EP0789219B1 - System state change display device - Google Patents

Abstract

The device for visualising the change of state of a system (1) includes a passive oscillating circuit (2), solidly attached to the system, which is tuned to a specific frequency. The circuit is capable of being connected in a short circuit by a switch (7) which is activated at the moment when the monitored system changes state. The passive circuit is intended to put into resonance by a detection device, external to the system or the passive circuit. The detection device may be tuned to the frequency at which the passive circuit has its resonant frequency. Thus from an external source, the state of the passive circuit and hence the state of the monitored system may be detected.

Description

The technical field of the invention is that of change visualization devices of a system, and more particularly that of devices for viewing the neutralized state ammunition, such as a mine.

To drive quickly and safely landmine clearance operations it's necessary to be able to reliably recognize the ammunition or mines which are neutralized and which do not no longer present any danger.

Neutralized ammunition means ammunition whose the primer worked (without causing the explosion of ammunition), or ammunition whose primer cannot no longer be initiated because the energy source intended for feeding the primer is exhausted.

We know from patent FR2563001 a device for neutralization and visualization of the neutralized state of an explosive device.

This device provides a gas generator which has for effect of operating a lock, or opening a contact of the firing chain, and which at the same time ejects a weight with a ribbon.

The display of the neutralized state of the ammunition is so done by observing the weight and the ribbon which must be clearly visible.

Such a solution has drawbacks.

Indeed, the flyweight is a mechanical element which may be stuck or stuck in its housing, its failure does not allow the detection of a state neutralized, even effective.

In addition, this solution implements a composition gas generator which can also be faulty and fail to account for the neutralized state.

Such a solution is unsuitable for dispersed mines or buried. Indeed in the case of dispersion, we is not sure of the position adopted by the mine during his arrival on the ground. Viewing the status neutralized is made more difficult, the ejection of the weight can even be impossible.

In the case of a buried mine the ejection of the counterweight above ground is impossible.

It is the object of the invention to propose a device for visualizing the change of state of a system which does not have such disadvantages.

The device according to the invention thus allows the remote and reliable visualization of the status neutralized ammunition, regardless of its position on the ground or in the ground.

The invention allows this visualization with a higher reliability than known devices, everything by not consuming energy and having a lifespan almost unlimited.

The invention makes it possible to view remotely the change of state of any system, and can be implemented works outside the armaments field.

Indeed, the device according to the invention does not use no pyrotechnic composition and can be easily operated by any mechanical or electronic device.

The device according to the invention also makes it possible to spot dummy mines in an actual minefield at after a certain time interval.

Thus the subject of the invention is a device for visualization of the change of state of a system and in particular for viewing the neutralized state of a ammunition such as a mine, device characterized in that it comprises at least one passive oscillating circuit, integral with the system, and tuned to a certain frequency, circuit to terminals of which a short circuit is mounted, the short circuit being capable of being opened by cutting means activated when the system status changes, passive oscillating circuit intended to be put into resonance by a means of detection external to the system and comprising at least one tunable active oscillating circuit on the natural frequency of the passive oscillating circuit.

According to a first embodiment, the means of are activated in response to the operation of a primer intended to initiate ammunition.

The cutting means may thus include a part of the short circuit which is a conductor placed at near or in contact with the primer.

According to a second embodiment, the means of break can include at least one passive switch semiconductor which is activated when changing system status.

The passive switch may be actuated in response to the discharge of an energy source arranged in the ammunition and intended to ensure the firing of a primer initiation of ammunition.

Advantageously, the passive switch is a MOS transistor whose base is connected to the source of energy and that sits open when the voltage of the energy source is less than a threshold voltage the transistor.

According to another embodiment, the means of break may include a passive semiconductor switch connected in series with a conductor passing through near or in contact with the primer.

According to another embodiment, more particularly intended for a dummy mine placed among actual mines, the cut-off means include a portion of circuit likely to corrode up to opening of the circuit after a certain time.

The unprotected part of the circuit may be at least partially covered during installation from the mine by a corrosive substance.

The unprotected part of the circuit can receive at less material forming an electrolytic couple with it.

