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

Abstract

The invention relates to a lighting system (1) of a motor vehicle, comprising an emission module (2) including: a first lighting module (21) including a first elementary light source (211a) emitting a first elementary light beam (F11a) having a first peak between 400 nm and 505 nm to form a first light beam (F11); a second lighting module (22) emitting a second light beam (F12); characterized in that it includes a control unit (C) of the first and second lighting modules (21, 22), including a modulation unit (221a) for modulating the first elementary light beam emitted by the first elementary light source from a received modulating data sequence (Seq_m); the control unit being arranged to control the first and second lighting modules so that the first beam has a color substantially identical to that of the second beam.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] Conversely, 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 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 increase in the price of the lighting system, which is undesirable.

[0010] 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 time 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 of the light source, but this then necessarily leads to a degradation of the telemetry function, particularly in terms of detection range.

[0011] This variability in the color emitted by the light source, which is dedicated to both a photometric and a telemetry function, is therefore a drawback when the lighting system includes another light module dedicated to the same photometric function. Indeed, the colors of the light beams emitted by the light modules can differ from one another, which poses a problem in terms of homogeneity, the illuminated appearance of the lighting system, and the perception of the photometric function by road users.

[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 first light module comprising a first elementary light source capable of emitting a first elementary light beam whose spectrum has a first peak between 400 nm and 505 nm, the first light module being capable of emitting, from said first elementary light beam, a first light beam for the realization of a given photometric function; and a second light module capable of emitting a second light beam for the realization of said given photometric function.

[0015] The system according to the invention is characterized in that it comprises a control unit arranged to control the first and second light modules for the simultaneous emission of the first and second light beams for the realization of said 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; and in that the control unit is arranged to control the first and second light modules so that the first light beam has a color substantially identical to that of the second light beam.

[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 The first light module is generated using a data sequence. The resulting first elementary light beam could, for example, be a pulsed beam, with 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 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 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 first 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 first modulated elementary light beam forms, alone or in combination with other elementary light beams emitted by the first light module, a first light beam contributing to the realization of a photometric function. The first elementary light source is thus dedicated to both the rangefinding and photometric functions. A second light beam emitted by a second light module distinct from the light system participates only in the realization of this same photometric function, and not in the rangefinding function.

[0018] The control unit can thus control the second light module, for example by modulating the second elementary light beam at low frequency so that the two light beams have the same 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 it, decrease it, or keep it constant, and also control the power supply control device for a light source of the second light module so that the colors of these two light beams are adjusted to be identical and remain in accordance with the requirements of the desired photometric function.

[0019] Since the first peak of the spectrum of the first elementary light beam is between 400 nm and 505 nm, this beam is essentially blue or cyan in color. 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 blue or cyan light, and between 30 and 120 nm otherwise. Therefore, it is possible to modulate the light beam natively emitted by the first elementary light source to increase the accuracy of the rangefinding function.In addition, the color of the first elementary light beam allows for the realization, alone or in combination with other elementary light beams, of different photometric functions, including functions such as autonomous driving indicator (ADS marker), direction indicator (TI) or rear position light (RL), depending on whether the second elementary light beam is amber or red, or daytime running light (DRL) or position light (PL).Adjusting the color of the second light beam, or of one or more elementary light beams emitted by other elementary light sources from the first light module to form the first light beam, makes it possible to compensate for 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, or to compensate for color variations due to the temperature sensitivity of the first elementary light source, particularly when it is modulated at high frequency. This ensures that the color of the first and second 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 first 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 first elementary light source from the elementary sequence received for the emission of the first Modulated elementary light beam. If necessary, the modulation unit can be arranged to control a power supply provided to this first elementary light source, to modulate the first elementary light beam.

[0023] In one embodiment of the invention, the modulation unit is arranged to modulate said first elementary light beam emitted by said first 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 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, in particular, 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 peak light power setpoint. 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.

[0025] It may be advantageous to provide that the control unit is common to the different light modules of the emission module.

[0026] Advantageously, the first light source may be capable of emitting a first elementary light beam whose spectrum has a first peak between 400 nm and 485 nm, said first elementary light beam being blue. Alternatively, 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.

[0027] 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 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.

[0028] 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 blue light, the first peak being, for example, located at 450 nm, or cyan, the first peak being, for example, located at 490 nm.

[0029] In another embodiment, 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.

[0030] 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 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.

