FR2764625A1 - Battery-less remote locking and unlocking command mechanism for electronic locks - Google Patents

Abstract

The battery less distance command mechanism has a key which exchanges electronic coding with a lock either using direct energy transfer if the electrical generator module is in the lock or inductive coupling if the generator module is situated in the key. The electrical energy is created by lateral movement of two piezoelectric strip elements (41,42), and electrical outputs are produced from electrodes (43,44,45) and stored in a circuit and digital commands created to open the lock.

Description

 The present invention relates to a device for transmitting or triggering a remote action by induction or electrical conduction, under the control of an electronic system.

 The device collects energy in its environment, converts it into electrical energy, stores this energy then delivers it to an actuator which performs the action under the control of electronics.

 More specifically, the device consists of two modules connected by an inductive or conductive link. The first, called generator module, ensures the conversion of energy into electrical energy, its storage and transmission under the control of suitable electronics. The second called actuator module ensures the reception of energy, its storage and action under the control of suitable electronics.

 Such a device is particularly indicated wherever an action must be controlled by an electronic process, without recourse to an energy source such as a battery or a power supply being possible.

 According to a first embodiment of the invention, the generator module converts a flow of heat into electrical energy then stores and transmits this energy.

 According to a second embodiment of the invention, the generator module converts mechanical work into electrical energy, then stores and transmits this energy.

 The actuator receives energy by inductive coupling or wire connection, stores this energy in a reserve then triggers the action under control of the electronics. This action produces the expected work.

This invention applies to various fields, among which we will more particularly retain
- The electronic lock:
The expected action corresponds to the uncoupling. Electronic control corresponds to the exchange of codes between the lock and the key. Finally, energy can be converted from the work of inserting the key into the lock or from the heat dissipated in the key by the user's hand.

 The electronic lock comes up against the need to ensure perfect reliability in its operation. The use of batteries makes the lock dependent on their autonomy and imposes an unacceptable duty on the user, that of replacing the batteries and preventing their wear.

 The electronic lock is opened by an electronic key which transmits the opening codes to it.

 According to the invention the exchange of codes and energy between the key and the lock is carried out exclusively by inductive coupling.

 The electronics of the key and the lock are supplied by the generator module. After recognition of the code, the actuator module in the lock pins and releases the rotation of the cylinder for the translation of the bolt.

 According to the invention, if the generator module is in the key, and the actuator module in the lock, energy is transmitted from the key to the lock, and the codes are exchanged by means of an inductive coupling.

 On the other hand, if the generator module and the actuator module are in the lock, the energy required for the key is transferred by inductive coupling like the codes, then the energy required for actuation is transferred to the actuator module by direct electrical connection.

 The principle of a thermal generator is exposed in the French patent application 96 14 734 of the same inventor Energy converter circuit, power supply device using this converter and devices powered by this power supply device>>.

 In the context of the invention, the application of this converter to a module taking energy from a heat flow ensures the generation, storage and transmission of a quantity of energy.

 The first embodiment of the generator module comprises a device for converting heat flow into electrical energy, the means for storing and transmitting this energy under the control of electronics to a lock. This first module will preferably integrate with a key, secondly with the lock.

 Principles of generator modules based on a piezoelectric conversion of the work of introducing the key are known and exposed in particular in French patents 2500520 and European patents 0 339 102.

 To date these principles have not been implemented due to a low conversion efficiency of the piezoelectric materials. In the small footprint of a household lock such as a European format lock, converting part of the work of introducing the key into an energy of around 20 mJ requires piezoelectric devices which appeared in the 1990s.

 In the context of the invention, we describe a second embodiment of the generator module whose work-electric power converter is a piezoelectric element. Its structure is optimized to fit into a lock or key.

 It is associated with electronic energy management, storage and transfer. An example embodiment of the electronics uses the principles set out in the French patent application 96 14 734.

Next, there is described an actuator module intended to be inserted in a lock, performing the unlocking from
The energy transmitted by inductive or conductive link, under the control of a code exchange electronics.

 According to the invention, the actuator is piezoelectric, and is optimized in order to provide the best operational safety when pinning.

Description of the generator module according to the first embodiment:
According to the first embodiment of the generator module, the lock and the key are supplied from the conversion into electricity of a heat flow.