• la figure 1 est un schéma électrique simplifié d'un dispositif de visualisation selon l'invention,
• la figure 2 montre un premier mode de réalisation d'un dispositif selon l'invention,
• la figure 3 représente un deuxième mode de réalisation d'un dispositif selon l'invention,
• la figure 4 représente un troisième mode de réalisation d'un dispositif selon l'invention,
• les figures 5a, 5b montrent une mine inerte équipée d'un dispositif de visualisation selon un quatrième mode de réalisation, la figure 5b étant une vue partielle de la figure 5a suivant la direction F,
• la figure 5c représente seul le court circuit monté sur le circuit de la figure 5b.
• les figures 6a et 6b sont des vues recto et verso d'un cinquième mode de réalisation d'un dispositif selon l'invention.

The invention will be better understood on reading the description which follows of particular embodiments, description made with reference to the appended drawings and in which:

• FIG. 1 is a simplified electrical diagram of a display device according to the invention,
• FIG. 2 shows a first embodiment of a device according to the invention,
• FIG. 3 represents a second embodiment of a device according to the invention,
• FIG. 4 represents a third embodiment of a device according to the invention,
• FIGS. 5a, 5b show an inert mine equipped with a display device according to a fourth embodiment, FIG. 5b being a partial view of FIG. 5a in the direction F,
• Figure 5c shows only the short circuit mounted on the circuit of Figure 5b.
• Figures 6a and 6b are front and back views of a fifth embodiment of a device according to the invention.

Referring to FIG. 1, a device for visualization of the change of state of a system 1 (which is not shown in detail) includes a circuit passive oscillator 2, integral with system 1, and a means of detection 3, outside system 1.

The passive oscillating electric circuit 2 comprises a choke 4, at the terminals of which a capacity 5. At terminals A and B of the oscillating circuit 2 is finds a short circuit 6 which can be opened by switching means 7 (such as a switch), actuated by a control means 8 at the time of a change of state of the system.

The system could for example be a munition (such a dispersible mine), and the change of state considered will be the neutralization of this mine (put out of state to be initiated).

The system could also be a device used in the civil field. For example a system indicating risk when entering a hazardous area (system changing state when a radio appears activity). Or a system accounting for the corrosion of a pipe or a metallic structure (in this case the short circuit will be opened by the corrosion).

The detection means 3 here comprises on the one hand a generator 9, containing an active oscillating circuit, and coupled to a transmitting coil 10, and on the other hand a take-up coil 11 connected to an amplifier circuit reception 12. The active oscillating circuit is tuned to the natural frequency of the passive oscillating circuit 2.

A bandpass filter 13 receives the signals transmitted by the generator 9 and those received and amplified by circuit 12. It isolates in the signal received by the coil 11 the lines which are due to the magnetic field emitted by coil 10, this in order to avoid disturbances due to outdoor fields.

The filter 13 could for example be a filter synchronous whose principle is well known to the man of the job.

The filter is connected to a variation detector 14 which is itself connected to a signaling means 15 (display, headphones or speaker ...).

The operation of this device is as follows:

Switch 7 is closed when the system is located in its first state, for example for ammunition, the active state. Short-circuit 6 is then effective and the passive oscillating circuit 2 is inactive.

If we then approach the detection means 3, the field electromagnetic emitted by the coil 10 can not put in resonance of the passive circuit 2. The take-up coil 11 does not therefore detects no signal emitted by the inductor 4.

When system 1 changes state (for example when ammunition is neutralized), switch 7 is open by the control means 8.

Terminals A and B of passive circuit 2 are no longer then short-circuited and the passive oscillating circuit 2 can be brought into resonance by the detection means 3.

When the detection means 3 passes close to the system 1, the field emitted by the coil 10 generates a current in the passive circuit 2.

This current causes a modification of the field magnetic near the passive circuit. This modification results in a variation in the amplitude of the voltage across the receiving coil 11. This variation is detected by detector 14 which activates the signaling means 15.

Such an embodiment of the detection means 3 allows to separate the "generation of a field" function magnetic "and the function" detection of a disturbance of the field ". We can therefore choose inductance values different for coils 10 and 11, good values adapted to the function of each coil.

We then easily detect imbalances in the magnetic field caused by the passive circuit and it results in a significant sensitivity for the means of detection.

