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

Abstract

The invention relates to a lighting system (1) for a motor vehicle, comprising an emission module (2) comprising a light module (21) having a first elementary light source (211a) for emitting a first elementary light beam (F11a) having a first peak between 485 nm and 570 nm and a second elementary light source (211b) for emitting a second elementary light beam (F11b) having a second peak between 400 nm and 485 nm, and an optical device (231) having a common output face for said elementary light beams; characterized in that it comprises a control unit (C) comprising a modulation unit (221a) for one of the elementary light sources (211a), arranged to modulate the elementary light beam (F11a) emitted by this elementary light source based on a modulating data sequence (Seq_m). Figure to be published with the abbreviation: Fig. 1

Description

Title of the invention: Lighting system for 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 light system of a motor vehicle to perform a given photometric function.

[0003] Conventionally, the light source that emits this light beam is controlled by a pulse-width modulated (PWM) electrical signal. The light source is thus periodically switched on and off by this PWM signal, so that the emitted light 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 light beam is a function of the duty cycle of this PWM signal, making it possible to control it by adjusting this duty cycle and thus implement a photometric function.

[0004] Beyond performing one or more photometric functions, such as daytime running lights or low beams, various other functions can be implemented by this type of lighting module. For example, the light source of the lighting module 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 computer unit in the motor vehicle 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, in particular, in terms of colorimetry. Regulations may, for example, require a specific color for the light beam. This is the case, for instance, 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; or 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. Indeed, this type of element has a conversion rate lower than the emission rate of the generator. The modulation of this light emitted directly by the generator can therefore be faster and thus improve 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. While the color cyan is suitable for the photometric function of autonomous driving indicator, this is not the case for other photometric functions.

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

[0011] On the other hand, the color of the light emitted natively by the generator depends on its temperature. When the light source is operating at 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 color 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 of a motor vehicle, capable of performing both a given photometric function and a telemetry function, and therefore the 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 570 nm and a second elementary light source capable of emitting a second elementary light beam whose spectrum has a second peak between 400 nm and 485 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 of one of the first and second elementary light sources, the modulation unit being capable of receiving a data sequence, called modulating, and arranged to modulate the elementary light beam emitted by this 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 one of the elementary light beams emitted by the light module using a data sequence. The resulting 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 modulated elementary light beam is emitted with a peak light power, so the average light power of the emitted modulated elementary light beam is defined by the peak light power and the duty cycle of the modulating data sequence. Since the modulating sequence is generated cyclically, the emitted modulated elementary light beam will periodically contain this sequence while continuously performing the photometric function.A receiving module can thus receive this elementary modulated light beam emitted after reflection on an object in the vehicle's environment, and a computing unit can thus detect, from a data sequence demodulated from this light beam received by the receiving module, the presence of this modulating sequence in this 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 modulated elementary light beam is combined with another elementary light beam to perform, wholly or partially, a photometric function. This other light beam, emitted by the other 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 modulated elementary light beam, for example through the duty cycle of the modulating data sequence, in order to increase it, decrease it or keep it constant, and also control the control device of the power supply provided to the other light source so that the average powers of these elementary light beams are adjusted so that the color of the beam resulting from the combination of the first and second light beams remains in accordance with the requirements of the desired photometric function.

[0018] Since the first peak of the spectrum of the first elementary light beam is between 485 nm and 570 nm, this beam is cyan or green. Furthermore, since the second peak of the spectrum of the second elementary light beam is between 400 nm and 485 nm, this beam is substantially blue. Preferably, the full width at half maximum (FWHM) of the spectrum of the first, or second, light beam may be between 10 and 30 nm if the first, or second, elementary light source natively emits cyan or green, or blue, light, respectively, and may be between 30 and 120 nm otherwise. Therefore, the color of the beam resulting from the combination of these two beams corresponds to the colorimetric center of gravity, in a chromaticity diagram, of these two colors. weighted by the flux of these beams, namely turquoise, which makes it possible to satisfy the colorimetric requirements of the autonomous driving indicator function (ADS marker).

[0019] Under these conditions, it remains possible to use the light emitted natively by one of the elementary light sources to perform the rangefinding function. Adjusting the power of the other elementary light beam makes it possible to compensate for variations in production tolerance related to the color of the modulated elementary beam without having to sort the elementary light sources according to their BIN, or to compensate for color variations due to the temperature sensitivity of the elementary light source, particularly when it is modulated at high frequency. This ensures that the color of the light beam formed by the combination of the two elementary light beams remains controlled.

[0020] 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.

[0021] 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 modulated elementary light beam is formed by a train of light pulses carrying said received modulating data sequence. This modulation unit may, for example, be a high-frequency driver device.

[0022] Advantageously, the modulation unit may be arranged to, upon receiving the modulating data sequence, control said elementary light source based on the received elementary sequence for the emission of the modulated elementary light beam. If necessary, the modulation unit may be arranged to control a power supply provided to this elementary light source, in order to modulate the elementary light beam.

