Telemetry Lighting System for Vehicles

Abstract

The present invention relates to a system (1) for a motor vehicle, the system comprising a transmitting module (2) comprising: a light-emitting module (21) comprising a first light source (23a) capable of emitting a first beam (F1a) and a second light source (23b) capable of emitting a second beam (Flb), the spectrum (S1) of the first beam having a first peak (P1) with a wavelength shorter than an intermediate wavelength, and the spectrum (S2) of the second beam having a second peak (P2) with a wavelength greater than an intermediate wavelength, the intermediate wavelength being greater than 490 nm; and a control unit (22) arranged to control the first light source and the second light source to simultaneously emit the first beam and the second beam, the control unit comprising a modulation unit (22a) capable of receiving a data sequence (Seq) and arranged to modulate the emitted first beam based on the received data sequence.

Description

[0001] This invention relates to the field of automotive lighting and / or luminous signaling, and to the field of functions for detecting objects and estimating the distance between an object and a vehicle via a motor vehicle. More specifically, this invention relates to a lighting and / or signaling system for a motor vehicle capable of performing telemetry functions by means of the light it emits.

[0002] In the automotive industry, the known practice is to use pulsed beams emitted by the light-emitting modules of a motor vehicle's lighting system in order to perform a given optical function.

[0003] Conventionally, the light source used to emit this beam is controlled by a pulse-width modulation (PWM) electrical signal. Therefore, the PWM signal periodically enables and deactivates the light source, causing the emitted beam to consist of light pulses that occur sequentially at a sufficiently high frequency so that the human eye can no longer distinguish between them. The intensity of the emitted beam depends on the duty cycle of the PWM signal, allowing the intensity to be controlled by adjusting the duty cycle, and thus enabling optical functions.

[0004] In addition to performing one or more optical functions (such as daytime running lights or low beam illumination), this type of light-emitting module can perform various other functions. For example, the light source of the light-emitting module can be controlled to transmit a pulsed data sequence of the emitted beam. Therefore, the light-emitting system can be equipped with a receiving module to receive the emitted beam after it has been reflected from an object near the vehicle. Then, after detecting the data sequence in the received beam, the vehicle's computing unit can determine the time of flight of the emitted beam and thus assess the distance between the vehicle and the object.

[0005] In this way, the light beam can retain its original function, namely performing optical functions, while allowing the light-emitting system to perform telemetry functions, 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 use of a transmitting module capable of performing both optical emission and data transmission, has drawbacks. Specifically, the receiving module intended to receive the beam transmitting data (whether it is located in the same vehicle or in another vehicle) must include at least one photodetector for converting the beam into an electrical signal in order to demodulate the signal and extract the data sequence from it.

[0007] However, under certain conditions, given stray light sources in the vehicle environment (such as city lighting, car lights from approaching or following vehicles, or even sunlight), and the nature of objects in the environment, particularly their reflectivity, the signal-to-noise ratio (SNR) of such photodetectors can be severely degraded. This degradation in SNR can then reduce the accuracy of the computing unit in estimating the distance to the target object, or even lead to false alarms.

[0008] In this scenario, a specific wavelength is chosen for use where the normalized light from the sun is not very strong, or even absent. This is particularly true in the visible spectrum, specifically for the blue wavelength range between 430 nm and 460 nm. Therefore, if the peak of the beam emitted by the light source of the transmitting module lies at one of these wavelengths, a filter can be used in the receiving module to filter out the overly strong bands of sunlight, retaining only a narrower band centered on that emission wavelength where sunlight is less intense. This increases the signal-to-noise ratio.

[0009] However, this solution is not entirely satisfactory. Specifically, the optical functions must meet regulatory requirements, particularly regarding luminous power and color. For example, the maximum brightness of daytime running lights (DRLs) is limited by regulations to 1200 cd and must consist of white light. Typically, the light-emitting diodes used include a blue light generator associated with a phosphor that converts a portion of the blue light into yellow light; the additive combination of the remaining blue and yellow light forms white light.

[0010] However, from an energy (or radiation measurement, i.e., relative to the total energy of the light) perspective, the blue component of the light accounts for only about 30% of the light, and from an optical (i.e., relative to the energy of the portion of the light visible to the human eye, weighted by the sensitivity curve of the human eye) perspective, the blue component is less than 10%, making its power potentially insufficient under degraded sunlight conditions or for long-distance detection. To maintain a satisfactory signal-to-noise ratio, one solution is to increase the luminous power per pulse of the emitted beam. However, this solution would result in an increase in both the blue and yellow components of the emitted beam, and thus an increase in the average power of the emitted beam, making it unsuitable for performing the optical functions it is intended to perform. Another solution would be to increase the number of light sources, but this solution is quite incompatible with the compactness and cost requirements of the automotive lighting and optical signaling fields.

[0011] Therefore, there is a need for a light-emitting system for motor vehicles that can perform both a given statutory optical function and a telemetry function, and that is efficient and has the best signal-to-noise ratio under all weather conditions (including bright sunlight).

[0012] The present invention falls within this context and is intended to meet this need.

[0013] Therefore, the present invention relates to a light-emitting system for a motor vehicle, the light-emitting system comprising an emitting module, the emitting module comprising: a light-emitting module including a first light-emitting source capable of emitting a first light beam and a second light-emitting source capable of emitting a second light beam, the first light beam having a spectrum having a first peak value less than an intermediate wavelength, and the second light beam having a spectrum having a second peak value greater than an intermediate wavelength, the intermediate wavelength being greater than or equal to 490 nm; and a control unit, the control unit being designed to control the first light-emitting source and the second light-emitting source to simultaneously emit the first light beam and the second light beam, the control unit including a modulation unit capable of receiving a data sequence and being designed to modulate the emitted first light beam based on the received data sequence.

