Wireless electronic detonator including a power switch controlled by an optical signal, a wireless detonation system and a method for activating such a detonator

Abstract

A wireless electronic detonator (200) comprises a main energy source (230) and at least one functional module (250), a power switch (240) arranged between the main energy source and the functional module to connect or disconnect the functional module (250) and the main energy source (230), and a control module (210) comprising an optical receiver (220) for controlling the power switch, wherein the optical receiver (220) is used to detect and demodulate an optical signal (LU) emitted by a control console (100), and to generate a control signal according to the demodulated optical signal (LU) to control at least the power switch (240); a wireless detonation system (10) comprising such a wireless electronic detonator (200) and a control console (100) configured to emit an optical signal (LU), and a method for activating such a wireless electronic detonator.

Description

Technical Field

[0001] The invention relates to a wireless electronic detonator.

[0002] The invention also relates to a wireless detonation system and a method for activating an electronic detonator. Background Art

[0003] In this context, activation method refers to turning the electronic detonator on or off, regardless of its ignition.

[0004] The invention finds application in the field of pyrotechnic initiation, in any sector where one or more networks of detonators have to be implemented routinely. Typical examples of use relate to mining, quarries, seismic exploration or exploitation in the construction and public works sectors.

[0005] During its use, the electronic detonators are placed respectively in locations arranged to accommodate them and intended to be loaded with explosives. These locations are, for example, holes dug in the ground. The ignition of the electronic detonators is then achieved according to a predetermined sequence.

[0006] To achieve this result, a firing delay is associated individually with each electronic detonator, and a shared firing sequence is broadcast to the network of electronic detonators by means of a control console.

[0007] This shared firing order allows the countdown of the firing delays of all electronic detonators to be synchronized.

[0008] After receiving the firing order, each electronic detonator manages the specific countdown of the firing delay associated with it, as well as its own firing.

[0009] Wireless electronic detonators are known which are activated by a remote control station which is configured to communicate with the detonators by radio waves, for example to exchange commands or messages with them regarding their status or to issue firing commands to them. Energy independence is therefore an important condition for realizing wireless detonators.

[0010] Document WO 2019 / 073148 describes a wireless electronic detonator, which includes an energy source and a functional module, and a first switching device arranged between the energy source and the functional module to allow the energy source to be connected to the functional module or not to be connected to the functional module, and a control module for controlling the first switching device, the control module including a module for recovering radio energy, the module being configured to receive a radio signal from a console, recover electrical energy in the received radio signal, generate an energy recovery signal representing the level of the recovered electrical energy, and generate a control signal at an output according to the recovered energy, wherein the control signal controls the switching device.

[0011] Thus, a radio signal is sent by the control console to the detonator. On the detonator side, the principle involves recovering the energy present in the radio signal with the aid of a suitable receiving system (i.e. a module that recovers radio energy) in order to control the power switching mechanism. This solution offers, among other things, the following advantages:

[0012] - Activation involves no mechanical elements to be manipulated, which allows designing a completely sealed housing for the detonator, robust to environmental conditions and handling, and thus increasing the reliability of the system;

[0013] - activation of the detonator can be performed only by personnel with an appropriate control console, thus limiting the possibility of activation by any specific person who does not have the required equipment;

[0014] - The system is simple and quick to use: it is enough to approach the console that activates the detonators to remotely power the switching system and start the automatic controller of the wireless detonators.

[0015] However, this system has disadvantages.

[0016] In particular, the range of radio detonation systems is rather limited. In fact, it does not exceed a few tens of centimeters due to the restrictions imposed by regulations on radio power, which is an obstacle to easy use.

[0017] Furthermore, it is not always possible to aim at a specific detonator without confusion, in particular when several detonators are close to each other. However, this distinction is essential in order not to associate the wrong detonator with the firing plan or to assign the wrong firing delay to a detonator. There are techniques based on proximity, the directivity of the antenna or an estimation of the distance between the activation console and the detonator, such as proposed in document WO 2019 / 073148, but their practical implementation is complex. Summary of the invention

[0018] In this context, one object of the present invention is to at least partially overcome the aforementioned disadvantages, while also bringing about other advantages.

[0019] The object of the present invention is in particular to propose a technology for remote activation, thereby providing a more effective solution to the above-mentioned problem.

[0020] In particular, the object of the invention relates to a system for controlling a switch, ie a mechanism allowing the activation or deactivation of a detonator.

[0021] To this end, according to a first aspect of the present invention, a wireless electronic detonator is proposed, comprising a main energy source and at least one functional module, a power switch arranged between the main energy source and the functional module and configured to connect or disconnect the functional module from the main energy source, and a control module for controlling the power switch, characterized in that the control module for controlling the power switch comprises an optical receiver, the optical receiver is configured to detect and demodulate an optical signal emitted by a console, and generate a control signal at an output according to the demodulated optical signal, and the control signal is configured to control at least the power switch.

[0022] Therefore, the detonator is configured to receive and demodulate the optical signal received from the control console (also called the remote activation console).

[0023] When the optical signal is correctly demodulated, the power switch is activated and the rest of the detonator's electronics are powered on.

[0024] The primary energy source is configured to power various other elements of the detonator via the power switch.

[0025] The primary energy source comprises, for example, an onboard energy source, or an energy recovery module combined with local energy storage, or an energy supply module connected by a cable.

[0026] The primary energy source is, for example, also configured to transfer energy to an energy storage element dedicated to igniting an explosive fuse of the functional module.

[0027] The power switch can be similar to one of the embodiments proposed in document WO 2019 / 073148.

[0028] The power switch includes, for example, a switch.

[0029] According to the present invention, the detonator comprises a control module for controlling the power switch, ie a control module configured to control the power switch.

[0030] Thus, the control module is, for example, configured to receive an ignition command and to command the ignition of the explosive fuse in dependence on said ignition command.

[0031] To this end, the control module essentially comprises an optical receiver.