[0023] In one embodiment of the invention, the modulation unit is arranged to modulate said elementary light beam emitted by said elementary light source 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. The duration of each pulse may be between 10 nanoseconds and 200 nanoseconds, preferably between 20 nanoseconds and 100 nanoseconds.

[0024] 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 elementary light beam by said 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. In particular, the modulation unit may be provided to control said elementary light source so that said modulated elementary light beam is emitted only for high values ​​of said received modulating data sequence and so that the modulated elementary light beam is emitted according to a peak light power setpoint.It is thus understood that each pulse of the modulated elementary light beam is emitted with said peak light power and that the average light power of the emitted modulated elementary light beam, 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 one embodiment of the present invention, the control unit may be arranged to control the other of said first and second elementary light sources at low frequency, on the order of kHz, for the emission of the other of the first and second elementary light beams.

[0026] Alternatively, the modulation unit may be arranged to control each of said first and second elementary light sources from an elementary sequence received for the simultaneous emission of each of the first and second elementary light beams, each of these beams being modulated at high frequency.

[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 their distributions so that the light beam resulting from their combination at the common exit face has a photometric distribution that meets the requirements, particularly regulatory requirements, of the desired photometric function.

[0028] Advantageously, the optical device may be arranged to mix the elementary light beams so that the color of the beam resulting from their combination is homogeneous at the common exit face. For example, it may be a light guide, of considerable length relative to its cross-sectional dimensions. The cross-section of the light guide may have a faceted shape, such as an octagon or a hexagon, with the facets being either flat or concave. Alternatively, the optical device may 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 having one or more openings to receive the elementary light beams and an opening forming the common exit face, the walls of the housing being diffusing.

[0029] In one embodiment of the invention, the elementary light source capable of emitting the elementary light beam intended to be modulated by the modulation unit comprises a semiconductor light generator capable of directly emitting said elementary light beam. In this embodiment of the invention, the 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 make it possible to improve the accuracy of the telemetry function, the time-of-flight evaluation resolution being particularly high due to the speed at which the photons are emitted by the generator.

[0030] Advantageously, said light source capable of emitting the elementary light beam intended to be modulated by the modulation unit may be the first elementary light source. If so, said first light source may be capable of emitting a first elementary light beam whose spectrum has a first peak between 485 nm and 505 nm, said first elementary light beam being cyan. Alternatively, said first light source may be capable of emitting a first elementary light beam whose spectrum has a first peak between 505 nm and 570 nm, said first elementary light beam being green.

[0031] The semiconductor may, for example, be an alloy of gallium-indium nitride, or InGaN, capable of emitting, by electroluminescence and in response to an electric current passing through it, rays of cyan or green light.

[0032] Where applicable, the second elementary light source may comprise only a semiconductor light generator capable of directly emitting said second elementary light beam, the semiconductor being, for example, a gallium-indium nitride alloy, or InGaN, capable of emitting, by electroluminescence and, in response to an electric current passing through it, rays of blue light.

[0033] In this example, the first elementary light source is thus dedicated to both the telemetry function and the photometric function, while the second light source is dedicated only to the photometric function when combined with the first light source.

[0034] Alternatively, the light source capable of emitting the elementary light beam intended to be modulated by the modulation unit may be the second elementary light source, this second elementary light source comprising only a semiconductor light generator capable of directly emitting said second elementary light beam. In this example, the second elementary light source is thus dedicated to both the rangefinding and photometric functions, whereas the first light source is dedicated only to the photometric function when combined with the second light source.

[0035] Where applicable, the first elementary light source may comprise a semiconductor light generator and a photoluminescent element capable of converting light emitted by the light generator to obtain the first elementary light beam. This configuration makes it possible to obtain a thermally stable elementary light source.

[0036] The photoluminescent element may, for example, be in the form of a resin comprising europium-doped barium lithium borate or europium-doped lithium strontium borate, or even cerium- or europium-doped calcium lutetium hafnium aluminum garnet, or even a quantum dot or a perovskite, capable of absorbing blue light and, by photoluminescence and in response to the excitation produced by this light, of emitting cyan or green light rays. The photoluminescent element is arranged on the generator so that a portion of the blue light rays excites this element so that it emits cyan or green light rays by photoluminescence. The other portion of the blue light rays passes through this element.Thus, when electrically powered, the light source simultaneously emits rays of blue and cyan or green light in proportions such that the resulting light appears cyan or turquoise 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 light source, and in particular the peak wavelength of this spectrum.

[0037] 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").

[0038] 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, thereby facilitating assembly, electrical connection, thermal control of the elementary light sources, and mixing of the colors of the lights emitted by these chips.

[0039] The substrate on which the elementary light sources are mounted may be an electronic circuit, in particular an integrated circuit, comprising a functionally adapted switch assembly to power and / or control each of the elementary light sources. Additional layers may be added to the encapsulation resin, such as protective, adhesive, sealing, or aesthetically pleasing layers.

[0040] 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, such as a common printed circuit board.

