WIRELESS ELECTRONIC DETONATOR COMPRISING A POWER SWITCH CONTROLLED BY AN OPTICAL SIGNAL, WIRELESS DETONATION SYSTEM AND METHOD FOR ACTIVATING SUCH A DETONATOR

Abstract

A wireless electronic detonator includes a primary source of energy and at least one functional module. A power switch is disposed between the primary source of energy and the functional module to connect or disconnect the functional module and the primary source of energy. A controller controls the power switch and includes an optical receiver to detect and demodulate a light signal emitted by a control console, The controller generates a control signal according to the demodulated light signal to at least control the power switch. A wireless detonation system includes the wireless electronic detonator and the control console configured to emit a light signal, and method for activating the wireless electronic detonator.

Claims

1-20. (Canceled)

21. A wireless electronic detonator comprising a primary source of energy, at least one functional module, a power switch disposed between the primary source of energy and said at least one functional module, the power switch configured to connect or disconnect said at least one functional module and the primary source of energy, and a controller to control the power switch, wherein said at least one functional module comprises at least one explosive fuse and an energy storage element dedicated to an ignition of said at least one explosive fuse, and wherein the controller comprises an optical receiver configured to detect and demodulate a light signal emitted by a control console and the controller generates at an output a control signal according to the demodulated light signal, the control signal being configured to at least control the power switch.

22. The detonator according to claim 21, wherein the optical receiver comprises an optical detector configured to detect the light signal emitted by the control console and convert the light signal into an electric signal.

23. The detonator according to claim 22, further comprising at least one optical filter upstream of the optical detector.

24. The detonator according to claim 22, wherein the optical detector comprises a photovoltaic element.

25. The detonator according to claim 22, further comprising a demodulator configured to demodulate the electric signal.

26. The detonator according to claim 25, wherein the demodulator comprises an analog conditioner configured to transform the electric signal from the optical detector into a digital signal.

27. The detonator according to claim 26, wherein the demodulator comprises a digital processor configured to demodulate the digital signal and generate the control signal to control the power switch.

28. The detonator according to claim 27, further comprising a low-consumption mode configured to cut off a power supply to at least the digital processor.

29. The detonator according to claim 21, further comprising a general cutoff module configured to cut off a power supply to the optical receiver.

30. The detonator according to claim 29, wherein the general cutoff module comprises a phototransistor with a high gain, coupled with a detection resistor configured to detect a very low level of lighting, and a transistor, acting as a switch, the detection resistor being configured to control the transistor.

31. The detonator according to claim 21 is configured to emit a return signal when the optical receiver has at least detected the light signal emitted by the control console.

32. A wireless detonation system comprising the wireless electronic detonator according to claim 21 and the control console configured to emit the light signal to the wireless electronic detonator.

33. The detonation system according to claim 32, wherein the control console comprises a lens configured to focus the light signal towards at least one detonator.

34. The detonation system according to claim 32, wherein the control console comprises a modulator configured to modulate the light signal according to at least one modulation pattern to provide a modulated light signal.

35. The detonation system according to claim 34, wherein the modulated light signal comprises at least one activation sequence.

36. The detonation system according to claim 34, wherein the modulated light signal comprises a data sequence configured to send instructions to the wireless electronic detonator.

37. A method for activating a wireless electronic detonator comprising a primary source of energy, at least one functional module comprising at least one explosive fuse and an energy storage element dedicated to an ignition of said at least one explosive fuse, a power switch, disposed between the primary source of energy and said at least one functional module, the power switch configured to connect or disconnect said at least one functional module and the primary source of energy, and a controller to control the power switch, the method comprising steps of: receiving a light signal; demodulating the light signal received; and generating a control signal, according to the demodulated light signal, the control signal being configured to at least control the power switch.

38. The activation method according to claim 37, wherein the step of receiving the light signal comprises detecting the light signal and converting the light signal into an electric signal.

39. The activation method according to claim 38, wherein the step of demodulating comprises transforming the electric signal into a digital signal and identifying at least one activation sequence in the digital signal; and wherein the step of generating the control signal comprises activating the power switch in response to an identification of an activation sequence.

