Luminous system for a motor vehicle comprising a module for emitting a modulated light beam

Abstract

The invention relates to a luminous system (1) for a motor vehicle, comprising an emitting module (2) comprising a luminous module (21) comprising a first elementary light source (211a) emitting a first elementary light beam (F11a) having a first peak between 485 nm and 505 nm and a second elementary light source (211b) emitting a second elementary light beam (F11b) having a second peak between 585 nm and 680 nm, an optical device (231) with a common exit face of said elementary light beams (F11a, F11b); and a control unit (C) for controlling the first and second elementary light sources (211a, 211b), the control unit comprising a unit (221a) for modulating the first elementary light beam emitted by the first elementary light source based on a received modulating data sequence (Seq_m).

Description

Lighting system of a motor vehicle comprising a module for emitting a modulated light beam

[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] Photometric functions in automotive lighting and signaling are defined primarily in terms of colorimetry. Regulations may, for example, require a specific color for the light beam. This is the case for the turn signal (or TI), which must be amber or orange; the rear position light (or RL), which must be red; the daytime running light or front position light (DRL and PL, respectively), which must be white; and the autonomous driving indicator (ADS marker), which must be cyan or turquoise. The wavelength of the light beam must therefore fall within a wavelength range associated with the photometric function it performs.

[0008] However, it is particularly advantageous to use light emitted directly by a semiconductor light generator to perform the telemetry function rather than light converted by a photoluminescent element from the light emitted by the generator. This is because the latter type of element has a conversion rate lower than the emission rate of the generator. Modulating this light emitted directly by the generator can therefore be faster, thus improving the accuracy of the telemetry function, as the time-of-flight evaluation resolution is necessarily higher.

[0009] However, semiconductor light generators natively emit blue, cyan, or green light. These colors are therefore unsuitable for certain photometric functions, particularly those involving white, amber, or red light.

[0010] Furthermore, even when the color of the light emitted natively by the semiconductor light source matches that required by the photometric function, this color is not stable. There is a tolerance inherent in the manufacturing of the light source, which can introduce significant variability in the color of the light it emits. This variability is indicated by a value called the Binary Indicator Number (BIN), which allows for the identification of the color of the light emitted by a given light source. It is therefore possible to sort light sources during the production of a lighting system, or even to source only light sources with a specific BIN value, in order to mitigate this variability. However, this solution results in a significant and undesirable increase in the price of the lighting system.

[0011] On the other hand, the color of the light emitted natively by the generator depends on its temperature. When the light source operates at a normal temperature, for example, when its junction temperature is at its nominal value, the color corresponds to the expected color. However, this temperature can exceed critical thresholds, for example, when the light source heats up under various conditions, particularly when the power it emits is too high and / or when the emission duration is too long and / or when the modulation is too rapid. Under these conditions, the color can vary significantly and fall outside the wavelength range permitted for the desired photometric function.It is possible to control the colour by reducing the operating current to decrease the thermal stress on the light source, but this necessarily leads to a degradation of the telemetry function, particularly in terms of detection range.

[0012] There is therefore a need for a lighting system in a motor vehicle, capable of performing both a given photometric function and a telemetry function, and therefore colorimetry remains controlled with regard to the requirements of this photometric function, without degrading the price or the performance of the telemetry function.

[0013] Thus, the invention is placed in this context and aims to meet this need.

[0014] For these purposes, the invention relates to a lighting system for a motor vehicle, comprising an emission module comprising a light module having a first elementary light source capable of emitting a first elementary light beam whose spectrum has a first peak between 485 nm and 505 nm and a second elementary light source capable of emitting a second elementary light beam whose spectrum has a second peak between 585 nm and 680 nm, and an optical device arranged to receive the first and second elementary light beams and having a common output face for said elementary light beams.

[0015] The system according to the invention is characterized in that it comprises a control unit arranged to control the first and second elementary light sources for the simultaneous emission of the first and second elementary light beams for the realization of a given photometric function, the control unit comprising a modulation unit for the first elementary light source, the modulation unit being capable of receiving a data sequence, called modulating, and arranged to modulate the first elementary light beam emitted by this first elementary light source from the received data sequence.

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

[0017] Furthermore, this first modulated elementary light beam is combined with a second elementary light beam to perform, wholly or partially, a photometric function. The first elementary light source is thus dedicated to both the rangefinding and photometric functions, while the second elementary light source is dedicated solely to the photometric function.

[0018] The second elementary light beam, emitted by the second elementary light source, can be modulated at a low frequency so that the combination of the two elementary beams exhibits a color conforming to the requirements of this photometric function. The control unit can, in particular, control the average power of the first modulated elementary light beam, for example, through the duty cycle of the modulating data sequence, in order to increase, decrease, or maintain it constant. It can also control the power supply to the second elementary light source so that the average powers of these two elementary light beams are adjusted to ensure that the color of the beam resulting from the combination of the first and second light beams remains consistent with the requirements of the desired photometric function.

[0019] Since the first peak of the spectrum of the first elementary light beam is between 485 nm and 505 nm, this beam is essentially cyan. Furthermore, since the second peak of the spectrum of the second elementary light beam is between 585 nm and 680 nm, this beam is amber, orange, or red. Preferably, the full width at half maximum (FWHM) of the spectrum of the first light beam may be between 10 and 30 nm if the first elementary light source natively emits cyan light, and between 30 and 120 nm otherwise. Preferably, the FWHM of the spectrum of the second light beam will be between 30 and 120 nm otherwise.Therefore, the simultaneous activation of the first and second elementary beams enables various photometric functions, including autonomous driving indicator (ADS marker), turn signal (TI), and rear position light (RL) functions, depending on whether the second elementary beam is amber or red, or daytime running light (DRL) or position light (PL). More precisely, the power settings applied to the first and second elementary light sources define the color of the beam resulting from the combination of the first and second elementary beams. This is achieved by modulating the colorimetric center of gravity of these two colors, weighted by the flux of these beams, within a chromaticity diagram. This allows the colorimetric requirements of the desired photometric function to be met.