[0041] In one embodiment of the invention, the control unit comprises a power supply control unit for the other of the first and second elementary light sources, 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.

[0042] 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.

[0043] Preferably, the control unit may 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.

[0044] In one embodiment of the invention, the control unit is arranged to control said driving unit with a pulse-width modulated signal with a duty cycle such that the light beam formed by the addition of the first and second elementary light beams and originating from the output face of the optical device has a color whose abscissa on a chromaticity diagram is between 0.04 and 0.2 and whose ordinate is between 0.32 and 0.495. The color may, for example, be contained within a region defined by the following vertices: (0.012; 0.495); (0.2; 0.4); (0.2; 0.32) and (0.04; 0.32).

[0045] These coordinate ranges correspond to the different variations of the turquoise color as permitted for the implementation of an autonomous driving indicator or "ADS marker" function. According to this example, it is thus possible to calibrate, during the production of the lighting system and according to the BIN of said elementary light source capable of emitting the elementary light beam intended to be modulated by the modulation unit, a setpoint for the pulse-width modulated signal enabling the control of the other elementary light source so that the color of the light beam formed by the addition of the first and second elementary light beams conforms to the requirements of this autonomous driving indicator function.

[0046] In the present invention, the term "chromaticity diagram" means 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.

[0047] In one embodiment, the lighting system includes a temperature sensor of said elementary light source capable of emitting the elementary light beam intended to be modulated by the modulation unit, 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.

[0048] In this example, the control unit makes it possible to dynamically compensate for the color variations of the modulated elementary light beam induced by temperature variations of the 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.

[0049] It may be provided that the temperature sensor is capable of directly measuring the temperature of said elementary light source, or of measuring the temperature in the vicinity of said elementary light source, or of indirectly measuring the temperature of said elementary light source, for example through a measurement of the forward voltage of this source.

[0050] In one embodiment of the invention, the light module comprises a third elementary light source capable of emitting a third elementary light beam whose spectrum has a third peak between 585 nm and 680 nm, the optical device being arranged to receive the first, second, and third elementary light beams and its output face being 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 for the selective performance of several given photometric functions.

[0051] This third elementary light source is positioned opposite the first and second elementary light sources on the chromaticity diagram. 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 light 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 still possible to obtain other colours from this light beam in order to perform other photometric functions; and in particular a white beam, the temperature of which 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.

[0052] Advantageously, said third elementary light source may be capable of emitting a third elementary light beam whose spectrum has a third peak between 585 nm and 595 nm, said third elementary light beam being amber or orange in color. Alternatively, said third elementary light source may be capable of emitting a third elementary light beam whose spectrum has a third peak between 595 nm and 680 nm, said third elementary light beam being red in color.

[0053] Preferably, the third elementary light source may comprise a semiconductor light generator and a photoluminescent element capable of converting light emitted by the light generator to obtain said third elementary light beam.

[0054] The photoluminescent element may, for example, be in the form of a resin comprising a cerium-doped yttrium aluminum garnet, or CE:YAG, capable of absorbing blue light and, by photoluminescence and in response to the excitation produced by this light, of emitting yellow light rays. The photoluminescent element is arranged on the generator so that a portion of the blue light rays excites this element, causing it to emit yellow light rays by photoluminescence. The remaining portion of the blue light rays passes through this element. Thus, when electrically powered, the light source simultaneously emits blue and yellow light rays in proportions such that the light thus formed appears amber or orange to the human eye.

[0055] Where appropriate, the third elementary light source may 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.

[0056] In one embodiment of the invention, the emission module comprises another light module capable of emitting another light beam for performing said given photometric function. Where applicable, 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.

[0057] In this embodiment, the other light module is dedicated solely to performing the photometric function, and the control unit drives the sources elementary light beams are adjusted so that the color of the light beam resulting from the addition of the first and second elementary light beams matches that of the beam emitted by this other light module. This ensures that the implementation of the telemetry function does not generate colorimetric heterogeneity in the different light beams participating in the implementation of the photometric function.

[0058] It may be advantageous to provide that the control unit is common to the different light modules of the emission module.

[0059] According to an example of an embodiment of the invention, it may be foreseen that: a. The first light module comprises: i. A first elementary light source capable of emitting a first elementary cyan light beam, this elementary light beam being intended to be modulated by the modulation unit to perform the telemetry function; ii. A second elementary light source capable of emitting a second elementary light beam of blue color; iii. A third elementary light source capable of emitting a second elementary light beam of amber colour; b. The second light module comprises: i. A first elementary light source capable of emitting a first elementary light beam of turquoise color; ii. A second elementary light source capable of emitting a second elementary light beam of amber colour.

[0060] 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.

[0061] Furthermore, the first light module is capable of participating in the autonomous driving indicator function by simultaneously activating the first and second elementary light sources, the direction indicator function by simultaneously activating the first and third elementary light sources, and the daytime running light and / or position light function by simultaneously activating all three elementary light sources. 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 light source elementary remains activated in all cases, which ensures the continuity of the telemetry function regardless of the photometric function performed.