40. The activation method according to claim 39, wherein the step of demodulating comprises identifying at least one data sequence in the digital signal; and wherein in response to an identification of a data sequence, the step of generating the control signal comprises generating instructions corresponding to the data sequence.

Description

[0153] The invention, according to an exemplary embodiment, will be well understood and its advantages will appear better upon reading the following detailed description, given for informational and in no way limiting purposes, in reference to the appended drawings in which:

[0154] FIG. 1 outlines a detonation system according to an exemplary embodiment of the invention;

[0155] FIG. 2 shows an example of a pseudo-random sequence following a modulation pattern;

[0156] FIG. 3 shows a wireless detonator according to an exemplary embodiment of the invention;

[0157] FIG. 4 outlines an exemplary embodiment of an optical receiver;

[0158] FIG. 5 illustrates a first exemplary embodiment of an optical receiver;

[0159] FIG. 6 schematically shows an example of an emission spectrum of a light source containing LEDs according to the wavelength;

[0160] FIG. 7 schematically shows the spectral sensitivity of a photodiode according to the wavelength;

[0161] FIG. 8 shows the spectral characteristics of a filter resulting from the emission spectrum of FIG. 6 and the sensitivity of the photodiode of FIG. 7 according to the wavelength;

[0162] FIG. 9 illustrates a second exemplary embodiment of an optical receiver;

[0163] FIG. 10 illustrates a third exemplary embodiment of an optical receiver.

[0164] Identical elements shown in the aforementioned drawings are identified by identical numerical references.

[0165] According to an exemplary embodiment of an aspect of the invention outlined in FIG. 1, a detonation system 10 mainly includes:

[0166] a control console 100 configured to emit a modulated light signal LU, and

[0167] a detonator 200, autonomous in terms of energy, configured to detect and demodulate the light signal LU of the control console 100.

[0168] According to an exemplary embodiment, the control console 100 includes a modulated light source.

[0169] As outlined in FIG. 1, the control console 100 includes for example a light source 110 configured to emit a light beam including a light signal, and a modulator 120 configured to modulate the light signal according to at least one modulation pattern.

[0170] The light source 110 is preferably configured to emit a light signal in the visible range, that is to say a light signal having a wavelength between approximately 400-800nm.

[0171] A light source configured to emit a signal in the infrared or the ultraviolet can however be used, according to the needs or the intended use.

[0172] According to an option not shown, the control console can further include a variable lens, also called adjustable, configured to focus the light signal towards one or more detonators.

[0173] The control console can thus activate a single detonator, for example if the lens is adjusted to transmit a narrow beam, or simultaneously activate a group of detonators, if the lens is adjusted to transmit a wider beam allowing to illuminate several detonators.

[0174] According to an option of interest, the detonator is configured to emit a return signal when it is illuminated by the beam of the control console.

[0175] The detonator includes for example a visual or sound indicator.

[0176] The detonator can also be configured to emit a return signal configured to be consequently detected by the control console, for example a radio signal.

[0177] According to at least one other option of interest, the control console 100 can also include a detector, configured to detect a return signal emitted by the detonator, and an indicator, for example visual or sound, configured to alert the user that the light signal emitted by the light source 110 has at least been detected by at least the targeted detonator, or that the return signal has indeed been detected by the control console.

[0178] The indicator, of the control console or of the detonator, includes for example an LED or a buzzer.

[0179] The detonation system is thus provided with a system for assisting pointing.

[0180] The control console preferably emits the light sequence continuously, either for a predetermined time, or on demand by the user.

[0181] The user illuminates the zone in which the detonator 200 is located, or even more particularly an optical receiver 220 of the detonator 200 (described below), with a sweeping movement.

[0182] When the expected light sequence is detected by the detonator, a simple visual return, for example via an LED, or sound, for example via a buzzer, is triggered by the detonator.

[0183] FIG. 2 shows an example of a modulation pattern M used to modulate the light signal LU emitted by the control console 100.