In the environment of the lock, examples of heat flows can be used:
- Between the two faces of a door closing a room, there is a difference in temperature. This temperature difference is particularly high if the door is exterior, with one side in the open air and one side in the room.

 This temperature difference results either from the air conditioning of the room, or from the thermal inertia of the closed room.

 The heat of the room is exchanged with the outside by thermal leaks, in a closed room these leaks are slight, which ensures a permanent delay in the temperature balance between the inside and the outside.

 The heat flow passes through the metallic lock, therefore conductive. A fraction of this flow can be used to feed and maintain a reserve of energy integrated into the lock.

 The heat flux can be temporarily increased when taking a grip thermally connected to the lock and its thermal generator module.

 The principle is better explained in the light of Figure 1 which shows a half-lock in Europe format.

 The cylinder It is extended by a wheel 12 as for a lock.

Inductive contact or coupling with the key, 'actuator,
The code comparison electronics are not shown.

 The body of the lock 13 is integral with a thermally insulating bushing rod 14.

 The cylinder It is divided into two parts separated by a thermocouple module 16 electrically connected to electronics 17 described in patent application 96 14 734 with reference to FIG. 2/9. This electronics recharges a battery or a supercapacitor 18.

 The temperature is transmitted to the cylinder by the radiator wheel. The heat flow preferably passes through the metal cylinder then the thermocouple rather than the isolated door or rod 4. A temperature difference dT between the two faces of the door is transmitted by the cylinder 11 to the two faces of the thermocouple 16, the latter then generates a voltage and a current proportional to dT. This voltage is raised by the electronics 17 and the energy is permanently stored in the reserve 18.

 According to this process, a difference of 5 transmitted to the thermocouple makes it possible to generate approximately 30 microwatts, which is enough to use the lock 75 times a day.

 When the door is open, and the temperature difference between the faces is negligible, the lock remains activated by the battery or the super capacitor 18.

 The exchange of codes and energy with the key is carried out according to the state of the art, either through an inductive link, or through contacts. In this implementation, the generator module is integrated into the lock, it transmits its energy by direct connection to the actuator module, not shown.

- Between the epidermis of the key holder and the atmosphere, there is an almost permanent temperature difference of 15 ". This significant temperature difference can power a watch for example indefinitely. The function of an electronic key: to exchange codes, transmitting energy by inductive coupling or electrical contact, requires:
- a source of energy (for example thermal).

 - an analog energy management circuit.

 - a circuit for exchanging digital codes.

- a connection with the lock by induction or contact
dry.

 The energy source, the analog management circuit and the code management are resources that are profitably shared with a watch.

 Thus, the electronic key can be integrated into a wristwatch, be fed indefinitely by the heat flow which passes through it, share its digital resources with the watch, benefit from a display interface to communicate with the user.

 This key watch is equipped with a contactor or an inductive coupler to exchange codes and energy with the lock.

The lock is fitted with a contactor or an inductive coupler to exchange codes with the key watch and receive its energy.

 Figure 2 describes the electronic block diagram of the watch and the lock.

 21 represents the generator thermocouple, in contact with the temperature of the arm, connected to the conversion electronics 22 described in patent application 96 14 734 with reference to FIG. 1.

This electronics recharges the reserve 23, for example a supercapacitor, which powers a digital electronics and a watch mechanism 24. The digital electronics 24 contains the codes for opening the lock. The codes and the energy are transmitted by inductive link via an interface 25. The energy and the codes are received on the lock side via an inductive interface 26, the codes are exchanged with digital electronics 27,
The energy is transferred to an actuator 28.

 FIG. 3 represents the general structure of the montreclef 31 and its inductive contact 32. Opposite, there is shown the profile of the lock 33, the knob extending the cylinder 34, and the contact 35 used for the exchange of codes and the lock.

 The watch includes thermocouple sensors as shown in patent application 96 14 734 with reference to FIGS. 8 and 9.

 A watch powered as in patent application 96 14 734 has a power of about 100 microwatts, and a stored energy greater than the joule. This power and this reserve of energy are superabundant to control the unlocking of a lock.

 The opening of the lock occurs after connection of contacts 32 and 35 exchange and recognition of codes, by turning the cylinder by the knob 34. The connection from 32 to 35 is done simply by approaching the key watch of the lock and pressing 32 of 35.

