Light system for a motor vehicle comprising an auxiliary power supply device

Abstract

The invention relates to a light system (1) for a motor vehicle, the system comprising an emitter module (2) for emitting a light beam (F1) and a modulation unit (22) for modulating the beam; a receiver module (3) for generating a demodulated data sequence (Seq_di,j) from a received light beam (F2); a control system (4) comprising a generator (41) for generating a modulating data sequence (Seq_m) for the emission of a modulated beam (F1), a computing unit (42) for determining a time of flight (τ) of the modulated beam from the demodulated data sequence (Seq_di,j) and the modulating data sequence (Seq_m); characterised in that it comprises at least one auxiliary power supply device (52, 53, 54); the control system (4) being able to detect a failure of an element of the system; and arranged such that, following this detection, it connects the auxiliary device to the emitter module.

Description

Description Title of the invention: Lighting system for a motor vehicle comprising an auxiliary power supply device

[0001] The invention relates to the field of automotive lighting and / or signaling, specifically to the functions of detecting an object by a motor vehicle and estimating the distance between that object and the vehicle. More precisely, the invention relates to a lighting and / or signaling system for a motor vehicle capable of implementing telemetry functions.

[0002] It is known in the automotive field to use a pulsed light beam emitted by a light module of a vehicle's lighting system to perform a given photometric function.

[0003] Typically, the light source that emits this beam is controlled by a pulse-width modulated (PWM) electrical signal. The light source is periodically switched on and off by this PWM signal, so that the emitted beam consists of successive light pulses occurring at a frequency high enough that they are indistinguishable to the human eye. The intensity of the emitted beam is a function of the duty cycle of this PWM signal, allowing it to be controlled by adjusting this duty cycle and thus enabling a photometric function.

[0004] Beyond performing one or more photometric functions, such as daytime running lights or low beams, this type of lighting module can implement various other functions. For example, the module's light source can be controlled so that the pulses of the emitted light beam carry a data sequence. The lighting system can thus be equipped with a receiver module to receive the emitted light beam after reflection from an object near the vehicle. A vehicle's onboard computer can then, after detecting the data sequence in the received light beam, determine the time of flight of the emitted light beam and thus estimate the distance between the vehicle and the object.

[0005] In this way, the light beam can retain its original function, namely to perform a photometric function, while allowing the light system to implement a telemetry function, which can be particularly advantageous for example for driving assistance functions or in the context of autonomous or semi-autonomous driving.

[0006] However, this type of system, based on the emission and reception of a light beam capable of performing both a photometric light function and a telemetry function, has disadvantages.

[0007] It is indeed necessary for the light beam emitted by the light module to be modulated at a very high frequency, particularly to ensure that this modulation remains imperceptible to outside users and to maintain a high detection resolution for the telemetry function. This high-frequency modulation therefore requires a significant increase in the peak power of the electrical current used to power the light module, in order to extend the detection range.

[0008] In this context, this high-frequency modulation generates significant increases in the operating temperatures of various components of the lighting system, including the modulating sequence generator, which must keep pace with the modulation rate; the modulation unit itself, which must perform power modulation changes at very high frequencies for extended periods; and the processing unit. These increases in operating temperature can damage these components, potentially leading to a disruption in the lighting system's operation. However, maintaining the lighting function is essential, even when these components are malfunctioning.

[0009] There is therefore a need for a lighting system for a motor vehicle, capable of performing both a given regulatory photometric function and a telemetry function, and in which the photometric function remains ensured even in the event of failure of one of the high-frequency elements of the system.

[0010] Thus, the invention is placed in this context and aims to meet this need.

[0011] To this end, the invention relates to a lighting system for a motor vehicle, comprising:

[0012] an emission module comprising a first light module capable of emitting a light beam whose spectrum has at least a portion in the visible spectrum, and a modulation unit capable of receiving a data sequence, called modulating, and arranged to modulate said light beam emitted from the received data sequence;

[0013] a receiving module capable of receiving a light beam, in which the receiving module includes at least one elementary acquisition module comprising a photodetector capable of converting a light signal it receives into an electrical signal, said elementary acquisition module being capable of generating a data sequence, called demodulated, from the electrical signal converted by the photodetector;

[0014] a control system comprising a generator arranged to generate a modulating data sequence and to transmit said modulating data sequence to the modulation unit for the emission of a light beam modulated by the transmitting module, and a computing unit capable of receiving a demodulated data sequence generated by the or each elementary acquisition module from a light beam received by the receiving module, the computing unit being arranged to determine a time of flight separating the emission of said modulated light beam emitted from the reception of said light beam received from said demodulated data sequence and said modulating data sequence.

[0015] The system according to the invention is characterized in that it comprises at least one auxiliary power supply device; in that the control system is capable of detecting a failure of at least one of the elements of the lighting system; and in that, following the detection of a failure of one or more of the elements of the lighting system, the control system is arranged to connect the auxiliary power supply device to the emission module.

[0016] It is thus understood that the invention proposes, when a photometric function is required, to modulate a light beam emitted by the first light module using a data sequence. The modulated light beam thus performs the photometric function. The resulting light beam could, for example, be a pulsed beam, each pulse corresponding to one or more high values. The interval between two consecutive pulses of the modulating sequence corresponds to one or more consecutive low values ​​of the modulating sequence. Each pulse of the modulated light beam is emitted with a peak light power, so the average light power of the emitted modulated light beam, necessary to perform the photometric function, is defined by the peak light power and the duty cycle of the modulating data sequence. Since the modulating sequence is generated cyclically by the generator, the emitted modulated light beam will periodically contain this sequence while continuously performing the photometric function.The computing unit can thus detect, from the demodulated data sequence generated by the elementary acquisition module or modules from a light beam received by the receiving module, the presence of this modulating sequence in this received beam and thus detect the presence of an object in the environment of the vehicle and estimate its distance to the vehicle.