[0020] Under these conditions, it remains possible to use the light emitted natively by the first elementary light source to perform the telemetry function. Adjusting the power of the second elementary light beam allows for compensation of production tolerance variations related to the color of the first modulated elementary beam without having to sort the elementary light sources according to their BIN (Block Intensity Number). It also compensates for color variations due to the temperature sensitivity of the first elementary light source, particularly when modulated at high frequencies. This ensures that the color of the light beam formed by the combination of the two elementary light beams remains controlled.

[0021] In the context of the present invention, the "spectrum of a light beam" means the distribution of luminous power or intensity as a function of wavelength. The spectrum of a light beam may, in particular, be characterized by its peak(s), or local maximum values, and by the full width at half maximum (FWHM) of each of these peaks.

[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 light module according to the received modulating data sequence, in particular so that the first modulated elementary light beam is formed by a train of light pulses carrying said received modulating data sequence. This modulation unit could, for example, be a high-frequency driver device.

[0023] Advantageously, the modulation unit can be arranged to, upon receiving the modulating data sequence, control the first elementary light source based on the received elementary sequence to emit the first modulated elementary light beam. If necessary, the modulation unit can be arranged to control the power supply provided to this first elementary light source to modulate the first elementary light beam.

[0024] In one embodiment of the invention, the modulation unit is arranged to modulate the first elementary light beam emitted by the first elementary light source using a modulating data sequence received at a frequency greater than 5 MHz. The modulation frequency may be between 5 MHz and 200 MHz, and in particular between 30 and 150 MHz. The duration of each pulse may be between 10 nanoseconds and 200 nanoseconds, preferably between 20 nanoseconds and 100 nanoseconds.

[0025] Advantageously, the modulation unit is arranged to generate a pulse-width modulated control signal, to modulate said control signal from the modulating data sequence it receives, and to control the emission of said first elementary light beam by said first elementary light source from 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.It can be stipulated that the modulation unit controls the first elementary light source so that the first modulated elementary light beam is emitted only for high values ​​of the received modulating data sequence, and so that the first modulated elementary light beam is emitted according to a set peak light power. It is thus understood that each pulse of the first modulated elementary light beam is emitted with the said peak light power, and that the average light power of the first modulated elementary 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 the control signal.

[0026] In one embodiment of the present invention, the control unit may be arranged to control the second elementary light source at low frequency, on the order of kHz, for the emission of the second elementary light beam.

[0027] In the context of the present invention, the term "optical device" means any optical element or combination of optical elements capable of receiving each of the first and second elementary light beams and modifying their characteristics to combine them into a single light beam at the common exit face. This may include, in particular, lenses, reflectors, collimators, and / or light guides. Preferably, the optical device may be arranged to shape each of the elementary light beams, modify their trajectories and / or distributions so that the light beam resulting from their combination at the common exit face has a photometric distribution that meets the requirements, including regulatory requirements, of the desired photometric function.

[0028] Advantageously, the optical device can be arranged to mix the elementary light beams so that the color of the resulting beam is homogeneous at the common exit face. For example, it could be a light guide, long relative to its cross-sectional dimensions. The cross-section of the light guide could have a faceted shape, such as an octagon or a hexagon, with the facets being either flat or concave. Alternatively, the optical device could be a diffuser, such as a silicone element mounted directly on the emitting faces of the first and second elementary light sources, or alternatively, a housing with one or more openings to receive the elementary light beams and an opening forming the common exit face, the walls of the housing being diffusive.

[0029] In one embodiment of the invention, the first elementary light source comprises a semiconductor light generator capable of directly emitting said first elementary light beam. In this embodiment of the invention, the first elementary light beam emitted natively by the semiconductor light generator is directly modulated by the modulation unit, without being converted by a photoluminescent element. These characteristics improve the accuracy of the telemetry function, as the time-of-flight evaluation resolution is particularly high due to the photon emission velocity of the generator.

[0030] The semiconductor could, for example, be a gallium-indium nitride alloy, or InGaN, capable of emitting cyan light rays by electroluminescence in response to an electric current passing through it.

[0031] If necessary, the second elementary light source may include a semiconductor light generator and a photoluminescent element capable of converting light emitted by the light generator to obtain the second elementary light beam. This configuration makes it possible to obtain a thermally stable elementary light source.

[0032] The semiconductor, for example, is a gallium-indium nitride alloy, or InGaN, capable of emitting blue light through electroluminescence in response to an electric current passing through it. The photoluminescent element could, for example, be in the form of a cerium-doped yttrium aluminum garnet resin, or CE:YAG, capable of absorbing blue light and, through photoluminescence in response to the excitation caused by this light, emitting yellow light. The photoluminescent element is positioned on the generator so that some of the blue light excites it, causing it to emit yellow light through photoluminescence. The remaining blue light passes through the element.Thus, when electrically powered, the light source simultaneously emits blue and yellow light rays in proportions such that the resulting light appears orange, amber, or red to the human eye. The choice of semiconductor, with regard to the wavelengths it emits, and the choice of dopant for the photoluminescent element, with regard to the wavelengths it absorbs and emits, will determine the spectrum of the light emitted by the source, and in particular the peak wavelength of that spectrum.

[0033] Each of the first and second elementary light sources can thus 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").

[0034] In one embodiment, the first and second elementary light sources are encapsulated in a single structure to form a single light source capable of selectively emitting one or both of the first and second elementary light beams, the intensity of each of said elementary light beams being controllable. In this example, the two elementary light sources are light-emitting chips placed close to each other on the same substrate and sealed or packaged with the same encapsulation material, such as a transparent or translucent resin. They thus form a compact optical component called a bi-chip light-emitting diode (LED), thereby facilitating assembly, electrical connection, thermal control of the elementary light sources, and mixing of the colors of the light emitted by these chips.

