Vehicle lighting system comprising means for emitting a luminous signal coded at very high frequency

Abstract

The present invention relates to a vehicle lighting system (1) comprising a left front lighting device (22) and a right front lighting device (24) that are each able to project a lighting beam (222, 242), means for emitting a luminous signal coded at high frequency to the world outside the vehicle (2), and means for receiving such a luminous signal. According to the invention, the lighting system comprises a luminous device (26) arranged on the vehicle (2) between the lighting devices (22, 24), obstacle-detecting means (40), and means (38) for decoding a luminous signal received by the luminous device (26), which are able to deliver at least one value representative of a time shift between the luminous signal received by the luminous device (26) and a luminous signal sent, by the luminous device (26), to the obstacle-detecting means (40).

Description

Vehicle lighting system comprising means for emitting a very high frequency coded light signal

[0001] The present invention relates to the fields of automobiles and optoelectronics. More specifically, it relates to a lighting system for a vehicle.

[0002] In recent vehicles, LED assemblies are commonly used to create external lighting devices such as headlights or signal lights. These LED assemblies provide sufficient light intensity to ensure regulatory lighting functions and ensure an advantageous power-to-consumption ratio.

[0003] These sets of diodes also make it possible to create light signatures specific to each vehicle brand and are expected to be a future means of communication between vehicles or with road infrastructure, using optical communication technology such as VLC (Visible Light Communication) for example.

[0004] The inventors have discovered that other applications are possible, such as an obstacle detection application, by increasing the bandwidth of the light-emitting diodes, either by equalization techniques, or by using diodes smaller than 300 micrometers, or by combining these techniques. This application may require the use of a specific type of driver such as a high-speed driver or a laser driver.

[0005] Indeed, the bandwidth of a conventional light-emitting diode with a side of one millimeter is approximately 5 MHz (MegaHertz), and is therefore sufficient to enable light communication between vehicles or between a vehicle and a road infrastructure. However, this bandwidth is not suitable for obstacle detection applications. Such an application is nevertheless carried out optically in certain vehicles using LiDAR (Light Detection And Ranging) technology based on laser sensors allowing analysis of the reflected signal over a bandwidth of the order of several tens of MegaHertz, or even a few hundred MegaHertz. LiDAR systems embedded in vehicles are nevertheless very expensive.

[0006] The inventors have therefore made it possible to replace this expensive vehicle obstacle detection technology with vehicle lighting devices based on light-emitting diodes which, in addition to regulatory lighting functions, also perform an obstacle detection function.

[0007] However, the lighting devices are located on the sides of the front of the vehicle, and the regulations impose a distance between these lighting devices. As a result, there is an unlit area in front of the vehicle between these lighting devices. This constraint therefore does not allow the detection of obstacles located near the vehicle and in front of the vehicle, with the technology developed by the inventors, which in particular does not allow its use by a vehicle parking assistance system.

[0008] The present invention aims to remedy at least in part the drawbacks of the prior art by providing a vehicle lighting system based on light-emitting diodes, making it possible to detect obstacles in a parking situation, and an associated vehicle.

[0009] To this end, the present invention provides a lighting system for a vehicle, the lighting system comprising an optical assembly comprising a left front lighting device and a right front lighting device each capable of projecting a lighting beam, the optical assembly further comprising means for emitting a high-frequency coded light signal towards the outside of the vehicle, comprising photonic emitters, and means for receiving such a light signal arriving from outside the vehicle, comprising photonic receivers, characterized in that the optical assembly further comprises a lighting device intended to be arranged on the vehicle between the lighting devices, the lighting device comprising at least some of the photonic emitters and at least some of the photonic receivers, and in that the lighting system further comprises obstacle detection means,and means for decoding a light signal received by one of the photonic receivers of the light device, capable of providing at least one value representative of a time shift between, on the one hand, the light signal received by the photonic receiver of the light device and, on the other hand, a light signal sent by at least one of the photonic transmitters of the light device, to the obstacle detection means.,

[0010] The lighting beams emitted by the lighting devices are, for example, regulatory lighting lights such as high beam or dipped beam headlights. However, they do not allow light to be emitted in an area close to the vehicle located at the front of the vehicle between the two lighting devices. The lighting device of the lighting system according to the invention comprises light-emitting diodes for illuminating this area, and is coupled to the obstacle detection means, implemented at least in part in a computer of the vehicle. It therefore makes it possible to avoid obstacles located in this area.

[0011] In one embodiment, the photonic emitters are configured to emit wavelengths in the visible spectrum. For example, the photonic emitters may be light-emitting diodes.

[0012] In one embodiment, the photonic emitters and the photonic receivers of the light device are not directional, that is to say that their emission or reception surfaces are mounted fixed parallel to the front face of the vehicle, no mirror or other light device in the vehicle modifying the direction of emission of the light signals emitted or received by the light device. Indeed, the main function of the light device is obstacle detection, which is more easily implemented with emitters and receivers oriented in the same way.

