Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
  • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
  • G01S7/483—Details of pulse systems
  • G01S7/484—Transmitters
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
  • G01S17/88—Lidar systems specially adapted for specific applications
  • G01S17/93—Lidar systems specially adapted for specific applications for anti-collision purposes
  • G01S17/931—Lidar systems specially adapted for specific applications for anti-collision purposes of land vehicles
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
  • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
  • G01S7/481—Constructional features, e.g. arrangements of optical elements
  • G01S7/4814—Constructional features, e.g. arrangements of optical elements of transmitters alone
  • G01S7/4815—Constructional features, e.g. arrangements of optical elements of transmitters alone using multiple transmitters

Definitions

• the present invention relates to a lighting device, for a motor vehicle, suitable for object detection.
• the invention also relates to a system for assisting the driving of a motor vehicle comprising this light device.
• Lidar technology for “Light Detection And Ranging”, in Anglo-Saxon terminology
• Lidar technology the distance between the light source and the object is measured from the time lag between the emission of a laser pulse and the reception of the reflected pulse.
• An object detection device using a Lidar is relatively simple to implement because the light source emits a single high-power infrared signal which bounces off the object; the time of flight of the infrared signal is measured upon reception of said signal by a sensor.
• Such an object detection device requires specific equipment to emit the infrared signal and to receive the bounced signal.
• the light source of current light devices is generally a set of light-emitting diodes, controlled from of an attack circuit.
• light-emitting diodes, or LEDs for
• Light-Emitting Diode in Anglo-Saxon terminology
• vehicle lighting devices emit visible light continuously, which makes it difficult to detect after reflection on the object, in particular because it is combined with the natural light from the sun, street lights and other exterior light sources.
• the light beam emitted by the LEDs is then pulsed and modulated by a high frequency code.
• the modulation of the light beam must be precise; the LEDs forming the light source must therefore all emit their light rays simultaneously so as not to generate interference.
• pulse spreading degrades the signal-to-noise ratio. Indeed, all things being equal, the intensity of a simultaneous pulse is more easily detected at the sensor than the intensity of a plurality of emissions spread out over time.
• the applicant proposes a light device adapted to object detection, in which all the LEDs are connected equidistant from the circuit attack which commands them.
• the invention relates to a lighting device for a motor vehicle comprising:
• each light module comprising at least one driver circuit supplying electricity via the same driver circuit output to several light-emitting diodes , said driving circuit being configured to modulate, according to the high frequency code, an electrical power received by the light-emitting diodes in order to to emit pulsed visible light, and
• a device for receiving the light emitted by the at least one first light module, to receive part of the pulsed light, modulated according to the code, after reflection of the pulsed light emitted by the at least one first light module on an object external to the vehicle in which:
• the modulation frequency is greater than 10MHz
• each light-emitting diode is connected to the same output of the driver circuit by a conductive track, the conductive tracks connecting each of the light-emitting diodes to the driver circuit each comprising an impedance ensuring the same phase shift at the modulation frequency for all the LEDs , thus ensuring synchronous modulation of the electrical power perceived by the light-emitting diodes powered by the driving circuit.
• the characteristics of the conductive tracks such as their length, their width, their thickness and the shapes of any turns, influence their impedance and consequently the phase shift and therefore the delay of the signal perceived by an LED connected to the track.
• light-emitting diodes we mean electroluminescent sources emitting incoherent light, such as are known to be well suited to use for light devices for signaling or lighting motor vehicles, as opposed to to laser sources (including laser diodes).
• laser sources emit temporally and spatially coherent light, and have the disadvantage of posing risks to eye safety, which must be controlled by complex and expensive means.
• a device adapted to carrying out a DRL/PL function makes it possible to carry out a detection function using a large part of the LEDs necessary for the signaling function.