[0035] The substrate on which the individual light sources are mounted can be designed to be an electronic circuit, specifically an integrated circuit, incorporating a functionally adapted switch assembly to power and / or control each of the individual light sources. Additional layers can also be added to the encapsulation resin, such as protective, adhesive, sealing, or aesthetic enhancement layers.

[0036] Alternatively, it may be provided that each of the first and second elementary light sources is encapsulated in its own structure, the first and second elementary light sources being single-chip light-emitting diodes mounted on the same support, like a common printed circuit board.

[0037] In one embodiment of the invention, the control unit includes a power supply control unit for the second elementary light source, the control unit being arranged to control said control unit with a pulse-width modulated signal with a frequency lower than the frequency of the received data sequence.

[0038] In the present invention, the "duty cycle of a data sequence" means 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 with the value "1" in the binary sequence and the total number of bits in that sequence.

[0039] Preferably, the control unit can be arranged to simultaneously control the driving unit and the modulation unit so that the color of the beam formed by the addition of the first and second elementary beams at the common output face of the optical device conforms to the requirements of the desired photometric function.

[0040] In one embodiment, the lighting system includes a temperature sensor for the first elementary light source, and the control unit is arranged to control said control unit with a pulse-width modulated signal with a duty cycle determined from the temperature measured by said sensor.

[0041] In this example, the control unit dynamically compensates for color variations in the first modulated elementary light beam induced by temperature variations in the first high-frequency modulated elementary light source, so as to keep the color of the light beam formed by the addition of the first and second elementary light beams constant.

[0042] It may be provided that the temperature sensor is capable of directly measuring the temperature of said first elementary light source, or of measuring the temperature in the vicinity of said first elementary light source, or of indirectly measuring the temperature of said first elementary light source, for example through a measurement of the forward voltage of this source.

[0043] In one embodiment of the invention, the second light source is capable of emitting a second elementary light beam whose spectrum has a second peak between 585 nm and 595 nm, and the light module comprises a third elementary light source capable of emitting a third elementary light beam whose spectrum has a third peak between 595 nm and 680 nm. The optical device is arranged to receive the first, second, and third elementary light beams, and its output face is common to said first, second, and third elementary light beams. Optionally, the control unit is arranged to selectively control the first, second, and third elementary light sources for the selective or simultaneous emission of the first, second, and third elementary light beams to selectively perform several given photometric functions.

[0044] In this example, this third elementary light source, emitting red light, is placed on a chromaticity diagram opposite the first elementary light source, which emits cyan light, and next to the second elementary light source, which emits amber or orange light. The three elementary light sources thus define a triangle on the chromaticity diagram, within which the color of the first light beam can be controlled by the control unit by adjusting the contributions of each of the elementary light beams to this first beam. The third elementary light source therefore allows for the introduction of two-dimensional color variations on this chromaticity diagram and is consequently dedicated solely to the implementation of photometric functions.For example, it is possible to more precisely control the cyan or turquoise color of the light beam resulting from the addition of the three elementary light beams. It is also possible to obtain other colors of this light beam in order to perform other photometric functions; and in particular a white beam, whose temperature is controllable, to perform daytime running light (or DRL) or position light (or PL) functions, or a red or amber beam, depending on the spectrum of the third source, to perform rear light (or RL) or direction indicator (or TI) functions.

[0045] In the present invention, the term "chromaticity diagram" refers to a two-dimensional graphical representation of color in the CIE (International Commission on Illumination) colorimetric system, and in particular a diagram of the CIE 1931 2° Standard Observer type. It allows a color to be represented by its abscissa x and its ordinate y on axes of the diagram, these coordinates corresponding to standardized chromaticity coordinates. In this diagram, the color resulting from the additive synthesis of several colors can be calculated by finding the centroid of these colors weighted by the luminous flux of the beams exhibiting these colors.

[0046] In one embodiment of the invention, the control unit comprises a power supply control unit for the third elementary light source, and the control unit is arranged to control said control unit with a pulse-width modulated signal with a duty cycle such that the light beam formed by the summation of the first, second, and third elementary light beams from the output face of the optical device has a color whose abscissa on a chromaticity diagram is between 0.31 and 0.5 and whose ordinate is between 0.283 and 0.440. The color may, for example, be contained within a region defined by the following vertices: (0.31; 0.348); (0.453; 0.440); (0.5; 0.440); (0.5; 0.382); (0.443; 0.382) and (0.310; 0.283).

[0047] These coordinate ranges correspond to the different variations and temperatures of the color white as permitted for the realization of a daytime running light, or "DRL", or position light, or "PL" type function.

[0048] Preferably, the third elementary light source may include a semiconductor light generator and a photoluminescent element capable of converting light emitted by the light generator to obtain said third elementary light beam.

[0049] The photoluminescent element could, for example, be in the form of a cerium-doped yttrium aluminum garnet (CE:YAG) resin 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 it, causing it to emit yellow 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 red to the human eye.

[0050] If necessary, the third elementary light source can be encapsulated with the first and second elementary light sources in the same structure to form a single light source capable of selectively emitting one and / or the other of the first, second and third elementary light beams, the intensity of each of said elementary light beams being controllable.

[0051] In one embodiment of the invention, the emission module includes another light module capable of emitting another light beam for performing said given photometric function. If necessary, the control unit is arranged to control the first and second elementary light sources for the simultaneous emission of the first and second light beams with the other light beam for performing said given photometric function, the control unit being arranged to control the first and second elementary light sources such that the light beam formed by the addition of the first and second elementary light beams has a color substantially identical to that of the other light beam.