[0017] Furthermore, if one of the elements of the lighting system, particularly those involved in the telemetry function, fails—such as the first lighting module, the receiver module, the modulation unit, the generator, or the processing unit—the control system can connect an auxiliary power supply to the transmitting module. Although the telemetry function is no longer available, the photometric function remains operational. Specifically, it can be configured so that, following the detection of a failure in one or more elements of the lighting system, including the first lighting module, the receiver module, the generator, the modulation unit, and the processing unit, the control system is configured to disconnect the processing unit from the faulty element(s), or even the entire receiver module from the control system.

[0018] In the context of the present invention, and by way of non-limiting example, "failure of a lighting system element" means any behavior of a lighting system element that deviates from its normal behavior under normal operating conditions of the lighting system. This could include, for example, the unavailability of the element, a degradation in the element's operation, a hardware or software failure of the element, or an abnormal change in an element's operating parameter. This element could, for example, be a software or hardware component, such as a processor, a microcontroller, a corn- The control system may consist of an electronic component, a light source, a photodiode, or a sensor. It may be capable of detecting a failure in a component of the lighting system, for example, by monitoring an operating parameter of that component, such as the electric current flowing through it, the voltage across its terminals, or its temperature, and, for example, by comparing this parameter to a setpoint, a threshold value, or a nominal operating characteristic. The control system may also be capable of detecting a failure in a component of the lighting system, for example, by receiving an analog or digital signal emitted by the component or by a diagnostic device, containing a fault alert for the component.

[0019] In the invention, the lighting system may be provided for, comprising a plurality of switches, each arranged on an electrical connection between two distinct elements of the lighting system intended to cooperate. Each of these switches is capable of activating or deactivating the electrical connection between said two elements and is controllable by the control system to reconfigure the electrical architecture of the lighting system in response to failures of one or more of the generator, the modulation unit, and the processing unit detected by the control system.

[0020] It may be provided in particular that the lighting system includes a switch located between the generator and the modulation unit, a switch located between the generator and the computing unit, a switch located between the computing unit and a microcontroller controlling the switches, a switch between the auxiliary power supply device(s) and the modulation unit, a switch between the auxiliary power supply device(s) and the first lighting module and / or a switch between the modulation unit and the first lighting module.

[0021] Preferably, the lighting system may include a plurality of auxiliary power supply devices. If necessary, following the detection of a failure in one or more of the generator, modulation unit, and processing unit, the control system is configured to select one of the auxiliary power supply devices according to the type of failure detected and to connect the selected auxiliary power supply device to the transmission module.

[0022] In the context of the present invention, the term "modulation unit" means one or more electronic and / or software components capable of receiving a data sequence and controlling the power supply provided by an electrical power source to the first light module according to the received data sequence, so that the modulated light beam is formed by a train of light pulses carrying said received data sequence. This modulation unit could, for example, be a high-frequency driver device.

[0023] In one embodiment of the invention, the modulation unit is arranged to modulate the light beam emitted by the first light module using the modulating data sequence received at a frequency greater than 5 MHz. In particular, the modulation frequency may be between 5 MHz and 200 MHz, and especially between 30 and 150 MHz.

[0024] Advantageously, the modulation unit is arranged to generate a pulse-width modulated control signal, to modulate said control signal using the modulating data sequence it receives, and to control the emission of said light beam by the first light module using the modulated control signal. For example, the modulation unit may be arranged to convert the modulating data sequence it receives into a modulating signal and to modulate, for example, in amplitude, frequency, or phase, the control signal with this modulating signal. In particular, the modulation unit may control the first light module so that said modulated light beam is emitted only for high values ​​of said modulating data sequence received from the processing unit and so that the modulated light beam is emitted according to a peak light power value.It is thus understood that each pulse of the modulated light beam is emitted with said peak light power and that the average light power of the modulated light beam emitted, necessary for the realization of the photometric function, is thus defined by the peak light power, the duty cycle of the modulating data sequence and by the control signal.

[0025] In the present invention, the duty cycle of a data sequence is understood to be the ratio between the number of high values ​​and the total length of the data sequence. In the case where the data sequence is a binary sequence, the duty cycle therefore corresponds to the ratio between the number of bits of the value "1" of the binary sequence and the total number of bits in that sequence.

[0026] In one embodiment of the invention, the first light module comprises a light source, the modulation unit being arranged to, upon receiving the modulating data sequence, control said light source for the emission of the light beam modulated by the first light module.

[0027] In the context of the present invention, "computing unit" means one or more electronic and / or software components capable of receiving a first data sequence and a second data sequence and of detecting the presence of the first data sequence in the second data sequence, and of determining a time of flight separating the emission of a modulated light beam containing the first data sequence from the reception of a received light beam from which the second data sequence has been extracted.

[0028] Advantageously, the computing unit is arranged to estimate values ​​of a correlation function between said demodulated data sequence and said modulating data sequence and to determine a time of flight separating the emission of said modulated light beam emitted from the reception of said light beam received from the values ​​of the correlation function.

[0029] Each value of the correlation function estimated by the computing unit is associated with a time lag value in the modulating data sequence, or the demodulated data sequence, used to estimate that value of the correlation function. The correlation function between this demodulated data sequence and the modulating data sequence is therefore a function of the autocorrelation of this modulating data sequence.

[0030] We can thus detect the presence of this modulating data sequence in the received light beam, after reflection on an object in the environment of the vehicle and thus detect the presence of this object as well as estimate its distance from the vehicle.