Other means of detection could be envisaged, for example an active oscillating circuit comprising a single transmitting antenna and connected to a variation detector. The active circuit is then still tuned to a frequency which is the same as that of the passive oscillating circuit 2.

When the passive circuit is no longer short-circuited, the active oscillating circuit is unbalanced due to the coupling which takes place between it and the passive circuit 2.

This translates for example, for the active circuit, by a variation in its frequency, amplitude or consumption according to the assembly which is selected (such montages are classic and well known to the man of the job).

The variation detector chosen will also be of the type known (for example a synchronous detector) its threshold of sensitivity will be adapted to allow detection of the passive circuit at an acceptable distance (for example from the order of the meter).

The active oscillating circuit could also be a circuit generating a swept frequency (variable frequency) whose domain of variation will cover the natural frequency of the passive oscillating circuit 2.

Figure 2 shows the display device according to the invention adapted to a system 1 which is a munition (not shown in detail) with an explosive charge 16 (here a hollow charge), initiated by a relay 17, itself initiated by an electric primer 18 connected to a rocket electronics 19.

The primer 18 is carried by a drawer 20 which is part a security and arming device of known type (we see for example patent FR2650662 which describes a such device). The drawer is shown here in position safety (primer 18 not aligned with relay 17). he can translate so as to bring the primer 18 opposite of relay 17 (armed position).

The short circuit 6 is produced here in the form of a wire 24 of small diameter (of the order of 0.1 mm). Ways short circuit breakers are made up of a part 21 of the short-circuit wire 6 which is placed in contact with the primer 18.

We could for example glue this part 21 of the wire on the primer 18.

When the primer 18 is initiated in the position of safety of drawer 20 (as shown in the figure 2), the mechanical and thermal energy developed breaks the short circuit wire 6, which has the effect of making the passive circuit 2 detectable by the detection means 3.

With the drawer in the safety position, the initiation of the explosive charge does not intervene, but the ammunition is then found without primer, therefore neutralized.

The invention makes it possible to view this neutralized state, even if the ammunition is completely invisible (for example a buried mine).

Alternatively, it is possible to place the wire short circuit 6 at some distance from the initiator, the energy developed by it being sufficient to ensure the destruction of the wire.

Wire 24 can also be replaced by a ribbon thin conductor, for example a conductor deposited or screen printed on a plastic support.

The wire 24 can also be produced in the form a printed circuit track positioned in the vicinity or in contact with the primer.

It is also possible to make the wire short circuit attached to an organ which moves during the charge neutralization. For example an organ sterilization mechanics moving at the end of a period pre-programmed by a chronometric system and intended to block the primer holder drawer. We can by example consider a security and arming device of the type described by patent FR2662242.

In this case, the short circuit wire will be attached to the mobile organ which will ensure its rupture.

The cutting means 7 could also be constituted by a switch opened by the movement of the mobile organ.

Figure 3 shows a display device according to a second embodiment of the invention.

System 1 is again a munition whose charge explosive (not shown) is initiated by a primer electric 18 connected to an electronic rocket 19.

The rocket is powered by an energy source 22, like a lithium battery.

The ammunition is usually considered to be neutralized when the energy source is discharged because it can then no longer cause the initiation of the primer.

The breaking means 7 of the short circuit 6 are here constituted by a passive semiconductor switch which is for example a transistor 23 of MOS technology (Metal Oxide Semi conductor). This transistor is here of the type "channel N", that is to say that it lets the current flow for a positive tension between its base (G) and its source (S).

The Drain (D) and the source (S) of this transistor are connected to terminals A and B of the passive oscillating circuit 2. The base (Gate G) of the transistor is connected to the positive output (+) of the voltage source 22 which supplies the rocket 19. The negative output (-) of the voltage source 22 is also the common pole of all circuits and it is connected to the source (S) of transistor 23.

• lorsque la tension entre base (G) et source (S) est supérieure à Vmax, le transistor est saturé (Source (S) et Drain (D) sont reliés),
• lorsque la tension entre base (G) et source (S) est inférieure à Vmin, le transistor est bloqué (Source (S) et Drain (D) ne sont plus reliés).

A MOS type transistor has a threshold range, that is to say a voltage range Vmin / Vmax such that:

• when the voltage between base (G) and source (S) is greater than Vmax, the transistor is saturated (Source (S) and Drain (D) are connected),
• when the voltage between base (G) and source (S) is less than Vmin, the transistor is blocked (Source (S) and Drain (D) are no longer connected).