[0032] In a preferred exemplary embodiment, the optical receiver includes a photodetector configured to detect an optical signal emitted by the console and convert the optical signal into an electrical signal.

[0033] For example, the light detector comprises a photodiode, optionally with a sense resistor added.

[0034] In a preferred exemplary embodiment, the detonator further comprises a demodulator configured to demodulate the electrical signal.

[0035] According to an exemplary embodiment, the demodulator includes an analog modulator configured to convert an analog electrical signal from the photodetector into a digital signal.

[0036] The analog conditioner comprises, for example, at least one high-pass filter, or even a band-pass filter, configured to eliminate static components of the light beam.

[0037] According to an exemplary embodiment, the demodulator comprises a digital processing module configured to demodulate the digital signal, for example in order to detect a binary sequence transmitted by the console, and to generate a control signal, for example according to the binary sequence, to control the power switch.

[0038] The digital processing module comprises, for example, at least one calculator and, optionally, memory elements.

[0039] Here, memory elements designate both conventional memory and registers.

[0040] For example, the received signal is correlated with a reference signal, for example recorded in a memory element, in order to detect an activation sequence.

[0041] According to the correlation result, the digital processing module is configured to generate a signal for controlling the power switch.

[0042] In all cases, the optical receivers mentioned here must be powered.

[0043] Ideally, however, the detonation system should consume as little energy as possible to avoid reducing the life of the detonator before it can be used on the ground and to conserve as much energy as possible from the main energy source.

[0044] Therefore, consumption must be as low as possible.

[0045] The power consumption of the photodetector and digital processing blocks is a priority to be reduced, if possible, aiming for a system consumption of approximately a few microamps.

[0046] Photodetectors generally have a consumption that is proportional to the illumination.

[0047] According to a first example, the detonator advantageously comprises at least one optical filter upstream of the light detector in order to reduce the intensity of the ambient lighting without degrading the detection performance.

[0048] One goal is to maximize the received optical power corresponding to the optical signal while minimizing the received power corresponding to the ambient lighting.

[0049] This allows reducing the current consumed by the photodetector in relation to the intensity of the ambient lighting.

[0050] According to a second example, the light detector advantageously comprises a photovoltaic element.

[0051] Therefore, the detector was used here in photovoltaic mode.

[0052] For this purpose, for example, it is not polarized by the supply voltage.

[0053] This type of arrangement makes it possible to completely eliminate the consumption of light detectors.

[0054] Consumption is thus well controlled and more independent of the surrounding illumination conditions.

[0055] According to a third example, the detonator comprises a low-consumption mode configured to cut off the power supply to at least the digital processing module, which allows limiting the power consumption of the system.

[0056] Thus, for example, under natural lighting, the light intensity varies slowly and therefore there is no variation at the output of the analog regulator because of the high pass filtering.

[0057] In case of a sudden change in lighting, a transition occurs at the output of the analog regulator which wakes up the digital processing module.

[0058] This functionality can usually be achieved via a low-power mode of the microcontroller.

[0059] The consumption can thus be reduced to less than one microampere (1µA).

[0060] According to a fourth example, in order to avoid any residual consumption during, for example, the storage period of the detonators (which may last several months before their use), use is made of a switch-off of the power supply to the light receivers as a function of the illumination level (“dark mode”).

[0061] The detonator thus comprises, for example, a general disconnection module configured to disconnect the power supply to the optical receiver.

[0062] The total cutoff module, for example, includes a phototransistor with high gain (e.g. 40µA / 100Lux), which is optionally coupled with a sense resistor configured to detect extremely low levels of illumination (typically less than 100 lux, even 80 lux, even 60 lux, even 40 lux, even 20 lux, or even 1 lux).

[0063] The detonator, even a total cut-off module for example, also includes, for example, a transistor used as a switch, and the detection resistor is configured to control the transistor.

[0064] Thus, when the detonator is in darkness, for example when stored in a box, the power supply to the light receiver is completely cut off. The consumption is thus almost zero (except for the leakage current of the transistor and the phototransistor, which can be ignored).

[0065] When the detonator is taken out of the box for use, the master cut module energizes the light receiver and the detonator thus awaits light activation from the user (via the console).

[0066] The functional module here comprises, for example, at least one explosive fuse.

[0067] According to an exemplary embodiment of interest, the functional module further comprises an energy storage element dedicated to igniting the explosive fuse.

[0068] For safety reasons, the functional module advantageously also comprises a switch for isolating the energy storage element, the switch being configured to activate or deactivate the energy transfer from the main energy source to the energy storage element.

[0069] Also for safety reasons, the functional module may further include a discharge device configured to slowly discharge the energy storage element so as to return to a safe state in the event that, for example, the detonator is powered off.

[0070] According to an option of interest, the functional module may therefore also comprise an ignition switch configured to allow the transfer of energy between the energy storage element dedicated to ignition and the explosive fuse.

[0071] According to an exemplary embodiment, the functional module further comprises a computer configured to control the operation of the detonator.

[0072] For example, the calculator is connected or disconnected from the main energy source via a power switch.

[0073] Thus, the computer is, for example, configured to receive the signal and, as a function of the signal, to command the ignition of an explosive fuse of the functional module.

[0074] According to another interesting option, the detonator is configured to emit a return signal when an optical receiver of the detonator detects at least an optical signal emitted by the control console.

[0075] For example, a user may be alerted that a light signal emitted by the control console has been detected by at least a target detonator.

[0076] Therefore, energization of the detonator is performed by optical activation.

[0077] For example, the detonator is configured to emit a return signal that is directly perceptible to a user, such as a visual or audible signal.

[0078] According to another example, the detonator is configured to emit a return signal, such as a radio signal, configured to be detected thereby by the control console.

[0079] Such a detonator has at least the same advantages as the above-mentioned prior art, in particular:

[0080] - In terms of reliability: it allows to achieve sealed housings and eliminate mechanical elements, limiting or even avoiding the risk of false contact, etc.