[0031] Preferably, the computing unit is arranged to determine the value of a peak of said correlation function, to compare said peak value to a predetermined threshold value, and to detect the presence of said modulating data sequence in the demodulated data sequence based on said comparison. The computing unit may, for example, conclude that the modulating data sequence is present in the demodulated data sequence only if the peak value is greater than the predetermined threshold value.

[0032] In the context of the present invention, "data sequence generator" means one or more electronic and / or software components capable of periodically generating a data sequence, for example, composed of high values, namely "1s" in the case of a digital sequence or a "high" voltage in the case of an analog sequence, and low values, namely "0s" in the case of a digital sequence or a "low" voltage in the case of an analog sequence.

[0033] Advantageously, the generator is arranged to generate a pseudo-random binary modulating data sequence and to transmit the modulating data sequence to the modulation unit of the emission module for the emission of a light beam modulated by the emission module.

[0034] A pseudorandom binary sequence, or PRBS, is a data sequence composed of high values, namely "1s," and low values, namely "0s." This type of sequence exhibits particularly interesting properties. Its autocorrelation function is at its maximum for a zero time lag, that is, when the sequence is compared to itself, and is significantly lower than this maximum for all other time lags, that is, when the sequence is compared to time-shifted versions of itself. Furthermore, the cross-correlation function between two pseudorandom binary sequences is significantly lower than the maximum of the autocorrelation functions of these sequences.Finally, this type of sequence is generally generated using a linear feedback shift register, or LFSR (from the English "Linear Feedback Shift Register"), which produces a periodic recurrent sequence whose pattern is a pseudo-random binary sequence.

[0035] Given the autocorrelation properties of pseudo-random binary sequences, the computing unit can estimate values ​​of a correlation function between a modulating sequence and a demodulated sequence extracted from a light beam received by the receiving module. The correlation function will be maximum for The time-shift value corresponds to the time of flight of the modulated light beam as it is emitted, reflected, and then received, even in the presence of significant noise. Therefore, the processing unit can identify this time-shift value associated with the maximum value of the correlation function with high accuracy and deduce the distance between the object on which the beam was reflected and the motor vehicle. Furthermore, given the cross-correlation properties, it appears unlikely that receiving a modulated light beam emitted by an equivalent system from another motor vehicle would result in a false positive detection. Finally, it is understood that the detection is performed not on a single pulse but on a complete data sequence, thus improving the system's signal-to-noise ratio.

[0036] In the present invention, a modulating data sequence of the type "m-sequence or maximum length sequence", of the type "Gold code", of the type "Kasami code" or any other pseudo-random binary sequence exhibiting good autocorrelation and crosscorrelation properties, or even orthogonality, and for transmitting the modulating data sequence to the modulation unit of the emission module for the emission of a light beam modulated by the emission module.

[0037] In one embodiment of the invention, following the detection of a failure in the generator and / or the processing unit, the control system is arranged to connect the auxiliary power supply to the modulation unit of the transmission module. The invention thus aims, in this embodiment, to continue operating the modulation unit, despite the failure of all or part of the processing unit or the generator of the modulating data sequence, in order to perform the photometric function and optionally transmit a data sequence indicating to other road users, equipped with an equivalent lighting system, that the lighting system is operating in a degraded mode.

[0038] Preferably, following the detection of a failure of the generator and / or the computing unit, the control system is arranged to simultaneously connect the auxiliary power supply device to the modulation unit of the transmission module and disconnect the generator from the modulation unit, or even the computing unit from the generator.

[0039] Advantageously, the modulation unit includes at least one input for receiving the modulating data sequence. If necessary, following the detection of a generator and / or processing unit failure, the control system is arranged to connect the auxiliary power supply to said receiving input of the modulation unit. In this embodiment, the auxiliary power supply can, for example, be a DC / DC converter capable of providing a constant voltage to the control inputs of the modulation unit, so that, in the event of a failure, the light beam is modulated using a continuous sequence of "1"s.It should be noted that in this embodiment, the power supply source of the first light module can remain the same, in nominal operation or in the event of failure of the generator and / or the computing unit, and that only the source of the pulse width modulation varies.

[0040] Advantageously, the modulation unit always includes at least one enable input. If necessary, following the detection of a generator and / or processing unit failure, the control system is configured to transmit a predetermined, or degraded, modulating data sequence to the modulation unit via said enable input. In this example, the control system uses the enable, or "ENABLE," input of the modulation unit to control the power supply to the light sources and thus perform pulse-width modulation using a predetermined data sequence stored in the control system's memory. Alternatively, the degraded modulating data sequence may be provided directly by the control system to the receive input of the modulation unit.

[0041] According to one embodiment, the degraded modulating data sequence may include a continuous sequence of "1"s followed by a continuous sequence of "0"s, the number of "1"s in the continuous sequence being selected by the control system so that the duty cycle of the degraded modulating data sequence corresponds to a light intensity required by the photometric function performed by the lighting system upon fault detection by the control system.

[0042] Alternatively, the degraded modulating data sequence could be configured to encode a standard message indicating a telemetry system failure or a degraded mode of the lighting system.

[0043] In another alternative or cumulative embodiment of the invention, following the detection of a failure in the modulation unit, the control system is arranged to connect the auxiliary power supply to the first light module. The invention thus aims, in this embodiment, to change the power supply source in order to compensate for the failure of the modulation unit, thereby maintaining the active photometric function. It should be noted that in this embodiment, the power supply source for the first light module, under normal operating conditions, is separate from the one used during the failure of the modulation unit.