We could for example have Vmax = 2 volts and Vmin = 0.5 Volts.

When the voltage across the source 22 is greater than the transistor switching threshold range 23 (i.e. greater than 2 volts), the latter is saturated. The transistor then bypasses the circuit oscillating 2, Drain (D) and source (S) are connected.

When the energy source is discharged, its voltage becomes lower than the threshold range of transistor 23 (less than or equal to 0.5 Volts). The transistor is located then blocked, which means that Drain (D) and source (S) are no longer connected and the short circuit 6 is open.

The MOS will be chosen so that the voltage at which occurs its blocking (Vmin) is less than the minimum tension which would allow initiation of the primer.

This ensures that short circuit 6 opens when the source voltage no longer allows the initiation of the primer.

The oscillating circuit 2 can then be put into resonance by the detection means.

The ammunition which is neutralized following the discharge of its energy source can therefore be easily detected. Detection is possible even if it is a buried mine.

As a variant, it is possible to replace in circuit 2 capacitance 5 by MOS transistor 23 even. Indeed the latter has an internal capacity between Drain (D) and source (S) of the order of 100 pico-farads that it is possible to use to realize the circuit passive oscillating 2.

Figure 4 shows another embodiment of the invention in which the switching means comprise a static switch (MOS transistor 23) mounted in series with a wire 24 of small diameter comprising a part 21 placed in contact with the primer 18.

This embodiment makes it possible to make the passive circuit 2 when the neutralization is due to initiation of primer 18 or when it is consecutive to the discharge of the energy source 22.

Figures 5a, 5b, 5c illustrate another mode of embodiment of the invention more particularly intended for allow, during demining operations, detection dummy mines.

The invention makes it easy to detect mines neutralized among those that are still active. We thus facilitates and accelerates demining operations, because it is no longer necessary to take precautions for identify neutralized mines.

For reasons of savings, today more and more minefields in which are mixed real mines and dummy mines.

In order to maintain the effectiveness of the minefield, it is essential that dummy mines cannot be easily detected by enemy troops.

However, when looking at the end of the conflict to demining an area, it is not possible to distinguish a real mine still active and a dummy mine. It results in a slowdown (and an additional cost) in operations, because every precaution must be taken to treat seemingly suspect mines.

The preceding embodiments facilitate the demining operations by allowing the visualization of real mines which are neutralized.

However, they cannot be used in a dummy mine that contains no electronic circuit.

However, it is possible to adapt the display according to the invention to such dummy mines.

A first solution to this problem is to endow the dummy mine of a chronometry module which receives during laying of the mine a program corresponding to the duration of employment envisaged for the minefield.

This chronometric module can be mechanical and understand for example a piston which will move at the end of the period programmed to break the short circuit of a passive oscillating circuit according to the invention.

The time module can also be electronic and order at the end of the programmed interval the blocking a static switch.

FIG. 5a shows another very embodiment inexpensive in which no timekeeping system is necessary.

The dummy mine 25 includes a housing 26 in which a passive oscillating circuit 2 is placed.

This oscillating circuit is produced here in the form of electronic components soldered to a printed circuit 27 (see also Figure 5b).

The circuit is embedded in a protective resin 28 which fills the entire housing 26. The short circuit 6 has the shape of a jumper mounted on pins carried by the printed circuit 27. Only short circuit 6 is located the outside of the resin 28.

The short circuit 6 is shown alone in FIG. 5c. It includes a bulb-shaped support 29 (made of glass or plastic) on which the pins are fixed connection 30. A small diameter wire 31 is disposed between the pins 30 inside the bulb 29 which constitutes a sealed receptacle.

The wire is chosen from a material which oxidizes on contact air humidity (for example a material based of iron).

We will choose the wire diameter according to the duration of employment planned for the minefield.

When setting up the exercise mine, we breaks an upper face of the bulb 29 which puts the wire in communication with ambient air and humidity outside.

At the end of a time interval (of the order of a few days) which corresponds to the duration of use of the field corrosion, corrosion completely attacked wire 31 which broke thus making the passive oscillating circuit 2 detectable.