 These two exemplary embodiments of a generator module converting a heat flux are non-limiting. They illustrate the use of two types of heat source, by two original implementations. One can also imagine recovering thermal energy directly from the hand of the user placed before opening on a thermal drain plate in contact with the thermocouple. One can also imagine adding to the thermocouple connected to the circuit in patent application 96 14 734 with reference to Figure 1. a photovoltaic cell as mentioned in the same patent.

 According to the second embodiment of the generator module.

 energy is taken from the work of introducing the key.

 More specifically, the electrical energy is generated by a piezoelectric component deformed repeatedly, during the introduction of the key.

 These deformations cause voltage variations at the terminals of a piezoelectric component accompanied by current flow in a specific converter circuit.

 At the output of the converter, the voltage is high and rectified, it loads a reserve, and supplies analog and digital electronics for the transfer and exchange of codes.

 According to the invention, the generator module can be located either in the key or in the lock.

 - If it is located in the key, the excitation of the module during the introduction of the key generates an energy stored in the key.

The energy is partially transmitted to the lock by inductive link or by contact, prior to the codes.

 Then, after recognition of the codes, the energy is transferred to the actuator, by the same link.

 - If it is located in the lock, The energy is generated and stored in the lock, it is partially transferred in the key with the codes by contact or inductive link, after recognition of the codes, The energy is transferred in direct link to the actuator.

 According to the invention, the piezoelectric component is a bimetallic strip, the characteristic of which is to bend under the effect of a voltage imposed on its terminals, or alternatively, to generate a voltage between its terminals under the effect of an imposed flexion.

 More specifically, this bimetal strip preferably consists of a sandwich of at least two piezoelectric ceramic blades, each provided with two electrodes. According to the conventional implementation of such bimetallic strips, shown diagrammatically in FIG. 4, the two blades 41 and 42 share an electrode 43 associated with its connection. Each blade is connected to its electrode and its output connection 44 and 45.

 These bimetallic strips are preferably made of multilayer ceramic allowing very low control voltages, but a massive structure also adapts.

 Finally, the bimetallic strips operating in '3-3' mode adapt like those operating in '3-1' mode.

 The piezoelectric behavior of a material is obtained after having subjected it to a very intense electric polarization field. Subsequently subjected to a fraction of this field, the piezoelectric stretches in the axis of the field: d33 and retracts in the plane perpendicular to the field: d31. Subjected to a sign field opposite to the polarization field, the piezoelectric depolarizes and loses its properties.

Bimetallic strips can be prepolarized in two ways, one corresponding to the series type, an almost universal arbitrary standard,
The other corresponding to the non-standard parallel type.

 Fiaure 5 corresponds to the classic series type, where the positive voltages U and V applied to terminals 43-44 and 45-43 conform to the polarizations of the bimetallic strip and are of opposite effect.

 FIG. 6 corresponds to the parallel type, where the positive voltages U and V apply between the terminals 43-44 and 43-45 respectively and have the opposite effect.

 The series type is particularly suitable for controlling the piezoelectric bimetallic strip in an actuator.

 The parallel type is better suited to converting mechanical work into electrical energy.

 According to the invention, the piezoelectric generator bimetallic strip is of the parallel d31 type.

 Indeed, for a parallel bimetallic strip whose voltages U and V are positive, a bending of the bimetallic strip of a displacement dx results in a variation of the voltage U of an amplitude dv and a variation of V of an amplitude of -dv.

 For a bimetallic strip at rest whose voltages are equal and positive U = V, the bending of the bimetallic strip causes a potential difference between 44 and 45 of 2dv.

 This 2dv voltage is generator, its exploitation by a conversion and rectification electronics ensures the supply of the generator module.

According to a preferred embodiment of the invention,
Energy is taken from the work of introducing the key, through repetitive bending of the bimetallic strip.

 Then the energy of each flexion is converted and stored in a reserve.

According to the invention, the energy storage reserve consists of two capacitors 71 and 72 consisting of two contiguous piezoelectric blades, and according to the invention,
The power supply electronics transfer the energy of each bending into the blade capacitors.

 Indeed, the two adjoining blades of the bimetallic strip are high-performance capacitors, the charge of which is distributed equally over each at voltage U = V does not affect the elastic and piezoelectric behavior of the bimetallic strip. The efforts of the two blades opposing, the deformation is zero.

 According to the invention, the power supply electronics uses an inductor, preferably that also used for the transfer of codes and energy to the actuator.

