FR2826159A1 - Wireless switch for control of a luminous point, uses excited piezo-electric element to hold transmitter voltage at given level in order that its signal is completely transmitted - Google Patents

Abstract

Application of force of about 3 Newton's over distance of about 3 milli-meters is sufficient to cause an action (15) on moving part of trigger (16). The rectifier circuit includes rectifier (26) formed by 4 diodes in Gratz bridge for double alternating rectification, and capacitor (31). The rectifier input terminals (24,25) are connected to piezo electric element (18). The transmitter (14) and the capacitor are connected in parallel at rectifier circuits output terminals (27,28). Wireless device fitted with, moving part (16) of a trigger, transmitter circuit (14) of signal (13) in response to an action (15) exerted on the moving part (16). The device also includes: (a) a piezo-electric element (18); a current rectifier circuit (26,31) at the terminals (22,23) of the piezo-electric element and supply terminals (32,33) of the transmitter circuit, and; a system (19,20) which transforms the action (15) into an mechanical oscillatory excitation (17) which is exerted on the piezo-electric part. The excitation (17) is designed to produce at the piezo-electric terminals (22,23) an alternating voltage, such that the voltage, rectified and smoothed by the rectifier circuit appearing as a consequence at the supply terminals of the transmitter, remains greater than a predetermined level during a time period greater than a predetermined time so that the transmitter circuit can completely transmit the signal (13).

Description

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 The invention relates to wireless switches and more specifically to electrical devices capable of emitting a signal in response to an action exerted on a key or on another mobile triggering member.

 There is already known a wireless switch which is designed to cooperate with a switch-receiver to control a light point: each time the button of the wireless switch is pressed, the latter emits a signal which is received by the switch- receiver, which establishes or interrupts an electrical connection so that successive presses of the key alternately control the switching off and on of the light point.

 Such a control system is particularly appreciated because no wiring of the wireless switch is necessary, which in particular allows, in an existing installation, to modify or add control points without redoing the wiring.

 However, for their power supply, these wireless switches include a battery which must be changed regularly, which constitutes a relatively heavy maintenance constraint.

 The invention aims to provide an apparatus such as a wireless switch which does not have a battery or any other reserve of electrical energy which must be changed regularly.

 To this end, it provides a wireless electrical device provided with a movable trigger member and a transmitter circuit for emitting a signal in response to an action exerted on said member; characterized in that it further comprises said transmitter circuit:

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 a piezoelectric element; a current rectifier-shaping circuit disposed between the terminals of said piezoelectric element and the supply terminals of said transmitter circuit; and - movement transformation means for transforming said action exerted on said movable triggering member into an oscillatory mechanical excitation exerted on said piezoelectric element, said excitation being adapted to cause an alternating voltage to appear at the terminals of said element. the voltage, rectified and smoothed by said rectifier-conforming circuit, appearing accordingly at the supply terminals of the transmitter circuit, remains above a predetermined voltage threshold for a duration greater than a predetermined duration so that said transmitter circuit can transmit in full said signal.

 Thus, the electrical energy necessary for the transmitter circuit to be able to emit the entire signal, comes exclusively from the conversion of the energy provided by the action exerted on the movable triggering member.

 This conversion involves the movement transformation means in order to have an oscillatory mechanical excitation, involves the piezoelectric element in order to have an AC voltage and brings into play the rectifier-shaping circuit in order to have a continuous voltage.

 By using such means to carry out the energy conversion, it is possible, while the action exerted on the movable triggering member is almost instantaneous, to obtain a supply voltage of the transmitter circuit which remains above the threshold of operation of such a circuit for a relatively long period, for example a voltage remaining greater than 1 V for several tens of milliseconds.

 In fact, both the means for transforming movement and the rectifier-current-shaping circuit which the apparatus according to the invention comprises are capable of operating a certain form of storage then of energy restitution, first mechanical then electric after transduction by

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 the piezoelectric element, which also offers the advantage of operating such a transduction in a particularly simple, reliable and economical manner.

 It is in particular possible, as will be seen below, to provide, in the movement transformation means, a mechanical interface linked to the piezoelectric element and such that the element + interface assembly is capable of entering into resonance and therefore capable of allowing the oscillatory mechanical excitation to be exerted for a relatively long period, and of providing, in the rectifier-current-shaping circuit, a capacitor capable of storing electrical energy when the amplitude of the AC voltage produced by the piezoelectric element is high, and then to restore electrical energy when the amplitude of the AC voltage becomes small.

 According to preferred characteristics, the application of a force of at most 3 N over a stroke of at most 3 mm is sufficient to constitute said action exerted on said movable triggering member.

 Such an action is that which is conventionally exercised by a user when he controls the button of a switch. Thus, with these characteristics, the device according to the invention can be perceived exactly like a conventional switch.

 According to other preferred characteristics, said rectifier-transformer circuit comprises a rectifier assembly formed by four diodes arranged in a Grâtz bridge to operate a full-wave rectification and a capacitor, the input terminals of said rectifier assembly being connected to said piezoelectric element, the transmitter circuit and the capacitor being arranged in parallel between the output terminals of said rectifier assembly.

 Such a circuit is particularly suitable both for rectifying the alternating voltage produced by the piezoelectric element and for optimally shaping the supply current of the emitting circuit, and in particular for smoothing this alternating voltage as long as it remains relatively high and then gradually restore electrical energy when the AC voltage becomes small.

 Preferably, the apparatus according to the invention is further characterized:

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 said transmitter circuit having a substantially constant input resistance R, said rectifier-conforming circuit comprising a capacitor of capacity C, the term RC, R being expressed in Q and C in F, is substantially equal to said predetermined duration so that the transmitter circuit can transmit said signal in full, for example, due to the quality of the results obtained, with said oscillatory mechanical excitation, said piezoelectric element and the diodes of said rectifier assembly which are adapted so that the maximum voltage reached at the terminals the capacitor is between 1.7 and 3.7 times said predetermined voltage threshold so that said transmitter circuit can fully transmit said signal; and / or - said emitter circuit having a substantially constant input resistance R, said rectifier-conforming circuit comprising a capacitor of capacity C, said oscillatory mechanical excitation having a main frequency f, in that the term RCf is greater than 10, and for example, due to the quality of the results obtained, between 55 and 75, R being expressed in Q, C in F and f in Hz.

 According to other preferred characteristics, said predetermined voltage threshold is at least equal to 1 V and said predetermined duration is at least equal to 20 milliseconds.

 The power and energy required by the transmitting circuit to emit the entire signal are thus relatively low. However, the transmitting power that it is possible to obtain for the signal offers a range of several meters which is sufficient when the device to receive this signal is in the same room as the wireless device, such voltage threshold and such a minimum duration offering the advantage, taking into account the yield likely to be obtained in practice, of being compatible with the energy supply corresponding to the action conventionally exerted by a user on the key a switch.

