically connected to the arm and the cable to detect a contact between the member and the cable. The spring blade comprises two branches connected with each other by a bent portion that is made from elastic material.

Description

1

The present invention relates to an intrusion detection device in a site to be protected and in particular a device for detecting any attempt to escalate or deteriorate a fence delimiting the site to be protected. Devices are known to be mounted on the top of a fence. The device conventionally comprises a movable arm intended to carry one or more fence wires, for example barbed wires, the movable arm being elastically mounted on the upper end of a post of the fence. When an intruder tries to climb the fence with his bare hands or by means of a ladder, the mobile arm pivots under the weight of the intruder and / or the ladder, thus hindering the intruder in his progression. Detection means are further provided for detecting movement of the movable arm and triggering an alarm signal to alert security personnel present or not to the site to be protected. Such a device is for example described in US Pat. No. 4,081,177. In this document, the mobile arm is in the form of a hollow tube comprising a vertical portion extending at its upper end by an inclined portion. Means in the form of a sleeve are provided to assemble the lower end of the vertical portion of the movable arm at the upper end of a fence post. A helical spring is disposed both in the inner passage of the upper portion of the fence post and in the inner passage of the vertical portion of the movable arm to provide the elastic connection between the movable arm and the fence post. Thus, when an external force is exerted on the movable arm, it leaves its rest position and pivots. As soon as the external force disappears, the movable arm returns to its rest position. Any movement of the moving arm is detected by a motion sensor

2 disposed within the inclined portion of the movable arm. This device detects all movements of the moving arm, not only those caused by individuals attempting to climb the fence by leaning on the arm or barbed wire supported by the movable arm, but also those caused by rain , the wind or by a simple vibration. To avoid false alarms, this device requires the individual adjustment of the motion sensor of each of the arms arranged along the fence. This setting is not necessarily easy to perform and is long to achieve. Another disadvantage concerns the installation and reliability of the device. Indeed, the use of a sensor or a contactor for each of the articulated arms requires each arm an electrical connection outside to a detection box. This type of connection is expensive to perform and brings a significant risk of malfunction in case of oxidation.

The object of the present invention is to provide a device overcoming all or part of the aforementioned drawbacks, and in particular to provide an intrusion detection device that is simple in design, easy to adjust, automatically re-armor and inexpensive. For this purpose, the subject of the present invention is an intrusion detection device in a site to be protected, comprising: at least one first element comprising a mobile arm resiliently mounted on a base, said movable arm supporting a barrier element, such as a barbed wire and / or a mesh and / or a net and / or a roll of barbed wire, delimiting at least one zone of said space, said movable arm being able to move elastically from a rest position to a position of alarm under the effect of an external force exerted on

3 said movable arm directly or indirectly via said barrier element, and - detection means for detecting movement of the movable arm relative to the base, characterized in that the detection means comprise: - a fixed detection electric cable relative to the base and positioned near the movable arm, extending transversely relative to the movable arm and cooperating with a detecting member of the movable arm so that, when the movable arm is in the alarm position, the detecting member of the movable arm is in contact with the sensing electrical cable, and a sensing circuit electrically connected to the movable arm and said sensing electrical cable for detecting a contact between the sensing member of the movable arm and the electrical cable detection. The intrusion detection is thus performed by means of an electrical detection cable cooperating with a movable arm detecting member. When an intruder attempts to climb the barrier element and is supported, either himself or through a ladder, on the barrier element (barbed wire and / or wire and / or net and / or roll of barbed wire) or directly on the movable arm or when it is trying to lift the latter and / or the barrier element, the sensing element comes into contact with the electric detection cable and the movable arm goes into alarm position. The detection circuit then detects this position of the movable arm and then possibly emits an alarm signal. According to a particular embodiment, the detection member comprises an opening, for example circular, positioned and dimensioned so that the electric detection cable is disposed in the opening, preferably in the center thereof, when

4 the movable arm is in the rest position and such that an edge of the opening is in contact with the electric detection cable when the movable arm is in the alarm position.