[0044] The lighting system may include a means for measuring the electric current flowing from the power supply to the modulation unit. The control system may be capable of receiving data from this measuring means and detecting, based on this data, a malfunction of the modulation unit. Alternatively, the electric current measurement means may be replaced or supplemented by a means for measuring the temperature of the modulation unit, or by any other sensor capable of acquiring information indicating a malfunction of the modulation unit.

[0045] In one embodiment of the invention, the first light module is capable of emitting a first light beam whose spectrum has a wavelength in the visible range, in particular between 400 nm and 500 nm. Advantageously, the light source comprises a semiconductor generator capable of emitting an elementary light beam, in particular whose spectrum has a wavelength in the visible range, and a photoluminescent element capable of converting said elementary light beam to obtain said light beam. Optionally, the modulation unit may be arranged to control the light source of the first light module, and in particular a power supply provided to this light source, to modulate the light beam.

[0046] The semiconductor could, for example, be gallium nitride, or GaN, capable of emitting blue light rays through electroluminescence in response to an electric current passing through it. The photoluminescent element could, by For example, it could be in the form of a resin containing a cerium-doped yttrium aluminum garnet, or CE:YAG, capable of absorbing blue light and, through photoluminescence and in response to the excitation caused by this light, emitting yellow light rays. The photoluminescent element is positioned on the generator so that some of the blue light rays excite this element, causing it to emit orange light rays through photoluminescence. The remaining blue light rays pass through this element. Thus, when electrically powered, the light source simultaneously emits blue and yellow light rays in proportions such that the resulting light appears white to the human eye.

[0047] The light source can therefore be a laser type source, a light-emitting diode, a vertical-cavity surface-emitting laser diode, also called VCSEL (from the English "Vertical-Cavity Surface-Emitting Laser") or a superluminescent diode or SLED (from the English "Superluminescent diode").

[0048] Advantageously, the first light module may include an optical unit arranged to project the light rays emitted by the light source to form said light beam.

[0049] In one embodiment of the invention, the transmitting module includes a second light module capable of emitting a light beam whose spectrum includes at least a portion in the visible spectrum. If necessary, following the detection of a failure in one or more of the first light module, the receiving module, the generator, the modulation unit, and the processing unit, the control system is configured to activate the second light module. These features ensure compliance with regulatory photometric requirements. Indeed, in the various failure modes, the first light module continuously emits a light beam whose spectrum may contain a proportion of a wavelength, particularly blue, that is too high with regard to the regulatory requirements of the photometric function that this beam must perform.The second light module thus allows this light beam to be supplemented with another beam, bringing the overall emitted light beam into colorimetric conditions that comply with these regulatory requirements. For example, the second light module could be designed to emit an "orange" light beam.

[0050] In one example implementation, it can be assumed that the light modules share the same optical unit.

[0051] Advantageously, the lighting system includes a color sensor capable of measuring the amount of light emitted by the first light module of the emission module. If a failure is detected in one or more of the generator, modulation unit, and processing unit, the control system is configured to regulate the light emission of the second light module based on the color sensor measurement. This allows for the control of the second light module to ensure that the overall light beam emitted by both modules is white, regardless of the fault conditions.

[0052] In one embodiment of the invention, the receiving module comprises a plurality of elementary acquisition modules, each including at least one photodetector capable of converting a received light signal into an electrical signal. Advantageously, the plurality of elementary acquisition modules is arranged in a matrix. For example, all the photodetectors of a single elementary acquisition module can form a sensor, for example, a single electronic component. Again, for example, each photodetector, or each plurality of photodetectors, may have a width and / or length of less than ten micrometers, which makes it possible to obtain a receiving field of view of the elementary acquisition module of a maximum of 0.1° and thus increase the spatial resolution of the receiving module.

[0053] Advantageously, each photodetector of each elementary acquisition module is an avalanche photodiode, specifically a single-photon one. This type of photodetector is also known as a SPAD, from the English "Single-Photon Avalanche Diode." A collection of avalanche photodiodes can thus form a silicon photomultiplier, or SiPM (from the English "Silicon Photomultiplier"). This type of photodetector makes it possible to detect the impact of a single photon with a significant gain, for example, on the order of 10⁶ (i.e., one million), and therefore to compensate for signal-to-noise ratio degradation due to external conditions.

[0054] According to one embodiment of the invention, the receiving module may include an optical unit arranged in front of the elementary acquisition modules.

[0055] For example, the elementary acquisition module or modules is capable of generating an elementary detection signal as a function of the electrical signal or signals converted by the photodetector(s) of the elementary acquisition module; and each elementary acquisition module is arranged to compare said elementary detection signal to a threshold value associated with said elementary acquisition module and to generate said data sequence, called demodulated, from said comparison.

[0056] In one particular embodiment, the outputs of the photodetectors of each elementary acquisition module are connected in parallel to a comparator configured to compare the sum of the electrical signals converted by these photodetectors to the threshold value associated with that elementary acquisition module and to generate the demodulated data sequence based on this comparison. The comparator thus forms a demodulation unit for the light beam received by the receiving module, capable of extracting a demodulated data sequence from the electrical signals converted by the photodetectors. Alternatively, the comparator can be replaced by active circuits.

[0057] In one embodiment of the invention, the transmission module is arranged in a front headlight of the motor vehicle. Preferably, the reception module and the transmission module are arranged in the same front headlight of the vehicle.

[0058] Advantageously, the emitting module is arranged so that the light beam participates, wholly or partially, in fulfilling a predetermined regulatory photometric function. For example, it could be a daytime running light (DRL), which has the advantage of being emitted over a wide area with low intensity.

[0059] The invention also relates to a method for detecting an obstacle located in the environment of a motor vehicle and estimating the distance separating this object from the vehicle, the method being implemented by a light system according to the invention.