[0184] This is in particular in this figure an OOK (On/Off Keying) modulated pseudo-random sequence, but other types of optical modulations are possible.

[0185] A modulation of the OOK type has the advantage of being simple to implement, and not very complex to demodulate, which allows to limit the cost of the detonator.

[0186] Preferably, a pseudo-random sequence known to the receiver is used to modulate the optical signal emitted by the console, in order to be able to distinguish it with the least error possible from a natural or artificial light (certain artificial lighting indeed has a hashed signal in the form of a square wave).

[0187] The size of the pseudo-random sequence must be sufficiently long, typically greater than 32 bits, in order to avoid false alarms.

[0188] Preferably, a modulation rate (frequency) is typically between 100 Hz and 10 kHz.

[0189] This value is sufficient to not be too sensitive to the movements of the user, and is not too high to be able to limit the cost of the receiver 220 by using for example a photodiode 231 (outlined in FIG. 5) having limited performance.

[0190] This example is not limiting. Other types of modulation, other types of sequences, other modulation rates could be used.

[0191] Another advantage of the system by optical modulation is to be able to use the modulated light signal to transmit information, that is to say digital data, useful to the detonator, optically.

[0192] For this, in the control console, the modulated light signal LU includes for example preferably an activation sequence having good autocorrelation properties, typically a Kasami sequence.

[0193] This allows the receiver, i.e. the detonator, to suitably synchronize itself on the received signal in order to extract the data therefrom.

[0194] The data sequence includes for example binary data that is simply concatenated after the activation sequence.

[0195] The message sent by the control console includes for example the following sequences: [activation sequence]−[data sequence].

[0196] The data sequence is configured to send for example a delay value, and/or an identifier, and/or an ignition code, or others.

[0197] According to one example, an integrity control of the CRC (Cyclic Redundancy Check) type can optionally be added to the message, in order to be able to control the result of the demodulation of the data sequence in the detonator (i.e. of the receiver).

[0198] The message sent by the control console thus includes for example the following sequences: [activation sequence]− [data sequence]− [control sequence].

[0199] According to another example, it would also be possible to add a correction code.

[0200] The message sent by the control console thus includes for example the following sequences: [activation sequence]− [data sequence]− [control sequence]− [correction sequence].

[0201] Thus, according to an exemplary embodiment, it is possible to use a block code of the Hamming type, which includes a data sequence and a correction sequence.

[0202] On the receiver side, i.e. detonator side, conventional digital demodulation techniques can be used.

[0203] The activation sequence allows to synchronize the receiver on the beginning of the sent message.

[0204] A simple regular sampling, or a front detection, then allows to demodulate the contents of the message.

[0205] According to yet another option of interest, the modulated light signal LU includes a stop signal.

[0206] In order to carry out the same function as a manual switch, the detonation system using an optical modulation preferably allows to power off a detonator.

[0207] This provides an additional level of security, in the case for example in which abandoning of the firing is decided, or simply to stop a detonator powered on by mistake.

[0208] With a view to using this stop function, two different sequences can be used: a sequence for the powering on, another sequence for the powering off.

[0209] The two sequences are preferably quasi-orthogonal, in order to limit the risks of poor detection of the sequence emitted.

[0210] For example, two different Kasami sequences allow to satisfy this condition.

[0211] One alternative can be to use the sign of the sequence: normally emitted, the sequence leads to a positive correlation peak for the start-up, but emitted in an inversed manner, it thus gives a negative correlation peak, for example for the stoppage.

[0212] In the end, a single correlator is necessary, only the sign of the result making the difference.

[0213] Kasami sequences are, however, preferred since they give a result close to 0 for an intercorrelation, regardless of the offset between the sequences.

[0214] Consequently, the control console must allow the user to select one sequence or another (that is to say an activation sequence or a stop sequence).

[0215] In the receiver, a digital processing module of the optical receiver of the detonator (described below) is for example configured to detect one sequence or the other. Correlation processings are for example duplicated, by alternatingly using one sequence then the other as a reference sequence.

[0216] FIG. 3 shows an exemplary embodiment of a detonator 200.