[0081] - In terms of safety: it is necessary to have an appropriate control console (which includes a light source) to activate the detonator,

[0082] - Or in terms of ease and rapidity of implementation: it is not necessary to physically and electrically connect the console to the detonator to activate it, and activation takes place without contact.

[0083] And such a detonator also has at least the advantage of providing a simplified mode of operation by virtue of the remote activation range: for example, it is not necessary to use accessories to activate the detonator, such as a rod for activating the detonator on the ground without leaning over, or a basket for activating the detonator located high in an underground gallery.

[0084] According to a second aspect of the present invention, a wireless detonation system is also provided, comprising a wireless electronic detonator including at least part of the above-mentioned features and a control console configured to transmit an optical signal to the wireless electronic detonator.

[0085] In practice, the user thus directs the light signal in the direction of the detonator they wish to activate.

[0086] The wireless detonation system has similar features and advantages to those described above with respect to the wireless electronic detonators.

[0087] In addition, such a detonator associated with a corresponding control console also has at least the following advantages:

[0088] - In terms of range: the range is increased, which in fact allows to activate the detonator at a distance of several meters, depending on the ambient light level and the power of the light source.

[0089] - In terms of regulations: the system is not subject to restrictive regulations like those for radio-activated systems proposed in the prior art, which allows the development of systems with better performance.

[0090] - In terms of safety: the console allows precise aiming of the desired detonator and, if the signal is emitted within the visible range, the direction of the beam is perfectly visible to the user, which avoids any ambiguity.

[0091] - In terms of flexibility: the system adapts to different use cases than normal. By using a wider lens that allows illuminating multiple detonators, it is indeed possible to activate a group of detonators simultaneously. This technology can be beneficial in underground environments, or when a firing plan has been established and the goal is to energize multiple detonators very quickly.

[0092] In a particularly convenient exemplary embodiment, the console includes a light source configured to emit a light signal.

[0093] The light source is preferably configured to emit a light signal in the visible range, ie having a wavelength comprised between about 400-800 nm.

[0094] However, depending on the requirements of the application, it is also possible to emit light signals in the infrared region (IR) or in the ultraviolet region (UV).

[0095] The technology used is the same.

[0096] Regarding the visible range, light signals emitted in the IR or UV are not perceptible (visible) to the user, which may make the use of the detonator system less easy, especially for precise aiming of the detonator.

[0097] To overcome this difficulty, the detonation system therefore advantageously comprises an auxiliary pointing system.

[0098] However, when using signals within the visible range, auxiliary pointing systems may also be useful.

[0099] For example, depending on the power of the light beam or if the ambient light level is high, the optical signal may not be easily perceived.

[0100] Therefore, aiming the detonator is more complicated for the user.

[0101] In one practical example, the console includes a detector configured to detect a return signal emitted by the detonator.

[0102] According to an option of interest, the console also comprises a warning device configured to emit a warning signal, for example visual or acoustic, allowing the user to be warned that the light signal emitted by the light source has been detected by at least the target detonator, or that the return signal has indeed been detected by the console.

[0103] The control console thus comprises, for example, an LED or a buzzer.

[0104] This configuration of the detonation system thus forms an auxiliary pointing system.

[0105] The detonator is thus, for example, configured to fire back when it is illuminated by a light beam from the control station.

[0106] Thus, in an exemplary embodiment of interest, the console is configured to emit the light signal continuously, either for a predetermined duration, or upon request by a user.

[0107] The user illuminates the area where the detonator is located, or even more specifically, the detonator's light receptor, in a sweeping motion.

[0108] When the detonator detects the expected light sequence, it triggers a simple visual return (for example by means of an LED) or a sound (for example by means of a buzzer).

[0109] According to another interesting option, the console further comprises a lens configured to focus the optical signal towards the at least one detonator.

[0110] The lens referred to here is referred to as an adjustable or variable optical lens.

[0111] Using such lenses allows for greater flexibility in the system.

[0112] For example, by using a wider lens that allows multiple detonators to be illuminated, a group of detonators can thus be activated simultaneously.

[0113] This technique may be beneficial in an underground environment, or when a firing plan has been established and the goal is to energize multiple or all detonators very quickly.

[0114] In terms of safety, a lens used on the console allows precise aiming of the desired detonator or detonators.

[0115] In another exemplary embodiment, the console further includes a modulator configured to modulate the optical signal according to at least one modulation mode.

[0116] Thus, the optical signal may be modulated with a modulation pattern that allows it to be distinguished from natural or artificial ambient lighting, in order to avoid energizing the detonator in an untimely manner.

[0117] Advantageously, therefore, the modulated optical signal comprises at least one activation sequence.

[0118] Thus, one advantage of an initiation system using light modulation is that useful digital data can be sent to the detonator using the modulated signal.

[0119] For example, it allows:

[0120] - The ignition delay is directly transmitted to the detonator via an optical channel during its optical activation.

[0121] -Provides the identifier of the console that has been used to activate the detonators or the identifier of the ignition console that will be used. This allows multiple teams to deploy a network of detonators in the same area at the same time.

[0122] -Provide a detonator-specific firing code, thereby allowing to avoid accidental firing of a detonator without an assigned code.

[0123] Thus, for example, the modulated optical signal includes a data sequence configured to send instructions to the detonator, such as a delay value and / or an identifier, and / or a firing code, or others.

[0124] The data sequence is transmitted in the optical signal after the activation sequence.

[0125] Furthermore, in the case of emitting a visible beam, the target detonator is visually identified by the user and the information may be difficult to intercept or scramble, making the system more secure.

[0126] According to another interesting option, the modulated light signal comprises a stop signal.

[0127] In order to perform the same function as a manual switch, an initiation system using light modulation preferably allows for de-energization of the detonator.

[0128] This provides an additional level of safety, for example in the event that a decision is made to abort firing or simply to deactivate a detonator that was energized by mistake.