[0060] Of course, the different features, variants and embodiments of the invention can be combined with each other in various ways as long as they are not incompatible or mutually exclusive.

[0061] Furthermore, various other features of the invention become apparent from the attached description made with reference to the drawings which illustrate non-limiting embodiments of the invention and where:

[0062] [Fig. 1] represents, schematically and partially, a view of a lighting system of a motor vehicle according to an example of an embodiment of the invention;

[0063] [Fig. 2] schematically and partially represents an example of the implementation of the electronic architecture of the lighting system of [Fig. 1]; and

[0064] [Fig. 3] represents, schematically and partially, an example of the operation of the system of [Fig.1] during the implementation of a telemetry process.

[0065] It should be noted that in these figures the structural and / or functional elements common to the different variants may have the same references.

[0066] Of course, various other modifications can be made to the invention within the scope of the attached claims.

[0067] With reference to [Fig. 1], the present invention is a vehicle lighting system 1 comprising an emission module 2, a reception module 3, and a control system 4. [Fig. 3] represents a detailed view of the electronic architecture of system 1.

[0068] The emission module 2 includes a first light module 21 capable of emitting a first light beam F1, and a modulation unit 22 capable of receiving a modulating data sequence Seq_m generated by a generator 41 of the control system 4 and arranged to modulate the light beam F1 emitted from said modulating sequence Seq_m.

[0069] The first emission module 2 is, for example, arranged in a headlight of the motor vehicle.

[0070] The first light module 21 comprises a plurality of light sources, for example, connected in series. In the example described, each light source is a light-emitting diode (LED) smaller than 500 micrometers, preferably approximately 300 micrometers in size, and the first light module comprises at least three sources connected in series. Each light source may be formed from a block of several elementary light sources connected in parallel, without departing from the scope of the present invention. The first light module 21 may also be provided with further branches of light sources connected in series, the branches being connected in parallel, without departing from the scope of the present invention.

[0071] The first light module 21 is arranged so that the light beam F1 it emits has an electromagnetic spectrum in which at least a portion lies within the visible spectrum. Preferably, the spectrum of this light beam F1 exhibits a peak intensity, or line, in the blue at 450 nm. It should be noted that the spectrum may also contain other peak intensity in the visible and / or infrared regions.

[0072] Since the light beam F1 is composed, partially or entirely, of white light, it is possible to use this light beam to contribute, partially or entirely, to the performance of a predetermined photometric function, particularly a regulatory one. In this case, the first light module 21 may include an optical unit arranged to shape this light beam F1 so that its photometric distribution meets the requirements of said function. For example, it may be possible for the light beam F1 to contribute to the performance of a daytime running light (DRL) function.

[0073] In addition to this photometric function, the F1 light beam allows system 1 to perform functions of detecting and evaluating the position of an obstacle on the road and / or communicating with another vehicle or with road infrastructure.

[0074] For these purposes, the modulation unit 22 is arranged to modulate the light beam F1 emitted by the first light module 21, based on the data sequence modulating Seq_m that it receives, for example by controlling the power supply provided to the series of light sources 21 a of the first light module.

[0075] For this purpose, the modulation unit 22 is a high-frequency driver and includes a generator (not shown) of a pulse-width modulated control signal. This control signal controls a switched-mode power supply 51 supplied to the light sources of the first light module 21. Conventionally, the duty cycle of this control signal, set by the modulation unit 22, allows control of the average electrical power supplied to the light sources, and therefore of the luminous intensity of the light beam F1, so as to satisfy the requirements of the photometric function it performs.

[0076] In the example described, the modulation unit 22 is arranged to convert the data sequence Seq_m into a modulating signal and to modulate the initial control signal using this modulating signal. It should be noted that several types of modulation can be used interchangeably within the framework of the present invention, and in particular on-off keying (OOK), pulse code modulation (PCM), pulse amplitude modulation (PAM), pulse width modulation (PWM), or pulse position modulation (PPM).

[0077] The light beam F1 emitted by the first light module 21 is composed of a train of successive light pulses with a sufficiently high frequency, for example greater than 30 MHz, specifically between 50 MHz and 100 MHz, so that the human eye can no longer distinguish them. Furthermore, the amplitude, width, and / or position of each pulse relative to the period allows the light beam F1 to carry the data sequence Seq_m.

[0078] If an object is present in the environment of the motor vehicle, it can reflect this light beam F1 towards the receiving module 3, which thus receives a light beam F2.

[0079] This receiving module 3 comprises a plurality of elementary acquisition modules 32i,j. Each elementary acquisition module 32i,j includes several photodetectors 32ak, I, each capable of converting a light signal it receives into a Selk electrical signal, I. Each elementary acquisition module 32i,j also includes a demodulation unit 34, comprising a comparator, to the input of which all the outputs of the photodetectors 32ak,l are connected in parallel. The comparator thus receives an elementary detection signal Sdeij formed from the sum of the Selk electrical signals from these photodetectors 32ak,l. The comparator is configured to compare this elementary detection signal Sdeij to a given threshold value, the comparison yielding a high value, or a "1", when the elementary detection signal Sdeij is greater than the threshold value, and a low value, or a "0", when the elementary detection signal Sdeij is less than the threshold value. The demodulation unit 34 is thus configured to generate a demodulated binary sequence Seq_di,j, which it transmits to a processing unit 42 of the control system 4.

[0080] In the example described, the photodetectors 32ak,l are identical and each consists of a single-photon avalanche photodiode (SPAD). These photodiodes and the demodulation unit 34 are integrated into a silicon photomultiplier (SiPM). It should be noted that the dimensions of the photodetectors are on the order of a micrometer. The assembly thus forms a sensor with a spatial reception resolution on the order of 1°, or even 0.1°, and whose detection capabilities, due to the use of avalanche photodiodes, are particularly high, even under degraded acquisition conditions.