 According to other preferred characteristics, in particular for the possibility of storing energy mentioned above, and also for reasons of space, in particular if one has to be compatible with the

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 usual volume of a domestic switch, said movement transformation means comprise: a mechanical interface linked to said piezoelectric element; and activation means, to which said movable trigger member belongs, for transforming said action exerted on said movable trigger member into an action exerted on said interface to bring into resonance the piezoactive member formed by said piezoelectric element. electric and through said interface.

 Preferably, for reasons of simplicity and convenience of implementation: - said activation means are adapted so that said action exerted on said interface is a punctual mechanical action; and / or - said piezoactive member is adapted to enter into resonance at a main frequency of several kHz, in particular a main frequency between 2.5 and 5 kHz; and / or - said mechanical interface comprises an elastically deformable shell with a substantially elliptical profile having four vertices opposite two by two, respectively two vertices of minor axis and two vertices of major axis with the distance separating the two vertices of major axis which is greater that the distance separating the two vertices of minor axis, said piezoelectric element being disposed in said shell between the two vertices of major axis.

 Preferably, with regard to these latter characteristics: - said interface further comprises a counterweight integral with said shell at a vertex of minor axis and having a mass greater than that of the shell, and in particular a mass greater than four times that of the shell ; and possibly - said mechanical interface comprises a said counterweight integral with said shell at each of the two vertices of minor axis, with in particular each said counterweight which has substantially the same mass.

 More preferably still for reasons of simplicity and convenience of implementation, said mechanical interface is disposed between

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 said movable trigger member and the bottom of said device, said bottom being located away from said movable trigger member depending on the thickness of the device.

 The invention also relates, in a second aspect, to a system comprising a first device as set out above and a second device comprising a receiver circuit adapted to receive the signal emitted by the first device and electrical control means sensitive to receiving said signal, in particular switching means, this system being used in particular to control a light point.

 The description of the invention will now be continued with the description of exemplary embodiments, given below by way of illustration and not limitation, with reference to the appended drawings. On these: - Figure 1 is a schematic representation of a system according to the invention comprising, on the one hand, a wireless electrical device provided with a transmitter circuit and, on the other hand, a connected electrical device both at the network and at a light point and provided with a receiving circuit in order to control the light point according to the signals emitted by the wireless device; - Figure 2 is a perspective view of a piezoactive member known per se comprising a piezoelectric element and a shell with a substantially elliptical profile in which the piezoelectric element is disposed; - Figure 3 is a graph, obtained from a modeling, based on various assumptions, of the electrical circuit of the wireless device shown in Figure 1, showing how varies, as a function of time, plotted on the abscissa, the voltage, carried on the ordinate, respectively at the terminals of the piezoelectric element and at the supply terminals of the transmitter circuit when the piezoelectric element is subjected to an oscillatory mechanical excitation of the type to which the piezoelectric element is subjected the piezoactive member illustrated in FIG. 2 from the moment when this member is brought into resonance by a specific mechanical action; - Figure 4 shows in enlargement along the ordinate axis how the voltage across the emitter circuit varies;

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 - Figure 5 is a similar graph, but obtained by direct measurement with an oscilloscope, showing the envelope of the voltage variation curve across the piezoelectric element of the wireless device shown in Figure 1 from the moment when the piezo-active organ of this device has been brought into resonance by a specific mechanical action; - Figure 6 is a perspective view similar to Figure 2 showing the piezoactive member which is provided with the wireless device shown in Figure 1; - Figure 7 is a schematic representation of the mechanical system formed by the piezo-active member shown in Figure 6, by the frame on which this member is fixed and by a percussion weight provided to strike one of the weights of this body when an action is exerted on the button of the apparatus shown in FIG. 1; - Figures 8 to 11 are other schematic representations of this system, showing the movements of the percussion weight and launching means with which it cooperates as well as the way in which the member illustrated in Figure 6 is deformed after having been struck by the percussion weight, Figures 8 to 11 showing more precisely the rest position, the armed position of the percussion weight, the shock position and a position where the piezoactive member is both in resonating and oscillating with respect to the frame following the impact exerted on it by the percussion weight; - Figure 12 is a graph showing the current-voltage characteristic of the transmitter circuit of the wireless device shown in Figure 1; - Figure 13 is a graph similar to that of Figure 4, but obtained by direct measurement with an oscilloscope at the supply terminals of the transmitter circuit of the wireless device shown in Figure 1; - Figure 14 is a perspective view of the wireless device shown schematically in Figure 1; - Figure 15 is an exploded view; - Figure 16 shows in the same way, but in enlargement, the only mechanism of this device;

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 - Figure 17 is an elevational view of the latter; - Figure 18 is the sectional view taken as indicated in XVIIIXVIII in Figure 17; - Figure 19 is a perspective view of the lever, flat to the launching means, which includes the mechanism between the key and the percussion weight; - Figure 20 is the elevation-sectional view of the button taken as indicated in XX-XX in Figure 15; - Figure 21 is a schematic representation of the mechanical system formed by the key and the lever; - Figure 22 is a view similar to Figure 17 for a variant of the mechanism of the wireless device; and - Figure 23 is a schematic representation similar to Figure 7 but for the mechanism of Figure 22.

 The system 1 represented in FIG. 1 comprises a wireless electrical appliance 2 for remote control and an electrical switch-receiver appliance 3 connected to a light point 4 as well as to the electrical distribution network 5 of the room in which the point is installed light 4, the system formed by devices 2 and 3 being designed to control the light point 4.

 In FIG. 1, the mechanical aspect of the apparatus 2 is illustrated in broken lines while the electrical aspect is illustrated in solid lines, it being specified that, for convenience, the piezoelectric element which this apparatus comprises has been drawn in solid lines while it also plays a mechanical role, due to its elasticity.

 The apparatus 3 has three terminals 6,7 and 8 connected respectively to the neutral pole N of the network 5, to the phase pole L and to the terminal 9 of the light point 4, the other terminal 10 of the latter being connected to the pole from neutral N.

 In the apparatus 3, there is provided a receiver circuit 11 connected to a switching means 12 disposed between the terminals 7 and 8. The receiver circuit 11 is sensitive to the reception of a signal 13 emitted by the transmitter circuit 14 of the device 2 in response to an action 15 exerted by a user on the key

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 16 of this device, the switching means 12 establishing or interrupting the connection between the terminals 7 and 8 alternately on each reception of a signal 13.

 Thus, each time an action 15 is exerted on the key 16, there is alternately switching on and off of the light point 4.

