ES2376453B1 - CAPACITIVE SENSOR SYSTEM FOR PERIMETER PROTECTION DEVICES. - Google Patents

Abstract

Capacitive sensor system for perimeter protection devices. # The system of the invention is easily integrated into walls and other perimeter protection devices, remaining unnoticed and isolated from adverse weather conditions. For this, the system that is recommended is made up of two fundamental elements, a sensor element (1), materialized in a flexible capacitor of reduced thickness but of high length, intended to be integrated camouflaged into the surface of the rigid fence , and a control electronics module, which is responsible for measuring the variations in capacity of the sensor element through an integrator (13) connected to said element and associated with a microcontroller (12) that registers said possible variations. # The device thus described It allows to monitor different levels of pressure for the sensor, which in turn prevents the firing of false alarms.

Description

CAPACITIVE SENSOR SYSTEM FOR DEVICES PERIMETER PROTECTION

OBJECT OF THE INVENTION

The present invention relates to a perimeter protection device, fundamentally applicable to rigid fences, although it can be applied in another type of perimeter protection devices, based on a flexible capacitive sensor element applied along the entire surface of the object wall. of protection.

The object of the invention is to provide security means that allow the detection of a perimeter protection device, such as a fence or rigid wall, so that the sensor element is integrated into the wall itself and camouflaged, being Immune to weather factors such as rain, snow, etc.

It is also the object of the invention that said system allows detecting different levels of pressure on the wall in order to discriminate small values, thus avoiding the firing of false alarms.

The invention thus falls within the scope of security systems, and more specifically within the technical field of composite materials, also covering aspects of electromagnetism and electronics.

BACKGROUND OF THE INVENTION

The protection of a certain area of the intruder input is the object of any perimeter protection device.

In this sense, numerous technologies have been developed whose purpose is the monitoring of the perimeters surrounding certain areas.

In some cases they are electrified safety fences (ZA200000809 (A)), in other occasions laser technology is used to detect the presence of an object in a certain area (US6259365) by the interruption of the light beam from one end to another from the protected area.

Another option is a device that induces mechanical tension in a fiber optic cable (US6259365 / US2006 / 0054796 A1). This type of device is useful for detecting a person trying to violate a security fence by climbing over it. In this case, the voltage inducing device is placed on the top of each fence security post. A fiber optic cable passes through the top of the fence and passes through each of the voltage inducing devices. Once activated, a pressure element of the voltage inducing device will prick the fiber optic cable causing an alarm. The voltage induction device will be activated if a person supports a ladder on the fiber optic cable or on the voltage generating device itself.

There are other options such as the one posed by the electronic magnetic device for the control of perimeter protection systems using the mechanism known as LVDT (Linear Voltage Differential Transformer) (WO01 / 08470 A1) to detect the mechanical tension of a security fence. This sensor consists of a core that is placed inside a pole and a concentric tube with said core that is fixed to the supports of the fence. The mission of the sensor is to detect the variation of the signal that occurs when the part of the sensor attached to the wire moves with respect to that fixed to the post.

The above devices are used primarily when the perimeter protection system is a fence. The sensors are placed on the corresponding posts.

The method of protection varies when it comes to walls or rigid fences, in these cases any of the previous technologies would require the periodic placement of sensor elements along the protection wall. Another option for this type of enclosures is the use of microwave, infrared or laser (US6259365).

Other problems posed by this type of systems are the fact that they are visible from the outside, and do not allow different levels of pressure to be detected in the wall, which in many cases causes false alarms to be triggered, in addition to being subjected to weather factors such as rain, snow, etc, which over time can lead to such a system to a malfunction.

DESCRIPTION OF THE INVENTION

The capacitive sensor system for perimeter protection devices that the invention proposes solves in a fully satisfactory way the problem previously exposed, being camouflaged in the wall itself, being immune to adverse weather conditions, and allowing to detect different levels of pressure in order to avoid the false alarm firing.

For this, the system that is recommended is made up of two fundamental elements, a sensor element and the control electronics associated therewith.

More specifically, the sensor element is embodied in a flexible capacitor of reduced thickness but of high length, intended to be camouflagedly integrated into the surface of the rigid fence.