[0052] In this embodiment, the other light module is dedicated solely to performing the photometric function, and the control unit directs the elementary light sources to match the color of the light beam resulting from the addition of the first and second elementary light beams to that of the beam emitted by this other light module. This ensures that the performance of the rangefinding function does not generate colorimetric heterogeneity in the different light beams participating in the photometric function.

[0053] It may be advantageous to provide for the control unit to be common to the different light modules of the emission module.

[0054] According to an example of an embodiment of the invention, it may be provided that: The first light module comprises: A first elementary light source capable of emitting a first elementary light beam of cyan colour, this elementary light beam being intended to be modulated by the modulation unit to perform the telemetry function; A second elementary light source capable of emitting a second elementary light beam of amber or orange colour; The second light module comprises: A first elementary light source capable of emitting a first elementary light beam of cyan or turquoise colour; A second elementary light source capable of emitting a second elementary light beam of amber or orange colour.

[0055] According to this example, the second light module is thus able to participate in the realization of an autonomous driving indicator function by activating only its first elementary light source, a direction indicator function by activating only its second elementary light source, and a daytime running light and / or position light function by simultaneously activating both elementary light sources.

[0056] Furthermore, the first light module can participate in the autonomous driving indicator function by simultaneously activating the first and second elementary light sources, the direction indicator function, or the daytime running light and / or position light function by simultaneously activating both elementary light sources and modulating their proportions to ensure colorimetry. It should be noted that controlling the different light sources ensures color uniformity of the beams between the first and second light modules, and that the first elementary light source remains activated in all cases, thus guaranteeing the continuity of the telemetry function regardless of the photometric function being performed.

[0057] Finally, it should be noted that the line joining the elementary light sources of the first light module and the line joining the elementary light sources of the second light module on the chromaticity diagram intersect, so that the control unit can ensure that the colors of the first and second light beams emitted by these first and second light modules match perfectly.

[0058] Alternatively, the second light module may include a light source capable of emitting white light, such as an elementary light source capable of emitting an elementary beam of white light or three elementary light sources capable of emitting elementary beams of red, green and blue light respectively.

[0059] In one embodiment of the invention, the lighting system comprises: 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, said demodulated, from the electrical signal converted by the photodetector; 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 the elementary light beam emitted by said elementary light source.

[0060] Advantageously, the control system includes a computing unit capable of receiving a demodulated data sequence generated by the elementary acquisition module or modules from a light beam received by the receiving module, the computing unit being arranged to determine a duration relative to a time of flight separating the emission of said first modulated elementary light beam emitted from the reception of said light beam received from said demodulated data sequence and said modulating data sequence.

[0061] 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.

[0062] In one embodiment of the invention, the control system is arranged to transmit a duty cycle command to the generator, and wherein the generator is arranged to generate said modulating data sequence as a function of said duty cycle command.

[0063] Advantageously, the generator is arranged to generate a modulating sequence of pseudo-random binary type data as a function of said duty cycle setpoint.

[0064] 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.

[0065] Given the autocorrelation properties of pseudo-random binary sequences, the lighting system's processing unit can estimate the values ​​of a correlation function between a modulating sequence and a demodulated sequence extracted from a light beam received by the receiver module. The correlation function will be at its maximum for the time-shift value corresponding 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. Consequently, 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.

[0066] In the invention, the generator can be arranged to generate, according to said duty cycle setpoint, a modulating data sequence of Kasami code type, of "m-sequence or maximum length sequence" type, of "Gold code" type, or any other pseudo-random binary sequence exhibiting good autocorrelation and crosscorrelation properties, or even orthogonality, and to transmit the modulating data sequence to the modulation unit of the emission module for the emission of a first elementary light beam modulated by the emission module.

[0067] 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.

[0068] Advantageously, each photodetector of each elementary acquisition module is an avalanche photodiode, specifically a single-photon type. 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 high gain, for example, on the order of 10⁶, and therefore to compensate for signal-to-noise ratio degradation due to external conditions.

[0069] According to one embodiment of the invention, the receiving module may include an optical unit arranged in front of the elementary acquisition modules.

[0070] 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.

[0071] 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.

[0072] 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 duration relative to 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.

[0073] 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 duration relative to a time of flight separating the emission of said modulated elementary light beam emitted from the reception of said light beam received from the values ​​of the correlation function.

[0074] 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.

[0075] 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.

[0076] Preferably, the computing unit is configured to determine the value of a peak in 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 said modulating data sequence is present in said demodulated data sequence only if said peak value is greater than the predetermined threshold value.

[0077] In one embodiment of the invention, the receiving module includes a bandpass type optical filter placed in front of the photodetector, said optical filter being capable of transmitting a wavelength range and being arranged so that the width, in particular at half-height, of said range is substantially less than 15 nm and that said filter has a transmission peak at a wavelength corresponding to the first peak.

[0078] In one embodiment, 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. Alternatively, the transmission module may be arranged in a rear light of the motor vehicle.

[0079] 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.

[0080] 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.

[0081] 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:

[0082] represents, schematically and partially, a view of a lighting system of a motor vehicle according to an example of an embodiment of the invention;

[0083] represents, schematically and partially, an example of how the system functions during the implementation of a telemetry process; and

[0084] represents, schematically and partially, a chromaticity diagram of type CIE 1931 2° Standard Observer on which the elementary light sources of the lighting system have been placed according to an embodiment of the invention.

[0085] It should be noted that in these figures the structural and / or functional elements common to the different variants may have the same references.

[0086] Of course, various other modifications can be made to the invention within the scope of the attached claims.

[0087] With reference to the, the present invention is a lighting system 1 of a vehicle comprising an emission module 2, a reception module 3, and a control system 4. Figure 1 represents a detailed view of the electronic architecture of the system 1.

[0088] The first emission module 2 is, for example, arranged in a headlight of the motor vehicle.