[0014] Advantageously, the intermediate wavelength is equal to 490 nm. Alternatively, the intermediate wavelength is greater than 490 nm to cover the wavelengths corresponding to turquoise light. If applicable, the intermediate wavelength is preferably less than 510 nm, and more preferably 500 nm.

[0015] Turquoise light can be used, for example, to signal the execution of autonomous driving modes.

[0016] Therefore, the present invention proposes to decompose a beam intended to perform an optical function into two beams, the two beams including a first beam having a spectrum with peaks substantially in the blue range when the first light source emits generally blue light, or a first beam having a spectrum with peaks substantially in the turquoise range when the first light source emits generally turquoise light, and thus enabling telemetry functions to be performed with a good signal-to-noise ratio, especially when taking into account the spectral distribution of light emitted by the sun.

[0017] The first beam can be, for example, a pulsed beam, where each pulse corresponds to one or more consecutive high values ​​of the data sequence, and the interval between two consecutive pulses corresponds to one or more consecutive low values ​​of the data sequence. Each pulse of the modulated first beam is emitted at its peak luminous power, such that the average luminous power of the emitted modulated first beam is thus defined by the peak luminous power and the duty cycle of the modulated data sequence. Therefore, the presence of the data sequence in the first beam can be detected after reflection from an object in the vehicle environment, and thus the presence of the object can be detected and the distance of the object from the vehicle estimated.

[0018] The second beam has a spectrum with peaks in the visible light range, which is complementary to the spectrum of the first beam, such that the simultaneous emission of these first and second beams produces an overall white light beam. In this invention, "simultaneous emission" should be understood as meaning that the first and second beams together perform all or part of the same optical function. The overall beam performing this optical function can be generated by an additive combination of the first and second beams, or by alternating pulses of these first and second beams at a sufficiently high frequency, so that the light thus formed appears white to the human eye.

[0019] According to the invention, each beam is emitted by its dedicated light source. In particular, it is conceivable to use one or more light sources to emit each beam. In this way, the power of the pulse emitted by the first light source can be increased to improve the efficiency and signal-to-noise ratio of the telemetry function performed by the first beam, while adapting the power of the second beam emitted by the second light source to meet regulatory requirements for the optical functions performed by the overall beam.

[0020] Advantageously, the first light source is designed such that the spectrum of the emitted first beam has a first peak value in the range of 380 nm to 490 nm, preferably in the range of 420 nm to 460 nm, and the second light source is designed such that the spectrum of the second beam has a second peak value in the range of 520 nm to 580 nm, or even in the range of 530 nm to 555 nm. Preferably, the first light source is designed such that the spectrum of the first beam has a full width at half maximum (FWHM) between 15 nm and 30 nm, and the second light source is designed such that the spectrum of the second beam has a FWHM between 70 nm and 140 nm. In other words, the first light source emits substantially blue light, thereby greatly increasing the power of the pulse constituting the first beam. The second light source emits substantially yellow light complementary to the substantially blue light, and the intensity of the first beam and the intensity of the second beam can be modulated, particularly by modulating the duty cycle, to obtain a legally defined white overall beam. Advantageously, the first light source is designed such that the spectrum of the emitted first beam has a first peak value in the range of 480 nm to 510 nm, preferably in the range of 490 nm to 500 nm, and the second light source is designed such that the spectrum of the second beam has a second peak value in the range of 520 nm to 680 nm, or even in the range of 585 nm to 680 nm. Preferably, the first light source is designed such that the spectrum of the first beam has a full width at half maximum (FWHM) between 15 nm and 30 nm, and the second light source is designed such that the spectrum of the second beam has a FWHM between 70 nm and 140 nm. In other words, the first light source emits approximately turquoise light, thereby greatly increasing the power of the pulse constituting the first beam. The second light source emits orange (e.g., amber) light, which is complementary to the approximately turquoise light, and the intensity of the first and second beams can be modulated, particularly by modulating the duty cycle, to obtain a legally defined white overall beam.

[0021] Preferably, the first and at least the second light source are designed such that the overlap of their spectra is substantially zero. Alternatively, the first and at least the second light source are arranged such that the overlap of their spectra extends beyond a given wavelength, for example, 460 nm when the first light source emits generally blue light, or 500 nm when the first light source emits generally turquoise light. The overlap band can be, for example, a band where the spectral power of each of the first and second beams is greater than 10% of the peak spectral power of the first beam. If the width of such an overlap band is less than 5 nm, it can be considered substantially zero. These characteristics particularly ensure that photons emitted by the second light source will not be added to the portion of the first beam used for telemetry, which would otherwise generate noise that could degrade the signal-to-noise ratio of the system used for telemetry, especially when the receiving module designed to perform this function is equipped with a blue filter.

[0022] In one exemplary embodiment, the first light source includes a generator capable of emitting the first light beam, and the first light source does not have a photoluminescent element. Preferably, in the case of the first light source, the generator may be a semiconductor generator. The semiconductor may be, for example, gallium nitride (GaN), which is capable of emitting turquoise and / or blue and / or ultraviolet rays by electroluminescence and in response to a current flowing through it.

[0023] If applicable, the second light source may include a generator capable of emitting light. For example, in the case of a second light source, the generator may be a semiconductor generator capable of emitting yellow, orange, or amber light. The semiconductor may be, for example, gallium phosphide (GaP), gallium arsenide phosphide (GaAsP), or silicon carbide (SiC), which are capable of emitting yellow, orange, or amber light rays by electroluminescence and in response to a current flowing through them.

[0024] If applicable, the second light source may include a light-emitting generator capable of emitting light and a photoluminescent element capable of absorbing most of the light and emitting a second beam. For example, the semiconductor may be gallium nitride (GaN), which is capable of electroluminescence and emits turquoise and / or blue and / or ultraviolet rays in response to a current flowing through it. If applicable, the doping ratio of the semiconductor and / or the semiconductor may differ between the first and second light sources to ensure that the peak value of the spectrum of the first beam differs from the peak value of the spectrum of the second beam.