In this way, the presence of an intruder on the surface of the fence translates into a deformation of the sensor element that is accompanied by a variation in its electrical capacity. The feeding of the sensor element as well as the detection of the corresponding capacity variations are carried out by means of the electronic control module.

Thus, the sensor element will be applied along the entire surface of the rigid fence, materializing in a parallel flat sheet capacitor whose dielectric core has mechanical flexibility, and in which the metal sheets of the capacitor have a very low thickness, while the condenser is protected in its lower and upper part by a waterproofing material that prevents the variation of the capacity by contact with liquids in the environment.

For its part, the control electronics module is responsible for measuring the capacity variations of the sensor element through an integrator connected to said element and whose integration constant depends on the capacity of this module.

From this structuring, it should be taken into account that the dielectric and geometric characteristics of the sensor element must be such that they confer an electrical capacity detectable by the control electronics module.

Optionally, the condenser bottom sheet of the sensing element can be the rigid fence itself in the case of being metallic or in its absence a layer of metallic paint or adhesive metallic tape. The thickness of said sheet, in the case of being metallic paint or adhesive metallic tape, will preferably be between 25 and 250 microns.

On the other hand, and also optionally, the condenser top sheet can also be a layer of metallic paint or adhesive metallic tape, its thickness being provided in that case preferably between 25 and 250 microns.

This structuring allows the total surface of each and every one of the condenser sheets to vary between 10 and 20,000 cm2, with an optimum level of sensorization.

In addition, the flexible dielectric material of the intermediate sheet can be made of silicone, flexible paint, rubber or foam, with a thickness between 0.1 and 10 mm, and with a dielectric constant that can vary between 2 and 9.

As is evident, the long width ratio of the sensor element will be determined by the application and specific needs of each case, while the dielectric constant chosen for each application will be determined by the range of voltages subject to detection.

On the other hand, the electrical capacity of the sensor module is conditioned by the control electronics which is constituted from a microcontroller and a constant variable integrator, the latter being responsible for measuring the variations in the capacity of the sensor element.

In this way, the integrator constant changes when the capacity of the sensor module varies, caused by a deformation of said module.

Variations in the integrator constant are recorded by the microcontroller, responsible for generating a square signal, with a frequency conditioned by the electrical capacity of the sensor module, being of the order of mHz. This signal is transmitted to the integrator which transforms it into a triangular signal with a certain slope.

The slope of the triangular signal is directly related to the capacity associated with the sensor module, so that variations in the slope of the triangular signal are associated with variations in the capacity of the sensor module.

To measure the slope of the triangular signal, a high reference voltage and a low reference voltage are established. The slope value of the triangular signal is made from the measurement of the time elapsed between the high and low reference voltage.

The minimum alarm level is set when the increase in voltage variation exceeds 10% with respect to the voltage in the absence of mechanical stress.

Thus, the detection levels are established based on the percentages of variation of the slope of the triangular signal, so that the control electronics allow monitoring of capacities in a range between 50 pF and 7 nF

DESCRIPTION OF THE DRAWINGS

To complement the description that is being made and in order to help a better understanding of the characteristics of the invention, according to a preferred example of practical implementation thereof, a set of drawings is attached as an integral part of said description. In an illustrative and non-limiting manner, the following has been represented:

Figure 1.- It shows a schematic representation of the capacitive sensor system for perimeter protection object of the present invention, where the sensor module and the electronic measurement module as well as the fundamental parts of each one are shown.

Figure 2. - It shows the diagram of fundamental functional blocks of the set of the previous figure.

Figures 3a and 3b.-They show a couple of graphs in which the square signal generated by the microcontroller can be observed as well as the corresponding and triangular signal obtained by the integrator. The threshold voltages as well as the corresponding times are shown on the triangular signal.

Figures 4a and 4b.-Show a couple of graphs corresponding to the sensitivity of the sensor element with the applied load.

PREFERRED EMBODIMENT OF THE INVENTION

In view of the figures outlined, and especially in Figure 1, it can be seen how in the capacitive sensor system for perimeter protection devices of the invention two main elements are defined, a sensor element (1) and an electronic control module (2), connected to each other through a BNC connector (3), it being provided that said electronic control module has an input (4) for its supply through a voltage generator (5) of 5 volts, thus as a connection port (6) to a computer (7), and a second port (8), to which a programmer (9) is connectable for programming said electronic module.