[0089] The emission module 2 includes a first light module 21 capable of emitting a first light beam F11.

[0090] The light module 21 comprises a plurality of elementary light sources, including a first elementary light source 211a, a second elementary light source 211b and a third elementary light source 211c.

[0091] According to the invention, the first elementary light source 211a is capable of emitting a first elementary light beam F11a of cyan color, the spectrum of which has a first peak between 485 nm and 505 nm and a full width at half maximum (FWHM) between 10 and 30 nm. The second elementary light source 211b is capable of emitting a second elementary light beam F11b of amber or orange color, the spectrum of which has a second peak between 585 nm and 595 nm and a FWHM between 30 and 120 nm. The third elementary light source 211c is capable of emitting a third elementary light beam F11c of red color, the spectrum of which has a third peak between 595 nm and 680 nm and a FWHM between 30 and 120 nm. It should be noted that it is possible that these spectra may show other intensity peaks, in the visible and / or in the infrared.

[0092] It can be foreseen, without departing from the scope of the present invention, that the light module 21 comprises several identical elementary light sources, for example mounted in series one after the other.

[0093] It can also be predicted that the first elementary light source 211a is capable of emitting a first elementary light beam F11a of blue color, whose spectrum has a first peak between 400 nm and 485 nm. It can also be predicted that the second elementary light source 211b is capable of emitting a second elementary light beam F11b of red color, whose spectrum has a second peak between 595 nm and 680 nm, the light module 21 in this case being without a third elementary light source.

[0094] In the example shown, the first elementary light source 211a comprises a semiconductor light generator, for example a gallium-indium nitride alloy, capable of directly emitting, by electroluminescence, the first elementary light beam F11a of cyan color. Each of the second and third elementary light sources 211b and 211c may comprise a semiconductor blue light generator, for example a gallium-indium nitride alloy, and a photoluminescent element, for example a cerium-doped yttrium aluminum garnet, capable of absorbing light emitted by the light generator and emitting yellow light in response, the addition of the unabsorbed blue light and the yellow light forming respectively said second elementary light beam F11b of amber or orange color and said third elementary light beam F11c of red color.

[0095] In the example of the, the elementary light sources 211a, 211b and 211c are encapsulated in the same transparent resin to form a single light source, of the multi-chip light-emitting diode type, capable of selectively emitting the elementary light beams F11a, F11b and F11c, the intensity of each of said elementary light beams being controllable.

[0096] The emission module 2 includes a control unit C arranged to control the elementary light sources 211a, 211b and 211c for the selective emission of the elementary light beams F11a, F11b and F11c.

[0097] In addition, the light module 21 includes an optical device 231 arranged to receive the first, second and third elementary light beams F11a, F11b and F11c and having an output face common to said first, second and third elementary light beams F11a, F11b and F11c.

[0098] In the example described, the optical device 231 is a faceted light guide, long relative to its cross-sectional dimensions, which mixes the elementary light beams F11a, F11b, and F11c so that the color of the resulting beam is homogeneous at the common exit face. Other embodiments of the optical device 231, including a diffuser, may be provided without departing from the scope of the present invention.

[0099] It is thus understood that the control unit C allows the first, second and third elementary light sources 211a, 211b and 211c to be selectively controlled for the selective or simultaneous emission of the first, second and third elementary light beams F11a, F11b and F11c so that the elementary light beams actually emitted form a first light beam F11 at the common output face of the optical device 231, the emission parameters of the elementary light beams F11a, F11b and F11c determining in particular the color of this first light beam F11 which participates in the realization of a given photometric function, the emission instruction of which is provided upstream to the control unit C.

[0100] The emission module 2 includes a second light module 22 capable of emitting a second light beam F12 to participate in the realization of the same photometric function.

[0101] In the example shown, the second light module 22 comprises one or more elementary light sources 212a and an optical device 232, for emitting one or more elementary light beams F12a of white, orange, amber, red, green, or blue color (depending on the nature of the sources 212a). These elementary light beams together form a second light beam F12, which, along with the first light beam F11, performs the same photometric function. The control unit C also allows control of this or these elementary light sources 212a.

[0102] In addition to this photometric function, system 1 can perform a telemetry function, namely a function of detecting and evaluating the position of an obstacle on the road.

[0103] The control unit C includes a modulation unit 221a capable of receiving a modulating data sequence Seq_m generated by a generator 41 of the control system 4 and arranged to modulate the first elementary light beam F11a emitted from said modulating sequence Seq_m.

[0104] For these purposes, the modulation unit 221a is arranged to modulate the first elementary light beam F11a emitted by the first elementary light source 211a, from the modulating data sequence Seq_m that it receives, for example by controlling the power supply provided to this first elementary light source 211a.

[0105] The modulation unit 221a 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 provided to the first elementary light source 211a. Typically, the duty cycle of this control signal, set by the modulation unit 221a, controls the average electrical power supplied to the first elementary light source 211a, and thus controls the luminous intensity of the first elementary light beam F11a.

[0106] In the example described, the modulation unit 221a 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, including on-off keying (OOK), pulse code modulation (PCM), pulse amplitude modulation (PAM), pulse width modulation (PWM), and pulse position modulation (PPM).

[0107] The first elementary light beam F11a, emitted by the first elementary light source 211a, 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, that the human eye can no longer distinguish them. Furthermore, the amplitude, width, and / or position of each pulse with respect to the period allows the first elementary light beam F11a to carry the data sequence Seq_m.

[0108] It should be noted that the control unit C includes units 221b and 222a for controlling the power supply of the other elementary light sources 211b and 211c of the first light module 21 and the elementary light sources 212a of the second light module 22. Each control unit 221b and 222a is a low-frequency driver, arranged to control a switching power supply provided to the elementary light sources to which it is associated with a pulse-width modulated (PWM) signal whose duty cycle is determined in particular according to the desired photometric function, the frequency of the modulated signal being lower than the frequency of the modulating data sequence Seq_m.