 In the apparatus 2, the action 15 is transformed into an oscillatory mechanical excitation 17 exerted on a piezoelectric element 18 by means of movement transformation means which comprise a mechanical interface 19 and activation means 20 to which belongs the key 16, the action 15 exerted by the user on the key 16 being transformed by the activation means 20 into a punctual mechanical action 21 exerted on the interface 19, which brings the mechanical oscillator into resonance formed by the interface 19 and by the element 18 mechanically linked to this interface, this oscillator then resonates freely while being the seat of the oscillatory mechanical excitation 17 which has the effect that the element 18 produces an alternating voltage.

 The two terminals 22 and 23 of the piezoelectric element 18 are respectively connected to the input terminal 24 and to the input terminal 25 of a rectifier assembly 26 formed by four diodes arranged in a bridge of Grâtz to operate a full wave rectification, the output terminals 27 and 28 of the assembly 26 being connected respectively to terminal 29 and to terminal 30 of a capacitor 31, terminals 29 and 30 being also connected respectively to terminal 32 and to terminal 33 which are the supply terminals of the emitter circuit 14, the rectifier assembly 26 and the capacitor 31 disposed in parallel with its output terminals 27 and 28 forming a rectifier-transformer circuit disposed between the terminals 22 and 23 of the piezo element -electric 18 and the supply terminals 32 and 33 of the transmitter circuit 14.

 As indicated above, the oscillatory mechanical excitation 17 exerted on the piezoelectric element 18 causes an alternating voltage to appear between the terminals 22 and 23. This voltage is rectified by the assembly 26 and smoothed by the capacitor 31 so that there appears between the terminals 32 and 33 of the emitter circuit 14 a voltage rectified and smoothed which allows it to emit

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 signal 13, the latter being emitted in full provided that the voltage between terminals 32 and 33 remains greater than 1 Volt (V) for a duration greater than 20 milliseconds (ms).

 The piezoactive member 34 illustrated in FIG. 2 is known per se, in particular from French patent application 2,740,276, as an amplified piezoactive actuator with high stiffness intended to be integrated into micropositioning devices. various objects or control mechanisms.

 The member 34 comprises a piezoelectric element 35 and an elastically deformable metal shell 36 with a substantially elliptical profile extending along a minor axis 37 and along a major axis 38 arranged transversely relative to one another, the shell 36 having four opposite vertices two by two, respectively two vertices 39 of minor axis (couple of opposite vertices closest to each other) and two vertices 40 of major axis (couple of vertices the furthest one from the other), the piezoelectric element 35 being disposed in the shell 36 between the vertices 40.

 In the rest state illustrated in FIG. 2, the shell 36 is deformed with respect to the equilibrium state which it would take if it were alone, in order to exert on the element 35 a compression force oriented as follows the axis 38, the vertices 40 being kept further apart from each other than in the state of equilibrium by virtue of the element 35 and shims 41 A and 41 B interposed between one of the vertices 40 and one of the ends of the element 35.

 Here, the distance between the vertices 39 is approximately equal to half the distance between the vertices 40 so that if the element 35 expands, under the effect of an electric voltage applied between its terminals, the vertices 40 deviate from each other by a distance equal to the amplitude of the expansion of the element 35 while the vertices 39 approach each other by a distance which is substantially the double the expansion of the bar 35. The movements of the tops 39 are thus amplified with respect to the movements of expansion and moreover of contraction of the element 35.

 Of course, the conditions of service provided for the member 34 are such that the element 35, when contracted to the maximum, remains

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 compressed by the shell 36, a compression force being necessary for the subjection between the element 35 and the shell 36.

 In addition, the compression force existing in the rest state is such that the element 35 has the same propensity to expand as to contract, so that the response of the member 34 is symmetrical.

 To allow the member 34 to be fixed to the elements with which it must cooperate, the shell 36 has at each vertex 39, on the external side, a flat face 42 at the center of which is a tapped hole 43.

 Although the shell 36 has been designed, as indicated above, to amplify the expansion and compression movements of the element 35 in response to variations in tension across the latter, the member 34, due to the elasticity of the shell 36 and of the piezoelectric element 35 is capable of entering into resonance when it is subjected to a punctual mechanical action constituted by a shock or by rapid relaxation from a deformed state , or even by a succession of such actions.

 When one of the vertices 39 is blocked, in particular when it is rigidly fixed to a frame, while the other vertex 39 is free, the member 34 has, taking into account the high rigidity which is imparted to it jointly by the element 35 and by the shell 36, a resonant frequency which is of the order of 2.9 kilohertz (kHz).

 The oscillatory mechanical excitation of which the member 34 is then the seat, shows at the terminals of the element 35 an alternating voltage whose characteristics, in particular in frequency and in amplitude, reflect those of the mechanical excitation.

 Given the choice, explained above, of the compression force in the rest state, this AC voltage is centered on an average value which is considered below as equal to 0.

 To clearly understand the operation of the device 2, more particularly in the electrical aspect, we have illustrated in FIG. 3 two voltage timing diagrams obtained by modeling the electrical circuit of the device 2, the model used:

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20 uF ; et - supposant que le circuit émetteur 14 a une résistance d'entrée constante, quelque soit la tension entre les bornes 32 et 33, d'une valeur de 1 ko. - assuming that the piezoelectric element 18 is subjected to the same oscillatory mechanical excitation as that which is exerted on the element 35 from the moment when the organ 34 is brought into resonance under the conditions indicated above ; - assuming that the piezoelectric element 18 comprises, in addition to the source of electrical energy due to the mechanical excitation acting on it, a resistance of 10 kilo-ohms (ko) and a capacity of 0.64 microfarad ( uF) each arranged in parallel with the terminals of the energy source; - assuming that the rectifier assembly 26 is formed by perfect diodes; - assuming that the smoothing capacitor 31 has a capacity of

20 uF; and - assuming that the transmitter circuit 14 has a constant input resistance, whatever the voltage between the terminals 32 and 33, of a value of 1 kb.

 On the basis of this model, and assuming that the member 34 enters into resonance at time T = 0, the timing diagram of the voltage existing between the terminals 22 and 23 is represented by the curve 44 in FIG. 3.

 We see that this is an alternating voltage at around 2.9 kHz (29 periods in 10 ms) with an amplitude which increases rapidly exponentially up to a peak located at about time T = 2.4 ms then with an amplitude which decreases exponentially slowly, with a time constant (duration where the voltage amplitude goes from its maximum value U to your value U / e, e being the Neper number, that is to say 2.718) substantially equal to 10 ms, which reflects, as indicated above, the characteristics of the oscillatory mechanical excitation.