[0031] In a non-limiting example of an embodiment, the generator for emitting blue light whose spectrum has a peak at 480 nm and the photoluminescent element will be emit by photoluminescence green light whose spectrum has a peak at 510 nm, the first peak in this case being located at 490 nm.

[0032] In one embodiment of the invention, the first elementary light source is capable of emitting a first elementary light beam whose spectrum has a first peak between 400 nm and 485 nm, and the first light module comprises a second elementary light source capable of emitting a second elementary light beam whose spectrum has a second peak between 485 nm and 570 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. Optionally, the control unit is arranged to control the first and second elementary light sources for the simultaneous emission of the first and second elementary light beams to form the first light beam.

[0033] Advantageously, the control unit can 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.

[0034] In this embodiment, the second elementary light beam, emitted by the second elementary light source, can be modulated at low frequency by the control unit so that the combination of the two elementary beams has a color conforming to the requirements of the photometric function. In particular, the control unit can control the power supply control device for the second elementary light source so that the average powers of these two elementary light beams are adjusted so that the color of the first light beam resulting from the combination of the first and second light beams remains conforming to the requirements of the desired photometric function.

[0035] Since the second peak of the spectrum of the second elementary light beam is between 485 nm and 505 nm, this beam is cyan. The choice of power settings applied to the first and second elementary light sources allows the color of the beam resulting from the combination of the first and second elementary beams to be defined by modulating the colorimetric center of gravity, in a chromaticity diagram, of the colors weighted by the fluxes of these two beams, thus satisfying the colorimetric requirements of the desired photometric function. Furthermore, the control unit can precisely control the color of the first light beam to match the color of the second light beam, particularly when the photometric function is an autonomous driving indicator, or "ADS marker."

[0036] 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.

[0037] 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, long 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.

[0038] Preferably, the second 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 second elementary light beam.

[0039] 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").

[0040] In one embodiment, the first and second elementary light sources are encapsulated in the same 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 by the same encapsulation material. like a transparent or translucent resin. They thus form a compact optical component called a bi-chip light-emitting diode, facilitating assembly, electrical connection, thermal control of elementary light sources and mixing of the colors of the lights emitted by these chips.

[0041] 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. Other layers may also be added to the encapsulation resin, such as protective, adhesive, sealing, or aesthetically pleasing layers.

[0042] 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.

[0043] In one embodiment of the invention, the control unit comprises 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] In this example, the control unit makes it possible to dynamically compensate for the color variations of the first modulated elementary light beam induced by temperature variations of the first modulated elementary light source at high-frequency, so as to keep the color of the light beam formed by the addition of the first and second elementary light beams constant.

[0048] 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.

[0049] In one embodiment of the invention, the first light module comprises an additional light source capable of emitting an additional elementary light beam whose spectrum has a peak between 585 nm and 680 nm, and an optical device arranged to receive the first elementary light beam and the additional elementary light beam, its output face being common to said first elementary light beam and additional elementary light beam. Optionally, the control unit is arranged to selectively control the first elementary light source and the additional elementary light source for the selective or simultaneous emission of the elementary light beam and the additional elementary light beam for the selective performance of several given photometric functions.

[0050] In this example, this additional elementary light source, emitting amber, orange, or red light, is placed on a chromaticity diagram opposite the first elementary light source emitting cyan light. It thus allows for the introduction of color variations along the entire line joining these two sources on this chromaticity diagram and is therefore dedicated solely to the performance of photometric functions.For example, it is possible to obtain other colours for the first light beam in order to perform other photometric functions; and in particular a white colour beam, whose temperature is controllable, to perform daytime running light (or DRL) or position light (or PL) functions, or a red or amber colour beam, depending on the spectrum of the third source, to perform rear light (or RL) or direction indicator (or TI) functions.

[0051] 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 chromatic coordinates. In this diagram, the color resulting from the additive synthesis of several colors can be calculated by taking the center of gravity of these colors weighted by the luminous flux of the beams exhibiting these colors.

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

[0053] Preferably, this additional elementary light source is a third elementary light source capable of emitting a third elementary light beam, the first light module comprising the first elementary light source capable of emitting a first elementary light beam whose spectrum has a first peak between 400 nm and 485 nm and the second elementary light source capable of emitting a second elementary light beam whose spectrum has a second peak between 485 nm and 570 nm.