[0109] In other words, in the described embodiment, the first elementary light source 211a is thus dedicated to both the telemetry and photometric functions, while the other elementary light sources 211b and 211c of the first light module 21 and the elementary light sources 212a of the second light module 22 are dedicated only to the photometric function, the first and second light beams F11 and F12 being emitted simultaneously.

[0110] In examples not described, it may be possible to replace the control units 221b and 222a with a single control unit for all the light sources of the first light module 21 and the second light module 22 dedicated solely to the photometric function or with a plurality of control units, each dedicated to one of the light sources or to a group of light sources of the first light module 21 and the second light module 22 dedicated solely to the photometric function.

[0111] If an object is present in the environment of the motor vehicle, it can reflect the light beam emitted by the emission module and comprising the first elementary modulated light beam F11a towards the reception module 3, which thus receives a light beam F2.

[0112] This reception module 3 comprises a plurality of elementary acquisition modules 32 i,j Each elementary acquisition module 32 i,jincludes several 32a photodetectors k, l each capable of converting a light signal it receives into an electrical signal. k,l Each elementary acquisition module 32 i,j It also includes a demodulation unit 34, comprising a comparator, to the input of which all the outputs of the photodetectors 32a k, l are connected in parallel. The comparator thus receives an elementary detection signal Sde i,j formed from the sum of the electrical signals Sel k,l derived from these 32a photodetectors k,l The comparator is arranged to compare this elementary detection signal Sde i,j at a given threshold value, the comparison yields a high value, or a "1" when the elementary detection signal Sde i,j is greater than the threshold value, and a low value, or a "0", when the elementary detection signal Sde i,jis less than the threshold value. The demodulation unit 34 is thus arranged to generate a demodulated binary sequence Seq_d i,j , which it transmits to a computing unit 42 of the control system 4.

[0113] In the example described, the 32a photodetectors k, l These two components 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.

[0114] Note that a bandpass optical filter is placed in front of the 32a photodetectorsk,l said optical filter being capable of transmitting a range of wavelengths and being arranged so that the width of said range is substantially less than 15 nm and said filter has a transmission peak at a wavelength corresponding to the first peak of the spectrum of the first elementary light beam F11a.

[0115] Each electrical signal Salt k,l translates the activation and deactivation sequences of photodiode 32a k, l under the effect of photons that have struck this photodiode. An incident photon can indeed trigger an avalanche effect leading to the generation of an electrical signal. k,lfor an elementary period of one or a few nanoseconds, during which the photodiode is inoperative. Then, the photodiode again becomes inactive, waiting for a new incident photon; no electrical signal is generated by the photodiode in this state. The elementary detection signal Sde i,j resulting from the sum of these electrical signals Sel k,l This translates into an estimate of the number of photons that 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.

[0116] 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".

[0117] In the example described, the receiving module 3 is arranged in the headlight of the motor vehicle, next to the transmitting module 2.

[0118] The processing unit 42 is capable of receiving demodulated binary sequences Seq_d i,j , generated by the elementary acquisition modules 32 i,j and to detect in each demodulated binary sequence Seq_d i,j The presence of the modulating data sequence Seq_m. The demodulation units 34 thus reduce the amount of data that must be handled by the processing unit, thereby compressing the elementary detection signals Sde i,j .

[0119] For these purposes, the computing unit 42 is thus arranged to estimate values ​​of a correlation function Fcorr i,j between each demodulated binary sequence Seq_d i,j , and said modulating data sequence Seq_m, and to detect in this demodulated binary sequence Seq_d i,j, the presence of the modulating data sequence Seq_m from these values ​​of the correlation function Fcorr i,j . In case of detection, it can then determine a time of flight τ separating the emission of said first light beam emitted F11 from the reception of said light beam received F2.

[0120] 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 the one that represents a telemetry process implemented by the light system 1.

[0121] In a first step E1, the generator 41 periodically generates a modulating data sequence Seq_m, for example of Kasami code type, composed of "0" and "1", pseudo-random and of maximum size, exhibiting in nominal operating conditions a duty cycle of 50%.

[0122] Generator 41 transmits the modulating data sequence Seq_m to the modulation unit 221a of the emission module 2 for the emission of the first modulated elementary light beam F11a by the first elementary light source 211a.

[0123] Simultaneously, the control unit C determines, based on an instruction to emit a photometric function that it receives and with regard to the duty cycle of the modulating data sequence Seq_m, the duty cycles τ1b and τ1c of the pulse-width modulated signals allowing the other elementary light sources 211b and 211c of the first light module 21 to selectively emit the elementary light beams F11b and F11c for their combination with the elementary light beam F11a to form a first light beam F11 conforming to the requirements of the desired photometric function, in particular in terms of color.

[0124] Similarly, the control unit C determines the duty cycle(s) τ2a of the pulse-width modulated signals, allowing the elementary light sources 212a of the second light module 22 to selectively emit the elementary light beam(s) F1 2a pour leur combinaison forme un deuxième faisceau lumineux F12conforme aux exigences de la fonction photométrique souhaitée, notamment en termes de couleur.

[0125] It should be noted that the duty cycles τ1b and τ1c can be predetermined, through prior calibration, to compensate for a colorimetric deviation of the elementary light beam F11a introduced by a variation in the production tolerance of the first elementary light source 211a, and to remain compliant with the colorimetric requirements of the desired photometric function, and / or to adjust the color of the first light beam F11 so that it is substantially identical to that of the beam F12. The control unit C can thus select, from its computer memory, predetermined duty cycle values ​​associated with the desired photometric function.

[0126] Alternatively or cumulatively, the duty cycles τ1b and τ1c can also be determined dynamically by the control unit C, for example as a function of a measurement of the temperature of the first elementary light source 211a which is likely to induce a variation in the wavelength of the first peak of the spectrum of the first elementary light beam F11a.