 Curve 45, representing the voltage obtained between terminals 32 and 33 on the basis of the aforementioned modeling, increases from time T = 0 in approximately the same way as the amplitude of curve 44 while remaining slightly below the peaks of this curve, until reaching a maximum, as well as the curve 44, at about the instant T = 2.4 ms, the curve 45 then decreasing more slowly than the amplitude of the curve 44.

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 The value of 1 V is reached by curve 45 substantially at time T = 0.15 ms (point 46). The top of curve 45, reached as indicated previously substantially at T = 2.4 ms, is at a voltage value of the order of 7.5 V. Substantially at time T = 6 ms, curve 45 passes from a zone where it is less than a zone where it is greater than the amplitude of the curve 44, the voltage at this instant being approximately 6.5 V (point 47).

 Between time T = 0 and point 47, the electrical energy supplied by element 18 serves both to charge the capacitor 31 and to supply the emitter circuit 14.

 The simultaneity which exists in this time interval between the production of electrical energy by the piezoelectric element 18 and the consumption of electrical energy by the emitter circuit 14 offers the advantage of allowing better energy transfer than s 'there was first exclusively an electrical energy storage in the capacitor 31 then exclusively the consumption of the stored energy, thanks for example to a switching means which would connect the terminal 29 of the capacitor 31 either to the terminal 27 of the assembly 26 is at terminal 32 of the emitter circuit 14 depending on whether the voltage between terminals 29 and 30 is respectively lower and greater than the amplitude of the voltage between terminals 24 and 25.

 After point 47, the voltage between terminals 27 and 28 of the rectifier assembly 26 always remains greater than the voltage between terminals 24 and 25 of this assembly, in which no current can therefore flow.

The electrical energy consumed by the resistor which models the emitter circuit 14 is therefore then supplied exclusively by the capacitor 31.

 Curve 45 therefore follows, beyond point 47, the well-known curve of discharge of a capacitor in a resistor, the time constant of which is RC, R being the value of the resistance and C the capacitance of the capacitor, ie , here, respectively 1 kQ and 20 pF, so that the time constant is 20 ms.

 The voltage between terminals 32 and 33, taking into account the coordinates of point 47 (6ms and 6.5 V), will drop again to the value of 1 V at time T such that:

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soit à l'instant T = 43,4 ms.

or at the instant T = 43.4 ms.

 One thus obtains, according to the aforementioned modeling, a voltage higher than the threshold of 1 V at the terminals of the transmitter circuit 14 during approximately 43,2 ms, is much more than the above-mentioned duration of 20 ms necessary for the circuit 14 to transmit the signal 13 to the full.

 It will be noted that the capacity of 20 pF for the capacitor 31 has made it possible to optimize the period during which the voltage between the terminals 32 and 33 remained greater than 1 V.

 In fact, if the capacity had been greater, for example 100 uF, all the other conditions remaining equal, in particular the voltage variation represented by curve 44, then the voltage increase across the capacitor would have been slower and therefore the maximum voltage value reached, at time T = 2.4 ms when the amplitude of the curve 44 is maximum, would also have been smaller so that the threshold of 1 V would not have been achieved.

 If, on the contrary, the capacitor 31 was replaced by a capacitor having a smaller capacity, for example of 10 0 F, the maximum voltage reached at its terminals would be higher but then the voltage decrease would be faster so that the duration total during which the voltage would remain above the threshold would be smaller.

 What has just been said about the capacitance of the capacitor 31 applies more generally to the time constant RC.

 In FIG. 4, the curve 45 has been drawn perfectly smooth but in practice it has oscillations since the capacitor 31, previously at point 47, undergoes a succession of periods where its voltage increases and decreases at the rate of the half-vibrations of the curve 44.

 We know that the performance, on a rectified voltage, in particular full wave, of the smoothing performed by a capacitor located in parallel at the terminals of the rectifier bridge and at the terminals of a resistive load, depends on term RCf, where f is the frequency of the alternating voltage. . Here, where the term RC has

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 a value of 20 ms and where the frequency f is 2.9 kHz, the term RCf is equal to 58, which corresponds to a smoothing of good quality.

 FIG. 5 shows the envelope 48 of the alternating voltage, as measured with the oscilloscope, which appeared in practice between the terminals 22 and 23 of the piezoelectric element 18 after the mechanical interface 19 has been subjected to a punctual mechanical activation constituted by the shock of a percussion weight, the element 18 and the interface 19 being part, as will be seen below, of a piezoactive member of the same kind as the member 34 described above.

 It can be seen that the amplitude of this alternating voltage increases almost instantaneously up to its maximum value which is approximately 6 V, the amplitude of this voltage then decreases according to a generally exponential profile with respect to which ripples exist up to at about time T = 13.5 ms.

Examination of the unrepresented details of the oscilloscope recording shows that these undulations arise from the fact that the measured voltage is the superposition of two oscillatory movements each with exponentially damped amplitude, having a frequency of 4.6 kHz and 400 Hz.

 It will be noted that the main frequency of the overall oscillatory movement is that of 4.6 kHz, the movement at the frequency of 400 Hz having relatively little influence. In particular, the curve not shown of the rectified and smoothed voltage which appeared simultaneously between the terminals 32 and 33 of the emitter circuit 14 has the same general shape as the curve 45 of FIG. 4, in particular in its decreasing part.

 As can be seen in FIG. 6, the piezo-active member 50 of the device 2 is similar to the member 34, the piezo-active element 18 being similar to the piezo-active element 35 and being arranged in a metal shell 51 similar to the shell 36 and extending like it along a minor axis 52 and along a major axis 53, the element 18 being disposed in the shell 51 between the vertices of major axis 54, the shell 51 being integral , at each of the minor axis vertices 55, of a counterweight 56, the two counterweights being identical and therefore having

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 each the same mass, which is slightly greater than four times that of the shell 51.

 Each counterweight 56 includes for its subjection to the shell 51 a screw (not shown in FIG. 6) whose body and head are housed respectively in a bore 57 and in a countersink 58, the end of the screw cooperating with the threaded hole 59 of the shell 51 similar to the hole 43 of the shell 36, each counterweight 56 being arranged on the external side against the flat face provided at the level of a respective apex 55, each of the counterweights 56 being arranged centered on the minor axis 52.

 Thus, the mechanical interface 19 is formed by the shell 51 and by the two weights 56.

 To carry out the mounting of the member 50 on a frame which the device 2 comprises, there are provided two fixing blocks 60 each having a bore 61 for housing the body of a screw whose head comes to bear on the block 60 around the bore 61 and the end of the rod of which is engaged in a threaded hole in the frame. Each block 60 is connected to a respective counterweight 56 by a spring leaf 62, each end of which cooperates with embedding respectively with the block 60 and with the counterweight 56.