[0217] The detonator 200 according to the invention, autonomous in terms of energy, mainly includes here a control module 210 that includes an optical receiver 220 configured to activate the detonator optically.

[0218] The optical receiver 220 allows in particular to demodulate the light beam LU send by the console 100, and generate a signal for controlling the power switch 240.

[0219] Moreover, the detonator 200 includes for example here the following elements:

[0220] A primary source of energy 230 (for example an on board source of energy, or a module for recovering energy combined with a local energy storage, or a module for providing energy connected by cable), allowing to power the various other elements of the detonator via a power switch 240 and to transfer energy to an energy storage element 253 dedicated to the ignition of an explosive fuse 256.

[0221] The power switch 240, for example including a K10 switch, allowing to control the powering on of various electronic elements of a functional module 250 from the primary source of energy 230. This power switch 240 can be similar to one of the embodiments presented in the document WO 2019/073148.

[0222] And the functional module 250.

[0223] The functional module 250 includes here for example the following electronic elements:

[0224] A computer 251 allowing to control the operation of the electronic detonator. The computer 251 is connected, or disconnected, from the primary source of energy 230 via the power switch 240.

[0225] The energy storage element 253 dedicated to the ignition of the explosive fuse 256.

[0226] A switch 252 for isolating the energy storage element, including for example a K20 switch, allowing to activate or deactivate the transfer of energy from the primary source of energy 230 to the energy storage element 253, independently of the transfer of energy from the primary source of energy 230 to the computer 251.

[0227] A discharge device 254, forming a security mechanism allowing a slow discharge of the energy storage element 253 dedicated to the ignition, in order to go back to a state of security in the case of powering off.

[0228] An ignition switch 255, including for example a K30 switch, allowing the transfer of the energy between the energy storage element 253 dedicated to the ignition and the explosive fuse 256.

[0229] And the explosive fuse 256.

[0230] The optical receiver 220 according to an exemplary embodiment is outlined in FIG. 4.

[0231] The optical receiver 220 of FIG. 4 mainly includes:

[0232] an optical detector 221, configured to convert the light signal LU received into an electric signal; and

[0233] a demodulator 222 configured to demodulate the light signal received and generate a signal for controlling the power switch 240.

[0234] Here, the demodulator 222 includes for example:

[0235] an analog conditioner 223, configured to transform the electric signal of the optical detector 221, which is analog, into a digital signal; and

[0236] a digital processing module 224, configured to demodulate the digital signal in order to detect the binary sequence emitted by the control console 100 and generate a control signal to at least control the power switch 240 according to the binary sequence.

[0237] Here, the digital processing module 224 and/or the computer 251 are for example configured to:

[0238] manage the operation of the electronic detonator 200;

[0239] analyze the messages received via the control console 100;

[0240] act according to the meaning of the messages received;

[0241] activate the storage of energy in the energy storage element 253 for the ignition;

[0242] carry out the countdown of the ignition delay associated with the electronic detonator 200;

[0243] activate the transfer of energy from the energy storage element 253 to the explosive fuse 24 after the countdown, via the ignition switch 255;

[0244] activate the discharge device 254;

[0245] control the power switch 240;

[0246] control the isolation switch of the energy storage element 252.

[0247] FIG. 5 shows an exemplary embodiment of the optical receiver 220 outlined in FIG. 4.

[0248] The optical detector 221 includes here a photodiode 231 that converts the light signal LU into electric current.

[0249] The optical detector 221 also includes here a detection resistor 232 that allows to process a voltage, usable by the analog conditioner 223.

[0250] The detection resistor 232 is dimensioned in such a way that the signal is not saturated under strong luminosity, which would make the system ineffective. Inversely, a value that is too low reduces the dynamics of the electric signal, entailing a reduction in the range of the detonation system.

[0251] By supposing a maximum possible lighting of Emax (typically 130,000 lux), and a sensitivity of the photodiode 231 of S A/lux, and a power supply voltage Vdd, the detection resistor 232, having a resistance noted as R, must verify the relationship Vdd=R×S×Emax to be at the limit of saturation under maximum lighting.