• a large part we mean more than 50% of the LEDs assigned to the function transmit the code, preferably more than 75%, preferably all of the LEDs transmit the code. This is particularly relevant when LEDs are similar in terms of emitting flux and activation current characteristics. In this way, to the extent that the majority of LEDs participate in the signaling function illuminating objects located in front of the motor vehicle, the detection of pulsed light from the LEDs is not disturbed by the detection of non-pulsed light. emitted by the same function. A signal-to-noise ratio of the reception of the light code by the sensor is improved.
• LEDs representing more than 50% of the luminous flux allocated to the function transmit the code, preferably more than 75% of this flow, preferably all of this flow.
• the lighting functions such as the low beam and the main beam with light-emitting diodes whose power supply is modulated at high frequency to transmit the code.
• Several light-emitting diodes are usually used to produce the low beam and the main beam, sometimes within the same light module, for example a dual-function light module.
• At least one attack circuit capable of modulating at high frequency the power supply of the LEDs of a sector grouping together the first LEDs necessary for the low beam function, according to the code
• a circuit of attack capable of modulating at high frequency the electrical supply of the second LEDs of a sector grouping together LEDs necessary for the high beam function, according to the same code, in a manner synchronized with the electrical supply of the sector of the first LEDs.
• the high beam function and/or the low beam function comprise LEDs which can be individually activated and deactivated, for example to emit a partial high beam in which lighting zones are activated or deactivated, or , alternatively or cumulatively, a low beam in which LEDs corresponding to a light cut-off are activated or deactivated so as to move a central zone of a cut-off zone horizontally relative to the vehicle when the light device is mounted on the vehicle, and thus achieve a directive low beam function, known under the name DBL (from the Anglo-Saxon abbreviation Dynamic Bending Light).
• DBL from the Anglo-Saxon abbreviation Dynamic Bending Light
• the light module of this light device is capable of sending a synchronous light beam, without risk of interference.
• the light device according to the invention is thus adapted to object detection.
• the lighting device according to one aspect of the invention may have one or more complementary characteristics among the following, considered individually or in all technically possible combinations:
• the impedance of the conductive tracks is such that the driving circuit and the light-emitting diode furthest from said driving circuit perceive the mo- dulation of the electrical power with the same delay, the conductive tracks of the light-emitting diodes least distant from the driving circuit forming delay lines.
• the length of the conductive tracks is equal to the track length between the driver and the light-emitting diode furthest from said driver
• the substrate is a rigid PCB substrate, for example a rigid FR4 type substrate, a flexible PCB substrate, for example a flexible substrate comprising polyimides, or an SMI (Insulated Metal Substrate, also known to those skilled in the art under the name Anglo-Saxon abbreviation SMI, comprising a metal base on which an insulator is laminated as well as at least one conductive layer capable of forming tracks), for example an SMI whose base is made of aluminum.
• SMI Insulated Metal Substrate
• the reception device comprises at least one light sensor and an optical blue light filter, the filter being preferably configured to allow only a wavelength band corresponding to a main band of the emission spectrum of the LEDs, and to exclude wavelengths at which LEDs emit weakly or do not emit, for example where LEDs emit at less than 50% of the intensity emitted at their maximum.
• the reception device comprises a calculation unit for comparing, in particular by correlation, the modulation of the part of the pulsed light received with the modulation of the pulsed light emitted; and to thus determine a time of flight of modulated pulsed light waves from the light module to the object so as to provide a measurement of distance between the object and the light device.
• a second aspect of the invention relates to a system for assisting the driving of a motor vehicle, characterized in that it comprises at least a first and a second light device according to the first aspect, combined one with the other for the detection of the same object.
• a third aspect of the invention relates to a system for assisting the driving of a motor vehicle, characterized in that it comprises at least a first device for detecting an object in the environment of the motor vehicle, the light device according to the first aspect constituting a second object detection device ensuring redundancy to the first object detection device.
• FIG.l schematically represents an example of a vehicle equipped with lighting devices according to the invention
• FIG.2 schematically represents an example of modulated light pulses, emitted by a light device according to the invention.
• FIG.3 schematically represents an example of three LEDs connected to a driver circuit in accordance with the invention.
• FIG.l An example of a motor vehicle 10 equipped with two light devices 100 according to the invention is shown in [Fig.l]. This example shows a pedestrian 20 crossing in front of the vehicle 10.