[0025] Photoluminescent elements can be, for example, in the form of resins, including, for example, garnet, silicates, aluminates, oxynitrides, quantum dot particles, or perovskites. These resins can absorb turquoise, blue, or ultraviolet light and emit yellow rays through photoluminescence in response to excitation by the light. The photoluminescent element is disposed on the generator of a second light source, such that most of the blue or ultraviolet light rays excite the element, causing it to emit orange rays through photoluminescence. Therefore, when powered, the light source primarily emits yellow, orange, or amber rays.

[0026] The light source can therefore be a laser source, a light-emitting diode, a vertical-cavity surface-emitting laser (VCSEL), or a superluminescent diode (SLED).

[0027] As a variation, the second light source can be configured to include multiple light elements, each capable of emitting rays of different colors (specifically red or green). Changing the luminous intensity of each of these light elements can be used to change the color of the second beam, which can then supplement the first beam so that the overall beam is white.

[0028] In one embodiment, the control unit includes a drive unit for supplying power to the second light source. The control unit is designed to control the drive unit using a pulse-width modulated signal with a duty cycle greater than that of the received data sequence. The duty cycle of the data sequence can be defined, for example, as the ratio between the number of high values ​​and the total length of the data sequence. In this invention, the first light source is controlled at a high frequency such that pulses forming the first light beam occur successively at frequencies greater than 100 kHz or greater than 1 MHz, while the second light source is controlled at a low frequency of about 1 kHz with a sufficiently large duty cycle, such that the pulses of the second light beam have a time range such that the overall light beam produced by the first and second light beams appears white to the human eye.

[0029] Advantageously, the control unit is designed to determine the duty cycle of the pulse width modulation signal based at least on the duty cycle of the received data sequence and the peak power setting of the pulses forming the first beam. In particular, a control unit can be configured to determine the duty cycle of the pulse width modulation signal based on the duty cycle of the received data sequence, the peak power setting of the pulses forming the first beam, and optical function settings intended to be provided at least in part by the first and second beams.

[0030] In one embodiment, the light-emitting module includes an optical unit capable of receiving a first light beam and a second light beam and having a common exit surface for the first and second light beams. "Exit surface" should be understood as an imaginary wall, surface, or area through which the first and second light beams of the optical unit are emitted. Therefore, the optical unit may include a lens, a light guide, a reflector, or a combination of several of these optical elements. In this embodiment, the optical unit is therefore a common optical unit designed to project and / or deflect and / or shape the light emitted by the first and second light sources to form the first and second light beams.

[0031] In an exemplary embodiment of the invention, the optical unit includes a light guide comprising at least one coupling surface for a first beam and a second beam. The guide is designed such that light coupled via the coupling surface propagates within the guide by total internal reflection. If applicable, the guide includes a decoupling element capable of decoupling light propagating within the guide along a common exit surface. The guide includes a mixing portion between the coupling surface and the decoupling element for coupling the first beam and the second beam to the light guide. This mixing portion is used to spatially homogenize the color of the overall beam, such that the color and the illumination appearance of the light guide meet regulatory requirements for the optical functions intended to be performed by the overall beam.

[0032] Advantageously, the light guide has a generally cylindrical shape, and the cross-section of the guide at the mixing section is polygonal. The cross-section of the guide at the mixing section can, for example, have a square or hexagonal profile. These shapes are specifically used to optimize the mixing of the first and second beams.

[0033] The light guide may be configured to have an elliptical or circular cross-section at a horizontal plane including a common emitting surface in the main portion, and the decoupling element includes prisms and / or diffusers and / or micro-protrusions formed in at least a wall of the main portion opposite to the emitting surface. The light guide may, for example, include a joining portion between the mixing portion and the main portion, the joining portion being designed to continuously join the polygonal cross-section of the mixing portion to the elliptical or circular portion of the main portion.

[0034] As a variant, the cross-section of the mixing section can be configured to be the same as the cross-section of the main part of the light guide, including a common exit surface, and the length of the cross-section of the mixing section is sufficient to allow the first beam and the second beam to mix along the section.

[0035] In another exemplary embodiment, the light guide may have the shape of a light guide plate including coupling members (such as collimators). Light rays coupled to the plate via the coupling members propagate from opposite walls of the light guide plate by total internal reflection until they reach a decoupling member designed to deflect these rays toward a common exit surface of the light guide plate. If applicable, the mixing portion may be a translucent portion of the light guide plate, a diffusing member disposed on a wall of the light guide plate, or a portion of the light guide plate without a decoupling member and long enough to allow the first and second beams to mix.

[0036] Advantageously, the system may include at least two first light sources, arranged opposite to the same coupling surface of the light guide, with the first light sources surrounding the second light sources. For example, the system may be configured to include a plurality of first light sources aligned along a first direction and a plurality of second light sources aligned along different second directions intersecting the plurality of first light sources. As a variation, the first light sources may be configured to completely or partially surround one or more second light sources. These various arrangements also facilitate the mixing of the first and second light beams within the light guide.

[0037] Advantageously, the size of the second light source can be larger than the size of the first light source.

[0038] In one embodiment of the invention, the system includes a receiving module capable of receiving a light beam, the receiving module including at least one basic acquisition module comprising a photodetector capable of converting the received optical signal into an electrical signal. If applicable, the system includes a computing unit designed to generate a modulation data sequence and transmit the modulation data sequence to a modulation unit for emission of a modulated first light beam by a light-emitting module; the computing unit is designed to determine the time of flight between the emission of the modulated first light beam and the reception of the received light beam by the receiving module, based on the electrical signal converted by the photodetector based on the received light beam.