 In the example illustrated, each of the assemblies formed by a blade 62 as well as by the block 60 and the counterweight 56 between which this blade is located is in one piece and obtained by machining an elastically deformable metal bar.

 When each of the blocks 60 is fixed to the above-mentioned frame, the two blades 62 are arranged parallel to one another. Thus, if the piezoactive member 50 moves relative to the frame along the axis 52, the two blades 62 will deform in the same way and will therefore exert on the shell 51 the same force opposing this movement, so that the forces exerted by the blades 62 will not tend to deform the shell 51 (everything would pass as if the blades 62 were connected to the center of the piezoelectric element 18).

 If the aforementioned movement oriented along the minor axis 52 takes place while the member 50 is in resonance, with the vertices of small

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 axis 55 which move for example in phase opposition, the forces exerted by the two blades 62 will not be strictly identical, but since the amplitude of the oscillations of the vertices 55 is very small, the difference in deformation of the blades 62 will be almost without effect.

 As we have seen above in support of FIG. 5, which electrically reflects the characteristics of the mechanical excitation 17 which is exerted on the piezoelectric element 18, the member 50, when it is brought into resonance, oscillates according to a movement which is the superposition of two oscillatory movements each with exponentially damped amplitude, the main movement having a frequency of 4.6 kHz and the secondary movement having a frequency of 400 Hz.

 The addition, relative to the piezoactive member 34 known per se, of the flyweights 56, has a certain number of advantages, and in particular: - to limit as much as possible the phenomenon of complex behavior of the oscillator (several frequencies resonances); - To provide a displacement of the vertices of minor axis 55 which is in phase opposition, which gives the maximum deformation of the piezoelectric element 18 and therefore the best electromechanical coupling characteristics optimizing the possibilities of energy recovery; and to reduce the main resonant frequency with respect to a situation where the two vertices of minor axis would be movable relative to the frame on which the shell 51 would be mounted, without the counterweights 56.

 In this last regard, it will be noted that without the flyweights 56, the shell 51 with its two major axis vertices 55 free to move, would have had a main resonant frequency of the order of 11 kHz. The mechanical damping caused by the piezoelectric element 18 would therefore have been greater, which, on the one hand, would have been detrimental in terms of electro-mechanical coupling, and, on the other hand, the piezoelectric element electric 18 behaving like a generator of electric charges (the average current produced is directly proportional to the frequency of the mechanical excitation), would have had the consequence of leading to a very rapid charging of the capacitor 31 and therefore to a high voltage of circuit supply

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 transmitter 14 which would then consume more current (as indicated above, its input resistance R is roughly constant), so that the time when the voltage is above the threshold would drop, and could be less than the time needed when the signal is fully transmitted.

 Figure 7 is a schematic representation of the mechanical system formed by the piezo-active member 50, by the frame 63 on which is fixed this member through the spring blades 62 and by a percussion weight 64 provided to strike one weights 56 in order to bring the organ 50 into resonance, it being specified that, to simplify the drawing, it has been considered that the spring blades 62 were arranged between one of the weights 56 and the frame 63 (as indicated here above, it is assumed that the member 50 interacts with the blades 62 as if they were fixed to the center of the element 18 and therefore as if the member 50 was rigid).

 The assembly formed by the shell 51 and by the element 18 is assimilated to a simple spring whose mass is negligible, and likewise for the blades 62.

 The percussion weight 64 here has a mass of the order of 6 grams, which is substantially equal to that of the weight 56 with which it is facing and that it strikes, as explained below, at relatively high speed, for example 0.6 m / s, moving substantially along the minor axis 52, the equality of the masses of the counterweights 64 and 56 having the effect that all or almost all of the kinetic energy of the counterweight percussion 64 is communicated during the impact to the counterweight 56 which it strikes, the impact having the effect of almost instantaneously immobilizing the counterweight 64 at the location of the impact and causing the organ 50 to resonate, including the two weights 56, which are each movable relative to the frame 63, will oscillate in phase opposition.

 The alignment or the substantial alignment between the path of the counterweight 64 and the minor axis 52 promotes the transmission of the shock wave and is therefore favorable to the efficiency of the energy transfer between the counterweight 64 and the member 50.

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 The fact that the connection between the member 50 and the frame 63 is effected by the spring blades 62 offers the advantage of avoiding the member 50 transferring vibrations to the frame 63.

 The impact between the weights 64 and 56 also has the effect that the member 50, which cooperates with the spring blades 62 as if it were rigid, is animated by a certain oscillation movement relative to the frame 63, the frequency depends, in a well known manner, on the stiffness of the blades 62 and on the mass of the member 50.

 Due to the oscillations of the member 50 with respect to the frame 63 and the fact that the percussion mass 64 is immobilized as soon as it has struck the counterweight 56 which it is facing, the member 50 will return regularly to strike the percussion flyweight 64. This offers the advantage, provided that the stiffness of the blades 62 is carefully chosen, to enable the member 50 to be activated again and therefore to raise the voltage across the terminals of the transmitter circuit 14 , which further increases the period during which this voltage remains above the operating threshold of the transmitter circuit 14 (see below in support of FIG. 13).

 We will now explain with reference to FIGS. 8 to 11 how the movements of the percussion weight 64 are controlled.

 The latter is part of the activation means 20 (FIG. 1) of which it constitutes the inertia means which is adapted, after speeding up, to exert the punctual mechanical action 21 on the interface 19, the means of activation 20 comprising, in addition to the percussion weight 64, launching means, to which the key 16 belongs, to transform the action 15 into the setting in speed of the percussion weight 64.

 Figures 8 to 11 show schematically the piezoactive member 50, the frame 63, the spring blades 62 for mounting the member 50 on the frame, the percussion weight 64 and its launching means.

 The latter comprise, in addition to the button 16 (not illustrated in FIGS. 8 to 11), elastic means 65 for urging the counterweight 64 towards an impact position of the counterweight 56 which it faces, drive means 66, against the elastic means 65, the counterweight 64,

<Desc / Clms Page number 20>

 to bring it, when the action 15 is exerted on the key 16, from the rest position illustrated in FIG. 8 to the armed position illustrated in FIG. 9 and, finally, disengageable connection means 67 between the means d drive 66 and the counterweight 64, adapted, when the armed position (FIG. 9) is reached, to release the counterweight 64, which then undergoes the abovementioned speeding up under the effect of the elastic means 65 which drive it up to the impact position illustrated in FIG. 10, the counterweight 64 here having an impact position which coincides with its rest position (FIG. 8).