[0129] Considering the use of this stop function, two different sequences can be used: one sequence for powering on and another sequence for powering off.

[0130] Thus, the console comprises, for example, a selection module configured to allow the user to select one sequence or another (ie an activation sequence or a deactivation sequence).

[0131] Finally, according to the third aspect, a method for activating a wireless electronic detonator is proposed, which wireless electronic detonator includes a main energy source, at least one functional module, a power switch arranged between the main energy source and the functional module and configured to connect or disconnect the functional module from the main energy source, and a control module that controls the power switch.

[0132] According to the present invention, the method comprises the following steps:

[0133] - receiving optical signals;

[0134] - demodulate the received optical signal;

[0135] - generating a control signal according to the demodulated optical signal, the control signal being configured to control at least a power switch.

[0136] Thus, the functional module of the electronic detonator is activated or powered on via a power switch provided between the main energy source and the functional module, which is controlled by a control signal generated when the demodulated optical signal corresponds at least to an instruction for activating the electronic detonator.

[0137] This activation method has similar features and advantages to those described above with respect to the wireless electronic detonator and wireless detonation system.

[0138] According to an interesting embodiment, the step of receiving an optical signal comprises the steps of detecting the optical signal and converting the optical signal into an electrical signal.

[0139] According to an interesting embodiment, the demodulation step comprises a step of converting the electrical signal into a digital signal and a step of identifying at least one activation sequence in the digital signal.

[0140] If an activation sequence is identified, the step of generating a control signal comprises the step of activating a power switch.

[0141] For example, if the digital signal corresponds to a reference signal comprising at least one activation sequence, the power switch is activated.

[0142] Here, activation means the energization or de-energization of the electronic detonator, independently of its ignition (in other words, its control).

[0143] According to an option of interest, the demodulation step also comprises a step of identifying at least one data sequence in the digital signal.

[0144] If a data sequence is identified, the step of generating a control signal includes the step of generating instructions corresponding to the data sequence.

[0145] For example, once an electronic detonator is energized, an ignition delay may be associated with it.

[0146] This association can be performed immediately, or some time after it is powered on.

[0147] According to various embodiments, the power-on and delay association may be accomplished with the same console or with different consoles.

[0148] Therefore, the deployment of electronic detonators can be performed in different ways.

[0149] In the case of delayed association (where different consoles are used for power-up and delayed association), power-up may be performed at installation, and delayed association may be performed subsequently once all detonators have been powered up.

[0150] In the case of postponed delay association, all electronic detonators are first powered on via the console when they are installed. Then, the electronic detonators can be put into sleep or standby mode by a regular wake-up procedure. Once all electronic detonators have been installed and powered on, the delay is associated with all electronic detonators. To this end, the electronic detonators can be equipped with any positioning system (such as GPS, a system that optionally requires a post-processing step to measure the relative distance or received power between each electronic detonator of the network, etc.). The raw data related to each electronic detonator (such as absolute position, relative distance or received power, etc.) is collected by radio, for example, with a console, so as to generate a map of the electronic detonator network with its identifier. With the knowledge of this map, the delay can be associated with each electronic detonator.

[0151] An observed inconsistency between the intended firing plan and the actual map of an electronic detonator can be detected, allowing the detonator having the inconsistency to be de-energized.

[0152] When the power-on and delayed association are performed with different control consoles, these two operations are performed at moments far apart, varying from a few minutes to hours or even days, depending on the situation. A power-off condition can be taken into account during this interval, allowing the electronic detonator to return to the power-off state. For example, during the operation of the periodic wake-up of the electronic detonator, the digital processing module can power off the electronic detonator in the absence of a request by optical signal after a certain time, or in the absence of a message exchanged or received with the control console.

[0153] Finally, each of these methods ends with performing a traditional ignition procedure. BRIEF DESCRIPTION OF THE DRAWINGS

[0154] The present invention will be better understood in light of exemplary embodiments and its advantages will better appear after reading the following detailed description given for informative and non-limiting purposes with reference to the accompanying drawings, in which:

[0155] [ Figure 1 ] Figure 1 An initiation system according to an exemplary embodiment of the present invention is summarized;

[0156] [ Figure 2 ] Figure 2 An example of a pseudo-random sequence following a modulation pattern is shown;

[0157] [ Figure 3 ] Figure 3 A wireless detonator according to an exemplary embodiment of the present invention is shown;

[0158] [ Figure 4 ] Figure 4 An exemplary embodiment of an optical receiver is outlined;

[0159] [ Figure 5 ] Figure 5 A first exemplary embodiment of an optical receiver is illustrated;

[0160] [ Figure 6 ] Figure 6 schematically illustrates an example of an emission spectrum of an LED-based light source according to wavelength;

[0161] [ Figure 7 ] Figure 7 schematically illustrates the spectral sensitivity of a photodiode as a function of wavelength;

[0162] [ Figure 8 ] Figure 8 Shown by Figure 6 The emission spectrum and Figure 7 The spectral characteristics of the filter obtained according to the wavelength sensitivity of the photodiode;

[0163] [ Fig. 9 ] Fig. 9 A second exemplary embodiment of an optical receiver is illustrated;

[0164] [ Fig.10 ] Fig.10 A third exemplary embodiment of an optical receiver is illustrated.

[0165] The same elements shown in the above-mentioned figures are identified by the same reference numerals. DETAILED DESCRIPTION

[0166] according to Figure 1 In an exemplary embodiment of one aspect of the present invention as outlined in the accompanying drawings, a detonation system 10 generally comprises:

[0167] a control console 100 configured to emit a modulated optical signal LU, and

[0168] An energetically autonomous wireless electronic detonator 200 , configured to detect and demodulate the optical signal LU of the control station 100 .

[0169] According to an exemplary embodiment, console 100 includes a modulated light source.

[0170] like Figure 1 As outlined in , the console 100 , for example, includes a light source 110 configured to emit a light beam including an optical signal, and a modulator 120 configured to modulate the optical signal according to at least one modulation mode.