As a variant, it is possible to place in the bulb when laying the mine a material corrosive intended to attack the wire. This variant allows to control more easily the time necessary for break the short circuit, since the kinetics of the chemical reaction used is well known.

Figures 6a and 6b show another mode of particularly cheap realization in which the passive oscillating circuit 2 is carried by a label 32 made of a flexible plastic material, for example Nylon (or even paper).

A label with a passive oscillating circuit is known for example in the field of anti-theft systems intended for businesses (see for example the patent GB2105952).

The label 32 carries on each of its faces a deposit metallic. The deposit will be made for example by screen printing. All the conductive deposits constitute a oscillating electric circuit comprising an inductance 4 at the terminals of which a capacitor 5 is mounted, circuit shunted by a short circuit 6.

A reinforcement 5a of the capacity is carried by a face of label 32, the other frame 5b is carried by the other side of the label. Label material constitutes the dielectric of this capacitance.

The inductance is carried by a single face of the label and it is formed by a conductive track in spiral shape. The frame 5b of the capacity is connected to the inductance by a connection 33 which crosses the label.

We could for example make the connection by providing a hole through the label and which is filled after production by a conductive material. We will be able to also metallize the hole.

The short circuit 6 here passes from one face to the other by one of the edges 32a of the label. It will suffice for this to make the circuit on one side of a sheet which will then be folded along the edge 32a and glued, the connection 33 is made after gluing the sheet.

The entire circuit is covered with a layer of protective varnish except for zone 34 which leaves part of the short circuit 6.

This unprotected area is covered with an adhesive protector 35.

The circuit thus produced is glued to a mine dummy.

When the mine is used, the adhesive is removed protector 35 so as to leave in contact with moisture of air the part of the short circuit 6 which is not protected.

Corrosion will eventually destroy this part making thus the passive circuit 2 detectable.

We will choose the material of the short circuit as well as the size of the area which is not protected according to the expected length of employment for the minefield.

Alternatively, we can replace when applying the protective adhesive with another adhesive made of a material forming an electrolytic couple with the short circuit material. We could for example associate aluminum with copper.

The materials forming the electrolytic couple are mutually degrade according to chemical kinetics which is well known and easy to master.

Such an arrangement makes it possible to define more precisely reliable the time required to open the short circuit 6.

Claims (10)

1. A system state change display device and notably a device to display the neutralised state of a piece of ammunition such as a mine, characterised in that it incorporates at least one passive oscillating circuit, integral with the system, and tuned to a certain frequency, a short-circuit being mounted onto the terminals of said circuit, said short-circuit being able to be opened by circuit-breaking means activated when the system changes its state, such passive oscillating circuit being intended to resonate by a detection means external to the system and comprising at least one active oscillating circuit tuned to the frequency of the passive oscillating circuit.
2. A device according to Claim 1, characterised in that the circuit-breaking means are activated in response to the functioning of a primer intended to ensure the ignition of the ammunition.
3. A device according to Claim 2, characterised in that the circuit-breaking means comprise part of the short-circuit that is a conductor placed in the vicinity or in contact with the primer.
4. A device according to Claim 3, characterised in that the circuit-breaking means comprise at least one semi-conductor-based passive switch that is activated during a system state change.
5. A device according to Claim 4, characterised in that the passive switch is activated in response to the discharge of a power source placed in the ammunition and intended to ensure the ignition of an ammunition primer.
6. A device according to Claim 5, characterised in that the passive switch is a MOS transistor whose base is connected to the power source and that is opened when the voltage of the power source is below a threshold voltage of the transistor.
7. A device according to Claim 3 and one of Claims 5 or 6, characterised in that the circuit breaking means comprise a semi-conductor-based passive switch mounted in series with a conductor passing in the vicinity or in contact with the primer.
8. A device according to Claim 1 and more particularly intended for a dummy mine placed among real mines, characterised in that the circuit breaking means comprise a portion of circuit able to corrode until opening the circuit after a certain lapse of time.
9. A device according to Claim 8, characterised in that the non-protected- part of the circuit is covered at least partially by a corrosive substance when the mine is set into place.
10. A device according to one of Claims 8 or 9, characterised in that the non-protected part is able to receive at least one material with which it forms an electrolytic coupling.

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