EP0419347A1 - Protection system, especially for motor vehicles, of type comprising an apparatus such as an electronic control device of an alarm arragement - Google Patents

Abstract

The invention relates to a protection system. This system comprises an electronic control device (4) of an alarm device (5) and a lock (1) with a key (2) mounted in an electrical circuit with two states electrically linked to the said electronic device (4) and of which the two states are respectively determined by the position of the lock as a function of the position of the key, the establishment of one of the said states applying the electrical voltage to the system while in the other state the system is inhibited. The system is characterised in that the lock (1) is separated from the installation (6) of the electronic device (4) and linked to the latter by a bundle (3) of electrically conducting wires which comprises electrical linking wires (11, 12) between the lock (1) and the electronic device (4) and advantageously a plurality of supplementary wires (15, 16, 17), and in that the extremities of at least some (15) of the latter are free at the level of the area of electrical connection (9) of the linking wires (11, 12) to the lock. The invention is usable for automobile vehicles. <IMAGE>

Description

The invention relates to a protection system, in particular for motor vehicles, of the type comprising an apparatus such as an alarm device, for controlling an alarm, a siren or the like, and a switching device controlled by a control member. advantageously personalized actuation, and mounted in an electrical circuit with two states determined by the position of the switch device, the establishment of one of said states putting the system in operating state or in standby, while in the other state, the system is inhibited, the switch device being separated from the device and connected to the latter by electrically conductive wires of electrical connection.

In known systems of this type, the device, generally an electronic device, is arranged inside a box. The switch device, generally a lock, is mounted thereon so that the electrical connection device of the lock to said electronic device is also inside the box and is therefore inaccessible.

However, it has proved advantageous to be able to separate the lock locally and the electronic device and to have them at locations more or less distant from each other. However, such an arrangement has the major drawback that the device for the electrical connection of the lock to the electronic device, when it is established by electrically conductive wires, becomes accessible, which makes unauthorized interventions possible with a view to inhibiting the electronic device and so the alarm device, reproducing the same conditions at the entry of the electronic device that causes the installation of the key in the lock.

The present invention therefore aims to provide a protection system which is adapted to provide security against such unauthorized inhibitions of the system.

To achieve this object, the protection system according to the invention is characterized in that the device is placed in a location that is difficult to access, that the state of the switching device causes a predetermined type of electrical connection between said electrical connection wires, the device comprising means for recognizing the type of link and for putting the device in the on or standby state or in the stop state depending on the type of link detected, and in that these link wires electrical are arranged in a bundle of conductive wires, which further comprises at least one additional wire which extends into the electrical connection area of the connecting wires to the switching device, without being electrically connected thereto, the electrical connection area being carried out so as to prevent access to this zone and the distinction between the connecting wires and the additional wire.

According to an advantageous characteristic of the invention, the additional wire is free at the level of the electrical connection zone of the wires connecting to the switching device.

According to another advantageous characteristic of the invention, at least two additional wires of the bundle are connected to each other in the area of aforementioned connection so as to form a closed loop connected at its two ends to the electronic device and in that the latter is suitable for detecting a break in the loop and triggering an alarm.

According to yet another advantageous characteristic of the invention, the bundle of wires is covered in the connection zone by a means forming a cover, so as to prevent access to this zone and the distinction of the connection wires in the bundle.

• La figure 1 montre schématiquement un premier mode de réalisation d'un système de protection selon la présente invention ;
• La figure 2 est une vue de détail d'un détecteur de coupure du faisceau, selon l'invention ; et
• Les figures 3 et 4 montrent schématiquement deux autres modes de réalisation de l'invention.

The invention will be better understood and other objects, characteristics, details and advantages thereof will appear more clearly during the explanatory description which follows, made with reference to the appended schematic drawings given solely by way of example illustrating a mode of the invention and in which:

• Figure 1 schematically shows a first embodiment of a protection system according to the present invention;
• Figure 2 is a detail view of a beam cutoff detector according to the invention; and
• Figures 3 and 4 schematically show two other embodiments of the invention.

In its embodiment shown by way of example in FIG. 1, the protection system according to the invention comprises a switching device 1 formed by a lock with its key 2 forming the control member, which is connected by a beam 3 electrically conductive wires to the electronic device 4 for controlling an alarm device 5. These two devices are only shown schematically. Indeed, their structure itself is not part of the invention. These are devices known per se. They are placed in a location that is difficult to access in the vehicle and advantageously enclosed in a box indicated diagrammatically at 6. The bundle 3 of electrical wires is placed in a sheath 7.