[0054] In this case, the three elementary light sources define a triangle on the chromaticity diagram, within which the color of the first light beam can be controlled by the control unit by driving the contributions of each of the elementary light beams to this first light beam.

[0055] 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 power supply 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 (0.31; 0.283).

[0056] These coordinate ranges correspond to the different variations and temperatures of the white color as permitted for the realization of a daytime running light, or "DRL" type function or a position light, or "PL" type function.

[0057] Preferably, the additional 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 additional elementary light beam.

[0058] The semiconductor being, for example, a gallium-indium nitride alloy, or InGaN, capable of emitting blue light rays by electroluminescence in response to an electric current passing through it. 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 in response to the excitation produced by this light, of emitting yellow light rays. The photoluminescent element is arranged on the generator such that a portion of the blue light rays excites this element so that it emits yellow 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 blue and yellow light rays in proportions such that the light thus formed appears amber, orange, or red to the human eye.

[0059] Where appropriate, the additional elementary light source may be encapsulated with the first, and where appropriate the second, elementary light source in the same structure to form a single light source capable of selectively emitting one and / or the other of the elementary light beams, the intensity of each of said elementary light beams being controllable.

[0060] In one embodiment of the invention, the second light module comprises a light source capable of emitting the second light beam. If necessary, the control unit comprises a power supply control unit for said light source, the control unit being arranged to control said power supply unit with a pulse-width modulated signal having a frequency lower than the frequency of the received data sequence, the duty cycle of said signal being selected so that the first light beam has a color substantially identical to that of the second light beam.

[0061] 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 amber or orange colour; b. The second light module comprises: i. A first elementary light source capable of emitting a first elementary light beam of cyan or turquoise color; ii. A second elementary light source capable of emitting a second elementary light beam of amber or orange color.

[0062] According to this example, the second light module is thus capable of participating 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.

[0063] 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, 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 homogeneity 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.

[0064] 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.

[0065] 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.

[0066] In one embodiment of the invention, the lighting system comprises: a. a receiving module capable of receiving a light beam, wherein the receiving module comprises at least one elementary acquisition module including a photodetector capable of converting a light signal it receives into an electrical signal, said elementary acquisition module being capable of generate a data sequence, called 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.

[0067] 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 first modulated elementary light beam emitted from the reception of said light beam received from said demodulated data sequence and said modulating data sequence.

[0068] 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.

[0069] 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.

[0070] Advantageously, the generator is arranged to generate a modulating data sequence of pseudo-random binary type as a function of said duty cycle setpoint.

[0071] 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 shift, that is, when the sequence is compared to itself, and has a value substantially lower than this maximum for all other time shifts, 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 substantially lower than the maximum of the autocorrelation functions of these sequences. Finally, this type of sequence is generally generated using a shift register. linear feedback, or LFSR (from the English "Linear Feedback Shift Register"), which produces a periodic recurrent sequence whose pattern is a pseudo-random binary sequence.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] According to one embodiment of the invention, the receiving module may include an optical unit arranged in front of the elementary acquisition modules.

[0077] 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.

[0078] 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 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 may be replaced by active circuits.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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:

[0089] [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;

[0090] [Fig.2] represents, schematically and partially, an example of operation of the system of [Fig.1] during the implementation of a telemetry process;

[0091] [Fig.3] represents, schematically and partially, a chromaticity diagram on which the elementary light sources of the light system of [Fig.1] were placed;

[0092] [Fig.4] represents, schematically and partially, a view of a system luminous of a motor vehicle according to another embodiment of the invention;

[0093] [Fig.5] 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. 4] were placed; and

[0094] [Fig.6] represents, schematically and partially, a chromaticity diagram of type CIE 1931 2° Standard Observer on which the elementary light sources of a lighting system have been placed according to yet another embodiment of the invention.

[0095] It should be noted that in these figures the structural and / or functional elements common to the different variants may have the same references.

[0096] Of course, various other modifications can be made to the invention within the scope of the annexed claims.

[0097] 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.

[0098] The first emission module 2 is for example arranged in a headlight of the motor vehicle.

[0099] The emission module 2 comprises a first light module 2i capable of emitting a first light beam Flb

[0100] 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.