[0062] 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.

[0063] 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 respectively elementary beams of red, green and blue light.

[0064] In one embodiment of the invention, the lighting system comprises: a. 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 that it receives into an electrical signal, said elementary acquisition module being capable of generating a data sequence, said to be demodulated, from the electrical signal converted by the photodetector; b. 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.

[0065] Advantageously, the control system includes 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 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 said demodulated data sequence and said modulating data sequence.

[0066] 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.

[0067] 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.

[0068] Advantageously, the generator is arranged to generate a modulating data sequence of pseudo-random binary type as a function of said duty cycle setpoint.

[0069] A pseudo-random 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. Indeed, its autocorrelation function is at its maximum for a zero time lag, that is, when the sequence is compared to itself, and has a value 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 pseudo-random 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 recurrence sequence whose pattern is a pseudo-random binary sequence.

[0070] Given the autocorrelation properties of pseudo-random binary sequences, the processing unit of the lighting system can estimate the 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 corresponding to the time of flight of the modulated elementary light beam emitted, reflected, and then received, even in the case 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 elementary 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.

[0071] In the invention, the generator can be arranged to generate, according to said duty cycle setpoint, a modulating data sequence of code type Kasami, of the "m-sequence or maximum length sequence" type, of the "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 an elementary light beam modulated by the emission module.

[0072] 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 a length of less than ten micrometers, which makes it possible to obtain a reception field of the elementary acquisition module of a maximum of 0.1° and thus increase the spatial resolution of the receiving module.

[0073] Advantageously, the photodetector(s) of each elementary acquisition module(s) is an avalanche photodiode, in particular a single-photon one. This type of photodetector is also known as a SPAD, from the English "Single-Photon Avalanche Diode". The set 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 incidence of a single photon with a high gain, for example on the order of 10⁶, and therefore to compensate for the degradation of the signal-to-noise ratio due to external conditions.

[0074] According to one embodiment of the invention, the receiving module may include an optical unit arranged in front of the elementary acquisition modules.

[0075] 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 or photodetectors 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, said demodulated, from said comparison.

[0076] In a particular embodiment, the outputs of the photodetectors of each elementary acquisition module are connected in parallel to a comparator arranged 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 that comparison. The comparator thus forms a demodulation unit for the received light beam. by the receiving module, capable of extracting a demodulated data sequence from the electrical signals converted by the photodetectors. Alternatively, the comparator could be replaced by active circuits.

[0077] 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.

[0078] 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 received light beam from the values ​​of the correlation function.

[0079] Each value of the correlation function estimated by the computing unit is associated with a time lag value of the modulating data sequence, or of the demodulated data sequence, used to estimate this 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.

[0080] It is thus possible to 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.

[0081] 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 said modulating data sequence is present in said demodulated data sequence only if said peak value is greater than the predetermined threshold value.

[0082] In one embodiment of the invention, the receiving module comprises a bandpass optical filter positioned in front of the photodetector, said optical filter being capable of transmitting a wavelength range and being arranged such that the width, particularly at half maximum (HMM), 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. Alternatively, said filter has a transmission peak at a wavelength between the first and second peaks.

[0083] 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.

[0084] 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.

[0085] Of course, the different features, variants and embodiments of the invention can be combined with each other in various ways insofar as they are not incompatible or mutually exclusive.

[0086] In addition, 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:

[0087] [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;

[0088] [Fig.2] schematically and partially represents an example of the operation of the system in [Fig.1] during the implementation of a telemetry method; and

[0089] [Fig.3] represents, schematically and partially, a chromaticity diagram of type CIE 1931 2° Standard Observer on which the elementary light sources of the light system of [Fig.1] have been placed according to an embodiment of the invention.

[0090] It should be noted that in these figures the structural and / or functional elements common to the different variants may have the same references.

[0091] Of course, various other modifications can be made to the invention within the scope of the annexed claims.

[0092] With reference to [Fig. 1], 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. [Fig. 3] represents a detailed view of the electronic architecture of the system 1.

[0093] The first emission module 2 is for example arranged in a headlight of the motor vehicle.

[0094] The emission module 2 comprises a first light module 2i capable of emitting a first light beam Flb

[0095] The light module 2i comprises a plurality of elementary light sources, including a first elementary light source 21 ia, a second elementary light source 21ib and a third elementary light source 21 iC.

[0096] According to the invention, the first elementary light source 21 ia is capable of emitting a first elementary light beam Flia 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 21 ib is capable of emitting a second elementary light beam Flib of blue color, the spectrum of which has a second peak between 400 nm and 485 nm and a FWHM between 10 and 30 nm. The third elementary light source 21 iC is capable of emitting a third elementary light beam FliC of orange or amber color, the spectrum of which has a third peak between 585 nm and 595 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.

[0097] It may be foreseen, without departing from the scope of the present invention, that the light module 2i comprises several identical elementary light sources, for example mounted in series one after the other.