[0081] Each electrical signal Selk,l represents the activation and deactivation sequences of the photodiode 32ak,I under the influence of photons that have struck it. An incident photon can indeed trigger an avalanche effect, leading to the generation of an electrical signal Selk,l for an elementary period of one or a few nanoseconds, during which the photodiode is inoperative. Then, the photodiode becomes, once again, in a state of waiting for a new incident photon, with no electrical signal being generated by it in this state. The elementary detection signal Sdeij, resulting from the sum of these electrical signals Selk,l, therefore represents an estimate of the number of photons that have reached the sensor during each elementary period. It thus contains information relating to the optical power incident on the sensor, which may include a portion of the beam emitted by the transmitting module and then reflected by an obstacle.

[0082] Alternatively, it may be possible to replace the comparator of the demodulation unit 34 with active circuits, the demodulated data sequence in this case being directly a digital sequence made up of "1" and "0".

[0083] In the example described, the receiving module 3 is arranged in the headlight of the motor vehicle, next to the transmitting module 2.

[0084] The processing unit 42 is capable of receiving the demodulated binary sequences Seq_di,j, generated by the elementary acquisition modules 32i,j, and of detecting in each demodulated binary sequence Seq_di,j, the presence of the modulating data sequence Seq_m. The demodulation units 34 thus make it possible to reduce the amount of data that must be handled by the processing unit, thereby compressing the elementary detection signals Sdeij.

[0085] To this end, the computing unit 42 is configured to estimate values ​​of a correlation function Fcorrij between each demodulated binary sequence Seq_di,j and the modulating data sequence Seq_m, and to detect the presence of the modulating data sequence Seq_m in this demodulated binary sequence Seq_di,j, based on these values ​​of the correlation function Fcorrij. Upon detection, it can then determine a time of flight T separating the emission of the first modulated light beam F1 from the reception of the received light beam F2.

[0086] The computing unit 42 can thus perform functions of detection and evaluation of the position of an object on the road, as will be described in connection with [Fig. 3] which represents a telemetry process implemented by the light system 1.

[0087] In a first step E1, the generator 41 periodically generates a modulating data sequence Seq_m, for example of binary type, composed of "0" and "1", pseudo-random and of maximum size, also called M-sequence, exhibiting a duty cycle of 50%.

[0088] The generator 41 transmits the modulating data sequence Seq_m to the modulation unit 22 of the emission module 2 for the emission of the light beam F1 by the emission module 2.

[0089] In a second step E2, the modulation unit 22 modulates the light beam F1 emitted by the first light module 21 from this data sequence Seq_m. Thus, the modulation unit 22 converts the data sequence Seq_m into a modulating signal and modulates the initial control signal using this modulating signal.

[0090] It should be noted that, in the example described, each light pulse of the light beam F1 emitted by the first light module 21 corresponds to a bit with a value of "1" in the modulating sequence Seq_m. The average power of a portion of the light beam F1 containing the Seq_m sequence is thus defined by the number of bits with a value of "1" in this Seq_m sequence relative to the total number of bits in this sequence, by the duration of the pulses, and by the peak power of these pulses.

[0091] The light beam F1 is thus emitted until it reaches an object O, located in the environment of the vehicle, which reflects it towards the receiving module 3.

[0092] Depending on the angular position of the object O, the light beam F2 received by the receiving module 3 is thus concentrated on one of the elementary acquisition modules 32i,j.

[0093] When the sunlight conditions in the vicinity of the vehicle are particularly important, the sunlight is added to the light beam F2 received by the receiving module 3. The light beam F2 received by the receiving module 3 is thus composed of a part of the light beam F1 reflected by the object O and noise, for example generated by sources of stray light such as urban lighting, car lighting, or even the sun.

[0094] In a third step E3, each of the elementary acquisition modules 32i,j thus extracts, using its demodulation unit 34, a demodulated binary sequence Seq_di j which it transmits to the calculation unit 42.

[0095] For each demodulated binary sequence Seq_di,j that it receives, the computing unit 42 estimates, in a fourth step E4, values ​​of a correlation function Fcorrij between the modulating sequence Seq_m and this demodulated binary sequence Seq_di,j.

[0096] Calculation unit 42 thus evaluates, for a plurality of time offset values, the value of the cross correlation, using a cyclic convolution product, between each demodulated binary sequence Seq_di,j and the modulating sequence Seq_m delayed according to each of the time shift values.

[0097] Given the autocorrelation and cross-correlation properties of the modulating sequence, the correlation function Fcorrij will thus be maximum for a time shift value corresponding to the time of flight of the light beam F1, separating the instant when it is emitted by the emission module 2 and the instant when it is received by an elementary acquisition module 32i,j of the reception module 3, the modulating sequence Seq_m delayed by this value thus corresponding substantially to the demodulated binary sequence Seq_di,j up to noise.

[0098] In a fifth step E5, the computing unit 42 identifies the maximum value Fcorr_max of each correlation function Fcorrij associated with each elementary acquisition module 32i,j and compares it to a threshold value Vs.

[0099] If this maximum value Fcorr_max is greater than the threshold value Vs, the modulating sequence Seq_m is considered to be detected by the processing unit 42 in the demodulated binary sequence Seq_di,j from the elementary acquisition module 32i,j associated with this correlation function Fcorrij. An object O is therefore detected within the angular range, or pixel, monitored by this elementary acquisition module 32i,j, and the processing unit 42 can then estimate, in a sixth step E6, the value T of the time of flight of the light beam F1 between the object O and the vehicle, associated with this maximum value, as well as the distance d separating the object O from the vehicle.