The lock 1 of which only the barrel is shown diagrammatically is provided with a sleeve 8 which is fitted coaxially on the barrel and engages by its other end on the sheath 7, delimiting an internal space 9 into which the sheath 7 which surrounds the bundle of wires 3 including two wires indicated in 11 and 12 are electrically connected to lugs 13 associated with the lock and constituting the connection terminals of an internal electrical circuit of the lock 1. This circuit is not shown in the since its configuration does not come within the scope of the invention. It is known per se. It suffices simply to remember that this circuit is of the type with two states each caused by a position of the lock determined by a predetermined position of the key 2. The wires 11 and 12 pass through the sheath 7 to the casing 6 to the inside of which they are connected by a specific assembly to the electronic device 4. As clearly shown in FIG. 1, the wire 11 is connected, on the one hand, by a resistor R1 to the device 4 and, on the other hand, by a resistor R2 to the control electrode of a switch member TR, such as a field effect transistor, for example of the N-MOS type. The wire 12 is connected directly to the source of the transistor TR, which is grounded. The control and source electrodes are interconnected by a capacitor C1. The drain of the transistor is connected to the electronic device 4. At the connection terminal of resistor R1 at device 4 has a positive potential so that the circuit formed by resistors R1 and R2 and capacitor C1 constitutes a delay circuit.

The bundle 3 comprises, in addition to the wires 11, 12 for electrical connection, a plurality of additional wires. In the example shown there are three of these wires. It can be seen that one of the three wires, indicated at 15, is connected at one end to the drain electrode of the transistor TR, while its other end, inside the covering sleeve 8, that is to say say in the connection zone 9 of the harness to the lock 1, is free, that is to say in the air. The other two wires 16 and 17 are electrically connected to each other, at 18, in the zone of connection to the lock 1 of the wires 11 and 12. By their other ends, the wires 16 and 17 are respectively connected in the box 5 to ground and to the electronic device 4.

The electronic device 4 comprises a circuit for detecting the state of the loop formed by the wires 16 and 17. This circuit is shown diagrammatically in FIG. 2 and includes a comparator 20 advantageously produced in the form of an operational amplifier 20, the l negative input is connected to wire 17 via a resistor R3. This input is also connected, on the one hand, by a resistor R4 to a positive potential and, on the other hand, by a capacitor C2 to ground. The positive input is connected by resistors R5 and R6 respectively to a positive potential and to ground. The output of comparator 20 produces a signal for example in the form of a transition from a logic state "1" to a logic state "O" following a detection of a change of state of the loop formed by wires 17 and 16, for example produced by a break in this loop.

The operation of the protection system which has just been described will be described below with reference to FIGS. 1 and 2.

The electrical circuit associated with the lock 1 is adapted so that the positioning of the lock, in a predetermined position by the key, causes the circuit to close, which corresponds to a short-circuiting of the wires 11 and 12 of the electrical connection of the lock 1 to the electronic device 4. This state causes inhibition of the electronic device and thus of the protection system. On the other hand, another position of the lock 1, determined by the key and, if necessary, allowing its removal, causes the opening of the lock circuit and the supply of electrical energy to the protection system. It is easily understood that a short circuit of the connecting wires 11, 12 at any place between the lock and the box 6 would then also produce inhibition of the system. However, these wires are accessible and there is therefore the risk that unauthorized third parties cut these wires and, by short-circuiting them, inhibits the system. However, by providing in the bundle 3 a certain number of additional wires which are not electrically active, such as the wire 15, the aforementioned unauthorized person is obliged to combine the wires with each other in order to short-circuit the wires 11 and 12. Since the ends of all the wires are hidden in the space 9 delimited by the sleeve 8, an identification of the active wires 11 and 12 from the connection lugs 13 is excluded. In addition, all the wires in the bundle have the same appearance. It can also be seen that a general short circuit, due to the connection of wire 15 to the drain electrode of the transistor TR restores the electrical energy supply to the system.

By providing in the bundle of wires 16, 17 which form a loop, cutting the bundle of wires would cause the loop to break and thus change its state. This change will be detected by the circuit according to FIG. 2. In fact, the output of comparator 20 is in the high state as long as the loop is closed. To this end, the electrical potential at the negative input of the comparator is negative with respect to the positive input, the reference potential of which is determined by the resistors R5 and R6. A break in the loop changes the potential at the negative input which therefore goes from its potential below the reference potential at the positive input to a level above the reference potential, which causes a change of state at the output of the comparator, which then goes from high level to low level, as indicated schematically in FIG. 2. This change of state is likely to trigger the alarm.