By way of example only, and in relation to the tests corresponding to figures 3 and 4, the sensor element may be 20 meters long, 1 cm wide and 3 mm thick, being constituted from a pair of conductive sheets (10-10 ') and a dielectric sheet (11), adopting the sandwich structure of a capacitor, so that in the practical example chosen, the conductive sheets (10-10') are adhesive tapes of 70 microns thick copper and the dielectric sheet (11) is a flexible foam.

In this way, the sensor element (1) modifies its capacity when pressed, which leads to the generation of an intrusion alarm.

From a functional point of view, the described system would be simplified as shown in Figure 2, in which the sensor (1) behaves as a capacitor (1) of variable capacity, while in the electronic control module two are defined fundamental elements, a microcontroller (12) and an integrator (13).

The microcontroller (12) generates a square signal that the integrator (13) transforms into a triangular signal, by integrating the square signal.

The slope of the triangular signal is a direct relationship of the value of the capacitive sensor module, so a variation of the capacitor value implies a variation of the slope of the square signal.

The slope of the signal is measured between fixed reference values on the supply voltage as shown in Figure 3. The frequency of the square signal is conditioned by the capacity of the sensor element which in this case varies between 514 pF and 633 pF. The device does not measure capacity but arbitrary units that correspond to a value of 2025 for the capacity of 514 pF and a value of 2492 units for 635 pF.

The sensitivity of the sensor, at 16 ° C, with the load is shown in Figures 4 a). The load is expressed in Kg / 10cm2, up to a maximum of 15 Kg / 10cm2, with the understanding that this would be the maximum load corresponding to a 150 kg person with one hand. It is a linear variation that allows to distinguish between the different intruders that produce variation (bird, cat, rain, humans, etc.)

Finally, Figure 4 b) shows the tests performed with extreme loads. The sensor element was subjected to several loading cycles, from 25 to 100 kg / cm2. The measurements are repetitive and also show the sensor element is capable of detecting very high loads.

Claims (2)

1st.- Capacitive sensor system for protection devices perimeter, which is constituted:

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from a sensor element (1), materialized in a flexible capacitor, the sensor element (1) is embodied in a parallel flat-plate condenser waterproofed on its outer face and between which an intermediate sheet is disposed that acts as a dielectric that has a thickness between 0.1 and 10 mm, and with a dielectric constant that can vary between 2 and 9, where the sensor is intended to be integrated, preferably camouflaged on the surface of a rigid fence,

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and a control electronics module (2) and measurement of the capacity variations of the sensor element (1) through an integrator (13) connected said element and associated with a microcontroller (12) for registering said possible variations, where before a variation of the condenser value the microntrolator generates a square signal that the integrator (13) transforms into a triangular signal.

2nd.- Capacitive sensor system for perimeter protection devices, according to claim 1, characterized in that the sensor element (1) connects to the electronic control module (2), through a BNC connector (3). 3.- Capacitive sensor system for perimeter protection devices, according to claim 1, characterized in that the electronic control module (2) incorporates an input (4) for its supply through a voltage generator (5). 4th.- Capacitive sensor system for perimeter protection devices, according to claim 1, characterized in that the electronic control module (2) incorporates a connection port (6) to a computer (7). 5th.- Capacitive sensor system for perimeter protection devices, according to claim 1, characterized in that the electronic control module (2) incorporates a second port (8), to which a programmer (9) is connectable. 6th.-Capacitive sensor system for perimeter protection devices, according to claim 1, characterized in that, one of the condenser sheets of the sensor element is the rigid fence itself in the case of being metallic or in its absence a layer of metallic paint or tape adhesive metal 7th.-Capacitive sensor system for perimeter protection devices, according to claim 6, characterized in that, the thickness of the sheet, in the case of metallic paint or adhesive metallic tape, will preferably be between 25 and 250 microns. 8th.-Capacitive sensor system for perimeter protection devices, according to claim 1, characterized in that, one of the condenser sheets is materialized in a layer of metallic paint or adhesive metallic tape, its thickness being provided in said case being preferably between 25 and 250 microns. 9th.-Capacitive sensor system for perimeter protection devices, according to claim 1, characterized in that the flexible dielectric material of the intermediate sheet is silicone or flexible paint, or rubber or foam, SPANISH OFFICE OF THE PATENTS AND BRAND Application no .: 201030275 SPAIN Date of submission of the application: 25.02.2010 Priority Date: REPORT ON THE STATE OF THE TECHNIQUE 51 Int. Cl.: G08B13 / 26 (2006.01) G01R27 / 26 (2006.01) RELEVANT DOCUMENTS