 According to a first embodiment, the power generated under voltage 2dv between terminals 44 and 45 is amplified rectified and reinjected between terminals 43 and 45 or 43 and 44. This operation is carried out by the circuit in patent application 96 14 734 in reference to Figure 2, associated with a bimetallic strip whose polarization voltages U and V are negative. The bimetallic strip is connected to this circuit by its terminals 43 and 44 in place of the element 21. The terminal 43 of the piezoelectric is then connected in U + of the element 32.

 According to a second embodiment, a parallel bimetallic strip with positive voltages U, V is associated with a single inductance, also intended for the transfer of codes and energy to the actuator module.

 According to the invention, this inductor is used in step-up type voltage booster mode to raise the 2dv voltage between 44 and 45 into a U or V voltage between 43 and 44 or 43 and 45, and this with the best efficiency.

 2dv being proportional to the bending, The energy is maximum when v is maximum. The conversion electronics detects the maximum of the voltage v and then triggers the conversion of this energy by transiently transferring it into the step-up inductance in the form of current. As of the charged inductance (which corresponds to a zero voltage across its terminals) a switching takes place and the relaxation then charges the capacitors associated with the two adjoining blades.

 The block diagram of the conversion electronics appears in FIG. 7 The bimetallic strip is electrically represented by its two associated capacitors 71 and 72, and the electrodes 43, 44 and 45.

Associated with this bimetal two switching and rectifying diodes 73 and 74, as well as an inductor 75. Finally the two identical functional blocks 76 ensure the switching of the currents.

 In addition, two additional switches, 77 and 78 serve for the function of exchanging codes and transferring energy to the actuator, their action is explained later.

 An exemplary embodiment of the module 76 is shown in Figure 8. Connected on one side to 44, the other to 45 and finally to the inductor, the module includes a switching transistor 81 protected by a diode 82. This transistor is controlled by a transistor 83 itself controlled by a transistor 84 whose emitter is connected to a peak detector made up of a diode 85 and a capacitor 86. Finally, the transistor 87 ensures the relaxation of the capacitor 86.

 At zero voltage the transistor 81 is blocked. As 2dv increases, the output potential of the diode 85 follows and the transistor 84 remains blocked. When 2dv decreases, the maximum having been reached, the output potential of the diode 85 becomes greater than the potential 44. Then 84 leads, 83 leads and 81 also. The current then flows freely through the inductor 75 and the diode 82bis of the second switch circuit.

As soon as the potential 44 becomes lower than the potential 45, the transistor 87 relaxes the charge of the capacitor 86, and jointly, the transistor 81 abruptly switches and interrupts the current.

 The inductor 75 then behaves as a current generator and relaxes through the diode 73 and the diode 86 bis in the piezoelectric capacitor 72.

Following this cycle, the capacitor 72 being charged,
The initial state of the two modules 76 is found and they will repeat the cycle symmetrically.

 The principle exposed is an example of implementation, the diagram can be applied to MOS transistors, one can add to it various protections.

 In addition, this circuit only includes transistors, diodes, and two low-value capacitors 86 and 86bis, so it is highly integrable and compact.

 Finally, the inductor 75 is a discrete component which is also essential for communication and transfer of energy to the actuator by inductive coupling.

 Its function will therefore be profitably shared, under the control of unrepresented digital electronics.

 The inductive transfer of energy takes place after complete insertion of the key in the lock.

 According to the invention, the inductance of the generator module and the inductance of the actuator module are air gap inductors whose magnetic circuit closes in the air as long as the key is not fully inserted, and whose coupling closes when the key is inserted.

 Thus, the generator module includes an inductor during the entire insertion phase of the key, phase during which the energy is generated converted and stored.

 Then, the inductance of the generator being coupled to that of the actuator module, the two coupled inductors constitute a transformer, through which the transfer of codes and energy takes place efficiently.

 For the exchange of codes as well as for the transfer of energy, the transistors 81 and 81 bis and the transistors 77 and 78 connected to the primary of the transformer that constitutes the inductor 75 produce a conventional H cutter known to man. art.

The piloting of these transistors under the control of a synchronization electronics makes it possible to transfer the power either at constant voltage ratio, or in step-up mode with variable ratio. In addition, the code exchange will be carried out simply in constant ratio transformer mode.