[0098] It may also be provided that the first elementary light source 21 ia is capable of emitting a first elementary light beam F^a of green color, the spectrum of which has a first peak between 505 nm and 570 nm. It may also be provided that the third elementary light source 21 ic is capable of emitting a third elementary light beam FliC of red color, the spectrum of which has a third peak between 595 nm and 680 nm.

[0099] In the example of [Fig. 1], each of the first and second elementary light sources 21 ia and 21 ib comprises a semiconductor light generator, for example, a gallium-indium nitride alloy, capable of directly emitting, by electroluminescence, the first elementary light beam F^a of cyan color, and respectively the second elementary light beam Flib of blue color. The third elementary light source 21iC 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 sum of the unabsorbed blue light and the yellow light forming said third elementary light beam FliC of amber or orange color.

[0100] In the example of [Fig.1], the elementary light sources 21ia, 21ib 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 Flia, Flib and Flic, the intensity of each of said elementary light beams being controllable.

[0101] The emission module 2 includes a control unit C arranged to control the elementary light sources 21 ia , 21 ib and 21 iC for the selective emission of the elementary light beams Fha , Flib and Flic.

[0102] In addition, the light module 2i includes an optical device 23i arranged to receive the first, second and third elementary light beams F^a , Flib and Flic and having an output face common to said first, second and third elementary light beams F11 a , Flib and FliC.

[0103] In the example described, the optical device 23i is a faceted light guide, long relative to its cross-sectional dimensions, which mixes the elementary light beams F^a, Flib, and FliC so that the color of the beam resulting from their combination is homogeneous at the common exit face. Other embodiments of the optical device 23b, and in particular a diffuser, may be provided without departing from the scope of the present invention.

[0104] It is thus understood that the control unit C allows the first, second and third elementary light sources 21 ia , 21 ib and 21 ic to be selectively controlled for the selective or simultaneous emission of the first, second and third elementary light beams F^a , Flib and FliC so that the elementary light beams actually emitted form a first light beam Fli at the common output face of the optical device 23b the emission parameters of the elementary light beams F^a , Flib and FliC determining in particular the color of this first light beam Fli which participates in the realization of a given photometric function, the emission instruction of which is provided upstream to the control unit C.

[0105] The emission module 2 includes a second light module 22 capable of emitting a second light beam Fl2 to participate in the realization of the same photometric function.

[0106] In the example of [Fig.1], the second light module 22 comprises one or more elementary light sources 212a and an optical device 232, to emit one or more elementary light beams Fl2a of white, orange, amber, red, green or blue color (depending on the nature of the sources 212a), these elementary light beams together forming a second light beam Fl2 participating with the first light beam Fli in the same photometric function. The control unit C also allows control of this or these elementary light sources 212a.

[0107] In addition to this photometric function, the system 1 can perform a telemetry function, namely a function of detecting and evaluating the position of an obstacle on the road.

[0108] The control unit C includes a modulation unit 22ia 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 Flia emitted from said modulating sequence Seq_m.

[0109] For these purposes, the modulation unit 22ia is arranged to modulate the first elementary light beam F^a emitted by the first elementary light source 211 a, from the modulating data sequence Seq_m that it receives, for example by controlling the electrical supply provided to this first elementary light source 21 ia.

[0110] The modulation unit 22ia 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 21ia. Conventionally, the duty cycle of this control signal, set by the modulation unit 22ia, controls the average electrical power supplied to the first elementary light source 21ia, and thus controls the luminous intensity of the first elementary light beam F^a.

[0111] In the described example, the modulation unit 22ia 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).

[0112] The first elementary light beam Flia emitted by the first elementary light source 2ha is composed of a train of successive light pulses with a sufficiently high frequency, for example greater than 30 MHz, in particular 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 The impulse with respect to the period allows the first elementary light beam Flia to carry the data sequence Seq_m.

[0113] It will be noted that the control unit C includes units 22ib and 222a for controlling the power supply of the other elementary light sources 21ib and 21i c of the first light module 2i and of the elementary light sources 212a of the second light module 22. Each control unit 22ib 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.

[0114] In other words, in the described embodiment, the first elementary light source 21 ia is thus dedicated to both the telemetry function and the photometric function, while the other elementary light sources 21 ib and 21 ic of the first light module 2i 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 Fli and Fl2 being emitted simultaneously.

[0115] In examples not described, it may be possible to replace the control units 22ib and 222a by a single control unit for all the light sources of the first light module 2i and the second light module 22 dedicated only to the photometric function or by 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 2i and the second light module 22 dedicated only to the photometric function.

[0116] If an object is present in the environment of the motor vehicle, it can reflect the light beam comprising the first modulated elementary light beam Fli a towards the receiving module 3, which thus receives a light beam F2.