• the vehicle 10 is equipped with two light devices 100, for example daytime running lights, which illuminate the road scene SR at the front of the vehicle.
• the light devices 100 are integrated into a driving assistance system through which the pedestrian 20 can be detected.
• the lighting device 100 can be any basic lighting device present on a vehicle.
• the light device 100 can, for example, be a daytime running light, a position light, a signaling light, a side light strip, a front light grid or any other means of exterior lighting usually integrated on a vehicle to allow its visibility on the road; the light device is then used for pedestrian or object detection on the road scene or in the exterior environment of the vehicle.
• the light device can also be an internal lighting device in the vehicle; it can then be used for object or person detection inside the vehicle
• the light device 100 is used to emit pulsed light, modulated by a high frequency light code.
• This light code is a cyclic binary code composed of a succession of 1s and 0s, the 1s corresponding to a pulse, the 0s to non-emission of light.
• the light beam emitted by the LEDs contained in the light device is modulated to transmit the light code.
• the LEDs thus emit a succession of light pulses lasting approximately 10 to 20 ns, which corresponds to a high modulation frequency of the electrical power supply. LEDs from 10 MHz to 400 MHz, preferably 30 MHz to 200 MHz, preferably 50 to 100 MHz.
• a light device 100 comprises several light modules 110 which each include a drive circuit 120 and several white EEDs 130.
• the EEDs 130 of the same module are connected to the same attack circuit 120.
• An attack circuit 120 also called driver, is equipment allowing the direct current supply of the EEDs to which it is connected.
• a driver circuit 120 controls several LEDs 130, three in the example of [Fig.3].
• the three LEDs 131, 132, 133 connected to the driving circuit 120 are positioned at different distances from the driving circuit 120. So that the light beam emitted by the light module 110 is modulated precisely, the three LEDs 131, 132, 133 of the light module 110 must emit their light ray simultaneously.
• each of the three LEDs 131, 132, 133 is connected to the driver circuit 120 by a conductive track, respectively 141, 142, 143; these conductive tracks 141, 142, 143 are all of the same length. The length of the conductive tracks is determined based on the LED furthest from the driver circuit.
• all the conductive tracks 141, 142, 143 have a length equal to the length of the conductive track 143 making it possible to connect the driving circuit 120 to the LED furthest from said driving circuit, namely the LED 133 in the example of [Fig.3].
• the conductive track 143 connecting the Led 133 to the driver circuit 120 is therefore a conventional conductive track.
• the distance between the driver circuit and an LED is a physical distance, that is to say a “point-to-point” length determined between the control output of the driver circuit and the input terminal of the LED.
• the notion of "farthest away” must therefore be understood in terms of physical distance, the LED furthest from the driver circuit being the Led whose distance from the driver circuit is the greatest compared to the distances of the other LEDs at attack circuit.
• the notion of “more "close” must be understood in terms of physical distance, the Led closest to the driver circuit being the Led whose distance to the driver circuit is shortest compared to the distances of the other LEDs to the driver circuit.
• the physical distance between a driving circuit 120 and the LEDs 130 that it controls can vary, while the connection distance between this driving circuit 120 and these LEDs 130 is identical.
• the conductive tracks 141, 142 of the LEDs closest to the driving circuit include loops and/or detours making it possible to generate the delay lines .
• the control signal emitted by the drive circuit 120 is received simultaneously by all the LEDs connected to the drive circuit.
• the LEDs therefore emit their light rays at the same time, in a synchronized manner.
• the light beam emitted by the light module 110 is therefore synchronous, which ensures effective modulation of the light beam with all the light rays of the LEDs of the module simultaneously emitting the same bit of the code.
• the LEDs, the driver circuit and the conductive tracks are formed on a substrate. Whether they are conventional or form a delay line, the conductive tracks are made on the substrate in the same way as any conductive track, only the length of the track may vary.
• a single substrate supports all the LEDs and the driving circuit of the same module.
• all the LEDs and the driver circuit are made on the same substrate, for example a flexible or rigid PCB type substrate (for “Printed Circuit Board” in English terminology) or even an IMS substrate (Substrate Metallic Isolated).
• the conductive tracks 141-143 are therefore formed in this same substrate.
• a light module 110 may be formed on at least two substrates connected to each other by connectors, for example pin, blade or jaw. In this case, all or only some of the conductive tracks 141, 142, 143 can extend over the two substrates; the length of the conductive tracks can be determined by taking into account the delay induced by the connection between the two substrates.