[0171] The light source 110 is preferably configured to emit a light signal in the visible range, ie having a wavelength approximately comprised between 400-800 nm.

[0172] However, depending on the need or intended application, a light source configured to emit a signal in the infrared region or the ultraviolet region may be used.

[0173] According to an option not shown, the console may also include a variable lens, also called tunable lens, configured to focus the optical signal towards one or more detonators.

[0174] Thus, the console can, for example, activate a single detonator if the lens is adjusted to transmit a narrow beam, or activate a group of detonators simultaneously if the lens is adjusted to transmit a wider beam allowing multiple detonators to be illuminated.

[0175] Depending on the option of interest, the detonator is configured to emit a return signal when it is illuminated by the beam of the control console.

[0176] The detonator may include, for example, a visual or audible warning device.

[0177] The detonator may also be configured to emit a return signal (eg, a radio signal) that is configured to be detected thereby by the control console.

[0178] According to at least one other option of interest, the console 100 may also include a detector configured to detect a return signal emitted by a detonator, and an alerter, such as a visual or audible alert, configured to alert a user that the light signal emitted by the light source 110 has at least been detected by at least the target detonator, or that the return signal has indeed been detected by the console.

[0179] The warning device of the control console or detonator includes, for example, an LED or a buzzer.

[0180] The detonation system is therefore provided with an auxiliary pointing system.

[0181] Preferably, the console emits the light sequence continuously, either for a predetermined duration or upon request by a user.

[0182] With the sweeping motion, the user illuminates the area where the wireless electronic detonator 200 is located, or even more specifically illuminates the light receiver 220 (described below) of the wireless electronic detonator 200 .

[0183] When the detonator detects the expected light sequence, it triggers a simple visual return (for example by means of an LED) or a sound (for example by means of a buzzer).

[0184] Figure 2 An example of a modulation pattern M for modulating the optical signal LU emitted by the console 100 is shown.

[0185] This is in particular a pseudo-random sequence of OOK (On / Off Keying) modulation in this figure, but other types of optical modulation are also possible.

[0186] The advantage of OOK type modulation is that it is simple to implement and the demodulation is not very complex, which allows limiting the cost of the detonator.

[0187] Preferably, the light signal emitted by the console is modulated with a pseudo-random sequence known to the receiver, so that it can be distinguished from natural or artificial light with as little error as possible (some artificial lights do have a hash signal in the form of a square wave).

[0188] The size of the pseudo-random sequence must be long enough, usually larger than 32 bits, to avoid false alarms.

[0189] Preferably, the modulation rate (frequency) is typically comprised between 100 Hz and 10 kHz.

[0190] This value is sufficient not to be overly sensitive to the user's movements, and not too high to be able to be detected by, for example, using a photodiode 231 ( Figure 5 ) to limit the cost of the optical receiver 220.

[0191] This example is not limiting. Other types of modulation, other types of sequences, other modulation rates may be used.

[0192] Another advantage of optical modulation systems is the ability to use the modulated light signal to transmit information useful to the detonator, ie digital data, via an optical channel.

[0193] To this end, at the control station, the modulated optical signal LU preferably comprises, for example, an activation sequence with good autocorrelation properties, typically a Kasami sequence.

[0194] This allows the receiver, i.e. the detonator, to synchronize itself appropriately on the received signal in order to extract data from it.

[0195] The data sequence comprises, for example, binary data simply concatenated after the activation sequence.

[0196] The message sent by the console includes, for example, the following sequence: [activation sequence] - [data sequence].

[0197] The data sequence is configured to send, for example, a delay value, and / or an identifier, and / or an ignition code, or others.

[0198] According to one example, a CRC (Cyclic Redundancy Check) type integrity control may optionally be added to the message in order to be able to control the result of the demodulation of the data sequence at the detonator (ie at the receiver).

[0199] The message sent by the control console thus comprises, for example, the following sequence: [activation sequence] - [data sequence] - [control sequence].

[0200] According to another example, a correction code may also be added.

[0201] The message sent by the control console thus comprises, for example, the following sequence: [activation sequence] - [data sequence] - [control sequence] - [correction sequence].

[0202] Therefore, according to an exemplary embodiment, a Hamming type block code may be used, which includes a data sequence and a correction sequence.

[0203] At the receiver end, i.e. the detonator end, conventional digital demodulation techniques can be used.

[0204] The activation sequence allows the receiver to be synchronized at the beginning of a sent message.

[0205] Simple regular sampling or front-end detection then allows the content of the message to be demodulated.

[0206] According to another interesting option, the modulated optical signal LU comprises a stop signal.

[0207] In order to perform the same function as a manual switch, an initiation system using light modulation preferably allows for de-energization of the detonator.

[0208] This provides an additional level of safety, for example in the event that a decision is made to abort firing or simply to deactivate a detonator that was energized by mistake.

[0209] Considering the use of this stop function, two different sequences can be used: one sequence for powering on and another sequence for powering off.

[0210] The two sequences are preferably quasi-orthogonal in order to limit the risk of undesired detection of the transmitted sequence.

[0211] For example, two different Kasami sequences allow this condition to be met.

[0212] An alternative approach could be to use the sign of the sequence: in case the sequence is transmitted normally it results in a positive correlation peak for start-up, but in case the sequence is transmitted in the opposite way it thus gives a negative correlation peak for example for stop.

[0213] Finally, a single correlator is necessary and only the sign of the result matters.

[0214] However, the Kasami sequence is preferred because it gives results close to 0 for the inter-group correlation regardless of the offset between the sequences.

[0215] Therefore, the console must allow the user to select one sequence or the other (i.e., activate the sequence or deactivate the sequence).

[0216] At the receiver, the digital processing module of the detonator's optical receiver (described below) is configured to detect one sequence or the other, for example, by replicating the correlation process by alternating one sequence and then the other as a reference sequence.