[0117] This receiving module 3 comprises a plurality of elementary acquisition modules 3¾. Each elementary acquisition module 3¾ includes several photodetectors 32ak>i, each capable of converting a light signal it receives into an electrical signal Selk>i. Each elementary acquisition module 32ij also includes a demodulation unit 34, comprising a comparator, to the input of which all the outputs of the photodetectors 32ak>i are connected in parallel. The comparator thus receives an elementary detection signal Sde^ formed from the sum of the electrical signals Selk>i from these photodetectors 32ak>i. The comparator is arranged to compare this elementary detection signal Sdc, , to a given threshold value, the comparison yielding a high value, or a "1" when the detection signal The elementary detection signal Sde^ is greater than the threshold value, and a low value, or a "0", when the elementary detection signal Sde^ is less than the threshold value. The demodulation unit 34 is thus arranged to generate a demodulated binary sequence Seq_dij, which it transmits to a computing unit 42 of the control system 4.

[0118] In the example described, the photodetectors 32ak> ; are identical and each consists of a single-photon avalanche photodiode, or SPAD, these photodiodes and the demodulation unit 34 being integrated into a silicon photomultiplier, or 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.

[0119] It will be noted that a bandpass type optical filter is placed in front of the 32akJ photodetectors, said optical filter being capable of transmitting a wavelength range and being arranged so that the width 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 of the spectrum of the first elementary light beam Flia.

[0120] Each electrical signal Selkj; represents the activation and deactivation sequences of the photodiode 32ak; 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 Selkj for an elementary period of one or a few nanoseconds, during which the photodiode is inoperative. Then, the photodiode again becomes inactive, awaiting a new incident photon, with no electrical signal being generated by this photodiode in this state. The elementary detection signal Sde^ resulting from the sum of these electrical signals Selk4 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

[0121] Alternatively, the comparator of the demodulation unit 34 may be replaced by active circuits, the demodulated data sequence in this case being directly a digital sequence made up of "1" and "0".

[0122] In the example described, the receiving module 3 is arranged in the headlight of the motor vehicle, next to the transmitting module 2.

[0123] The computing unit 42 is capable of receiving the demodulated binary sequences Seq_d;j, generated by the elementary acquisition modules 3¾ and of detecting in each The demodulated binary sequence Seq_d;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 has to be handled by the computing unit, therefore operating a compression of the elementary detection signals Sde^.

[0124] To this end, the computing unit 42 is thus arranged to estimate values ​​of a correlation function Fcorr, between each demodulated binary sequence Seq_dij and said modulating data sequence Seq_m, and to detect in this demodulated binary sequence Seq_dij, the presence of the modulating data sequence Seq_m from these values ​​of the correlation function Fcorr,. In the event of detection, it can then determine a time of flight r separating the emission of said first emitted light beam Flide from the reception of said received light beam F2.

[0125] 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.2] which represents a telemetry process implemented by the light system 1.

[0126] In a first step El, 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 under nominal operating conditions a duty cycle of 50%.

[0127] The generator 41 transmits the modulating data sequence Seq_m to the modulation unit 22ia of the emission module 2 for the emission of the first modulated elementary light beam Flia by the first elementary light source 21 ia.

[0128] Simultaneously, the control unit C determines, according to an instruction to emit a photometric function which it receives and with regard to the duty cycle of the modulating data sequence Seq_m, the duty cycles Ti b and Tic of the pulse width modulated signals allowing the other elementary light sources 21 ib and 21 iC of the first light module 2i to selectively emit the elementary light beams Flib and Flic for their combination with the elementary light beam F^a forms a first light beam Fli conforming to the requirements of the desired photometric function, in particular in terms of color.

[0129] Similarly, the control unit C determines the duty cycle(s) r2a of the pulse width modulated signals enabling the elementary light sources 212a of the second light module 22 to selectively emit the elementary light beam(s) Fl2a for their combination to form a second light beam Fl2 conforming to the requirements of the desired photometric function, in particular in terms of color.

[0130] It should be noted that the duty cycles Tib and Tic can be predetermined, by prior calibration, to compensate for a colorimetric deviation of the elementary light beam Flia introduced by a variation in the production tolerance of the first elementary light source 21 ia and remain compliant with the colorimetric requirements of the desired photometric function and / or to adjust the color of the first light beam Flipour so that it is substantially identical to that of the beam Fl2. The control unit C can thus select, from a computer memory it possesses, predetermined duty cycle values ​​associated with the desired photometric function.

[0131] Alternatively or cumulatively, the duty cycles Tib and Tic 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 21 ia capable of inducing a variation in the wavelength of the first peak of the spectrum of the first elementary light beam Flia.

[0132] In a second step E2, the modulation unit 22ia modulates the first elementary light beam modulated by the first elementary light source 21ia using this data sequence Seq_m and a light power setpoint pic Pp. Thus, the modulation unit 22ia converts the data sequence Seq_m into a modulating signal and modulates the initial control signal using this modulating signal.

[0133] It should be noted that, in the example described, each light pulse of the first elementary modulated light beam F^a corresponds to a bit with a value of "1" in the modulating sequence Seq_m. The average power of a portion of the first elementary modulated light beam Flia containing the sequence Seq_m is thus defined by the number of bits with a value of "1" in this sequence Seq_m 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 Pp.