[0039] Advantageously, the receiving module comprises multiple basic acquisition modules arranged in a matrix, each basic acquisition module including a photodetector capable of converting the received optical signal into an electrical signal. For example, this group of photodetectors can form a sensor, such as a single electronic component. Also, for example, each photodetector can have a width and / or length of less than about ten micrometers, which allows for a basic acquisition module with a receiving field of at most 0.1°, and thus improves the spatial resolution of the receiving module.

[0040] Advantageously, the photodetector of the basic acquisition module, or each basic acquisition module, is an avalanche photodiode. This type of photodetector is also known as a single-photon avalanche diode (SPAD). Therefore, this group of avalanche photodiodes can form a silicon photomultiplier (SiPM). This type of photodetector can detect high gain (e.g., 10). 6 The single photon incident with a gain on the order of magnitude, and thus compensates for the degradation of the signal-to-noise ratio due to external conditions.

[0041] According to one embodiment of the present invention, the receiving module may include an optical unit arranged in front of the basic acquisition module.

[0042] Advantageously, the system includes a demodulation unit connected to a photodetector and designed to extract a data sequence, referred to as a demodulated data sequence, from the electrical signal converted by the photodetector. Where applicable, a computing unit is capable of receiving the demodulated data sequence from the electrical signal converted by the photodetector based on the beam received by the receiving module. The computing unit is designed to estimate the value of a correlation function between the demodulated data sequence and the modulated data sequence, and to determine the time of flight between the emission of the transmitted modulated first beam and the reception of the received beam based on the value of the correlation function.

[0043] In other words, in this embodiment, the computing unit can estimate the value of the correlation function between the demodulated data sequence and the modulated data sequence, each value of the correlation function being associated with a time shift of the modulation or demodulation sequence, the time shift being used to estimate that value of the correlation function.

[0044] Preferably, the computing unit is designed to generate the first modulated data sequence from an initial pseudo-random binary sequence. A pseudo-random binary sequence (PRBS) is a data sequence consisting of high values ​​(i.e., "1") and low values ​​(i.e., "0"). This type of sequence has particularly advantageous properties. Specifically, its autocorrelation function is at its maximum for a time shift of zero (i.e., when the sequence is compared to itself), and for any other time shift (i.e., when the sequence is compared to its time-shifted version), the value of the autocorrelation function is significantly lower than this maximum value. Furthermore, the cross-correlation function between two pseudo-random binary sequences is significantly smaller than the maximum value of the autocorrelation function of these sequences. Finally, this type of sequence is typically generated by means of a linear feedback shift register (LFSR), which produces a periodic recursive sequence whose pattern is a pseudo-random binary sequence.

[0045] Given the autocorrelation properties of the pseudo-random binary sequence, the estimated correlation function will be maximized for the time shift corresponding to the flight time of the emitted, reflected, and then received modulated beam, even under high noise conditions. Therefore, the computational unit can accurately identify this time shift associated with the maximum value of the correlation function and deduce the distance between the object reflecting the beam and the vehicle. Furthermore, given the cross-correlation properties, it seems unlikely that receiving a modulated beam emitted by an equivalent system of another vehicle would result in a false alarm. Finally, it should be understood that detection is performed over the entire data sequence, not on a single pulse, thus improving the system's signal-to-noise ratio.

[0046] In one embodiment of the invention, the computing unit is designed to estimate each value of the correlation function between the demodulated data sequence and the first modulated data sequence by evaluating the cross-correlation between the demodulated data sequence and a first delayed modulated data sequence for a given duration associated with the value. In other words, each value of the correlation function is therefore associated with a time shift of the first modulated sequence used to estimate that value of the correlation function. Therefore, the computing unit is designed to identify the time shift value associated with the maximum value of the cross-correlation function.

[0047] Advantageously, the basic acquisition module includes a blue light filter. Besides the fact that the spectral characteristics of light emitted by the sun can be used to increase the signal-to-noise ratio if the telemetry function uses a blue beam, it should be noted that if the first beam is emitted from a semiconductor light source (such as a light-emitting diode), then this beam is obtained from a blue light generator that emits photons rapidly relative to the conversion rate of the phosphorescent element. Therefore, in the context of detecting obstacles by analyzing the time-of-flight of the beam, the time-of-flight assessment resolution will necessarily be higher if the assessment is based solely on blue light rather than on another wavelength range, or even on the entire visible spectrum. Thus, the use of a blue light filter reduces the uncertainty in detecting the distance of obstacles from the vehicle.

[0048] A blue light filter can be configured to include a bandpass-type optical filter positioned in front of a photodetector, the optical filter being capable of transmitting a wavelength range and designed such that the width of the range is substantially less than 20 nm, and the filter has a transmission peak at a wavelength of substantially 450 nm. In this invention, "the width of the wavelength range of the filter" should be understood as the wavelength range in which the filter's transmittance is at least 80%. In this invention, "the transmission peak of the filter" should be understood as the wavelength in the range in which the filter's transmittance is highest.

[0049] Alternatively, if the first light source emits turquoise light, the basic acquisition module includes a turquoise light filter, thereby providing similar advantages to those provided by a blue light filter when using a first blue light source. Similarly, the turquoise light filter may include a bandpass-type optical filter positioned in front of the photodetector, the optical filter being capable of transmitting a wavelength range and designed such that the width of the range is substantially less than 20 nm, and the filter having a transmission peak at a wavelength close to 494 nm (with an error of no more than about 10 nm).

[0050] In one embodiment of the invention, the transmitting module is arranged in the headlight of a motor vehicle. Advantageously, both the receiving module and the transmitting module are arranged in the headlight of the motor vehicle.

[0051] Similarly advantageously, the transmitting module is designed such that the first beam and the second beam together contribute fully or partially to the performance of the predetermined statutory optical function.

[0052] For example, it could be a daytime running light (DRL), which has the advantage of emitting light at a low intensity over a wide field.