• the light module 110 allows the emission of a synchronously modulated light beam.
• this light module is associated with a device for receiving the light beam reflected by the object (not visible in the figures).
• This reception device is integrated into the light device 100 of the invention. It allows light beams to be received after they have been reflected by the object that we are trying to detect.
• This receiving device comprises a sensor or a set of sensors of light ; this/these sensors can be, for example, photon counters [0034], preferably avalanche diodes.
• the photon counters are preferably distributed on the same high density substrate, preferably so as to constitute a detection matrix.
• the sensor is preferably associated with an optical blue light filter, that is to say a band-pass filter adapted to capture only light of blue wavelength and suppress all other wavelengths.
• white LEDs suitable for signaling comprise an electroluminescent chip emitting blue light and to which a phosphor adapted to transform part of the blue light into yellow light is applied, the mixture of untransformed blue lights emitted by the chip and yellow transformed by the phosphor resulting in white light.
• amber LEDs suitable for signaling include a chip emitting blue light to which a suitable phosphor is applied.
• the blue light optical filter makes it possible to separate the blue light corresponding to the majority of the light beam, in particular corresponding to the emission line of the electroluminescent chip, sent by the light module 110 and reflected by the object 20 from the rest of the spectrum of light coming from the sun or any other external light sources emitting, in the environment of the vehicle, light in the visible range. In this way, the signal-to-noise ratio of detection is greatly improved.
• This reception device is connected to a calculation unit, mounted in the light device or housed in any other location of the vehicle, preferably directly mounted on the sensor, which determines the flight time of the light beam and deduces a value therefrom. measuring the distance between the vehicle and the detected object.
• the flight time is the propagation time of the waves of the light beam emitted by the light module 110, in the environment, that is to say the time necessary for the light beam to propagate to the object and return to the receiving device.
• the distance between the object and the vehicle is determined from this flight time.
• the light device 100 as just described can be used alone for object detection, particularly if the light device is an interior lighting device for the vehicle.
• the light device 100 can also be used in combination with another similar light device.
• the two light devices 100 for example the two front lighting devices of the vehicle, can be combined with each other for the detection of the same object.
• the light device 100 can also be integrated into a driving assistance system of a motor vehicle. Indeed, driving assistance systems generally require the combination of two, or even three, distinct object detection devices, that is to say operating using different technologies. These object detection devices must be complementary.
• the light device according to the invention can constitute one of these object detection devices. It has the advantage of using a specific technology not yet used since it ensures object detection using a light beam in the visible range. It has the additional advantage of not adding mass and bulk since it uses a lighting device already present on the vehicle. It also has the advantage of being able to be implemented on several lighting devices of the same vehicle (for object detection in the same area of the vehicle or in different areas) without risk of interference, simply by choosing a different light code for each of the light devices used.
• the lighting device according to the invention comprises various variants, modifications and improvements which will be obvious to those skilled in the art, it being understood that these variations, modifications and improvements are part of the scope of the invention.
• those skilled in the art will understand that it is easy to apply the principles to other lighting devices on the exterior of the motor vehicle, for example rear signaling lights of the motor vehicle.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Computer Networks & Wireless Communication (AREA)
• General Physics & Mathematics (AREA)
• Radar, Positioning & Navigation (AREA)
• Remote Sensing (AREA)
• Electromagnetism (AREA)
• Optical Radar Systems And Details Thereof (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=85685307

Family Applications (1)

Country Status (4)

Family Cites Families (3)

• 2022
  • 2022-12-29 FR FR2214675A patent/FR3144656B1/fr active Active
• 2023
  • 2023-12-22 EP EP23836534.0A patent/EP4643151A1/de active Pending
  • 2023-12-22 CN CN202380089749.5A patent/CN120435668A/zh active Pending
  • 2023-12-22 WO PCT/EP2023/087520 patent/WO2024141438A1/fr not_active Ceased

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