 As explained above, the member 50, after having been struck by the counterweight 64, enters into resonance with its two counterweights 56 which oscillate in phase opposition while the member 50 oscillates, by deformation of the blades 62, vis- with respect to the frame 63 so that it returns regularly to strike the counterweight 64.

 Of course, the deformations of the blades 62 and of the shell 51 illustrated in FIG. 11 are exaggerated for reasons of clarity. It will be noted that in practice these deformations are very small, the maximum amplitude of movement of the weights 56 relative to the rest state being for example a few tens of μm.

 In the example illustrated, the disengageable connecting means release the percussion weight when the elastic means 65 exert on the latter a predetermined force.

 These disengageable connecting means comprise an imprint 68, formed here in the drive means 66, and a ball under elastic prestressing 69, mounted here on the counterweight 64, by means of a piston which guides it, the ball 69 positioning themselves in the cavity 68 and remaining there as long as the force exerted by the elastic means 65 remains less than the aforementioned predetermined force.

 Of course, as a variant, the imprint can be made on the counterweight and the ball mounted on the drive means.

 In FIGS. 8 to 11, the drive means 66 are shown diagrammatically by a lever with two branches articulated around an axis 70 situated at the junction between the two branches. To simplify the schematic representation

<Desc / Clms Page number 21>

 Figures 8 to 11, the axis 70 is illustrated with a transverse orientation relative to that of the shell 51, but in practice, in the example described, as explained later, the axis 70 is arranged parallel to the shell 51 .

 Resetting means, not illustrated in FIGS. 8 to 11, are provided for returning the lever 66 to its initial position, and therefore the key 16 which cooperates with this lever, this return of the lever 66 to its initial position having the effect of '' disengageable connecting means 67.

 There is thus an automatic return to the rest position illustrated in FIG. 8.

 The curve 71 illustrated in FIG. 12 shows the current-voltage characteristic of the transmitter circuit 14.

 We see, as indicated above, that the supply voltage threshold from which the circuit 14 starts to operate is 1 V, and that the circuit 14 then absorbs an intensity of 2 mA, which corresponds to a input resistance R of 500 Q.

 When the input voltage is of the order of 3.3 V, the current absorbed by the circuit 14 is substantially equal to 8 mA, so that at this operating point the input resistance is substantially equal to 400 Q.

 It can thus be seen that the input resistance of the emitter circuit 14 remains substantially constant and that consequently, the higher the voltage between the terminals 32 and 33, the greater the power absorbed by this circuit.

 As indicated above, the curve 72 illustrated in FIG. 13 is similar to the curve 45 illustrated in FIG. 4, but shows, rather than the variation in voltage at the input terminals of the emitter circuit 14 obtained by modeling, the variation voltage measured by oscilloscope recording.

 Curve 72 has the same general appearance as curve 45, but the maximum value reached is only 2 V, mainly due to the fact that the point mechanical action 21 is in practice less strong than the modeling on which are based on Figures 3 and 4.

<Desc / Clms Page number 22>

 At this maximum voltage of 2 V, the transmitter circuit 14, as shown in curve 71, absorbs an intensity which is of the order of 4 mA.

 Thus, when the input terminals of circuit 14 are subjected to the voltage variation represented by curve 73, the input resistance R of this circuit remains substantially equal to 500 Q.

 The capacitor 31, for this experimental measurement, having in fact a capacity C of 30 uF, the time constant RC is 15 ms.

 As indicated above with reference to FIG. 5, the main frequency of the corresponding voltage which was present simultaneously at the terminals 22 and 23 of the piezoelectric element 18 is 4.6 kHz.

 The term RCf is therefore equal to 69.

 The smoothing performed by the capacitor 31 with the capacitance value which has just been indicated is therefore of good quality.

 As indicated above, due to its mounting on the frame 63 by means of the elastic means constituted by the spring blades 62, the member 50 oscillates relative to the frame and regularly strikes the percussion weight 64, which activates oscillator 19 again.

 It will be noted that the experiment during which the alternating voltage, the envelope of which is shown in FIG. 5, was recorded, was carried out, on the one hand, under conditions such that the punctual mechanical action 21 was stronger that during the experiment which led to the recording of the curve illustrated in FIG. 13, this is why the maximum value of the curve 72 is only 2 V, and, on the other hand, that the corresponding experiment in Figure 5 was carried out with a stiffness of the blades 62 such that, taking into account the mass of the member 50, the rebounds on the counterweight 69 had almost no effect on the recorded curve.

 On the other hand, the experiment which led to the recording of the curve 72 was carried out under conditions where the stiffness of the blades 72 and the mass of the organ 50 caused a rebound of the organ 50 on the percussion mass 64 with a period of approximately 7.4 ms.

 The first rebound that occurred had relatively little influence on the voltage across circuit 14, only a localized peak 73 appeared.

<Desc / Clms Page number 23>

 A second rebound occurred under conditions such that it had no influence on curve 72.

 On the other hand, the third and fourth rebounds occurred when the voltage across the terminals of the transmitter circuit 14 had already dropped enough for a voltage rise to be possible, as shown by the increasing parts 74 and 75 of the curve 72.

 The fifth rebound and the following rebounds, although they caused a rise in voltage across terminals 22 and 23 of the piezoelectric element 18, did not, however, have a sufficient intensity to cause growth of the curve 72.

 We will now describe how the wireless electrical appliance 2 is produced in practice.

 As can be seen in FIGS. 14 and 15, this device is in the conventional form of an electrical installation switch intended to be fixed on the surface, the device 2 comprising a base 80 intended to be fixed on a wall, a mechanism 81 snapped onto the base 80, a frame 82 snapped onto the base 80 and surrounding the mechanism 81 and the key 16 which is accessible on the front face of the frame 82 and which cooperates with the mechanism 81.

 Conventionally, it is expected that the application of a force of at most 3 Newtons (N) over a stroke of at most 3 millimeters (mm), or an energy input of at most 9 millijoules ( mJ), is sufficient to operate the key 16. Action 15 therefore corresponds to the application of such a force.

 For its fixing on a wall, the base 80 has an oblong fixing hole 83 in each corner.

 The snap-fit between the base 80 and the mechanism 81 is effected by means of two elastically flexible latches 84 provided on two opposite sides of the base 80 and by means of two conjugated tabs 85 of the mechanism 81.

 The latching between the base 80 and the frame 82 is effected by means of four flexible tabs 86 of the base 80 each provided to cooperate with a notch (not visible) of the frame 82.

 The key 16 comprises, for its tilting mounting on the mechanism 81, two opposite hooks 87 each disposed approximately at the

<Desc / Clms Page number 24>

 middle of one of its sides, each hook 87 being adapted to snap onto a respective cylindrical seat 88 of the mechanism 81.