[0053] The present invention also relates to a headlight for a motor vehicle, the headlight comprising a transmitting module according to the invention, and optionally a receiving module.

[0054] The present invention will now be described using examples that are merely illustrative and in no way limit the scope of the invention, and based on the accompanying drawings:

[0055] [ Figure 1 The diagram schematically and partially illustrates a view of a system for a motor vehicle according to an exemplary embodiment of the invention.

[0056] [ Figure 2 [Illustratively and partially showing] Figure 1 An exemplary embodiment of the light source of the system;

[0057] [ Figure 3 This schematically and partially illustrates the work of [[] Figure 2 The emission spectrum of the light beam simultaneously formed by the light source;

[0058] [ Figure 4 This schematically and partially illustrates the situation when performing telemetry methods. Figure 1 Examples of system operation; and

[0059] [ Figure 5 [Illustratively and partially showing] Figure 1 An exemplary embodiment of the optical unit of the system's transmitting module.

[0060] In the following description, unless otherwise stated, elements that are identical in structure or function and appear in the various figures use the same reference numerals.

[0061] [ Figure 1 The image shows a system 1 for a motor vehicle according to an exemplary embodiment of the present invention.

[0062] System 1 includes a transmitting module 2 designed to emit a beam F1 and a receiving module 3 designed to receive a beam F2.

[0063] In the described example, the transmitting module 2 and the receiving module 3 are arranged in the same headlight of the motor vehicle. Without departing from the scope of the invention, modules 2 and 3 may be arranged in different locations within the motor vehicle.

[0064] The emitting module 2 includes a light-emitting module 21 designed to emit a light beam F1 and a control unit 22.

[0065] The light-emitting module 21 includes a first light-emitting source 23a capable of emitting light and an optical unit 24 designed to project these light rays to form a first light beam F1a. The light-emitting module 21 also includes a second light-emitting source 23b capable of emitting light, and the optical unit 24 is designed to project these light rays to form a second light beam F1b.

[0066] In this invention, the optical unit 24 therefore has a common exit surface for the first beam F1a and the second beam F1b. The optical unit may also include one or more reflectors, one or more lenses, one or more apertures, one or more light guides, or one or more collimators, or a combination of several of these optical elements. Specific embodiments of the optical unit 24 will be described later.

[0067] [ Figure 2 An exemplary embodiment of light sources 23a and 23b is shown, and [ Figure 3 The spectrum of the light beam formed simultaneously by these light sources 23a and 23b is shown.

[0068] The light source 23a includes a semiconductor generator 23a1, such as gallium nitride (GaN), which is capable of emitting blue light rays intended to form a first beam F1a by electroluminescence and in response to a current flowing through it. The generator 23a may be arranged within a reflecting cavity. The light source 23a does not yet have a photoluminescent element intended to convert all or some of these blue light rays into light of another color. Therefore, the spectrum S1 of the first beam F1a has an emission peak P1 at 445 nm and a full width at half maximum (FWHM1) of 20 nm.

[0069] The light source 23b also includes a semiconductor generator 23b1, such as gallium nitride (GaN), which is capable of emitting blue light rays by electroluminescence in response to a current flowing through it. The light source 23b also includes a photoluminescent element 23b2 superimposed on the generator 23b1, which is in the form of an organic or inorganic encapsulant, particularly in the form of a resin containing cerium-doped yttrium aluminum garnet (CE:YAG), capable of absorbing blue light and emitting yellow, orange, or amber light rays by photoluminescence in response to excitation by the light.

[0070] A photoluminescent element 23b2 is disposed on a generator 23b1 such that most of the blue light rays emitted by the generator 23b1 excite the element 23b2 to emit yellow, orange, or amber light rays through photoluminescence, which are intended to substantially completely form the second beam F1b.

[0071] Therefore, the spectrum S2 of the first beam F1b has an emission peak P2 at 550 nm and a full width at half maximum (FWHM2) of 100 nm.

[0072] like[ Figure 3 As shown, the positions of emission peaks P1 and P2, as well as full width at half maximum (FWHM1) and full width at half maximum (FWHM2), ensure that the overlapping bands of spectra S1 and S2 extend beyond a wavelength of 460 nm.

[0073] Therefore, when beams F1a and F1b are emitted simultaneously under the control of the control unit 22, they form a total beam. The spectrum of this total beam corresponds to the superposition of emission spectra S1 and S2, as shown below. Figure 3 As shown in the figure. Then, depending on the power of beams F1 and F1b, the overall beam color may appear white to the human eye.

[0074] As long as the overall beam appears white, it can be used to partially or completely assist in performing a predetermined, particularly legal, optical function. In this case, the optical unit 24 is designed to shape the overall beam such that its optical distribution meets the requirements of the function. For example, the overall beam can be configured to assist in performing a daytime running light (DRL) function.

[0075] It should be noted that the present invention is not limited to a combination of a single first light source 21a and a single second light source 21b, and the number of the first and second light sources can be changed without departing from the scope of the invention. Similarly, without departing from the scope of the invention, it is conceivable to change the composition ratio of the semiconductor and / or photoluminescent element 23b2 of the generator 23a1, 23b1 of one and / or the other of the first light source 23a and the second light source 23b, to shift the peak values ​​P1, P2 and / or change the amplitude of the full width at half maximum (FWM1) and full width at half maximum (FWHM2) of the spectra S1 and S2. In particular, it is conceivable to replace [the previous invention] with chips that emit red and green light respectively. Figure 2 The second light source 23b described in the figure can selectively control these chips so as to control the color of the light beam emitted by these chips to complement the first light beam F1a to form a generally white overall light beam.

[0076] In addition to this optical function, the first beam F1a also allows system 1 to perform detection and evaluation functions on the position of objects on the road, such as referencing [ Figure 4 As described, the figure illustrates a telemetry method performed by the light-emitting system 1 using the light-emitting module 21.