[0134] Simultaneously, each of the control units 22ib and 222a controls the power supply provided to the light sources 21ib and 21iC of the first light module 2i and to the elementary light sources 212a of the second light module 22 with a pulse-width modulated signal according to the duty cycles Tib, Tic and r2a determined previously, so that the light beams Fli and Fl2 are emitted simultaneously to perform the photometric function together.

[0135] The light beams Fli and Fl2 are thus emitted until they reach an object O, located in the environment of the vehicle, which reflects them towards the receiving module 3.

[0136] 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.

[0137] When sunlight conditions near the vehicle are particularly strong, sunlight is added to the light beam F2 received by the receiver module 3. The light beam F2 received by the receiver module 3 is thus composed of a portion of the light beams F1 and Fl2 reflected by the object O and 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.

[0138] In a third step E3, each of the elementary acquisition modules 3¾ thus extracts, using its demodulation unit 34, a demodulated binary sequence Seq_dij which it transmits to the calculation unit 42.

[0139] For each demodulated binary sequence Seq_dij that it receives, the computing unit 42 estimates, in a fourth step E4, values ​​of a correlation function Fcorr, , between the modulating sequence Seq_m and this demodulated binary sequence Seq_dij.

[0140] The computing unit 42 thus evaluates, for a plurality of time-shift values, the value of the cross correlation, by means of a cyclic convolution product, between each demodulated binary sequence Seq_dij and the modulating sequence Seq_m delayed according to each of the time-shift values.

[0141] Given the autocorrelation and cross-correlation properties of the modulating sequence, the correlation function Fcorr; j will thus be maximum for a time-shift value corresponding to the time of flight of the light beam Eli, separating the instant when it is emitted by the emitting module 2 and the instant when it is received by an elementary acquisition module 3¾ of the receiving module 3, the modulating sequence Seq_m delayed by this value thus corresponding substantially to the demodulated binary sequence Seq_dij up to noise.

[0142] 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 32;j and compares it to a threshold value Vs.

[0143] In the case where this maximum value Fcorr_max is greater than the threshold value Vs, the modulating sequence Seq_m is considered to be detected by the computing unit 42 in the demodulated binary sequence Seq_dij from the elementary acquisition module 32ij associated with this correlation function Fcorrij. An object O is therefore detected in the angular range, or pixel, monitored by this elementary acquisition module 32ij and the computing unit 42 can then estimate, in a sixth step E6, the value r of the time of flight of the light beam Flientre the object O and the vehicle, associated with this maximum value, as well as the distance d separating the object O from the vehicle.

[0144] A chromaticity diagram of type CIE 1931 2° Standard Observer (x,y) has been represented in [Fig.3] in order to represent the colours of the first light beam Flipouvant be obtained using the elementary light sources 21ia, 21ib and 21ic of the first light module 2b 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.

[0145] A spectral curve of monochromatic colors, that is, pure colors corresponding to specific wavelengths of the spectrum between 420 nm and 680 nm, has also been plotted on this diagram. In addition, color areas Tu, Ye, Am, Re, and W, corresponding respectively to turquoise, yellow, amber, red, and white, have also been identified on this graph.

[0146] The colors of the elementary beams Flia, Flib and FliC likely to be emitted by the elementary light sources 21 ia, 21 ib and 21 ic have been identified on this diagram. Given the spectra of these beams, the points representing these beams are positioned as close as possible to the spectral curve.

[0147] The three elementary light sources 21 ia, 21 ib and 21 iC thus define a triangle on the chromaticity diagram, within which the color of the first light beam Flb can be controlled by the control unit C by controlling the contributions of each of the elementary light beams Fba, Flib and Flic to this first light beam Flb

[0148] More particularly, the contribution of the first elementary light beam Flia 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 Flib and F1,c can be modulated by varying the duty cycle Tib of the pulse-width modulated signal driving the elementary light sources 21 ib and 21 ic.

[0149] It should be noted that the first light beam Fli can, in particular, participate in the performance of the following functions: a. Autonomous driving indicator, or “ADS marker”, in cyan or turquoise colour, by activating only or primarily the first elementary light beam Flia. The second elementary light beam Fli b and / or the third elementary light beam FliC may be activated in order to shift the colour of the Fliau beam within the Tu zone, in particular to compensate for BIN or temperature tolerances; b. Direction indicator, or "TI", in amber or orange, by activating only or primarily the third elementary light beam Fli. c. The first elementary light beam F^a may be activated in order to keep the telemetry function active, while reducing the peak power Pp in order to stay within the Am zone; c. Daytime running light, or "DRL" or position light, or "PL", by simultaneously activating the first, second and third elementary light beams Flia, Flib and Flic so that the color of the Flisoit beam 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 Fl2 beam formed by the elementary light source 212a of the second light module 22, which has also been shown on the diagram.