It should also be noted that putting the key 2 in the lock 1 and thus the short-circuit of the wires 11 and 12 using the key cuts the transistor TR only after a time delay predetermined by the time constant the delay circuit formed by the resistors R1 and R2 and the capacitor C1. Of course, the transistor TR is conductive when the lock is in the "on" position, that is to say the switch is open. It should also be emphasized that in the absence of the loop formed by the wires 16 and 17, cutting the bundle of wires would have no effect on the system when the key is removed.

It appears from the above description that the invention is applicable to protection systems where the lock is separated from the remaining part of the system, this remaining part being in an inaccessible location. The invention makes it possible to remotely inhibit all the functions of the protection device which could be a device on board a vehicle. The bundle of electric wires connecting the lock to the remaining part of the system is constructed in such a way that a cut made using an appropriate tool does not modify the state of the system, in the same way as a short -circuit other than that of the two active wires 11 and 12 does not affect the state of the system. Among the many possible combinations between the different wires, only one combination, that is to say the short circuit of the wires 11 and 12, allows the inhibition of the system. If the beam includes a beam cutoff detection loop such as the loop formed by the wires 16 and 17, this break, which in the example shown is a ground break, triggered the alarm device.

Figure 3 shows the electrical diagram of a second embodiment of the invention. In this embodiment, the two electrical connecting wires 11, 12 of the wire bundle are connected in the zone 9 of connection of the bundle to the lock or, in general, to a switching device 1 actuable advantageously by a control member personalized, by a switchable circuit between two different impedance states. This circuit comprises two resistors or impedances R8 and R9 connected in series between the two wires 11 and 12. A switching member, such as the switch 22 is mounted in parallel on the resistor R8. In box 6, wire 11 is connected to the negative input of a first comparator 23 and the positive input of a second comparator 24. The positive and negative inputs of comparators 23 and 24 are respectively connected to potentials of reference PR1 and PR2, PR1 being greater than PR2 by predetermined differential value. The outputs of the two switches are connected to the two inputs of a NAND gate 25 whose output is connected via a resistor R10 to the control input of a switching transistor such as a unijontion transistor TRC mounted between ground and the electronic device 4 of the box 6. The control electrode of the TRC transistor is also connected to ground via a capacitor C3. Resistor R10 and capacitor C3 constitute a delay circuit. It should also be noted that the junction E of the wire 11 and the negative and positive inputs of the comparators 23, 24 is connected to a positive potential by a resistor R11.

In this embodiment, the device formed by the switches, the NAND gate and the TRC transistor constitute a circuit which makes it possible to detect a change in impedance of the connection circuit of the wires 11 and 12, following a actuation of the switch 22. The change in impedance causes a change in the state of the switch transistor TRC only when the potential at the combined inputs E of the comparators is between the two reference potentials PR1 and PR2. Indeed, it is only in this case that the outputs of the switches pass to state 1 which causes the output potential of gate 25 to go from its high state to low state and the change of state. of the TRC transistor.

Consequently, to cause the change of state of the transistor TRC entailing the inhibition of, for example, an alarm system, unauthorized persons, even after having successfully discovered the connecting conductive wires 11, 12 in the beam must still find the appropriate impedance so that the potential at point E takes a value between the two potentials of reference. This difficulty can be further increased by modifying at certain moments the reference potential values and impedances during the manufacture of a series of protection systems or even after their installation.

FIG. 4 illustrates a third embodiment of a protection system according to the invention, in which the change of state of the switching member OC inside the box 6, which is formed in the two other modes of realization by the transistors TR and TRC, is switched only by a predetermined code formed for example by a particular sequence of pulses. According to the diagram in FIG. 4, in addition to the conducting wires 11 and 12, a third active wire 27 is used which is used to transmit the code through the beam from the switching device 1 to the box 6 and to allow, if necessary, a dialogue between these two.

The protection system according to FIG. 4 comprises, on the side of the switching device 1, a switch 29 and a generator of a coded signal 30, between the wires 11 and 12. Inside the box 6, a module is provided recognition code 31 which is capable of producing a closing output signal from the switching member OC. The wire 27 connects the output of the code generator 30 to the appropriate input of the code recognition module 31. The generator 30 and the module 31 can be formed by circuits programmable by an OR computer. This measure makes it possible to change the code, for example using a control keyboard possibly associated with the computer. The signals which will be transmitted by the electronic device 4 via the wire 11 to the code generator 30, when the switch 29 is closed, can be constituted by a continuous signal or by pulses clock. In the latter case, the generator will be equipped with a rectifier circuit to produce the supply voltage necessary for the operation of the generator. Figure 4 shows that in this embodiment, as elsewhere in that of Figure 3, the additional son 15, 17, 18 can be provided as in the case of the first embodiment.

Of course, numerous modifications can be made to the system according to the invention as described and shown. Thus the number of wires can be greater, which further increases the security of the system against unauthorized inhibitions.