[0077] For this purpose, system 1 includes a computing unit 4, and control unit 22 includes a modulation unit 22a for controlling the first light source 23a and a drive unit 22b for controlling the power supply to the second light source 23b.

[0078] In the first step, computing unit 4 periodically generates an initial data sequence Seq. In the described example, the initial sequence Seq is a maximum-length pseudo-random binary sequence consisting of "0"s and "1"s, also known as the M-sequence, with a duty cycle of 50%.

[0079] In the second step, the modulation unit 22a modulates the first light beam F1a emitted by the first light source 23a of the light-emitting module 21 based on the data sequence Seq, for example by controlling the power supply supplied to the first light source 23a.

[0080] In the described example, modulation unit 22a includes a generator for a pulse frequency modulation control signal. This control signal can be used to control the switch-mode power supply (not shown) of the first light source 23a. Conventionally, the frequency setting value of this control signal (set by modulation unit 22a) can therefore be used to control the average electrical power supplied to the first light source 23a, and thus to control the luminous intensity of the first beam F1a.

[0081] Therefore, modulation unit 22a converts the data sequence Seq into a modulation signal and uses this modulation signal to modulate the initial control signal. In other words, the first beam F1a emitted under the control of the modulation signal Sseq consists of a train of optical pulses. The pulses occur successively at a sufficiently high variable frequency (e.g., greater than 100 kHz, or greater than 1 MHz, particularly between 50 MHz and 100 MHz) so that the human eye can no longer distinguish them. Furthermore, the amplitude, width, and / or position of each pulse relative to the period allow the first beam F1a to transmit the data sequence to the receiving module 3.

[0082] It should be noted that in the described example, each optical pulse corresponds to a bit with a value of "1" in the modulation sequence Seq. Therefore, the average power of the portion of the first beam F1a containing the sequence Seq is defined by the following: the proportion of bits with a value of "1" in the sequence Seq to the total number of bits in the first sequence Seq, and the pulse duration T. p And the peak power P of these pulses p .

[0083] It should also be noted that other types of modulation can also be used within the scope of this invention, and in particular pulse code modulation (PCM), pulse amplitude modulation (PAM), pulse width modulation (PWM), or pulse position modulation (PPM).

[0084] In parallel with the second step, the control unit 22 determines the duty cycle DC, and the drive unit 22b controls the power supply to the second light source 23b according to the duty cycle.

[0085] In the described example, the driving unit includes a generator for a pulse width modulation control signal Spwm, which is based on a duty cycle DC. This control signal can be used to control the switch-mode power supply (not shown) of the second light source 23b. Conventionally, the duty cycle DC of this control signal (set by the control unit 22) can therefore be used to control the average electrical power supplied to the second light source 23b, and thus to control the luminous intensity of the second beam F1b.

[0086] In other words, the second beam F1b, emitted under the control of the signal Spwm, consists of a train of light pulses. The pulses occur sequentially at a sufficiently high variable frequency (although significantly lower than the frequency of the first beam F1a, for example, approximately 1 kHz) so that the human eye can no longer distinguish them. It should be noted that in the illustrated embodiment, the driving unit 22b is of a low-frequency type, while the modulation unit 22a is of a high-frequency type.

[0087] In addition, the duty cycle DC will be determined by the control unit 22, so that the pulse duration T of the second beam F1b is... H The period T of these pulses is compared with the duration T of the pulse of the first beam F1a. P Much longer.

[0088] More specifically, in this invention, the peak power P of the pulse of the first beam F1a p This can be significantly increased relative to known solutions, as long as this increase in power does not affect the power of the second beam F1b. Therefore, the detection distance can be increased and the signal-to-noise ratio of the telemetry function can be reduced.

[0089] However, the average power of the overall beam formed by the first beam F1a and the second beam F1b is constrained by regulatory requirements regarding the optical functions that this overall beam must perform. Based on the duty cycle of the data sequence Seq, the peak power P... p As well as the type of optical function that the overall beam must perform, calculation unit 4 can therefore determine the duty cycle DC so that the ratio of blue to yellow in the overall beam is correct and meets the regulatory requirements for the optical function.

[0090] Therefore, the beam consisting of the first beam F1a and the second beam F1b is emitted until it reaches an object O in the vehicle environment, which reflects the beam in the direction of the receiving module 3. Therefore, the beam F2 received by the receiving module consists of the portion of the overall beams F1a and F1b reflected by the object O and noise, such as that generated by stray light sources (e.g., city lighting, automotive lighting, or even the sun).

[0091] like[ Figure 1As shown, the receiving module 3 includes an optical unit 31, and a plurality of basic acquisition modules 32 are disposed downstream of the optical unit. The receiving module 3 also includes a demodulation unit 33.

[0092] Each of these basic acquisition modules 32 includes a photodetector 32a and a blue light filter 32b arranged in front of the photodetector 32a. Therefore, the light beam F2 received by the receiving module 3 is focused by the optical unit 31 onto one or more of these photodetectors 32a after passing through the filter 32b.

[0093] Each filter 32b is a bandpass blue light filter with a transmission peak centered at a wavelength of 450 nm. The bandpass blue light filter allows light with wavelengths between 440 nm and 460 nm to pass through, while the rest is absorbed by the filter 32b.

[0094] When sunlight conditions near the vehicle are particularly bright, sunlight is added to the beam F2 received by receiver module 3. Light from the sun in the visible spectrum is much brighter than light from optical functions (such as daytime running lights). Therefore, the beam F2 received by receiver module 3 is primarily composed of beams F1a and F1b emitted by transmitter module 2 and sunlight. For wavelengths within the visible light range, the intensity level of beam F2 far exceeds that of beam F1. On the other hand, due to some light absorption by the atmosphere, there are valleys in the solar spectrum where light levels are low or even zero. This is especially true for wavelengths between 440 nm and 460 nm in the visible spectrum.