[0150] In unrepresented variants, the telemetry function could be performed by the second elementary light source 21ib, or even by both elementary light sources 21ia and 21ib. Single-chip LED sources could be used. Finally, the first light module 2i and the second light module 22 could each incorporate light sources other than those described, 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.

[0151] 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 the colorimetry remains controlled with regard to the requirements of this photometric function, without degrading the price or the performance of the rangefinding function. These objectives are achieved in particular by means of a combination of a source capable of emitting a blue beam and a source capable of emitting a cyan beam, one enabling the simultaneous performance of the rangefinding and photometric functions, the other compensating for color variations in the first that might be induced by production tolerances or temperature variations.

[0152] 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, 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. Other photometric functions may also be provided for. described, and in particular dipped beam lighting functions or position light or direction indicator signaling functions.

Claims

Demands

1. Lighting system (1) of a motor vehicle, comprising an emission module (2) comprising a light module (2J) comprising a first elementary light source (21 ia) capable of emitting a first elementary light beam (Flia) whose spectrum has a first peak between 485 nm and 570 nm and a second elementary light source (21 ib) capable of emitting a second elementary light beam (Flib) whose spectrum has a second peak between 400 nm and 485 nm, and an optical device (23i) arranged to receive the first and second elementary light beams 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 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 (22ia) of one of the first and second elementary light sources (21ia), the modulation unit being capable of receiving a data sequence (Seq_m), called modulating, and arranged to modulate the elementary light beam (Flia) emitted by this elementary light source from the received data sequence.;

2. Light system (1) according to the preceding claim, characterized in that the elementary light source (21 ia) capable of emitting the elementary light beam (F^a) intended to be modulated by the modulation unit (221a) comprises a semiconductor light generator capable of directly emitting said elementary light beam (F 11 a).

3. Light system (1) according to any one of the preceding claims, characterized in that the first and second elementary light sources (21 ia, 21 ib) 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 (Fha, Flib), the intensity of each of said elementary light beams being controllable.

4. Lighting system (1) according to any one of the preceding claims, characterized in that the control unit (C) comprises a unit (22i b) for driving the power supply of the other of the first and second elementary light sources (21 ib), the control unit being arranged to control said driving unit with a pulse-width modulated signal with a frequency lower than the frequency of the received data sequence.

5. A lighting system according to the preceding claim, characterized in that the control unit (C) is arranged to control said driver unit (22ib) with a pulse-width modulated signal with a duty cycle (rib) such that the light beam (Fli) formed by the addition of the first and second elementary light beams (Flia, Flib) and originating from the output face of the optical device (23i) has a color whose abscissa on a chromaticity diagram is between 0.04 and 0.2 and whose ordinate is between 0.32 and 0.

495.

6. Light system (1) according to any one of claims 4 or 5, characterized in that it comprises a temperature sensor of said elementary light source (21 ia) capable of emitting the elementary light beam (Flia) intended to be modulated by the modulation unit (22ia), characterized in that the control unit (C) is arranged to control said control unit (22ib) with a pulse-width modulated signal with a duty cycle (rib) determined from the temperature measured by said sensor.

7. A lighting system (1) according to any one of the preceding claims, characterized in that the lighting module (2i) comprises a third elementary light source (21i) capable of emitting a third elementary light beam (Flic) whose spectrum has a third peak between 585 nm and 680 nm, the optical device (23i) being arranged to receive the first, second, and third elementary light beams (F1a, Flib, Flic) 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 (21i, 21i, 21i) for the selective or simultaneous emission of the first, second, and third elementary light sources (21i, 21i, 21i) and third elementary light beams for the selective realization of several given photometric functions.

8. A light 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 (Fl2) 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 (21 ia, 21ib) for the simultaneous emission of the first and second light beams (Flia, Flib) with the other light beam (Fl2) 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 (Fli) formed by the addition of the first and second elementary light beams has a color substantially identical to that of the other light beam.

9. A light system (1) according to any one of the preceding claims, characterized in that it comprises: a. a receiving module (3) capable of receiving a light beam (F2), in which the receiving module comprises at least one elementary acquisition module (32ij) comprising a photodetector (32akj) capable of converting a light signal that it receives into an electrical signal (Selkj), said elementary acquisition module (32ij) being capable of generating a data sequence, said to be demodulated, (Seq_dij) from the electrical signal converted by the photodetector; b.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 (22ia) for the emission of the elementary light beam (F^a) emitted by said elementary light source (21ia); and in that the control system comprises a computing unit (42) capable of receiving a demodulated data sequence (Seq_dij) generated by the or each elementary acquisition module from a light beam received (F2) by the receiving module, the unit. calculation (42) being arranged to determine a duration relative to a time of flight (r) separating the emission of said modulated elementary light beam emitted (Flia) from the reception of said light beam received from said demodulated data sequence (Seq_dij) and said modulating data sequence (Seq_m).

10. A light system (1) according to the preceding claim, characterized in that the receiving module (3) comprises a bandpass optical filter positioned in front of the photodetector (32ak4), said optical filter being capable of transmitting a wavelength range and being arranged such 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

11. 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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