[0101] According to the invention, the first elementary light source 21 ia is capable of emitting a first elementary light beam Fha 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 The spectrum exhibits a second peak between 400 nm and 485 nm, with a full width at half maximum (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, whose spectrum exhibits a third peak between 585 nm and 595 nm, with a FWHM between 30 and 120 nm. It should be noted that these spectra may exhibit other intensity peaks in the visible and / or infrared ranges.

[0102] 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.

[0103] It may also be provided that the first elementary light source 21 ia is capable of emitting a first elementary light beam Fha 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.

[0104] 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.

[0105] In the example of [Fig. 1], the elementary light sources 2ha, 21ib and 211c are encapsulated in the same transparent resin to form a single light source, of the multi-chip electroluminescent diode type, capable of selectively emitting the elementary light beams F^a, Flib and FliC, the intensity of each of said elementary light beams being controllable.

[0106] The emission module 2 comprises a control unit C arranged to control the elementary light sources 21ia, 21ib and 21ic for the selective emission of the elementary light beams F^a, Flib and F^c.

[0107] In addition, the light module 2i comprises an optical device 23i arranged to receive the first, second and third elementary light beams Flia, Flib and FliC and having a common output face for said first, second and third elementary light beams Fha, Flib and Flic.

[0108] 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 Flia, 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 231, and in particular a diffuser, may be provided without departing from the scope of the present invention.

[0109] 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 Fha , Flib and Fhc 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 Fha , Flib and Fhc 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.

[0110] 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.

[0111] In the example of [Fig. 1], 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 Fl2a 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 Fl2, which, along with the first light beam Fl1, performs the same photometric function. The control unit C also allows control of this or these elementary light sources 212a.

[0112] 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.

[0113] 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 system of control 4 and arranged to modulate the first elementary light beam Flia emitted from said modulating sequence Seq_m.

[0114] 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.

[0115] 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 Flia.

[0116] 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).

[0117] 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 pulse with respect to the period allows the first elementary light beam Flia to carry the data sequence Seq_m.

[0118] It should be noted that the control unit C comprises units 22ib and 222a for controlling the power supply of the other elementary light sources 21ib and 21i of the first light module 2i and 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 switched-mode power supply provided to the elementary light sources to which it is associated with a modulated signal. PWM pulse width 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.

[0119] 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 21ib and 21iC 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.

[0120] 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.

[0121] 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 Fha towards the reception module 3, which thus receives a light beam F2.

[0122] This receiving module 3 comprises a plurality of elementary acquisition modules 3¾. Each elementary acquisition module 3¾ includes several photodetectors 32akJ, each capable of converting a light signal it receives into an electrical signal Selkj. 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 32ak4 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 32akJ. 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 elementary detection signal Sde^ is greater than the threshold value, and a low value, or a "0", when the elementary detection signal Sdc, 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.

[0123] In the example described, the photodetectors 32akJ are identical and are each formed by 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 whose spatial reception resolution is on the order of 1°, or even 0.1°, and whose detection capabilities, due to the use of avalanche photodiodes, are particularly important, even in the case of degraded acquisition conditions.

[0124] 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.

[0125] Each Selk>i electrical signal represents the activation and deactivation sequences of the 32akJ photodiode under the influence of photons that have struck it. An incident photon can indeed trigger an avalanche effect, leading to the generation of a Selk4 electrical signal 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 the photodiode in this state. The elementary detection signal Sdc, resulting from the sum of these Selk4 electrical signals, 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 emitting module and then reflected by an obstacle.

[0126] 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".

[0127] In the example described, the receiving module 3 is arranged in the headlight of the motor vehicle, next to the transmitting module 2.

[0128] The processing unit 42 is capable of receiving the demodulated binary sequences Seq_dij, generated by the elementary acquisition modules 3 and 4, and of detecting in each demodulated binary sequence Seq_dij, the presence of the modulating data sequence Seq_m. The demodulation units 34 thus make it possible to reduce the amount of data to be handled by the processing unit, thereby compressing the elementary detection signals Sdc.

[0129] 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 sequence binary demodulated Seq_d;j, the presence of the modulating data sequence Seq_m from these values ​​of the correlation function Fcorr,,. In case of detection, it can then determine a time of flight r separating the emission of said first emitted light beam Fli from the reception of said received light beam F2.

[0130] 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.

[0131] 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%.

[0132] 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.

[0133] 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.

[0134] 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.

[0135] 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 F^a 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 Fli so that it is substantially identical to that of the beam Fl2. The control unit C can thus select, from a computer memory that it possesses predetermined duty cycle values ​​associated with the desired photometric function.