More generally, the opening comprises at least one upper edge and at least one lower edge so that one of the lower and upper edges of the opening comes into contact with the electrical detection cable when the intruder presses the movable arm and / or the barrier element and that the other of the lower and upper edges of the opening comes into contact with the electric detection cable when the intruder attempts to lift the movable arm and / or the element barrier, or vice versa (where the detection member is placed below the movable arm). According to one feature, the movable arm is mounted on the base by means of a spring blade now or bringing the movable arm into its rest position when no force is exerted on it. Thus, a device is automatically re-armable. According to a particular embodiment, the base consists of a substantially vertical tube of rectangular cross section, for example square, and the movable arm comprises a first portion for its assembly to the base via said leaf spring. The leaf spring comprises a first leg fixed to the first portion of the movable arm and a second leg fixed to the base, said first and second legs being connected to each other by a bent portion of elastic material. The movable arm further comprises a second portion extending upwardly from said first portion, preferably in an oblique direction, said second portion being adapted to support said barrier member. In a particular embodiment, the first portion of the movable arm is arranged substantially horizontally. The first and second branches of the spring blade are then substantially perpendicular. According to a particular embodiment, the detection member is a lug mounted on the first portion of the movable arm and extending upwards, preferably in a vertical direction, from said first portion. The opening of the detection member is an opening in the leg. This opening is for example arranged in the upper part of the tab and fastening means to the first portion of the movable arm are arranged in the lower part of the tab.

Advantageously, the fixing means are adjustable in position on the first portion of the movable arm in order to easily adjust the positioning of the detection member relative to the electric detection cable.

In a particular embodiment, the device further comprises an isolator of insulating material for carrying the electrical detection cable, which insulator is fixed to the base by means of a bracket.

According to a particular embodiment, the detection circuit detects not only a contact between the electric detection cable and the movable arm but also a cut or a grounding of the electric detection cable.

According to a particular embodiment, the detection electric cable being traversed by a detection signal supplied by the detection circuit and the movable arm being connected to ground, the detection circuit detects any grounding of the electrical detection cable. .

The detection signal is preferably a very low voltage pulse current. According to an improved embodiment, the barrier element comprises a detection cable traversed by a second detection signal supplied by the detection circuit, and the detection circuit is able to detect the interruption of the detection cable of the element. barrier. Thus, any attempt to cut the detection cable in the barrier element is detected by the detection circuit. Advantageously, the device comprises at least a second element identical to the first element and shifted transversely relative to the first element, said second element comprising a mobile arm resiliently mounted on a base and supporting said barrier element, said arm comprising a cooperating detecting element with said electric detection cable such that, when the movable arm is in the alarm position, the detecting member of the movable arm is in contact with the electrical detection cable, and the detecting means are able to detect a contact between the detecting member of the movable arm of the second element and the electric detection cable. According to a particular embodiment, the barrier element is mechanically connected to the movable arm so that any force exerted on the barrier element is transmitted to the movable arm.

The invention will be better understood, and other objects, details, features and advantages will become more clearly apparent from the following detailed explanatory description, with reference to the accompanying drawings, which show: FIG. an overall perspective view of a device according to the invention mounted

7 on the fact of a wall, which device supports a roll of barbed wire concertina type; - Figure 2, a view identical to that of Figure 1, without the concertina roll; and, - Figure 3, a perspective view of a detail D of Figure 1; - Figure 4, a partial front view of the device of Figure 1; Figure 5 is a side view of the device of the invention of Figure 1; FIG. 6, an electrical diagram illustrating the intrusion detection according to a first embodiment of the invention; FIG. 7, an electrical diagram illustrating the intrusion detection according to a second embodiment of the invention; and FIG. 8, an electrical diagram illustrating the intrusion detection in a case where the site to be monitored is divided into 4 zones. Figures 1 to 5 illustrate an intrusion detection device according to the invention, which device is attached to the wall M fact, this device supporting a roll of concertina-type barbed wire C. Referring to Figures 1 to 5, the device comprises a plurality of elements 1 arranged at regular intervals on the fact of the wall. The elements are for example arranged every 2 or 3 meters. 2 bars, said spacing, are provided to maintain the spacing between the elements 1. Each element 1 comprises a movable arm 11 resiliently mounted on a base 10 by means of a leaf spring 12. The base 10 is intended to bear, at least partially, by its rear face against the front wall of the wall M. The movable arm 11 is