[0127] In a second step E2, the modulation unit 221a modulates the first elementary light beam modulated F11a by the first elementary light source 211a using this data sequence Seq_m and a peak light power setpoint P p Thus, the modulation unit 221a converts the data sequence Seq_m into a modulating signal and modulates the initial control signal using this modulating signal.

[0128] It should be noted that, in the example described, each light pulse of the first modulated elementary light beam F11a corresponds to a bit with the value "1" of the modulating sequence Seq_m. The average power of a portion of the first modulated elementary light beam F11a containing the Seq_m sequence is thus defined by the number of bits with the value "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 light power of these pulses P p .

[0129] Simultaneously, each of the control units 221b and 222a controls the power supply provided to the light sources 211b and 211c of the first light module 21 and to the elementary light sources 212a of the second light module 22 with a pulse width modulated signal according to the duty cycles τ1b, τ1c ​​and τ2a determined previously, so that the light beams F11 and F12 are emitted simultaneously to perform the photometric function together.

[0130] The light beams F11 and F12 are thus emitted until they reach an object O, located in the environment of the vehicle, which reflects them towards the receiving module 3.

[0131] 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.

[0132] When sunlight conditions near the vehicle are particularly intense, sunlight is added to the F2 light beam received by the receiver module 3. The F2 light beam received by the receiver module 3 is thus composed of a portion of the reflected light beams F11 and F12, as well as noise, for example, generated by stray light sources such as streetlights, car headlights, or even the sun. The bandpass filter placed upstream of the photodetectors of the receiver module 3 significantly reduces this stray light.

[0133] In a third step E3, each of the 32 elementary acquisition modules i,j thus extracts, using its demodulation unit 34, a demodulated binary sequence Seq_d i,j which it transmits to the calculation unit 42.

[0134] For each demodulated binary sequence Seq_d i,jthat it receives, the computing unit 42 estimates, in a fourth step E4, values ​​of a correlation function Fcorr i,j between the modulating sequence Seq_m and this demodulated binary sequence Seq_d i,j .

[0135] The computing unit 42 thus evaluates, for a plurality of time-shift values, the value of the cross-correlation, using a cyclic convolution product, between each demodulated binary sequence Seq_d i,j and the modulating sequence Seq_m delayed according to each of the time shift values.

[0136] Given the autocorrelation and cross-correlation properties of the modulating sequence, the correlation function Fcorr i,j will thus be maximum for a time offset 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 32 i,jof the receiving module 3, the modulating sequence Seq_m delayed by this value thus corresponds approximately to the demodulated binary sequence Seq_d i,j almost to the point of noise.

[0137] In a fifth step E5, the computing unit 42 identifies the maximum value Fcorr_max of each correlation function Fcorr i,j associated with each elementary acquisition module 32 i,j and compares it to a threshold value Vs.

[0138] If this maximum value Fcorr_max is greater than the threshold value Vs, the modulating sequence Seq_m is considered to have been detected by the processing unit 42 in the demodulated binary sequence Seq_d i,j from the elementary acquisition module 32 i,j associated with this correlation function Fcorr i,j An object O is therefore detected within the angular range, or pixel, monitored by this elementary acquisition module 32 i,jand the computing unit 42 can then estimate, in a sixth step E6, the value τ of the time of flight of the light beam F11 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.

[0139] A chromaticity diagram of type CIE 1931 2° Standard Observer (x,y) has been represented in order to represent the colours of the first light beam F11 that can be obtained using the elementary light sources 211a, 211b and 211c of the first light module 21. The colours are located on this diagram by their abscissa x and ordinate y on axes of the diagram, these coordinates corresponding to normalised chromatic coordinates.

[0140] A spectral curve of monochromatic colors—that is, pure colors corresponding to specific wavelengths of the spectrum between 420 nm and 680 nm—was also plotted on this diagram. Furthermore, color areas Tu, Ye, Am, Re, and W, corresponding respectively to turquoise, yellow, amber, red, and white, were also identified on this graph.

[0141] The colors of the elementary beams F11a, F11b, and F11c that can be emitted by the elementary light sources 211a, 211b, and 211c have been identified on this diagram. Given the spectra of these beams, the points representing them are positioned as close as possible to the spectral curve.

[0142] The three elementary light sources 211a, 211b and 211c thus define a triangle on the chromaticity diagram, within which the color of the first light beam F11 can be controlled by the control unit C by driving the contributions of each of the elementary light beams F11a, F11b and F11c to this first light beam F11.

[0143] In particular, the contribution of the first elementary light beam F11a can be modulated by varying the duty cycle of the modulating data sequence Seq_m or the peak power Pp, while the contributions of the other elementary light beams F11b and F11c can be modulated by varying the duty cycle τ1b, τ1c ​​of the pulse-width modulated signal driving the elementary light sources 211b and 211c.

[0144] It should be noted that the first light beam F11 can participate in the following functions: Autonomous driving indicator, or "ADS marker," in cyan or turquoise, by activating only or primarily the first elementary light beam F11a. The second elementary light beam F11b and / or the third elementary light beam F11c can be activated to shift the color of the F11 beam within the Tu zone, notably to compensate for BIN or temperature tolerances; Direction indicator, or "TI," in amber or orange, by activating only or primarily the second elementary light beam F11b. The first elementary light beam F11a can be activated to maintain the active telemetry function, while reducing the peak power P PTo remain within the Am zone; Rear position light, or "RL", red in color, by activating only or primarily the third elementary light beam F11c. The first elementary light beam F11a may be activated to maintain the active telemetry function, while reducing the peak power P P in order to remain within the Am zone; Daytime running light, or "DRL" or position light, or "PL", by simultaneously activating the first, second and third elementary light beams F11a, F11b and F11c so that the color of the beam F11 is located within the W zone. It should be noted that the contributions of the elementary light beams can be modulated to modify the temperature of the white thus formed and obtain a color identical to that of the beam F12 formed by the elementary light source 212a of the second light module 22, which has also been shown on the diagram.