[0217] Figure 3 An exemplary embodiment of a wireless electronic detonator 200 is shown.

[0218] The wireless electronic detonator 200 according to the invention is autonomous in terms of energy and here mainly comprises a control module 210 including an optical receiver 220 configured to activate the detonator via an optical channel.

[0219] The optical receiver 220 notably allows demodulation of the light beam LU transmitted by the console 100 , and generation of a signal for controlling the power switch 240 .

[0220] In addition, the wireless electronic detonator 200 here includes, for example, the following elements:

[0221] - A main energy source 230 (for example, an on-board energy source, or an energy recovery module combined with a local energy storage, or an energy supply module connected by a cable), which allows powering the various other elements of the detonator via the power switch 240 and allows energy to be transferred to the energy storage element 253 dedicated to igniting the explosive fuse 256.

[0222] A power switch 240, for example comprising a switch K10, which allows controlling the energization of the various electronic components of the functional module 250 from the main energy source 230. This power switch 240 may be similar to one of the embodiments proposed in document WO 2019 / 073148.

[0223] - and functional module 250.

[0224] The functional module 250 here includes, for example, the following electronic components:

[0225] A calculator 251 allowing the operation of the electronic detonator to be controlled. The calculator 251 is connected or disconnected from the main energy source 230 via the power switch 240 .

[0226] - Energy storage element 253, dedicated to igniting explosive fuse 256.

[0227] A switch 252 isolating the energy storage element, comprising for example a switch K20 , the switch 252 allowing activation or deactivation of the energy transmission from the main energy source 230 to the energy storage element 253 independently of the energy transmission from the main energy source 230 to the calculator 251 .

[0228] - A discharge device 254 forming a safety mechanism allowing a slow discharge of the energy storage element 253 dedicated to ignition, in order to return to a safe state in the event of a power failure.

[0229] An ignition switch 255 , comprising, for example, a switch K30 , which allows energy to be transferred between an energy storage element 253 dedicated to ignition and an explosive fuse 256 .

[0230] - and explosive fuse 256.

[0231] Figure 4 An optical receiver 220 according to an exemplary embodiment is outlined in FIG.

[0232] Figure 4 The optical receiver 220 mainly includes:

[0233] - a light detector 221 configured to convert a received optical signal LU into an electrical signal; and

[0234] A demodulator 222 configured to demodulate the received optical signal and generate a signal for controlling the power switch 240 .

[0235] Here, the demodulator 222 includes, for example:

[0236] - an analog regulator 223 configured to convert the analog electrical signal of the light detector 221 into a digital signal; and

[0237] A digital processing module 224 configured to demodulate the digital signal to detect the binary sequence emitted by the console 100 and to generate a control signal according to the binary sequence to control at least the power switch 240 .

[0238] Here, the digital processing module 224 and / or the calculator 251 is configured, for example, as follows:

[0239] - Manage the operation of the wireless electronic detonator 200;

[0240] - analyzing the messages received via the console 100;

[0241] -Act according to the meaning of the received message;

[0242] - Activate energy stored in energy storage element 253 for ignition;

[0243] - countdown of the ignition delay associated with the wireless electronic detonator 200;

[0244] - activating the energy transfer from the energy storage element 253 to the explosive fuse 24 via the ignition switch 255 after the countdown has ended;

[0245] - activating the discharge device 254;

[0246] - Control the power switch 240;

[0247] - Isolating switch 252 controlling the energy storage element...

[0248] Figure 5 Shows Figure 4 An exemplary embodiment of the optical receiver 220 is outlined in FIG.

[0249] The light detector 221 here comprises a photodiode 231 which converts the light signal LU into an electric current.

[0250] The light detector 221 here also includes a detection resistor 232 which allows processing of a voltage that can be used by the analog regulator 223 .

[0251] The sense resistor 232 is sized so that the signal does not saturate at high light levels, which would render the system ineffective. Conversely, a value that is too low would reduce the dynamics of the electrical signal, resulting in a reduced range of the detonation system.

[0252] By assuming the maximum possible illumination Emax (typically 130,000 lux) and the sensitivity SA / lux of the photodiode 231 and the supply voltage Vdd, the sense resistor 232 having a resistance denoted by R shall verify the relationship Vdd = R×S×Emax at the saturation limit at maximum illumination.

[0253] Therefore, the sizing of [photodiode 231 - sense resistor 232] largely determines the performance of the system in terms of range.

[0254] The analog conditioner 223 here comprises at least one high-pass filter in order to eliminate static components associated with natural lighting and user movements.

[0255] It may comprise a bandpass filter (which thus corresponds to a highpass filter to which a lowpass filter has been added) in order to also eliminate possible high-frequency interferences.

[0256] exist Figure 5 In the example of implementation shown, the analog regulator 223 includes a bandpass filter (a pair of R1C1 (resistor-capacitor) on the "+" (plus) pin of the comparator 233 determines high frequencies, while a pair of R2C2 on the "-" (minus) pin determines low frequencies), allowing the static components of the signal related to the ambient lighting level to be eliminated.

[0257] The filtered signal is injected into the comparator 233 to obtain a binary signal at the output of the comparator 233 and thus at the output of the analog regulator 223 .

[0258] The analog regulator 223 includes, for example, a comparator and / or an operational amplifier.

[0259] Finally, the digital processing module 224 into which the digital signals are injected comprises, for example, at least one calculator, typically a microcontroller or a dedicated digital circuit, and optionally memory elements.

[0260] The received signal is correlated with an expected reference signal in order to detect the presence of an activation signal.

[0261] The expected reference signal may be pre-recorded in the digital processing module 224 .

[0262] At this point, any known digital signal demodulation technique may be used.

[0263] When the activation sequence is detected, the digital processing module 224 generates a control signal configured to control the power switch 240 to an active position (eg, a closed position if this is a switch) so as to energize the other elements of the detonator.

[0264] However, these functions can be used with Figure 5 The embodiments outlined in are performed differently.