 Thus, the device 2 has a conventional arrangement, involving a base 80 and a standard frame 82 for a whole range of devices, the elements specific to the device 2 being the mechanism 81 and the key 16, elements which together form which is generally called a composable mechanism.

 As seen more particularly in Figures 16 and 17, it is the mechanism 81 which comprises the frame 63 shown schematically in Figures 7 to 11, this frame being of generally rectangular shape and having a bottom 90 whose raise two uprights 91 each located in the middle of a respective one of two opposite sides, the uprights 91 carrying at their top a rod 92 oriented along an axis 93 (Figure 17) provided with the bearings 88 used for the snap-fastening of the hooks 87 of the key 16, so that after snap-fastening the latter is movable to tilt about the axis 93.

 In the bottom 90 is formed a hollow 89 where an electrical circuit 94 is installed comprising the rectifier assembly 26, the capacitor 31 and the emitter circuit 14.

 The assembly formed by the member 50, by the spring blades 62 and by the blocks 60 is fixed to the bottom 90 of the frame 63 by means of shims 95 which allow the member 50 to be sufficiently at distance from the bottom 90 in order to be able to carry out the movements necessary for its operation.

 Just as the member 50 is mounted resiliently with respect to the frame 63 by means of two spring blades 62, the percussion weight 64 is mounted on the frame 63 by means of two spring blades 65 (FIG. 17) each cooperating with an embedding at its two ends respectively with the percussion weight 64 and with a fixing block 97, each of the four embedding assemblies being effected by means of a screw 98.

 The drive lever 66 is disposed on uprights 99, at the top of which it is mounted for rotation about the axis 70 which, as indicated above, is not disposed transversely to the member 50 (such a representation has been adopted for the sake of simplification in FIGS. 8 to 11)

<Desc / Clms Page number 25>

 but is in fact parallel to the member 50, that is to say to the plane containing the minor axis 52 and the major axis 53, this plane itself being parallel to the general orientation of the bottom 90 of the frame 63.

 As can be seen more particularly in FIGS. 18 and 19, the lever 66 comprises, in addition to its portion 100 of generally tubular shape, the ends of which are mounted for rotation on the uprights 99, an angle iron oriented transversely to the tubular part 100, which is connected to it at the junction between the two branches 101 and 102.

 In the rest state, shown in FIGS. 15 to 18, the branch 102 is oriented in a transverse direction at the bottom 90 of the frame 63 and is arranged between the spring blades 65 opposite the percussion flyweight 64, the ball 69 under preload mounted on the percussion weight 64 being engaged in the cavity 68. Still in this rest position, the branch 101 is oriented in a direction substantially parallel to the bottom 90 of the frame 63, the supporting finger 103 projecting on the internal side of the button 16 (FIG. 20) then being against the branch 101.

 As best seen in the diagram of FIG. 21, when the key 16 is pushed on the projecting side of this key, that is to say on the side, with respect to the axis 93, where the finger 103, this has the effect of pivoting the lever 66 around the axis 70 in the direction indicated by the arrow 104, that is to say in the direction which drives the percussion weight 64, against spring blades 65, away from the counterweight 56 which faces it.

 As explained above, when the force exerted by the blades 65 on the counterweight 64 reaches a predetermined threshold by the elastic prestressing force exerted on the ball 69 and by the slope of a ramp that comprises the imprint 68, the ball 69 moves elastically towards the inside of the counterweight 64 by compressing the prestressing spring, the counterweight 64 thus being released and striking the member 50.

 The means for mounting the ends of the tubular portion 100 on the uprights 99 comprise a torsion spring (not shown) urging the lever 66 in the direction shown in FIG. 21 by the arrow 105, that is to say in the opposite direction to that represented by arrow 104, these

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 elastic return means returning the lever 66 to its initial position where the branch 101 is in abutment against the finger 103 with the key 16 which is in abutment against the frame 81 opposite, with respect to the axis 93, of the finger 103, the return to the initial position of the lever 66 also having the effect of engaging the disengageable connection means 67, that is to say again making the ball 69 penetrate into the cavity 68.

 It will be observed, in general, that in the apparatus 2, the percussion weight 64, the spring blades 65 and the drive lever 66 are disposed between the key 16 and the bottom 90, this bottom being located at the 'deviation of the key according to the thickness of the mechanism 81, and more generally according to the thickness of the device 2.

 The path followed by the percussion weight 64 thanks to its guidance by the spring blades 65 is substantially rectilinear and oriented, as is the minor axis 52, parallel to the bottom 90 of the frame 63.

 We will now describe the variant 181 of the mechanism 81 shown in FIG. 22.

 We have kept the same reference numbers for similar elements but added the number 100.

 In general, the piezoactive member 150 is similar to the member 34 but has a local counterweight 156 similar to the counterweight 56 which is integral with one of the vertices of minor axis 155 of the shell 151, in the vertex which is at the bottom in figure 22.

 The frame 163 of the mechanism 181 is similar to the frame 63 but has a rigid beam 300 which is connected to the rest of the frame 163 at the location where the wedges 95 are located in the frame 63, the beam 300 extending, beyond this connection zone, cantilevered above the electrical circuit 194.

 The member 150 is mounted on the frame 163 by screwing the apex of the minor axis 155 which can be seen at the top in FIG. 22 to the rigid beam 300.

 Thus, while the member 50 is mounted on the frame 63 so that each vertex of minor axis is movable relative to it, the member 150 has

<Desc / Clms Page number 27>

 one of the apexes of minor axis 155 which is subject to the frame while the other apex of minor axis, where the shell 151 is integral with the counterweight 156, is movable relative to the frame 163.

The percussion weight 164 is controlled exactly from the
5 same way as the flyweight 64 to strike the flyweight 156.

 The mechanical interface of the member 150, formed by the shell 151 and by the counterweight 156, is such that after the shock the piezoelectric element 118 produces an alternating voltage, reflecting the resonant movement of the member 150 , which, as mentioned above, has in particular a lower frequency than that of the member 50, the electrical circuit 194 being adapted to the characteristics of this alternating voltage.

 It will be noted that if the signal 13 emitted by the circuit 14 is here a radio signal, it is replaced as a variant by another type of signal transmitted by electromagnetic waves.

In a variant not shown, the shell 51 and the counterweight
56, or even the spring blades 62 and the fixing blocks 60 are assembled differently than by screwing, in particular by gluing or by welding or else are manufactured in one piece; and likewise for the shell 151 and the counterweight 156.

In another variant not shown, the electrical circuit is different, and in particular the rectifier assembly 26 is replaced by another type of rectifier assembly, for example simple alternation or voltage doubler.