Category

56 Documents cited Claims Affected

Y

US 3763482 A (BURNEY et al.) 02.10.1973, column 2, lines 40-51; column 3, lines 4-35; column 3, line 61 - column 4, line 35; Figures 1-4,6,7. 1-9

Y

US 4197529 A (RAMSTEDT et al.) 08.04.1980, column 4, lines 23-37; claims 1,9-12,15; figure 1C; summary. 1-9

Y

EP 0334531 A1 (ICI PLC) 27.09.1989, summary. 6.7

TO

US 2002101251 A1 (SHIMIZU AKIRA) 01.08.2002, paragraphs [12,27]; Figure 1; summary. one

TO

US 5283528 A (VAN SEETERS JOSEPHUS M) 01.02.1994, column 4, lines 34-55; figure 2. one

TO

GB 1585602 A (BEKAERT SA NV) 11.03.1981, page 2, line 45 - page 3, line 23; figures 1.6. 1-5

TO

WO 2008135040 A2 (UNIV KARLSRUHE et al.) 13.11.2008, paragraphs [32-37]; Figure 1; summary. 1.6-9

Category of the documents cited X: of particular relevance Y: of particular relevance combined with other / s of the same category A: reflects the state of the art O: refers to unwritten disclosure P: published between the priority date and the date of priority submission of the application E: previous document, but published after the date of submission of the application

This report has been prepared • for all claims • for claims no:

Date of realization of the report 29.02.2012

Examiner F. J. Olalde Sánchez Page 1/5

REPORT OF THE STATE OF THE TECHNIQUE Application number: 201030275 Minimum documentation sought (classification system followed by classification symbols) G08B13 / 26, G01R 27/26 Electronic databases consulted during the search (name of the database and, if possible, terms of search used) INVENES, EPODOC State of the Art Report Page 2/5  WRITTEN OPINION Application number: 201030275 Date of Written Opinion: 29.02.2012  Statement Novelty (Art. 6.1 LP 11/1986) Claims 1-9 YES Claims NO Inventive activity (Art. 8.1 LP11 / 1986) Claims YES Claims 1-9 NO The application is considered to comply with the industrial application requirement. This requirement was evaluated during the formal and technical examination phase of the application (Article 31.2 Law 11/1986). Opinion Base.- This opinion has been made on the basis of the patent application as published. State of the Art Report Page 3/5  WRITTEN OPINION Application number: 201030275 1. Documents considered.- The documents belonging to the state of the art taken into consideration for the realization of this opinion are listed below.

Document

Publication or Identification Number publication date

D01

US 3763482 A 10/02/1973

D02

US 4197529 A 04/08/1980

D03

US 2002101251 A1 08/01/2002

D04

WO 2008135040 A2 11/13/2008

D05

EP 0334531 A1 09/27/1989

D06

WO 2008135040 A2 11/13/2008

D07

GB 1585602 A 03/11/1981

2. Statement motivated according to articles 29.6 and 29.7 of the Regulations for the execution of Law 11/1986, of March 20, on Patents on novelty and inventive activity; quotes and explanations in support of this statement In accordance with article 29.6 of the Regulations for the execution of Patent Law 11/86, it is considered, preliminary and without obligation, that the objects defined by claims 1-9 apparently do not meet the requirement of inventive activity within the meaning of article 8.1 LP, in relation to the state of the art established by article 6.2 of said Law. Specifically: Previous considerations: The main claim expresses "... where before a variation of the capacitor value the microcontroller generates a square signal that the integrator transforms into a triangular signal", trying to define the microcontroller by means of the executed algorithm. However: Only one stage of the algorithm is established (generation of a square signal by the microcontroller and transformation of said square signal into a triangular signal by the integrator) so that the microcontroller is not properly limited (defined) by the algorithm used. Additionally, in the light of the description and drawings, said step is understood as "... where the microcontroller generates a square signal that the integrator transforms into a triangular signal whose slope varies before a variation of the condenser value"