[0265] For example, in order to share hardware resources, digital processing can be performed in the calculator 251 of the functional module 250. The overall architecture must therefore be slightly reworked in order to fit the calculator 251 upstream of the power switch 240.

[0266] In other words, the calculator 251 and the digital processing module 224 of the functional module 250 may thus be grouped together into a single entity, preferably located upstream of the power switch 240 , for example in the optical receiver 220 .

[0267] Additionally, a portion of the calculator may remain "inactive" (in a low-consumption mode) as long as no light sequence has been received.

[0268] Other strategies may also be used to demodulate the optical signal, which results in a different hardware architecture of the optical receiver 220. For example, the analog conditioner 223 may be replaced by digitizing the raw signal from the optical receiver with the aid of an ADC (Analog to Digital Converter), which may then be directly processed by the calculator of the digital processing module 224.

[0269] In all cases, the proposed optical receivers need to be powered.

[0270] Ideally, however, the detonation system must consume as little energy as possible to avoid reducing the life of the detonator before it can be used on the ground.

[0271] Therefore, in order for the system to have as much practical significance as possible, the consumption must be as low as possible.

[0272] The light receiver 220 generally has a consumption that is proportional to the illumination.

[0273] Typically, for a photodiode with a sensitivity of 40nA / 100Lux, the consumption is 52µA at maximum sunlight 130,000Lux.

[0274] Depending on the comparator or operational amplifier used, the consumption of analog regulator 223 is typically between 1 µA and 30 µA.

[0275] Selecting a comparator 233 with a reduced product [gain x bandwidth] allows the selection of a component that consumes in the vicinity of one microampere (µA).

[0276] This occurs at the expense of the allowed modulation rate, but is not a critical element of the system.

[0277] Finally, the digital processing module 224 typically consumes several milliamps while performing processing.

[0278] The power consumption of the photodetector 221 and the digital processing module 224 is therefore a priority to be reduced, aiming for a power consumption of approximately a few microamps, if possible.

[0279] Thus, a first approach involves, for example, adding an optical filter in front of the photodiode 231 of the light detector 221 in order to reduce the intensity of the ambient lighting without degrading the detection performance.

[0280] One goal is to maximize the received optical power corresponding to the optical signal while minimizing the received power corresponding to the ambient lighting.

[0281] This allows reducing the current consumed by the photodetector in relation to the intensity of the ambient lighting.

[0282] The light source of console 100 has a very specific emission spectrum ( Figure 6 ), and the photodiode 231 has a characteristic spectral sensitivity ( Figure 7 ).

[0283] These two elements thus represent gain filtering stages Gtx(λ) and Grx(λ), depending on the wavelength λ of the optical signal emitted by console 100 .

[0284] The optical power Prx converted into electrical power by the photodiode 231 is therefore expressed according to the following formula as a function of the power Ptx emitted by the console, the attenuation associated with the distance R, the illumination solid angle Ω and the respective gains Gtx and Grx:

[0285] Prx = [(Grx.Gtx) / ΩR²].Ptx

[0286] For a given distance and focal length, when the gain (Gtx.Grx) is maximum, that is, for a given wavelength λ, the received power is maximum ( Figure 8 ).

[0287] Therefore, adding an additional filter near this wavelength allows maximizing the reception at this wavelength and reducing the reception at other wavelengths, which corresponds to the desired goal.

[0288] Therefore, the optimal width of the optical filter is calculated based on the response of the optical filter to the natural light that it is desired to reduce.

[0289] In practice, the consumption of the photodetector can thus be reduced by a factor of three.

[0290] The second method involves, for example, using the photovoltaic effect of the photodetector 234 for the photodetector 221 .

[0291] Like in Fig. 9 As in the arrangement outlined in , the photodetector 234 is used here in photovoltaic mode.

[0292] For this reason, it is not polarized by the supply voltage.

[0293] Photodiodes like in the previous examples do not allow the generation of a current sufficient to be usable. It is necessary to increase the surface of the photosensitive element by using photovoltaic panels of reduced size or by connecting a plurality of photodiodes in parallel.

[0294] This arrangement makes it possible to completely eliminate the consumption of the photodetector.

[0295] Consumption is thus well controlled and more independent of the surrounding illumination conditions.

[0296] According to a third method, the power supply to the digital processing module can also be cut off to limit the consumption.

[0297] For example, the digital processing module 224 includes a low consumption mode that allows the clock and optionally the power to the digital electronics to be cut off.

[0298] The presence of a change of state of the digital signal at the output of the comparator is used, for example, to take the system out of a low consumption mode.

[0299] Therefore, under natural lighting, the light intensity varies slowly and therefore there is no variation at the output of the analog regulator because of the low pass filtering.

[0300] In case of a sudden change in lighting, a transition occurs at the output of the analog regulator which wakes up the digital processing module.

[0301] This functionality can usually be achieved via a low-power mode of the microcontroller.

[0302] The consumption can thus be reduced to less than one microampere (1µA).

[0303] According to a fourth method, a total cut-off of the power supply according to the illumination level ("dark mode") is used, for example in order to avoid any residual consumption during the storage period of the detonators before their use, which may last several months.

[0304] like Fig.10 As shown, an additional stage for detecting the illumination level is used, with adjustment means allowing the output signal to be automatically saturated as soon as extremely low levels of illumination occur.

[0305] To this end, an additional stage for detecting the illumination level comprises, for example, a phototransistor 235 with high gain (eg 40µA / 100Lux) and a detection resistor 237, whose adjusted value allows detection of very low levels of illumination, typically a few tens of Lux.

[0306] The voltage at the terminals of the detection resistor 237 allows controlling the transistor 236 which acts as a switch.

[0307] Thus, the light detection stage remains unchanged. An additional stage is added, located upstream of the light detection stage (but based on the same principle), which additional stage has a different adjustment means than the light detection stage.