[0095] Therefore, each filter 32b can be used to first minimize the influence of the sun by filtering out all wavelengths of the beam F2 (except for the range of wavelengths that include the peak of the spectrum of the emitted first beam F1a), and secondly minimize the component of the second beam F1b on the beam F2.

[0096] It should also be noted that filter 32b can then be used to retain only the component of beam F2 corresponding to the light from the first light source 23a, which emits yellow light rays with a longer response time due to the delay introduced by photoluminescence. Therefore, detection is performed based solely on the blue light received by receiver 3, thereby improving the resolution of the time-of-flight assessment of beam F2 and / or the data transmission rate between transmitter 2 and receiver 3.

[0097] The photodetector 32a is identical, and each is formed from an avalanche photodiode of a silicon photomultiplier. These photodiodes are distributed in an array. It should be noted that the size of the photodetector is in the micrometer range. Therefore, this assembly forms a sensor with a receiving spatial resolution on the order of 1° or even 0.1°, and its detection capability is particularly high even under degraded acquisition conditions due to the use of avalanche photodiodes.

[0098] In the third step, each of these photodetectors 32a converts a portion of the received beam F2 into an electrical signal Sel that is transmitted to the demodulation unit 33, from which the demodulation unit can then extract the so-called demodulated data sequence Seq2 in the fourth step.

[0099] In the described example, demodulation unit 33 can, for example, count from the electrical signal Sel in time with pulse duration T. p The number of photons received by the basic acquisition module 32 during the corresponding time interval is then compared with the peak power P. p The thresholding of the determined values ​​is used to determine whether the number of photons corresponds to a pulse of the first beam F1a, and therefore whether it corresponds to a bit with a value of "1" or a bit with a value of "0".

[0100] The demodulated binary sequence Seq2 is then transmitted to computing unit 4, which estimates the value of the correlation function Fcorr between the modulated sequence Seq and the demodulated sequence Seq2 in the fifth step.

[0101] Therefore, computation unit 4 evaluates the cross-correlation value between the demodulated sequence Seq2 and the modulation sequence Seq delayed according to each of these time shift values ​​by means of a circular convolution multiplication for multiple time shift values.

[0102] Given the autocorrelation and cross-correlation properties of pseudo-random binary sequences, the correlation function Fcorr will be the largest for the time shift value corresponding to the time of flight between the time when beams F1a and F1b are emitted by the transmitting module 2 and the time when they are received by the receiving module 3. The modulation sequence Seq delays this value, and therefore basically corresponds to the demodulation sequence Seq2, excluding noise.

[0103] In the sixth step, the calculation unit 4 identifies the maximum value of the correlation function Fcorr and estimates the flight time τ of the beams F1a and F1b between the object O and the vehicle, the value of which is associated with the maximum value.

[0104] In the seventh step, calculation unit 4 estimates the distance d between object O and vehicle.

[0105] Now refer to [ Figure 5This describes an exemplary embodiment of the optical unit 24.

[0106] exist[ Figure 5 In the example, the optical unit 24 includes a cylindrical light guide 5 formed from a single solid part, which is made of, for example, polymethyl methacrylate (PMMA) or polycarbonate (PC).

[0107] The light guide 5 includes a coupling surface 51 or an incident surface, and a first light source 23a and a second light source 23b are disposed opposite to the coupling surface or the incident surface.

[0108] In the described example, the light-emitting module 21 includes three first light-emitting sources 23a aligned along the diagonal of the coupling surface 51 and two second light-emitting sources 23b aligned along another diagonal of the coupling surface 51 intersecting the first diagonal. Other arrangements of the first light-emitting sources 23a and the second light-emitting sources 23b are contemplated without departing from the scope of the invention.

[0109] The light guide 5 includes three parts: a mixing portion 52 extending from the coupling surface 51, a joining portion 53 extending from the mixing portion 52, and a main portion 54 extending from the joining portion 53.

[0110] The coupling surface 51 is used to couple light rays emitted by the first light source 23a and the second light source 23b and enter the guide 5 via the coupling surface 51. The light rays thus propagate in the light guide 5 by total internal reflection.

[0111] Furthermore, the mixing section 52 has a hexagonal cross-section S52 and contains no decoupling components to prevent light from propagating through total internal reflection. Therefore, this hexagonal cross-section is used to optimize the mixing of light emitted by the first light source 23a and the second light source 23b, so that the color of the overall beam is spatially homogenized.

[0112] The main part 54 has a generally circular cross section S54 and includes prisms 54a on a portion of the periphery of the main part, which define the exit surface 54b of the light guide 5 on the opposite portion of the periphery of the main part 54.

[0113] These prisms 54a form decoupling elements that reflect light propagating in the guide toward the exit surface 54b by total internal reflection. This exit surface is therefore a common exit surface for light emitted by the first light source 23a and the second light source 23b.

[0114] It should be understood that, without departing from the scope of the invention, the same advantages can be obtained for light-emitting systems that include a turquoise first light source, especially when the light-emitting system includes a turquoise optical filter.

[0115] The above description clearly explains how the present invention achieves its set objective: to provide a light-emitting system for motor vehicles capable of performing both a given legally mandated optical function and a telemetry function, wherein, while meeting the regulatory requirements for the optical function, the power of the beam component performing the telemetry function can be increased without increasing the number of light sources. These objectives are achieved, in particular, firstly by means of an emitting module comprising two light sources, one dedicated to performing the telemetry function, and the other supplementing the first to perform the optical function.