[0136] 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.

[0137] 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 peak light power setpoint 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.

[0138] It should be noted that, in the example described, each light pulse of the first elementary modulated light beam Fha 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 F^a 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.

[0139] Simultaneously, each of the control units 22ib and 222a controls the power supply provided to the light sources 21 xb and 21 iC 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 iqb, and r2a determined previously, so that the light beams Fli and Fl2 are emitted simultaneously to perform the photometric function together.

[0140] The light beams Flx 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.

[0141] 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.

[0142] When sunlight conditions in the vicinity of 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 Fli and Fl2 reflected by the object O and noise, for example generated by stray light sources such as streetlights, car lights, even the sun. The bandpass filter placed upstream of the photodetectors of the receiving module 3 makes it possible to significantly reduce this stray light.

[0143] 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.

[0144] For each demodulated binary sequence Seq_djj that it receives, the computing unit 42 estimates, in a fourth step E4, values ​​of a correlation function Fcorrjj between the modulating sequence Seq_m and this demodulated binary sequence Seq_djj.

[0145] 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_djj and the modulating sequence Seq_m delayed according to each of the time-shift values.

[0146] Given the autocorrelation and cross-correlation properties of the modulating sequence, the correlation function Fcorrjj will thus be maximum for a time shift value corresponding to the time of flight of the light beam Fl, 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_djj up to noise.

[0147] In a fifth step E5, the computing unit 42 identifies the maximum value Fcorr_max of each correlation function Fcorrjj associated with each elementary acquisition module 32^ and compares it to a threshold value Vs.

[0148] 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_djj from the elementary acquisition module 32jj associated with this correlation function Fcorrjj. An object O is therefore detected in the angular range, or pixel, monitored by this elementary acquisition module 32jj 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 Fli 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.

[0149] A chromaticity diagram of the CIE 1931 2° Standard Observer type (x,y) is shown in [Fig. 3] to represent the colours of the first light beam Flj that can be obtained using the elementary light sources 21 21 ib and 21 ic of the first light module 2b The colours are identified on this diagram by their abscissa x and ordinate y on axes of the diagram, these coordinates corresponding to normalised chromatic coordinates.

[0150] 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.

[0151] 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.

[0152] The three elementary light sources 21 ia, 21 xb and 21 iC thus define a triangle on the chromaticity diagram, within which the color of the first light beam Fli can be controlled by the control unit C by controlling the contributions of each of the elementary light beams F^a, Flib and F^c to this first light beam Flb

[0153] 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, Tic of the pulse-width modulated signal driving the elementary light sources 21 ib and 21 iC.

[0154] 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 Fli beam within the Tu zone, in particular to compensate for BIN or temperature tolerances; b. Direction indicator, or "TI", in amber or orange color, by activating only or mainly 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 decreasing the peak power Pp in order to remain 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 F1]C so that the color of beam Fli is located within zone W. Note that the contributions of the beams elementary light sources 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.

[0155] 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.

[0156] Another example of an embodiment of a lighting system 10 according to the invention is shown in [Fig. 4]. This lighting system 10 is similar to the lighting system 1 of the embodiment in [Fig. 1], except for the elementary light sources of the light molds.

[0157] In the example of [Fig.4], the emission module 2 comprises a first light module 23 capable of emitting the first light beam Fli and a second light module 24 capable of emitting the first light beam Fl2.

[0158] The first light module 23 comprises a plurality of elementary light sources, including a first elementary light source 213a and a second elementary light source 213b.

[0159] The first elementary light source 213a is capable of emitting a first elementary light beam Fl3a of cyan color, the spectrum of which has a peak between 485 nm and 505 nm and a full width at half maximum (FWHM) between 10 and 30 nm, similarly to the first embodiment. The second elementary light source 213b is capable of emitting a second elementary light beam Fl3b of amber color, the spectrum of which has a second peak between 585 nm and 595 nm and a FWHM between 30 and 120 nm.

[0160] The first elementary light source 213a comprises a semiconductor light generator, for example a gallium-indium nitride alloy, capable of directly emitting, by electroluminescence, the first elementary light beam Fl3a of cyan color. The second elementary light source 213b 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 generator. light and to emit in response yellow light, the addition of unabsorbed blue light and yellow light forming said second elementary light beam Fl3b of amber color.