[0308] Thus, when the detonator is in darkness, for example stored in a box, the power supply is completely cut off. The consumption is thus almost zero (except for the leakage current of the transistor 236 and the phototransistor 235, which can be neglected).

[0309] When the detonator is taken out of the box for use, the main cut-off stage energizes the light receiver 220 and the detonator thus awaits light activation from the user (via the console).

Claims

1. A wireless electronic detonator (200), comprising a main energy source (230) and at least one functional module (250), a power switch (240) arranged between the main energy source (230) and the functional module (250) and configured to connect or disconnect the functional module (250) and the main energy source (230), and a control module (210) for controlling the power switch, characterized in that: The functional module (250) further comprises at least one explosive fuse (256) and an energy storage element (253) dedicated to igniting the explosive fuse (256), and is characterized in that the control module (210) for controlling the power switch comprises an optical receiver (220), the optical receiver (220) being configured to detect and demodulate an optical signal (LU) emitted by a control console (100), and generating a control signal at an output according to the demodulated optical signal (LU), the control signal being configured to control at least the power switch (240), and is also characterized in that the wireless electronic detonator (200) comprises a total cut-off module, the total cut-off module being configured to cut off the power supply to the optical receiver (220) according to the illumination level, the total cut-off module comprising a phototransistor (235) having a high gain coupled to a detection resistor (237) configured to detect an extremely low illumination level, and a transistor (236) used as a switch, the detection resistor (237) being configured to control the transistor (236).

2. The wireless electronic detonator (200) according to claim 1, characterized in that: The optical receiver (220) includes a light detector (221) configured to detect a light signal (LU) emitted by the console (100) and convert the light signal (LU) into an electrical signal.

3. The wireless electronic detonator (200) according to claim 2, characterized in that: The wireless electronic detonator includes at least one optical filter located upstream of the light detector (221) to reduce the intensity of ambient lighting without degrading detection performance.

4. The wireless electronic detonator (200) according to any one of claims 2 or 3, characterized in that: The light detector (221) includes a photovoltaic element (234).

5. The wireless electronic detonator (200) according to any one of claims 2 or 3, characterized in that: The wireless electronic detonator includes a demodulator (222) configured to demodulate the electrical signal.

6. The wireless electronic detonator (200) according to claim 5, characterized in that: The demodulator (222) includes an analog regulator (223) configured to convert the electrical signal from the photodetector (221) into a digital signal.

7. The wireless electronic detonator (200) according to claim 6, characterized in that: The demodulator (222) includes a digital processing module (224) configured to demodulate the digital signal and generate a control signal to control the power switch (240).

8. The wireless electronic detonator (200) according to claim 7, characterized in that: The wireless electronic detonator includes a low consumption mode configured to cut off power to at least the digital processing module (224) to limit power consumption of the system.

9. The wireless electronic detonator (200) according to claim 6, characterized in that: The demodulator (222) includes a digital processing module (224) configured to demodulate the digital signal to detect a binary sequence transmitted by the console (100), and to generate a control signal according to the binary sequence to control the power switch (240).

10. The wireless electronic detonator (200) according to claim 6, characterized in that: The light detector (221) includes a photodiode (231) and a detector resistor (232) connected thereto, and the analog regulator (223) includes at least one high-pass filter configured to eliminate a static component of the light beam.

11. The wireless electronic detonator (200) according to any one of claims 1 to 3, characterized in that: The wireless electronic detonator is configured to transmit a return signal when the optical receiver (220) detects at least a light signal (LU) transmitted by the control station (100).

12. A wireless detonation system (10), comprising the wireless electronic detonator (200) according to any one of claims 1 to 11, and a control console (100) configured to transmit an optical signal (LU) to the wireless electronic detonator (200).

13. The detonation system (10) according to claim 12, characterized in that The console (100) comprises a lens configured to focus the optical signal (LU) towards at least one wireless electronic detonator (200).

14. The detonation system (10) according to any one of claims 12 or 13, characterized in that The console (100) comprises a modulator (120) configured to modulate the optical signal (LU) according to at least one modulation mode (M).

15. The detonation system (10) according to any one of claims 12 or 13, characterized in that The modulated optical signal (LU) comprises at least one activation sequence.

16. The detonation system (10) according to any one of claims 12 or 13, characterized in that The modulated optical signal (LU) includes a data sequence configured to send instructions to the wireless electronic detonator (200).

17. An activation method for activating a wireless electronic detonator (200), the wireless electronic detonator (200) comprising a main energy source (230), at least one functional module (250), a power switch (240) arranged between the main energy source (230) and the functional module (250) and configured to connect or disconnect the functional module (250) and the main energy source (230), and a control module (210) for controlling the power switch, the functional module (250) comprising at least one explosive fuse (256) and a special An energy storage element (253) for igniting the explosive fuse (256), the wireless electronic detonator further comprising a total cut-off module, the total cut-off module being configured to cut off the power supply to the optical receiver (220) according to the illumination level, the total cut-off module comprising a phototransistor (235) having a high gain coupled to a detection resistor (237) configured to detect extremely low illumination levels and a transistor (236) used as a switch, the detection resistor (237) being configured to control the transistor (236), the method comprising the following steps: •Receive optical signal (LU); •Demodulate the received optical signal (LU); • generating a control signal according to the demodulated optical signal (LU), the control signal being configured to control at least the power switch (240).

18. The activation method according to claim 17, wherein: The step of receiving the optical signal (LU) includes the steps of detecting the optical signal (LU) and converting the optical signal (LU) into an electrical signal.

19. The activation method according to claim 18, wherein: The demodulating step includes the steps of converting the electrical signal into a digital signal and identifying at least one activation sequence in the digital signal, and if an activation sequence is identified, the generating control signal includes the step of activating the power switch (240).

20. The activation method according to claim 19, wherein: The demodulating step includes the step of identifying at least one data sequence in the digital signal, and if a data sequence is identified, the step of generating a control signal includes the step of generating instructions corresponding to the data sequence.

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