[0013] According to an advantageous characteristic of the lighting system according to the invention, at least one of the lighting devices comprises another part of the photonic emitters of the emission means and another part of the photonic receivers of the reception means. Preferably, the two lighting devices of the optical assembly comprise photonic emitters and photonic receivers. The lighting devices thus also participate in a communication and / or obstacle detection function, managed from a computer of the vehicle.

[0014] In one embodiment, the photonic emitters of the at least one of the lighting devices are of the same type as the photonic emitters of the lighting device. This simplifies the processing of the signals that are to be transferred to the lighting devices and to the lighting device to perform the obstacle detection function. Indeed, there is no need to convert signals between different formats and / or different to adapt to the type of photonic emitter. For example, the photonic emitters of the at least one of the lighting devices are configured to emit wavelengths in the visible spectrum. Preferably, they are light-emitting diodes.

[0015] In addition or as a variant, the photonic receivers of at least one of the lighting devices are of the same type as the photonic receivers of the lighting device. Thus, in the proposed lighting system, the lighting devices and the lighting device are designed in the same way with regard to the obstacle detection aspect. Of course, this does not prevent each of these devices from having additional configurations to perform another function, for example the lighting function for the lighting devices and the light decoration function for the lighting device.

[0016] The decoding means are for example capable of decoding a light signal received by one of the photonic receivers of the lighting device, and of providing at least one value representative of a time shift between the light signal received by the photonic receiver of the lighting device and a light signal sent by at least one of the photonic emitters of the lighting device, to the obstacle detection means. Thanks to the invention, obstacle detection is possible over the entire area in front of the vehicle by using the light-emitting diodes of the lighting devices and of the light device.

[0017] Advantageously, the light device is also capable of performing a display or signaling function. The light device is, for example, capable of performing a communication function by display, or by projecting signs onto the roadway, or by VLC communication.

[0018] According to an advantageous characteristic of the invention, the transmission means comprise means for coding a high-frequency signal intended to be transmitted by photonic transmitters of the light device, at a frequency of between 5 and 200 MHz. Such a frequency makes it possible to carry out the obstacle detection function. Preferably, the frequency of the light signal transmitted by the transmission means is, however, between 30 and 150 MHz.

[0019] According to another advantageous characteristic of the invention, the transmission means are configured to transmit to the photonic emitters of the lighting device an electrical signal encoding a first sequence of square pulses, and to transmit to the photonic emitters of the lighting device an electrical signal encoding a second sequence of square pulses. The first sequence of square pulses is preferably different from the second sequence of square pulses. This avoids interference between the signals emitted by the lighting devices, and the signals emitted by the lighting device, for obstacle detection. Alternatively, the first sequence of square pulses is identical to the second sequence of square pulses.In both cases, whether the first sequence is identical or different from the second sequence, in an alternative embodiment limiting this interference: - the electrical signal encoding the first sequence of slots has a lower electrical power than an electrical power of the electrical signal encoding the second sequence of slots, and / or - the first sequence of slots is sent at a frequency different from a sending frequency of the second sequence of slots.

[0020] Preferably, the photonic emitters of the lighting devices emit the same light signal for obstacle detection. Indeed, the risk of interference between the lighting devices is low at short distances from the vehicle. In addition, if the distance to the obstacle is large enough, the reception by one of the lighting devices of a light signal emitted by the other lighting device will give an analysis of the distance to the obstacle with sufficient accuracy.

[0021] In one embodiment of the invention, in the lighting system according to the invention, the decoding means comprise means for thresholding a light signal received by one of the photonic receivers of the lighting system, providing a thresholded light signal, and means for correlating the thresholded light signal with a light signal sent by at least one of the photonic emitters of the lighting system, the correlation means providing a value representative of a time shift between the thresholded light signal and the light signal sent by the photonic emitter of the lighting system, and the obstacle detection means comprise means for converting the representative value from the correlation means into a distance relative to an obstacle. The thresholding means make it possible in particular to eliminate the light components due to sunlight.

[0022] The invention also relates to a vehicle comprising a lighting system according to the invention, in which the left front lighting device is arranged on a left front part of the vehicle, the right front lighting device is arranged on a right front part of the vehicle, and the lighting device is arranged on a front face of the vehicle between the left front lighting device and the right front lighting device. Thus, the lighting system as proposed takes advantage of the space available on the front face to install a lighting device participating in the detection of obstacles in front of the vehicle. The lighting device and the right and left front lighting devices make it possible to cover the entire scene in front of the vehicle, which increases the driving safety of the vehicle.

[0023] In one embodiment of the invention, the emitting surface of the photonic emitters of the light device and the receiving surface of the photonic receivers of the light device are fixedly mounted parallel to the front face of the vehicle. This is a simple and effective arrangement which is suitable for the position of the light device on the front face of the vehicle.