[0100] In the example described, the telemetry function relies on several components: the modulation unit 22, the generator 41 of the modulating sequence Seq_m, and the processing unit 42. These components operate at very high frequencies and can therefore experience significant increases in their operating temperature, which can damage them and, beyond disrupting the telemetry function, interrupt the lighting function. In this context, system 1 is equipped with various components to maintain the lighting function, either when these components 22, 41, and 42 fail, or as a precaution against future failures.

[0101] For these purposes, system 1 includes two auxiliary power supply sources. 52 and 53, an auxiliary power supply control device 54. In the example described, the sources 52 and 53 are direct current sources and the device 54 is a voltage step-down device, for example according to a Buck architecture.

[0102] as well as a plurality of T switches. More specifically, system 1 comprises:

[0103] a switch T1 arranged between the output of generator 41 and an input 22a for receiving the modulating sequence Seq_m of the modulation unit 22,

[0104] a switch T2 arranged between the output of generator 41 and an input of the computing unit 42,

[0105] a switch T3 and T4 between each auxiliary power supply 51 and 52 and the first light module 21,

[0106] a switch T5 between the auxiliary power supply 53 and the input 22a for receiving the modulating sequence Seq_m of the modulation unit 22,

[0107] a switch T6 between the output of the modulation unit 22 and an input of the first light module 21,

[0108] a T7 switch between the auxiliary power supply control device 54 and the first light module 21.

[0109] Each of these T switches, if applicable, is capable of activating or deactivating the electrical connection between the two elements it links. Switches, transistors, or any other controllable electronic component can be used to allow or prevent the flow of an electric current.

[0110] The control system 4 further includes a microcontroller 43 capable of controlling each of the switches T and can thus reconfigure the electrical architecture of the lighting system 1, according to failures of the generator 41, the modulation unit 22 and the computing unit 42 detected or anticipated by the control system.

[0111] Different failure scenarios will now be described, in connection with [Fig. 2].

[0112] In a first scenario, the control system 4 detects a failure of the generator 41 and / or the computing unit 42. These failures may be detected in particular via failure alerts issued by the generator 41 and / or the computing unit 42 themselves, or through measurements made by sensors (not shown), such as current or temperature sensors, relayed to the control system 4.

[0113] Following the detection of this fault, the microcontroller 43 controls the switch T5 to connect the auxiliary power supply 53 and the input 22a of the modulating sequence Seq_m of the modulation unit 22.

[0114] The microcontroller 43 also disconnects, by opening switch T1, the output of generator 41 from input 22a of modulation unit 22, and disconnects control unit 42 from generator 41 by opening switch T2. The telemetry function is therefore disabled. It would also be possible to disconnect the entire receiver module 3 from the control system 4 without departing from the scope of the present invention.

[0115] In this scenario, despite the failure of the generator 41 or the computing unit 42, the modulation unit 22 thus continuously receives, on its input 22a, a constant voltage, generated by the auxiliary source 53.

[0116] The microcontroller 43 is also connected to the activation input 22b, or "ENABLE", of the modulation unit 22. This microcontroller 43 can thus transmit to the modulation unit 22, via this activation input 22b, a predetermined modulating data sequence, known as the degraded Seq_md sequence. This Seq_md sequence successively activates and deactivates the modulation unit 22, which modulates the power supply provided by the source 51 to the first light module 21 with a sequence of "1"s for activation durations corresponding to the "1" values ​​of the degraded Seq_md sequence.

[0117] In other words, the F1 light beam still performs the photometric function it performed before the failure, and is modulated using this degraded Seqjnd sequence, which can thus indicate to other road users that the telemetry function is deactivated.

[0118] In a second scenario, the control system 4 detects a failure of the modulation unit 22. These failures may be detected in particular via failure alerts issued by the modulation unit 22 itself, or through measurements made by sensors (not shown), such as current or temperature sensors, relayed to the control system 4.

[0119] Following the detection of this failure of the modulation unit 22, the microcontroller 43 controls the switches T3 and T4 to connect the auxiliary power supply 52 to the first light module 21, in place of the auxiliary power supply 51.

[0120] The microcontroller 43 also controls the switches T6 and T7 for the auxiliary power supply control device 54 to the first light module 21, in place of the modulation unit 22.

[0121] Finally, as in the first scenario, the microcontroller 43 also disconnects, by opening switch T1, the output of generator 41 from input 22a of modulation unit 22 and disconnects control unit 42 from generator 41, by opening switch T2. The telemetry function is therefore deactivated.

[0122] The auxiliary power supply control device 54 and auxiliary power supply source 52 can thus perform a conventional switching power supply of the first light module 21, in which the intensity of the light beam F1 emitted by the first light module 21 is controlled by a duty cycle of an amplitude-width modulation performed by the device 54.

[0123] Given that the light sources used by the first light module 21 are selected to perform both a rangefinding and a photometric function, the spectrum of the light beam F1 exhibits an intensity peak, or line, in the blue at 450 nm, as described above. However, in the degraded modes described above, the light beam F1 is emitted for continuous periods, unlike in normal operating mode. It is therefore possible that the colorimetry of the light beam F1 falls outside the regulatory requirements governing the photometric function that this beam is intended to perform.

[0124] To overcome this drawback, the second emission module includes a second The light module 61 is capable of emitting a light beam F1' whose spectrum has an intensity peak in the "orange" region, thus complementing the spectrum of the beam F1. The emission module 2 also includes a device 62 for controlling the power supply provided to the second light module 61.