 The excitation of the bimetallic strip during the introduction of the key is described by two nonlimiting examples of implementation.

 The key introduction movement is a translation, the key is commonly in the form of a rod, the cylinder of the lock receives the rod of the key.

 The elongated bimetallic strip fits naturally either in the key shank or in the cylinder body, as mentioned on page 7.

 According to the invention, during the insertion of the key, the bimetallic strip is flexed repeatedly.

 The passage of the end of the bimetallic strip for example on notches excites the latter.

 This is shown in Figure 9. the bimetallic strip 91 contained in the key 92, connected to digital and analog electronics 93 connected to an inductor 94, is provided with a notched end 95 which rubs against the notches 96 of the lock 97 provided with an inductor 98.

After complete insertion, the bimetallic strip 91 is loaded,
The inductance of the lock is coupled to that of the lock and the exchanges take place.

 Another example of implementation uses a different mode of excitation, so as not to use notches to induce forced deformations of the bimetallic strip.

 This excitation mode is based on the resonance of the generator bimetallic strip, at its natural frequency. This principle optimizes the yield and the robustness of the process. The high quality factor of the bimetallic strip guarantees lasting resonance, the excitation just compensates for the energy taken up by the converter, in order to maintain the maximum amplitude of the oscillation.

 FIG. 10 schematizes this process: the bimetallic strip 11 inserted in the cylinder of the lock 12 is in contact with a rubbing roller 13 for example made of Bakelite, itself driven in rotation by the metal rod 14 of the key 15. The friction achieves the entrainment of the end of the bimetallic strip in an unstable mode which maintains the oscillation. By this process any degrading wear is avoided, and the power transfer is optimized.

 According to the invention, the bimetallic strip can be located in the key or the lock, it can be excited in resonance or in cyclic deformation, the inductive coupler can exchange codes and actuation energy between the key and the lock or the codes only, and in the latter case the actuating energy is transmitted directly to the actuator after recognition.

 According to the invention, the actuator module comprises a piezoelectric actuator.

 The actuator module in inductive or conductive connection with the generator module performs an action under the control of its digital electronics and energy conversion.

 This action consists of the translation or rotation of a mechanical part, under the action of a piezoelectric actuator.

 According to the invention, the actuator is a piezoelectric bimetallic strip preferably of type d31, or else of type d33. The bimetallic strip is preferably of the parallel type, but the series type is also suitable.

 This bimetallic strip flexes under the effect of the electric charge stored in one of its blades, transferred by the generator module.

 Applied for example to locksmithing, the bimetallic strip of the actuator module is necessarily located in the lock, it ensures pinning and unbuckling under the control of an electronic code comparison and energy management.

 According to the usual case, the pinning blocks the rotation of the cylinder therefore that of the bit. Unpinning frees this rotation and allows the bit to be driven.

 According to a less common implementation, the rotation of the cylinder is free, and the disconnected bit is not driven. Unpinning then consists in linking the bit to the cylinder in order to make its drive effective. Pinning then consists of releasing the bit from the cylinder. This reverse implementation has the advantage of complicating break-ins, since the cylinder offers no grip for a force action.

 Finally, it is also envisaged that the pinning links the cylinder to the body of the lock by releasing the pin, and that the pinning releases the cylinder and binds it to the pin.

 According to the invention, the exchange of codes with the key is carried out by inductive coupling; in the case where the generator module is integrated into the lock, the energy and transferred directly by conductive link; in the case where the generator module is in the key, the energy is transferred to the lock by inductive coupling.

Several examples of pinning are adapted:
- Simple pinning consists of the translation of a pin at the end of the bimetallic strip. Its stroke is limited due to the small amplitudes of deformation of bimetallic strips to around 1 mm.

The bending of the bimetallic strip, under the effect of a load transfer in one of the adjoining blades after identification of the codes, releases the pin from a housing. The pin remains free as long as the load is maintained.

 - Bistable pinning consists of adding an elastic device as shown in Figure 11 to the end of the bimetallic strip.

 The bimetal strip 111 connected by its electrodes 112,113,114 receives a load switched by the control electronics 115, between 112 and 113. The bimetallic strip initially repelled by a spring 116 at the limit of travel then flexes by pushing the spring back to reach the symmetrical position.

 The amplitude of movement then commonly reaches 2 mm.