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 Document D01 disclosed a capacitive sensor system for perimeter protection devices constituted from a sensor element, embodied in a flexible capacitor waterproofed on its outer face, intended to be integrated into the surface of a rigid fence and a control electronics module and measurement of the capacity variations of the sensor element through an integrator connected to said element.

Differences: 1) the capacitor is not flat with parallel sheets 2) the integrator is not associated with a microcontroller that generates a square signal applied to the input of the integrator) for recording said variations but to an analog alarm circuit. 3) It does not disclose the claimed thicknesses of the dielectric sheet or the range of variation of the dielectric constant.

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 Document D02 disclosed a capacitive sensor system for perimeter protection devices constituted from a sensor element, embodied in a flexible capacitor. The sensor element is embodied in a flat-plate parallel condenser waterproofed its outer face, whose intermediate sheet has a thickness of the order of 0.1mm, intended to be integrated into the surface of a rigid fence and an electronic control and measurement electronics module. the capacity variations of the sensor element connected to said element.

Differences: 1) The control electronics module does not materialize in an integrator associated with a microcontroller. 2) Does not disclose the range of variation of the dielectric constant.

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 Document D03 disclosed an integrator associated with a processing device for measuring capacity variations.

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 Document D04 disclosed a system of measurement of relative capacities highlighting the known fact of obtaining, when integrating a square wave, a triangular wave whose slope is proportional to the amplitude of the square wave obtained by differentiating, by means of a capacitor, said triangular signal.

State of the Art Report Page 4/5  WRITTEN OPINION Application number: 201030275

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 Document D06 disclosed a pressure (force) sensing element from the impedance measurement of a capacitor with a tape structure of parallel conductive sheets separated by a dielectric.

In view of the disclosure, the apparent lack of inventive activity of the object defined by claim 1 is inferred by multiple reasoning and combination of state of the art documents, eg. Starting from D01 as a state of the art closest to the object claimed, the person skilled in the art would obviously use the structure of the sensing element disclosed in D02 or D06 (parallel flat-plate condenser) as an obvious alternative to the structure of the disclosed sensing element in D01. Additionally, the substitution of analog circuits by processors is of general knowledge and common use in the art, the substitution of the analog circuit arranged behind the D01 integrator by a processor, for capacity measurement (D03) being evident. The integration of square waves to obtain triangular waves whose slope varies with the variation of capacity of an associated capacitor is of general knowledge (D07). The specific values of thicknesses (D02) and dielectric constant derive from the design of the system and lack inventive activity. Conversely, starting from D02, the lack of activity of the object defined by the main claim is also inferred, using the integrator of the D01 system for measuring capacity variations and general knowledge about microprocessors. DEPENDENT CLAIMS:

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 It does not seem that dependent claims 2-5 include technical characteristics that, in combination with those contained in those on which they depend, imply inventive activity, for being of general knowledge and common use in the art, solving known problems in a known manner (R2 : BNC connector to connect cables, R3: voltage generator to power the circuits, R4: computer connection port, R5: programmer connection port).

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 D05 disclosed the use of conductive paint for the materialization of a capacitor in a capacitive detector. The use of such a capacitor in any of the systems disclosed in D01 or D02 would juxtapose the expected effect by solving the same problems, so claim 6 is not considered to involve inventive activity.

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 It does not appear that dependent claims 7-9 include technical characteristics that, in combination with those contained in those on which they depend, involve inventive activity, as they are derived from design and experimentation, lacking inventive activity.

Notwithstanding the above, it seems that an object of protection in which the microcontroller is defined by the complete detection and discrimination procedure (executed algorithm) could imply inventive activity against the state of the art defined by the cited documents. State of the Art Report Page 5/5