8 able to move elastically from a so-called rest position to an alarm position under the effect of an external force exerted on the movable arm. As soon as the external force is no longer exerted on the movable arm, the movable arm returns to its rest position. The force exerted to reach the alarm position is for example between 10 and 60 decanewtons, for example 20 decanewtons. The base 10 is a hollow tube oriented substantially vertically and of rectangular section, for example square. The movable arm 11 comprises a first portion, referenced 110, for assembling the movable arm to the base 10 via the leaf spring 12 and a second portion, referenced 111, extending upwards from the portion 110 in an oblique direction, which portion 111 is intended to serve as a support for the concertina roll C. The portions 110 and 111 are T-section bars. The angle formed between the portions 110 and 111 is between 90 ° and 170 ° °. In the example shown, the portion 110 is perpendicular to the base 10 and the angle a is equal to about 135 °. The spring blade 12 resiliently connects the movable arm 11 to the base 10. It comprises a first branch 120 fixed flat to the bottom wall of the portion 110 of the movable arm and a second branch 121 fixed flat on the front face of the The two branches 120 and 121 are interconnected by a bent portion 122. In the example shown, the portion 110 of the movable arm being perpendicular to the base 10, the two branches 120 and 121 are perpendicular and the angled portion 122 is a 90 ° elbow. The movable arm 11 is shifted laterally relative to the base 10. To allow the fixing of the spring blade on the base 10, the branch 121 comprises 9 therefore a laterally offset portion relative to the branch 120. The leaf spring 12 is made of an elastic material, for example unalloyed steel or stainless steel 5 with a suitable coefficient of stiffness. The base 10 is fixed to the wall M by means of a support 13 of general L-shaped shape disposed on the top of the wall in a substantially horizontal plane. The support 13 comprises at one of its ends a stirrup 130 protruding from the outer front wall of the wall M. The base 10 is clamped between the branches of the stirrup by means of a clamping screw and of a nut. The support 13 is fixed on the top of the wall by screws or bolts. According to an alternative embodiment, the vertical base 10 is directly fixed against the outer front wall wall M. The concertina roll C is positioned between the base 10 and the distal end of the support portion 111 of the movable arm. It is held in position by wires 5, 6 and connecting rods 7. To hold the wire 5, a wire support 51 is mounted on the upper end of the base 10 of each element 1 and the wire 5 is The wire holder 61 is mounted on the base 10 of each member 1 in the middle portion of the base and the wire 6 is tensioned between the wire holders 51. Similarly, to hold the wire 6, a wire support 61 is mounted between Finally, the connecting rods 7 connect the distal ends of the movable arms 11 between them. The concertina roll is held by stapling to the threads 5 and 6 and possibly to the connecting rods 7. According to an important feature of the invention, the device comprises means for detecting the movement of the movable arm relative to the base . These means essentially comprise an electric detection cable 14 cooperating with a

Detecting 112 of the movable arm and a detection circuit capable of detecting an electrical contact between the sensing element 112 and the cable 14. The cable 14 is fixedly mounted relative to the base 10 and extends transversely to the movable arm 11. This cable is for example a stainless steel cable. It is carried and held at a fixed distance from the base 10 by an insulator 15 of insulating material fixed to the base by a support lug 16. The support lug 16 is fixed on a lateral face of the base 10 by means of of a fixing screw 161. In the example illustrated in FIGS. 3 to 5, the support lug 16 comprises an outward recess for displacing the insulator 15 with respect to the detection member 112 and for the cable 14 extends beyond the detection member. This recess is specific to the elements 1 arranged at both ends of the device. For the other elements 1 of the device, the support lug 16 is a rectilinear tab fixed on the other lateral face of the base 10, as shown in FIG. 2. The cable 14 is stretched between the insulators 15 of the different elements 1 of the device. The sensing member 112 is a tab mounted on the portion 110 of the movable arm and extending upwardly from the portion 110 in a substantially vertical direction. The tab comprises in its upper part an opening 113 through which the electric cable 14 passes and in its lower part of the fixing screws 114 to fix the tab to the portion 110 of the movable arm. In the example illustrated in Figures 1 to 5, the opening 113 is circular in shape and, when the movable arm is in the rest position, the electric cable is substantially disposed in the center thereof. It is also positioned and dimensioned so that one of