[0116] In any event, the invention is not limited to the embodiments specifically described in this document, but is particularly extended to all equivalent devices and any technically operable combinations thereof. In particular, the emitting module may be configured to have other configurations, and specifically, the emitting module may be configured to use light source types other than those described, such as laser diodes, VCSELs, SLEDs, or RGB diodes, or to use optical unit types other than those described, such as light guide plates. It may also be provided to perform optical functions other than those described, and particularly low beam illumination functions, or position light or turn signaling functions. Wavelength ranges other than those described are also contemplated.

Claims

1. A light-emitting system (1) for a motor vehicle, the light-emitting system comprising an emitting module (2), the emitting module comprising: The light-emitting module (21) includes a first light source (23a) capable of emitting a first light beam (F1a) and a second light source (23b) capable of emitting a second light beam (F1b), wherein the spectrum (S1) of the first light beam has a first peak (P1) smaller than the intermediate wavelength, and the spectrum (S2) of the second light beam has a second peak (P2) larger than the intermediate wavelength, wherein the intermediate wavelength is greater than or equal to 490 nm; and a control unit (22) designed to control the first light source and the second light source to simultaneously emit the first light beam and the second light beam, wherein the control unit includes a modulation unit (22a) capable of receiving a data sequence (Seq) and designed to modulate the emitted first light beam based on the received data sequence.

2. The light-emitting system (1) as described in the preceding claim, characterized in that, The intermediate wavelength is 490 nm.

3. The light-emitting system (1) as described in the preceding claim, characterized in that, The first light source (23a) is designed such that the spectrum (S1) of the emitted first light beam (F1a) has a first peak (P1) in the range between 380 nm and the intermediate wavelength, and the second light source (23b) is designed such that the spectrum (S2) of the second light beam (F1b) has a second peak (P2) in the range between 520 nm and 580 nm.

4. The light-emitting system (1) as described in the preceding claim, characterized in that, The first light source and the second light source (23a, 23b) are designed such that the overlap bands of the spectra of the first light source and the spectra of the second light source (S1, S2) are essentially zero.

5. The light-emitting system (1) as described in any one of the preceding claims, characterized in that, The first light source (23a) includes a generator (23a1) capable of emitting the first light beam (F1a), the first light source has no photoluminescent element, and the second light source (23b) includes a generator (23b1) capable of emitting light and a photoluminescent element (23b2) capable of absorbing most of the light and emitting the second light beam (F1b).

6. The light-emitting system (1) as described in any one of the preceding claims, characterized in that, The control unit (2) includes a drive unit (22b) for supplying power to the second light source (23b). The control unit is designed to control the drive unit using a pulse width modulation signal (Spwm) with a duty cycle (DC) greater than the duty cycle of the received data sequence (Seq).

7. The light-emitting system (1) as described in the preceding claim, characterized in that, The control unit (2) is designed to set a peak power value (P) of the pulse forming the first beam (F1a) based at least on the duty cycle of the received data sequence (Seq). p The duty cycle (DC) of the pulse width modulation signal (Spwm) is determined.

8. The light-emitting system (1) as described in any one of the preceding claims, characterized in that, The light-emitting module (21) includes optical units (24, 5), which are capable of receiving the first light beam and the second light beam (F21a, F21b) and have a common exit surface (54b) for the first light beam and the second light beam.

9. The light-emitting system (1) as described in the preceding claim, characterized in that, The optical unit (24) includes a light guide (5) having at least one coupling surface (51) for the first beam and the second beam (F1a, F1b), the guide being designed such that light coupled via the coupling surface propagates in the guide by total internal reflection, the guide including a decoupling element (54a) capable of decoupling light propagating in the guide along the direction of the common exit surface (54b), and the guide including a mixing portion (52) between the coupling surface and the decoupling element for coupling the first beam and the second beam to the light guide.

10. The light-emitting system (1) as described in the preceding claim, characterized in that, The light guide (5) has a generally cylindrical shape, and the cross section (S52) of the guide at the mixing portion (52) is polygonal.

11. The light-emitting system (1) as described in any one of the preceding claims, characterized in that, The light-emitting system includes a receiving module (3) capable of receiving a light beam (F2), wherein the receiving module includes at least one basic acquisition module (32), the at least one basic acquisition module includes a photodetector (32a) capable of converting the received light signal into an electrical signal (Sel), the light-emitting system includes a computing unit (4), the computing unit is designed to generate a modulation data sequence (Seq) and transmit the modulation data sequence to the modulation unit (22a) to emit the modulated first light beam (F1a) by the light-emitting module (21); and the computing unit is designed to determine the time of flight (τ) between the emission of the modulated first light beam and the reception of the received light beam by the receiving module (3) based on the electrical signal converted by the photodetector based on the received light beam.

12. The light-emitting system (1) as described in the preceding claim, characterized in that, The light-emitting system includes a demodulation unit (33) connected to the photodetector (32a) and designed to extract a data sequence (Seq2) called the demodulated data sequence from the electrical signal (Sel) converted by the photodetector; and the computing unit (4) is capable of receiving the data sequence demodulated by the demodulation unit from the electrical signal converted by the photodetector based on the beam (F2) received by the receiving module (3), the computing unit being designed to estimate the value of the correlation function (Fcorr) between the demodulated data sequence and the modulated data sequence (Seq), and to determine the time of flight (τ) between the emission of the modulated first beam (F1) and the reception of the received beam based on the value of the correlation function.

13. The light-emitting system (1) as described in any one of claims 11 and 12, characterized in that, The basic acquisition module (32) includes a filter that allows light corresponding to the first peak (P1) of the first beam (F1a) to pass through, such as blue light or turquoise light.

14. The light-emitting system (1) as described in any one of the preceding claims, characterized in that, The transmitting module (2) is arranged in the headlight of the motor vehicle.

15. The light-emitting system (1) as described in the preceding claim, wherein, The transmitting module (2) is designed such that the first beam and the second beam (F1a, F1b) together contribute fully or partially to performing a predetermined statutory optical function.

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