[0125] Thus, following the detection of a failure of the generator 41, the modulation unit 22 and / or the calculation unit 42, the microcontroller 43 activates the second light module 61, via the device 62. The overall light beam formed by the sum of the beams F1 and F1' thus satisfies the colorimetric conditions of the regulatory requirements governing the photometric function.

[0126] Other scenarios than those described can be considered, including scenarios designed to compensate for the failure of other elements of the lighting system 1 or scenarios in which the telemetry function is deactivated by the microcontroller 43, to prioritize the realization of the photometric function using one or more of the devices 52, 53 and 54, when the operating conditions of one or more of the elements of the lighting system 1 approach a critical range without this or these elements being faulty, such as for example when the operating temperature of the modulation unit 22 exceeds a given threshold value.

[0127] The preceding description clearly explains how the invention achieves its objectives, namely, to provide a lighting system for a motor vehicle capable of performing both a given regulatory photometric function and a telemetry function, and in which the photometric function remains operational even in the event of a failure of one of the system's high-frequency elements. These objectives are achieved, in particular, through a control system capable of reconfiguring the electronic architecture of the lighting system, in response to the detection of a failure, in order to use an auxiliary power supply to maintain the performance of the photometric function.

[0128] In any event, the invention is not limited to the embodiments specifically described in this document, and extends in particular to all equivalent means and to any technically feasible combination of these means. In particular, other configurations of the emission modules may be envisaged, and notably an emission module employing other types of light source than Those described, such as a laser diode, a VCSEL, an SLED, or an RGB diode. It will also be possible to implement other photometric functions besides the one described, including dipped beam lighting functions or signaling functions such as position lights or direction indicators.

Claims

Tl Demands

1. A lighting system (1) of a motor vehicle, comprising: a. an emission module (2) comprising a first light module (21) capable of emitting a light beam (F1) whose spectrum has at least a portion in the visible spectrum, and a modulation unit (22) capable of receiving a data sequence, called modulating, (Seq_m) and arranged to modulate said light beam emitted from the received data sequence; b. a reception module (3) capable of receiving a light beam (F2), in which the reception module comprises at least one elementary acquisition module (32i,j) comprising a photodetector (32ak, I) capable of converting a light signal that it receives into an electrical signal (Selk.l), said elementary acquisition module (32) being capable of generating a data sequence, called demodulated, (Seq_di,j) from the electrical signal converted by the photodetector;c. a control system (4) comprising a generator (41) arranged to generate a modulating data sequence (Seq_m) and to transmit said modulating data sequence to the modulation unit (22) for the emission of a modulated light beam (F1) by the transmitting module, and a computing unit (42) capable of receiving a demodulated data sequence (Seq_di,j) generated by the or each elementary acquisition module from a light beam received (F2) by the receiving module, the computing unit (42) being arranged to determine a time of flight (T) separating the emission of said modulated light beam emitted from the reception of said light beam received from said demodulated data sequence (Seq_di,j) and said modulating data sequence (Seq_m); characterized in that it comprises at least one auxiliary power supply device (52, 53, 54);in that the control system (4) is capable of detecting a failure of at least one of the elements of the lighting system; and in that, following the detection of a failure of one or more of the elements of the lighting system, the control system is arranged to connect the auxiliary power supply device to the transmitting module.

2. Lighting system (1) according to the preceding claim, characterized in that, following the detection of a failure of the generator (41) and / or the computing unit (42), the control system (4) is arranged to connect the auxiliary power supply device (53) to the modulation unit (22) of the transmission module (2).

3. Lighting system (1) according to the preceding claim, characterized in that the modulation unit (22) has at least one receiving input (22a) of the modulating data sequence (Seq_m), and in that, following the detection of a failure of the generator (41) and / or the computing unit (42), the control system (4) is arranged to connect the auxiliary power supply device (53) to said receiving input of the modulation unit.

4. Lighting system (1) according to the preceding claim, characterized in that the modulation unit (22) has at least one activation input (22b), and in that, following the detection of a failure of the generator (41) and / or the computing unit (42), the control system (4) is arranged to transmit to the modulation unit, via said activation input, a predetermined modulating data sequence, referred to as degraded (Seq_md).

5. Lighting system (1) according to any one of the preceding claims, characterized in that, following the detection of a failure of the modulation unit (22), the control system (4) is arranged to connect the auxiliary power supply device (54) to the first lighting module (21).

6. A lighting system (1) according to any one of the preceding claims, characterized in that the emitting module (2) comprises a second lighting module (61) capable of emitting a light beam (F1) whose spectrum has at least a portion in the visible spectrum and in that, following the detection of a failure of one or more of the first lighting module (21), the receiving module (3), the generator (41), the modulation unit (22) and the computing unit (42), the control system (4) is arranged to activate the second lighting module.

7. A light system (1) according to the preceding claim, characterized in that it comprises a color sensor capable of measuring the quantity of light emitted by the light module (21) of the emission module (22) and in that, following the detection of a failure of one or more of the generator (41), the modulation unit (22) and the calculation unit (42), the control system (4) is arranged to control the emission of light by the second light module (61) according to the measurement of the color sensor.

8. A light system according to any one of the preceding claims, characterized in that the computing unit (42) is arranged to estimate values ​​of a correlation function (Fcorrij) between said demodulated data sequence (Seq_di,j) and said modulating data sequence (Seq_m) and to determine a time of flight (T) separating the emission of said modulated light beam emitted (F1) from the reception of said received light beam (F2) from the values ​​of the correlation function.

9. Lighting system (1) according to any one of the preceding claims, characterized in that the emission module (2) is arranged in a front headlight of the motor vehicle.

10. A light system (1) according to the preceding claim, wherein the emission module (2) is arranged so that the light beam (F1) participates, totally or partially, in the realization of a predetermined regulatory photometric function.

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