11 its edges is in contact with the cable 14 when the movable arm is in the alarm position. In general, the intensity of the external force required to reach the alarm position depends on the stiffness of the leaf spring, the distance between the detection member 112 and the base 10, the size of the spring. the opening 113 and its position on the detection member. Advantageously, the fixing screws 114 are adjustable in position on the portion 110. This adjustment is for example carried out by means of oblong slots provided in the lower part of the tab or in the portion 110 through which the fixing screws 114 can slide. It is thus possible to adjust the position of the detection member 112 relative to the base 110 and the cable 14. The position of the cable 14 relative to the detection member 112 can also be adjusted by changing the position of the support lug 16 relative to the base 10. For this purpose, for example, a light is provided in the support lug 16 at the fixing screw 161 to adjust the position of the support lug relative to the lug. 'base. According to the invention, the contact between the detection member 112 and the cable 14 is detected by a detection circuit 17, in the form of a housing, electrically connected to the movable arm 11 and to the cable 14. Figure 3, the cable 14 is connected to the housing 17 by a connecting wire 141, for example an electric wire with an insulating sheath on its outer periphery. The housing 17 is mounted on the base, for example on the rear face of the base 10. Advantageously, the detection circuit 17 is connected to the movable arms of several consecutive elements 1 and detects the contact between the cable 14 and the sensing element of these elements.

FIG. 6 shows an electrical diagram illustrating the detection of contact between the cable 14 and the movable arm of four consecutive elements 1. The movable arms of the four elements are connected to ground and to the detection circuit 17. The connection to the ground of the movable arms is illustrated by the connection referenced 50 and the ground connection of the detection circuit 17 is the connection referenced 51. The cable 14 is connected by a first end to the detection circuit which provides it with a detection signal. The other end of the cable 14 is connected to ground via a resistor R1, having a value of the order of 3 kilo-ohms (Kn). When the detecting member of a movable arm comes into contact with the cable 14, the cable 14 is grounded and this grounding is detected by the detection circuit 17. The detection circuit 17 then triggers a alarm or transmits an alarm signal to a remote administrator circuit 18 via a wired or wireless link. Advantageously, the detection circuit 17 also detects any cut or grounding of the cable 14. This type of detection circuit is known per se. According to an improved embodiment illustrated in FIG. 7, the concertina roll C carried by the movable arms of the elements 1 also comprises a detector cable traversed by a second electrical signal and the detection circuit 17 detects any interruption of the concertina roll C. detection signals flowing in the electrical cable 14 and the concertina roll C are preferably very low voltage currents (voltage less than 40 volts) without DC component, for example pulsed currents, to greatly limit the effects of electrolysis.

There is thus a detection loop for detecting a contact between the movable arms and the cable 14

13 and a detection loop for detecting a break of the concertina roll C. Each detection loop extends for example over predetermined lengths of 50, 100 or 200 meters. The detection box 17 then feeds 50, 100 or 200 meters of cable 14 and Concertina roll C. According to a particular embodiment illustrated in Figure 8, each detection box 17 is attached to four detection loops. Each detection box 17 supplies two detection loops disposed on an area upstream of the box (zone 1 or zone 3) and two detection loops disposed on an area downstream of the box (zone 2 or zone 4). For each of these zones, a first detection loop is intended to detect a contact between the mobile arms present in this zone and the cable 14 and a second detection loop is intended to detect a cut of the concertina roll. The detection box supplies these four detection loops with four detection signals offset temporally relative to one another to enable short-circuit detection between loops. Indeed, to deceive the detection system, an intruder could want to electrically short-circuit the electrical detection cable 14 and the detector cable concertina C and then cut them so as to facilitate the passage without being detected.

Thus, according to the invention, any attempt to support the movable arm or the barrier element generates contact between the cable and the detecting member of the movable arm and triggers an alarm. Any attempt to lift the barrier member generates contact between the cable and the movable arm detecting member and triggers an alarm.