[0252] The dimensioning of the pair [photodiode 231−detection resistor 232] thus determines for the most part the performance of the system in terms of range.

[0253] The analog conditioner 223 includes here at least one high-pass filter, in order to eliminate the static component related to the natural lighting and to the movements of the user.

[0254] It can include a pass-band filter (which thus corresponds to a high-pass filter to which a low-pass filter has been added) to also eliminate possible high-frequency disturbers.

[0255] In the example of implementation shown in FIG. 5, the analog conditioner 223 includes a pass-band filter (a pair R.sub.1C.sub.1 (resistor-capacitor) on a “+” (plus) pin of a comparator 233 determines the high frequency and a pair R.sub.2C.sub.2 on a “−” (minus) pin the low frequency) allowing to eliminate the static component of the signal, related to the level of ambient lighting.

[0256] The filtered signals are injected into the comparator 233 to obtain a binary signal at the output of the comparator 233, thus at the output of the analog conditioner 223.

[0257] The analog conditioner 223 includes for example a comparator and/or an operational amplifier.

[0258] Finally, the digital processing module 224, into which the digital signal is injected, includes for example at least one computer (typically a microcontroller or a dedicated digital circuit), and optionally a memory element.

[0259] The received signal is correlated with the expected reference signal, in such a way as to detect the presence of an activation signal.

[0260] The expected reference signal is possibly prerecorded in the digital processing module 224.

[0261] At this level, any known technique for demodulation of a digital signal can be used.

[0262] When the activation sequence is detected, the digital processing module 224 generates a control signal configured to control the power switch 240 in an active position, for example in a closed position if this is a switch, in such a way as to power on the other elements of the detonator.

[0263] These functionalities can, however, be carried out differently from the embodiment outlined in FIG. 5.

[0264] For example, in order to share the hardware resources, it is for example possible to carry out the digital processing in the computer 251 of the functional module 250. The general architecture must thus be slightly redone, in such a way as to assemble the computer 251 upstream of the power switch 240.

[0265] In other words, the computer 251 of the functional module 250 and the digital processing module 224 can thus be grouped together into a single entity, preferably located upstream of the power switch 240, for example in the optical receiver 220.

[0266] Moreover, a part of the computer can remain “inactive” (in low-consumption mode) as long as the light sequence has not been received.

[0267] It is also possible to use other strategies to demodulate the light signal, which lead to a different hardware architecture of the optical receiver 220. For example, the analog conditioner 223 could be replaced by a digitization using an ADC (Analog-to-Digital Converter) of the raw signal coming from the optical receiver, which can then be processed directly by the computer of the digital processing module 224.

[0268] In all cases, the optical receiver presented needs to be powered.

[0269] However, ideally, the detonation system must consume as little energy as possible, to avoid reducing the battery life of the detonator before its use on the ground.

[0270] The consumption must therefore be as low as possible for the system to be of as much practical interest as possible.

[0271] The optical receiver 220 generally has a consumption that is directly proportional to the lighting.

[0272] Typically, for a photodiode having a sensitivity of 40 nA/100 lux, the consumption is 52 μA under a maximum sunlight of 130,000 lux.

[0273] The consumption of the analog conditioner 223 is typically located between 1 μA and 30 μA according to the comparator or the operational amplifier used.

[0274] The choice of a comparator 233 having a reduced [gain x bandwidth] product allows to select components, the consumption of which is located around one microampere (μA).

[0275] This occurs to the detriment of the allowed modulation rate, but this is not a critical element of the system.

[0276] Finally, the digital processing module 224 typically consumes several milliamperes when the processing is carried out.

[0277] The consumption of the optical detector 221 and of the digital processing module 224 is thus that which must be reduced first and foremost, to aim at a consumption of approximately several microamperes, if possible.

[0278] A first approach thus involves for example adding an optical filter in front of the photodiode 231 of the optical detector 221, in order to reduce the intensity of the ambient lighting, without reducing the detection performance.

[0279] One goal is to maximize the received light power corresponding to the optical signal, while reducing as much as possible the received power corresponding to the ambient lighting.