In addition, the extreme positions are stable, they are switched by a pulse on one or the other of the electrodes. It is therefore simple to control both the opening of the lock after complete insertion of the key, and its closure after extraction of the key, provided that the energies of introduction and extraction are transferred to the actuator for switch the bistable.

 - Amplified pinning consists of adding a lever at the end of the bimetallic strip which multiplies the stroke of the pin.

 - The amplified bistable splitting shown in FIG. 12 consists of the addition of an elastic lever 121 at the end of the bimetallic strip 122. The lever bears on the lock around an axis 123, and on the bimetallic strip around an axis 124. The elastic deformation of the lever 121 pushes the bimetal strip 122 at one or the other of the ends of its travel, the end of the bimetallic strip travels an amplified travel.

 Switching a load on the compressed blade reverses the position of the bistable.

 According to the choice of a person skilled in the art, the principle of pinning is adapted

 In addition, an actuator module of this kind also cooperates with a module that is not a generator, but simply powered by a battery.

 According to the invention, the coupling between the key and the lock is achieved by adding the inductance of the key with that of the lock. The description has exposed the action of the generator inductance during the conversion by step-up pumping, that of the inductances of the circuit of patent 96 14 734 and finally that of the actuator module. After bringing the two inductors closer together, they produce a transformer whose energy and code coupling action has been described.

 Figure 14 shows an example of an embodiment of these inductors, the 141 associated with the key 142, the 143 integrated in the lock 144. The shape of their core is optimized to reduce coupling losses, by constraining the majority of field lines. to stay confined, when they are joined.

Claims (13)

 1. Autonomous device for triggering a remote action under the control of electronics, applied to an electronic lock whose opening is conditioned by the exchange and recognition of a code between said lock and a key element characterized :  - in that the key element and the lock include code exchange electronics by inductive coupling,  - in that the device comprises two modules, one generator located either in the key or in the lock, the other actuator located in the lock.  - in that the action is carried out under the control of digital supervision electronics by a piezoelectric bimetallic bimetallic strip, within the actuator module.  - in that the generator module takes the energy necessary for the operation of the lock either from a heat flux, or from mechanical work  - in that the generator module transfers the energy necessary to the actuator module by direct connection if said generator module is located in the lock, by inductive coupling if said generator module is located in the key.  2. Device according to Claim 1, characterized in that the inductive coupling between the key and the lock is produced by two inductors with an air gap (141 142), one integral with the lock, The other secured to the key, whose flows close together when they are joined.  3. Device according to claim 2 comprising a bimorph bimetal actuator module 111 characterized by an operation of the bistable type, induced by the action of the repulsion force of a spring 116.  4. Device according to claim 2 characterized in that the stroke of the actuator 122 is amplified, by the addition to the bimetallic strip of a lever 121 for bistable operation.  5. Device according to claim 2 characterized in that the actuator bimetallic strip is provided at its end with a pin in a housing, released by the bending of the bimetallic strip.  6. Device according to claim 2 characterized in that the generator module converts a heat flux by the action of a thermocouple, a voltage booster circuit and an energy reserve.  7. Device according to claim 2 comprising a key containing a generator module according to claims 6 and 7 characterized in that the key combines the function of wristwatch.  8. Lock device according to claim 2 comprising a generator module according to claim 7 characterized in that said lock dissipates the heat flux which passes through it by heaters making a knurl 12, and confines the flow in the cylinder 11 making heat sink for thermocouple 16.  9. Device according to claim 2 characterized in that the generator module converts a work into electrical energy by the repetitive bending of a piezoelectric bimetallic strip 41, 42.  10. Device according to claims 2 and 10 characterized in that the generator module converts the work of introduction and / or extraction of the key into electrical energy delivered by a bimorph piezoelectric bimetallic strip of the parallel type in the form of alternating current rectified and converted by supply electronics, then stored in the structural bimetal capacitors.  11. Device according to claim 11 characterized in that the electronics are step-up switching comprising an inductor 75 and two slave switches 76.  12. Device according to one of claims 11, 12 or 13 characterized in that the bimetallic strip 41,42 is excited during the introduction of the key 92 by the friction of notches 95 placed on the blade of the key opposite notches 96 located in the lock.  13. Device according to claims 11, 12 or 13 characterized in that the bimetallic strip it is excited at its natural frequency of resonance by the friction of a cylinder 13 driven in rotation by the translation of the key 15.