Any attempt to cut or ground the cable also generates an alarm. The device of the invention also has the following advantages: insensitive to wind, rain and vibrations; - non-destructive detection; can be reset automatically without having to intervene on site (automatic return to rest position) to repair a fuse wire or reposition a switch; - ease of assembly; - adaptable to any type of wall or building.

Although the invention has been described in connection with a particular embodiment, it is obvious that it is not limited thereto and that it comprises all the technical equivalents of the means described and their combinations if they are within the scope of the invention. In particular, the base of the device can be fixed directly applied to a wall or be the upper part of a fence post. The concertina roll C may be replaced by barbed wire stretched between the movable arms and / or by a net hooked to the movable arms.

Claims (12)

REVENDICATIONS1. Intrusion detection device in a site to be protected comprising - at least a first element (1) comprising a movable arm (11) resiliently mounted on a base (10), said movable arm supporting a barrier element (C) such that a barbed wire and / or a grid and / or a net delimiting at least one zone of said space, said movable arm being able to move elastically from a rest position to an alarm position under the effect of a external force exerted on said movable arm, and detection means for detecting movement of the movable arm relative to the base, characterized in that the detecting means comprise: - an electric detection cable (14) fixed relative to the base extending transversely relative to the movable arm and cooperating with a detecting member (112) of the movable arm so that, when the movable arm is in the alarm position, the movable arm detecting member is in contact with with the detection electric cable, and - a detection circuit (17) electrically connected to the movable arm and to said electrical detection cable for detecting a contact between the detecting member of the movable arm and the electrical detection cable. 2. Device according to claim 1, characterized in that said detecting member (112) comprises an opening (113) positioned and dimensioned so that the electric detection cable is disposed in the opening when the movable arm is in position resting and such that an edge of the opening is in contact with the detection electric cable when the movable arm is in the alarm position. 3. Device according to claim 1 or 2, characterized in that the movable arm (11) is mounted on the base by means of a spring blade (12) bringing the movable arm or holding the movable arm in its rest position. when no force is exerted on the moving arm. 4. Device according to claim 3, characterized in that the base (10) is a substantially vertical tube and the movable arm comprises a first portion (110) for its assembly to the base via said spring blade and in that the leaf spring (12) comprises a first leg (120) fixed to the first portion (110) of the movable arm and a second leg (121) fixed to the base, said first and second legs being connected to each other by a bent portion ( 122) of elastic material. 5. Device according to claim 4, characterized in that the movable arm further comprises a second portion (111) extending upwardly from said first portion in an oblique direction, said second portion supporting said barrier element ( VS). 6. Device according to claim 4 or 5, characterized in that the detection member (112) is a tab mounted on the first portion of the movable arm and extending upwardly from said first portion, said tab comprising said opening (113). 7. Device according to any one of claims 4 to 6, characterized in that the detecting member comprises fastening means (114) to said first portion of the movable arm, said fixing means being adjustable in position. on said first portion of the movable arm. 8. Device according to any one of the preceding claims, characterized in that it comprises an insulator (15) of insulating material for carrying the cable (14) electrical detection, which insulator is fixed to the base via a support bracket (16). 9. Device according to any one of the preceding claims characterized in that said electrical detection cable is traversed by a detection signal provided by the detection circuit and in that, the movable arm is connected to ground, the circuit of detection (17) detects grounding of the electrical sensing cable. 10. Device according to claim 9, characterized in that the detection signal is a very low voltage pulse current. 11. Device according to any one of the preceding claims, characterized in that the barrier element comprises a detection cable traversed by a second detection signal provided by the detection circuit, and in that the detection circuit (17 ) is able to detect the cutoff of the detection cable of the barrier element. 12. Device according to any one of the preceding claims, characterized in that it comprises a second identical element to the first element 18 and shifted transversely relative to the first element, said second element comprising a movable arm resiliently mounted on a base and supporting said barrier member, said arm comprising a detecting member cooperating with said detecting electrical cable so that, when the movable arm is in the alarm position, the detecting member of the movable arm is in contact with the cable electrical detection, and and in that said detection means are able to detect a contact between the movable arm of the second element detection member and the electrical cable detection.