It should be emphasized that the switching device actuable by a personalized member can be of any suitable nature. It can be a lock actuated by a key or another more or less complex device. The device which is placed in a location which is difficult to access, that is to say the box 6 in the embodiment shown, can be formed by any suitable device, such as an electronic alarm control device, an alarm device, a siren or the like.

Claims (13)

1. Protection system, in particular for motor vehicles, of the type comprising an apparatus such as an alarm device, for controlling an alarm, a siren or the like, and a switch device controlled by an advantageously personalized actuating member. , and mounted in an electrical circuit with two states determined by the position of the switching device, the establishment of one of said states putting the system in operating or standby mode, while in the other state, the system is inhibited, the switch device being separated from the device and connected to the latter by electrically conductive wires of electrical connection, characterized in that the device (6) is placed in a location which is difficult to access, that the state of the switch device (1) causes a predetermined type of electrical connection between said electrical connection wires (11, 12), the apparatus comprising means for detecting the state of said electrical circuit risk (TR; 23 to 25, TRC; 31, OC) and to put the device in the on or standby state or in the stop state depending on the type of connection detected, and in that the wires of electrical connection (11, 12) are arranged in a bundle of conductive wires (7), which further comprise at least one additional wire (15) which extends into the electrical connection area (9) of the connection wires (11, 12) to the switching device (1), without being electrically connected thereto, the electrical connection area (9) being designed so as to prevent access to this area and the distinction of the connecting wires (11, 12 ) and additional wire (15). 2. Protection system according to claim 1, characterized in that the additional wire (15) is free at the level of the electrical connection area (9) connecting wires (11, 12) to the switching device. 3. Protective device according to one of claims 1 or 2, characterized in that at least two additional wires (17, 18) are connected to each other in the aforementioned connection zone (9) forming a closed loop connected at its two ends to the device (6) and in that the latter is suitable for detecting a break in the loop and triggering an alarm. 4. Protection device according to one of claims 1 to 3, characterized in that the bundle of wires (3) is covered in the connection zone (9) by means forming a cover, advantageously in the form of a sleeve (8 ), so as to prevent access to this zone and the distinction of the connecting wires (11, 12) in the bundle (3), and in that all the wires in the bundle have the same appearance. 5. Protection device according to one of the preceding claims, characterized in that the bundle of wires (3) is surrounded by a protective sheath (7). 6. Protection device according to one of the preceding claims, characterized in that it is adapted so that a cut in the beam (3) is considered as a change of state of the device (6), capable of triggering an alarm. 7. System according to one of the preceding claims, characterized in that it comprises a circuit detecting the state of the electrical circuit associated with the switching device (1) and electrical connecting wires (11, 12), which is connected to the device (6) and comprises a switch member (TR, TRC, OC) whose state is determined by the state of said circuit and said wires. 8. Protection system according to claim 7, characterized in that the detector circuit comprises a delay circuit (R1, R2, C1; R10, C3) which is adapted so that only on detection of a change of state of the connecting wire connection circuit (11, 12) having to produce the inhibition of the device, this inhibition occurs only after a predetermined period of time. 9. System according to one of the preceding claims, characterized in that the switch device (1) comprises an electrical connection circuit between the electrical connection wires (11, 12), which has two states determined by the control member (2), namely the short circuit and open circuit states, the closed circuit state being a condition of inhibition of the system. 10. Protection system according to one of claims 1 to 9, characterized in that the switch device (1) comprises an electrical connection circuit of the two wires (11 and 12), which is a circuit with two impedance states (R8, R9) different. 11. Protection system according to claim 10, characterized in that the electrical connection circuit with two different impedance states includes a series connection of two impedances (R8, R9) and a switch (22) actuable by the member control (2), which is mounted in parallel on one (R8) of the two impedances. 12. System according to one of claims 10 or 11, characterized in that the circuit detecting the state of the electrical circuit associated with the switching device (1) comprises two comparators (23, 24) to the negative and positive inputs of which a potential representative of the impedance of the connection circuit is applied while the respectively positive and negative outputs of the comparators (23, 24 ) are connected to different reference potentials so that only a potential representative of the state of the connection circuit generates a state change signal in the apparatus (6), which is between the two reference potentials. 13. Protection system according to one of claims 1 to 9, characterized in that the switch device (1) comprises an electrical connection circuit between the electrical connection son (11, 12), which comprises a generator of specific coded signal and a switch (29) operable by the control member of the switch device for the commissioning of the generator, and the apparatus (6) comprises a code recognition module (31) and a switch member (OC ) controlled by the module (31), to cause a change of state in the device following the sending by the generator (30) to the recognition module (31), of said coded signal.

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