 In still other variants not shown, the wireless device 2 is replaced by another wireless device also serving as a remote control, for example for opening the door of a vehicle, a gate or '' a garage door; or even constitutes an apparatus other than a remote control, for example a sensor or a device for transmitting brief signals at the rate of successive actions such as the action 15 exerted on the key 30 16 or on another mobile triggering member , for example a zipper.

 Still in other variants not shown, the means serving to transform the action 15 exerted on the key 16 into the excitation

<Desc / Clms Page number 28>

 mechanical oscillators 17 are different, and formed in particular by a mechanical system transforming the action 15 into a succession of shocks directly applied to the piezoelectric element 18, for example by means of a cam in the form of a rack acting on a hammer called back by spring towards the cam; or then by a system of the same type, but acting on the shell of a piezo-active member of the kind of member 34, member 50 or member 150; and / or another kind of piezoactive organ is used, in particular of the bimetallic strip type.

 Many other variants are possible depending on the circumstances, and it is recalled in this regard that the invention is not limited to the examples described and shown.

Claims (21)

1. Wireless electrical apparatus provided with a movable trigger member (16) and a transmitter circuit (14) for transmitting a signal (13) in response to an action (15) exerted on said member (16); characterized in that it further comprises said transmitter circuit (14): a piezoelectric element (18; 118); a circuit (26,31) rectifier-current shaper disposed between the terminals (22,23) of said piezoelectric element (18; 118) and the supply terminals (32,33) of said transmitter circuit (14); and motion transformation means (20,19) for transforming said action (15) exerted on said movable trigger member (16) into an oscillatory mechanical excitation (17) exerted on said piezoelectric element (18; 118 ), said excitation (17) being adapted to cause the terminals (22,23) of said element (18) to show an alternating voltage such as the voltage, rectified and smoothed by said circuit (26,31) rectifier-transformer, appearing accordingly at the terminals supply (32,33) of the transmitter circuit (14), remains above a predetermined voltage threshold for a duration greater than a predetermined duration so that said transmitter circuit (14) can fully transmit said signal (13).  2. Apparatus according to claim 1, characterized in that the application of a force of at most 3 N over a stroke of at most 3 mm is sufficient to constitute said action (15) exerted on said movable trigger member (16) 3. Apparatus according to any one of claims 1 or 2, characterized in that said rectifier-shaping circuit comprises a rectifier assembly (26) formed by four diodes arranged in bridge of Grâtz to operate a full-wave rectification and a capacitor (31 ), the input terminals (24,25) of said rectifier assembly (26) being connected to said piezoelectric element (18; 118), the emitter circuit (14) and the capacitor (31) being arranged in parallel between the terminals outlet (27,28) of said rectifier assembly (26). <Desc / Clms Page number 30>  4. Apparatus according to claim 3, characterized, said emitter circuit (14) having a substantially constant input resistance R, said rectifier-conforming circuit (26,31) comprising a capacitor (31) of capacity C, in that the term RC, R being expressed in Q and C in F, is substantially equal to said predetermined duration so that the transmitter circuit (14) can fully transmit said signal (13).  5. Apparatus according to claim 4, characterized in that said oscillatory mechanical excitation (17), said piezoelectric element (18; 118) and the diodes of said rectifier assembly (26) are adapted so that the maximum voltage reached at the terminals of the capacitor (31) is between 1.7 and 3.7 times said predetermined voltage threshold so that said transmitter circuit (14) can fully transmit said signal (13).  6. Apparatus according to any one of claims 1 to 5, characterized, said transmitter circuit (14) having a substantially constant input resistance R, said circuit (26,31) rectifier-shaper comprising a capacitor (31) of capacity C, said oscillatory mechanical excitation (17) having a main frequency f, in that the term RCf is greater than 10, R being expressed in Q, C in F and f in Hz.  7. Apparatus according to claim 6, characterized in that the term RCf is between 55 and 75.  8. Apparatus according to any one of claims 1 to 7, characterized in that said predetermined voltage threshold is at least equal to 1 V and said predetermined duration is at least equal to 20 milliseconds.  9. Apparatus according to any one of claims 1 to 8, characterized in that said movement transforming means comprise: a mechanical interface (19) linked to said piezoelectric element (18; 118); and activation means (20), to which belongs said movable trigger member (16), for transforming said action (15) exerted on said movable trigger member (16) into an action (21) exerted on said interface (19 ) to bring the piezoactive member (50; <Desc / Clms Page number 31>  150) formed by said piezoelectric element (18; 118) and by said interface (19).  10. Apparatus according to claim 9, characterized in that said activation means (20) are adapted so that said action (21) exerted on said interface (19) is a punctual mechanical action.  11. Apparatus according to any one of claims 9 or 10, characterized in that said piezoactive member (50; 150) is adapted to enter into resonance at a main frequency of several kHz.  12. Apparatus according to claim 11, characterized in that said piezo-active member (50; 150) is adapted to enter into resonance at a main frequency between 2.5 and 5 kHz.  13. Apparatus according to any one of claims 8 to 11, characterized in that said mechanical interface (19) comprises a shell (51; 151) elastically deformable profile substantially elliptical having four vertices (54,55; 154,155) opposite two two, respectively two vertices of minor axis (55; 155) and two vertices of major axis (54; 154) with the distance separating the two vertices of major axis (54; 154) which is greater than the distance separating the two minor axis vertices (55; 155), said piezoelectric element (18; 118) being disposed in said shell (51; 151) between the two major axis vertices (54; 154).  14. Apparatus according to claim 13, characterized in that said interface (19) further comprises a counterweight (56; 156) integral with said shell (51; 151) at an apex of minor axis (55; 155) and having a mass greater than that of the shell.  15. Apparatus according to claim 14, characterized in that said flyweight (56; 156) has a mass greater than four times that of the shell (51; 151).  16. Apparatus according to any one of claims 14 or 15, characterized in that said mechanical interface comprises a said flyweight (56) integral with said shell (51) to each of the two vertices (55) of minor axis. <Desc / Clms Page number 32>  17. Apparatus according to claim 16, characterized in that each said flyweight (56) has substantially the same mass.  18. Apparatus according to any one of claims 9 to 17, characterized in that said mechanical interface is disposed between said movable trigger member (16) and the bottom (90) of said device, said bottom being located away from said movable trigger member (16) depending on the thickness of the device.  19. System comprising a first device (2) according to any one of claims 1 to 18 and a second device (3) comprising a receiver circuit (11) adapted to receive the signal (13) emitted by the first device (2 ) and electrical control means (12) sensitive to the reception of said signal (13).  20. Apparatus according to claim 19, characterized in that said electrical control means comprise switching means (12).  21. Use of a system according to any one of claims 19 or 20 to control a light point (4).