[0280] This allows to reduce the current consumed by the optical detector related to the intensity of the ambient lighting.

[0281] The light source of the control console 100 has a very particular emission spectrum (FIG. 6), and the photodiode 231 has a characteristic spectral sensitivity (FIG. 7).

[0282] These two elements thus behave as gain filtering stages Gtx(A) and Grx(A), dependent on the wavelength λ of the light signal emitted by the control console 100.

[0283] The optical power Prx converted by the photodiode 231 into electric power is thus expressed according to the power Ptx emitted by the console, the attenuation related to the distance R, the illuminated solid angle Ω, and the respective gains Gtx and Grx, according to the following formula:

Prx=[(Grx.Math.Gtx)/ΩR.sup.2].Math.Ptx

[0284] For a given distance and focal distance, the received power is maximum when the gain (Gtx.Grx) is maximum, that is to say for a given wavelength λ (FIG. 8).

[0285] The addition of an additional filter around this wavelength thus allows to maximize the reception at this wavelength, and reduce the reception on the other wavelengths, which corresponds to the desired goal.

[0286] The optimal width of the optical filter is thus calculated according to the response of the filter with respect to the natural light, which it is desired to reduce.

[0287] In practice it is thus possible to reduce by a factor of 3 the consumption of the optical detector.

[0288] A second approach involves for example using the photovoltaic effect of a photodetector 234 for the optical detector 221.

[0289] The photodetector 234 is used here in photovoltaic mode, like in the assembly outlined in FIG. 9.

[0290] For this, it is not polarized by a power supply voltage.

[0291] A photodiode like in the preceding example does not allow to generate a current sufficient to be usable. It is necessary to increase the surface of the photosensitive element, by using a photovoltaic panel having reduced dimensions, or several photodiodes in parallel.

[0292] This assembly allows to eliminate, possibly totally, the consumption of the optical detector.

[0293] The consumption is thus very well controlled, and is more independent of the surrounding lighting conditions.

[0294] According to a third approach, it is also possible to cut off the power supply to the digital processing module in order to limit the consumption.

[0295] For example, the digital processing module 224 includes a low-consumption mode that allows to cut off the clock and optionally the power supply to the digital electronics.

[0296] The presence of a change of state on the digital signal at the output of the comparator is for example used to take the system out of low-consumption mode.

[0297] Thus, under natural lighting, the light intensity varies slowly, there is therefore no variation at the output of the analog conditioner, because of the low-pass filtering.

[0298] As soon as a sudden variation in lighting occurs, a transition appears at the output of the analog conditioner, used to awaken the digital processing module.

[0299] This functionality can typically be implemented via a low-consumption mode of a microcontroller.

[0300] The consumption can thus be reduced at least by a microampere (1pA).

[0301] According to a fourth approach, in order to avoid any residual consumption during a period of storage of the detonator for example (which can last several months before its use), a general cutoff of the power supply depending on the level of lighting is used (“darkness mode”).

[0302] As illustrated in FIG. 10, a stage for additional detection of the level of lighting is used, with a setting allowing to voluntarily saturate the output signal as soon as a very low level of lighting appears.

[0303] For this, the stage for additional detection of the level of lighting includes for example a phototransistor 235 with high gain (for example 40 μA/100 lux) and a detection resistor 237, a setting value of which allows a detection of a very low level of lighting, typically several tens of lux.

[0304] The voltage at the terminals of the detection resistor 237 allows to control a transistor 236 acting as a switch.

[0305] Thus, the optical detection stage 221 remains unchanged. An additional stage upstream of the latter (but based on the same principle) is added, this additional stage having a different adjustment of the optical detection stage.

[0306] In this way, when the detonator is in the dark, stored in a box for example, the power supply is totally cut off. The consumption is thus almost zero (except for the leak currents of the transistor 236 and of the phototransistor 235, which are negligible).

[0307] When the detonator is taken out of the box to be used, the general cutoff stage powers on the optical receiver 220, the detonator is thus waiting for an optical activation coming from the user (via the control console).