[0161] Similar to the first embodiment, the light module 23 includes an optical device 231 arranged to receive the first and second elementary light beams Fl3a and Fl3b and having an output face common to said first and second elementary light beams Fl3a and Fl3b.

[0162] The second light module 24 comprises a plurality of elementary light sources, including a first elementary light source 214a and a second elementary light source 214b.

[0163] The first elementary light source 214a is capable of emitting a first elementary light beam Fl3a of cyan color, the spectrum of which has a peak between 485 nm and 505 nm and a full width at half maximum (FWHM) between 30 and 120 nm. The second elementary light source 214b is capable of emitting a second elementary light beam Fl3b of amber color, the spectrum of which has a second peak between 585 nm and 595 nm and a FWHM between 30 and 120 nm.

[0164] The first elementary light source 214a comprises a semiconductor light generator, for example a gallium-indium nitride alloy, may comprise a semiconductor blue light generator, for example a gallium-indium nitride alloy, and a photoluminescent element, for example a europium-doped barium-lithium borate or a europium-doped lithium-strontium borate, or a cerium- or europium-doped calcium-lutetium-hafnium-aluminum garnet, capable of absorbing light emitted by the light generator and of emitting in response cyan or green light, the addition of the unabsorbed blue light and the yellow light forming said first elementary light beam Fl4a of cyan color.

[0165] The second elementary light source 214b may include 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 of emitting yellow light in response, the addition of the unabsorbed blue light and the yellow light forming said third elementary light beam Fl4b of amber color.

[0166] The light module 24 comprises an optical device 232 arranged to receive the first and second elementary light beams Fl4a and Fl4b and having a common exit face of the said first and second elementary light beams Fl4a and Fl4b.

[0167] In other words, in the described embodiment, the first elementary light source 213a of the first light module 23 is thus dedicated to both the telemetry function and the photometric function, while the other elementary light sources 213b of the first light module 23 and the elementary light sources 214a and 214b of the second light module 24 are dedicated only to the photometric function, the first and second light beams Fli and Fl2 being emitted simultaneously.

[0168] Since the operation of the light system 10 is identical to that of the light system 1 of [Fig.1], it will not be described.

[0169] A CIE 1931 2° Standard Observer (x,y) chromaticity diagram is shown in [Fig. 5] to represent the colors of the first light beam Fl1 that can be obtained using the elementary light sources 213a and 213b of the first light module 23 and of the second light beam Fl2 that can be obtained using the elementary light sources 214a and 214b of the first light module 2b

[0170] The colors of the elementary beams Fl3a, Fl3b, Fl4a and Fl4b likely to be emitted by the elementary light sources 213a, 213b, 214a, and 214b 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.

[0171] The two elementary light sources 213a and 213b thus define a line on the chromaticity diagram, along which the color of the first light beam Fli can be controlled by the control unit C by controlling the contributions of each of the elementary light beams Fl3a and Fl3b to this first light beam Flb

[0172] Similarly, the two elementary light sources 214a and 214b also define a line on the chromaticity diagram, along which the color of the second light beam Fl2 can be controlled by the control unit C by driving the contributions of each of the elementary light beams Fl4a and Fl4b to this second light beam Fl2.

[0173] Since these lines intersect at the level of the "white" area W, the control unit C can therefore ensure that the colours of the first and second light beams Fli and Fl2 emitted by the first and second light modules 23 and 24 match perfectly when emitting a photometric function requiring a white colour, such as a daytime running light or a position light.

[0174] A chromaticity diagram of type CIE 1931 2° Standard Observer (x,y) corresponding to a variant of the light system of [Fig.5] is shown in [Fig.6], in which the elementary light source 213a dedicated to both the photometric and telemetry functions has been replaced by two elementary light sources 213ai and 213a2 capable of emitting an elementary light beam of color respectively green and blue.

[0175] Only the elementary light source "blue" is dedicated to both the photometric function and the telemetry function, the other allowing a colorimetric barycenter to be positioned at the level of the "turquoise" zone Tu, at the level of the elementary light source 213a of the previous embodiment, when the light modules 23 and 24 have to perform a photometric function requiring a white color, such as a daytime running light or a position light.

[0176] The line joining this center of gravity and the second elementary light source 213b then crosses the line joining the two elementary light sources 214a and 214b at the level of the "white" zone W, as in the previous embodiment.