[0145] In variants not shown, single-chip LED light sources may be used. Finally, the first light module 21 and the second light module 22 could each incorporate other light sources than those described, and in particular "RGB" LEDs or white or green LEDs, in order to provide other color combinations and to consider other photometric functions than those described.

[0146] 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 rangefinding function, and in which colorimetry remains controlled with respect to the requirements of this photometric function, without degrading the price or the performance of the rangefinding function. These objectives are achieved in particular through a combination of a source capable of emitting a cyan beam, enabling it to perform both the rangefinding and photometric functions, and another source capable of emitting a red or amber beam, allowing it to compensate for color variations in the first source that might be caused by production tolerances or temperature variations.

[0147] 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 provided, including 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 may also be provided for the implementation of other photometric functions than that described, including dipped beam lighting functions or signaling functions such as position lights or direction indicators.

Claims

Lighting system (1) of a motor vehicle, comprising an emission module (2) comprising a light module (21) comprising a first elementary light source (211a) capable of emitting a first elementary light beam (F11a) whose spectrum has a first peak between 485 nm and 505 nm and a second elementary light source (211b) capable of emitting a second elementary light beam (F11b) whose spectrum has a second peak between 585 nm and 680 nm, and an optical device (231) arranged to receive the first and second elementary light beams (F11a, F11b) and comprising a common output face of said elementary light beams;characterized in that it comprises a control unit (C) arranged to control the first and second elementary light sources (211a, 211b) for the simultaneous emission of the first and second elementary light beams for the realization of a given photometric function, the control unit comprising a modulation unit (221a) of the first elementary light source, the modulation unit being capable of receiving a data sequence (Seq_m), called modulating, and arranged to modulate the first elementary light beam emitted by this first elementary light source from the received data sequence. Light system (1) according to the preceding claim, characterized in that the first elementary light source (211a) comprises a semiconductor light generator capable of directly emitting said first elementary light beam (F11a). Light system (1) according to any one of the preceding claims, characterized in that the first and second elementary light sources (211a, 211b) are encapsulated in the same structure to form a single light source capable of selectively emitting one and / or the other of the first and second elementary light beams F11a, F11b), the intensity of each of said elementary light beams being controllable. Light system (1) according to any one of the preceding claims, characterized in that the control unit comprises a unit (221b) for controlling the power supply of the second elementary light source (211b), the control unit (C) being arranged to control said control unit with a pulse width modulated signal with a frequency lower than the frequency of the received data sequence (Seq_m). Light system (1) according to any one of the preceding claims, characterized in that the second light source (211b) is capable of emitting a second elementary light beam (F11b) whose spectrum has a second peak between 585 nm and 595 nm, in that the light module (21) comprises a third elementary light source (211c) capable of emitting a third elementary light beam (F11c) whose spectrum has a third peak between 595 nm and 680 nm, the optical device (231) being arranged to receive the first, second and third elementary light beams (F11a, F11b, F11c) and its output face being common to said first, second and third elementary light beams;and in that the control unit (C) is arranged to selectively control the first, second and third elementary light sources (211a, 211b, 211c) for the selective or simultaneous emission of the first, second and third elementary light beams for the selective realization of several given photometric functions.; Light system (1) according to the preceding claim, characterized in that the control unit (C) comprises a drive unit (221b) for the power supply of the third elementary light source (211c), the control unit being arranged to control said drive unit with a pulse-width modulated signal with a duty cycle (τ1c) such that the light beam (F11) formed by the addition of the first, second and third elementary light beams (F11a, F11b, F11c) and originating from the output face of the optical device (231) has a color whose abscissa on a chromaticity diagram is between 0.31 and 0.5 and whose ordinate is between 0.283 and 0.

440. A lighting system (1) according to any one of the preceding claims, characterized in that the emission module (2) comprises another light module (22) capable of emitting another light beam (F12) for the realization of said given photometric function; characterized in that the control unit (C) is arranged to control the first and second elementary light sources (211a, 211b) for the simultaneous emission of the first and second light beams (F11a, F11b) with the other light beam for the realization of said given photometric function, the control unit being arranged to control the first and second elementary light sources so that the light beam (F11) formed by the addition of the first and second elementary light beams has a color substantially identical to that of the other light beam. A lighting system (1) according to any one of the preceding claims, characterized in that it comprises: a receiving module (3) capable of receiving a light beam (F2), in which the receiving module comprises at least one elementary acquisition module (32 i,j ) including a photodetector (32a k,l ) capable of converting a light signal it receives into an electrical signal (Sel k,l ), said elementary acquisition module (32 i,j ) being capable of generating a demodulated data sequence, (Seq_d i,j) from the electrical signal converted by the photodetector; 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 (221a) for the emission of the elementary light beam (F11a) emitted by said elementary light source (211a); and in that the control system comprises a processing unit (42) capable of receiving a data sequence (Seq_d i,j ) demodulated generated by the elementary acquisition module or modules from a light beam received (F2) by the receiving module, the processing unit (42) being arranged to determine a duration relative to a time of flight (τ) separating the emission of said modulated elementary light beam emitted (F11a) from the reception of said light beam received from said demodulated data sequence (Seq_d i,j ) and said modulating data sequence (Seq_m). Light system (1) according to the preceding claim, characterized in that the receiving module (3) comprises a bandpass optical filter placed in front of the photodetector (32a k,l said optical filter being capable of transmitting a range of wavelengths and being arranged so that the width of said range is substantially less than 15 nm and said filter has a transmission peak at a wavelength corresponding to the first peak. 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.

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