[0177] 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 cyan beam, enabling the simultaneous performance of the rangefinding and photometric functions, and a control unit for adjusting the color of the function performed by this beam to match that of the function performed by another lighting module.

[0178] 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 than that described may also be provided, and in particular low beam lighting functions or signaling functions such as position lights or direction indicators.

Claims

Demands

1. Lighting system (1) of a motor vehicle, comprising an emission module (2) comprising: a. a first lighting module (2i; 23) comprising a first elementary light source (21ia; 213a) capable of emitting a first elementary light beam (Fha; Fl3a) whose spectrum has a first peak between 400 nm and 505 nm, the first lighting module being capable of emitting, from said first elementary light beam, a first light beam (Fli) for the realization of a given photometric function; b. and a second lighting module (22, 24) capable of emitting a second light beam (Fl2) for the realization of said given photometric function;characterized in that it comprises a control unit (C) arranged to control the first and second light modules (2i, 22) for the simultaneous emission of the first and second light beams (Flb Fl2) for the realization of said given photometric function, the control unit comprising a modulation unit (22ia) 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; and in that the control unit is arranged to control the first and second light modules so that the first light beam has a color substantially identical to that of the second light beam.

2. A lighting system (1) according to the preceding claim, characterized in that the first elementary light source (21 ia; 213a) comprises a semiconductor light generator capable of directly emitting said first elementary light beam (Flia; Fl3).

3. a) Lighting system (1) according to claim 1, characterized in that the first elementary light source (21 ia; 213a) comprises a semiconductor light generator and an element photoluminescent capable of converting the rays emitted by the generator to form the first elementary light beam (Flia; Fl3a).

4. A lighting system (1) according to any one of the preceding claims, characterized in that the first elementary light source (2 ha; 213a) is capable of emitting a first elementary light beam (Flia; Fl3a) whose spectrum has a first peak between 400 nm and 485 nm, in that the first lighting module comprises a second elementary light source (21 ib; 213b) capable of emitting a second elementary light beam (Flib; Fl3b) whose spectrum has a second peak between 485 nm and 570 nm, and an optical device (231) arranged to receive the first and second elementary light beams (F^a, Fli b; Fl3a; Fl3b) and comprising a common output face of said elementary light beams, the control unit (C) being arranged to control the first and second elementary light sources (21 ia, 21 ib;213a, 213b) for the simultaneous emission of the first and second elementary light beams to form the first light beam.

5. Lighting system (1) according to the preceding claim, characterized in that the first and second elementary light sources (21 ia, 21ib; 213a, 213b) 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 (Flia, Flib; Fl3a; Fl3b), the intensity of each of said elementary light beams being controllable.

6. A lighting system (1) according to any one of the preceding claims, characterized in that the first lighting module (2J) comprises an additional elementary light source (21 ic) capable of emitting an additional elementary light beam (Flic) whose spectrum has a peak between 585 nm and 680 nm, and an optical device (231) arranged to receive the first elementary light beam (Flia) and the additional elementary light beam, and its output face being common to said first elementary light beam and additional elementary light beam; and in that the control unit (C) is arranged to selectively control the first elementary light source (21 ia) and the additional elementary light source to the selective or simultaneous emission of the first elementary light beam and additional elementary light beam for the selective realization of several given photometric functions.

7. A light system (1) according to any one of the preceding claims, characterized in that the second light module (22) comprises a light source (212a; 214a; 214b) capable of emitting the second light beam (F12), and in that the control unit (C) comprises a unit (222a) for controlling the power supply of said light source (212a), 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, the duty cycle (r2a) of said signal being selected so that the first light beam (F1) has a color substantially identical to that of the second light beam (F12).

8. 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 (Selk4), said elementary acquisition module (32^) 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 first elementary light beam (Flia; Fl3a) emitted by said first elementary light source (21ia; 213a); 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. of a light beam received (F2) by the receiving module, the calculation unit (42) being arranged to determine a duration relative to a time of flight (r) separating the emission of said first elementary modulated light beam emitted (Flia; Fl3a) from the reception of said light beam received from said demodulated data sequence (Seq_dij) and said modulating data sequence (Seq_m).

9. Light system (1) according to the preceding claim, characterized in that the receiving module (3) comprises a bandpass type optical filter placed in front of the photodetector (32ak4), 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 said filter has a transmission peak at a wavelength corresponding to the first peak.

10. 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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