[0024] In one embodiment, the lighting device is arranged at least partially offset downwards relative to the lighting devices. Here, the term 'down' is defined relative to the vertical direction. This makes it possible for the lighting device to provide obstacle detection at a lower level than the lighting devices. Therefore, the proposed lighting system makes it possible to cover not only the width of the scene in front of the vehicle but also the height, or different levels of the scene. Here, the width corresponds to the horizontal lateral dimension of the vehicle and the height to the vertical dimension of the vehicle.

[0025] Other characteristics and advantages of the invention will become apparent from the following description on the one hand, and from several examples of embodiment given for informational and non-limiting purposes with reference to the attached schematic drawings on the other hand, in which:

[0026] represents a vehicle according to the invention, provided with a lighting system according to the invention, in one embodiment of the invention, and

[0027] schematically represents in more detail the lighting system of the, used to detect an obstacle.

[0028] According to an embodiment of the invention shown, a vehicle 2 according to the invention comprises a lighting system 1. The lighting system 1 comprises an optical assembly. The optical assembly comprises a left front lighting device 22, arranged on a left end of the front face of the vehicle 2, a right front lighting device 24 arranged on a right end of the front face of the vehicle 2, and a lighting device 26 arranged on the front face of the vehicle 2, between the left front lighting device 22 and the right front lighting device 24. The left front lighting device 22 is capable of projecting a regulatory lighting beam 222, for example a high beam or a dipped beam. Likewise, the right front lighting device 24 is capable of projecting a regulatory lighting beam 242, for example a high beam or a dipped beam.

[0029] The regulatory lighting beams 222 and 242 generated by the front left 22 and front right 24 lighting devices leave an unlit area z at the front of the vehicle 2. The lighting device 26 comprises light-emitting diodes capable of illuminating this area z. The lighting device 26 is connected to a computer of the vehicle by a computer bus (commonly called CAN bus for the English “Controller Access Network”), and serves as a means for displaying messages by the computer. These messages are for example intended for pedestrians or other vehicles. The lighting device 26 possibly also serves as VLC communication means. The front left 22 and front right 24 lighting devices are also capable of being used by the computer as VLC communication means.

[0030] The devices 22, 24, 26 of the optical assembly of the lighting system 1 according to the invention each comprise a plurality 12 (referenced) of photonic emitters, which are, in this embodiment of the invention, blue light-emitting diodes adapted to emit white light, for example the light-emitting diodes referenced 121, 122 on the.

[0031] The light-emitting diodes 121, 122 comprise, for example, a layer of Galium-Indium Nitride (InGaN) on which a layer of phosphorus is deposited. Thus, they are suitable for producing a lighting beam of the high beam or low beam type. The light-emitting diodes 121, 122 of the lighting device 26 may, however, only emit blue light, in an alternative embodiment where the lighting device 26 is not used for display or signaling purposes.

[0032] Likewise, the devices 22, 24, 26 of the optical assembly of the lighting system 1 according to the invention each comprise a plurality 32 (referenced) of photonic receivers, which are in this embodiment of the invention, photodiodes, for example the photodiodes referenced 321, 322 on the. Of course, the lane only comprises two light-emitting diodes and two photodiodes to simplify, the devices 22, 24, 26 actually comprising many more diodes and photodiodes.

[0033] The diodes 121, 122 of the devices 22, 24, 26 of the optical assembly are part of means for emitting a light signal s1 (referenced) coded at high frequency towards the outside of the vehicle 2. Similarly, the photodiodes 321, 322 are part of means 32 for receiving such a light signal arriving from the outside of the vehicle 2. In this embodiment of the invention, in fact, the light device 26 and the front left 22 and front right 24 lighting devices are used by obstacle detection means 40 implemented at least partly in software in a computer of the vehicle 2.

[0034] More precisely, the devices 22, 24, 26 of the optical assembly are connected by the computer bus of the vehicle 2 to means 38 for decoding the light signals received by the photodiodes 321, 322, these decoding means 38 communicating via the computer bus with the detection means 40.

[0035] We will now describe in relation to the, how the lighting system 1 allows detection of an obstacle 6. In order to simplify, this description is limited to obstacle detection using the light-emitting diodes 121, 122 and the photodiodes 321, 322 of the lighting device 26, the use of the diodes and photodiodes of the front left 22 and front right 24 lighting devices to detect an obstacle being carried out in the same way. In addition, the transmission and reception means of the lighting system 1 specific to the lighting devices 22, 24 are similar to the transmission and reception means of the lighting system 1 specific to the lighting device 26.

[0036] The emission means of the lighting system 1 specific to the light device 26 comprise, in addition to the plurality 12 of light-emitting diodes, a source 10 of electrical signals in voltage square waves and an electronic control device 3 for these light-emitting diodes, connected at the input to the signal source 10 and at the output to the light-emitting diodes 121, 122 of the light device 26. To send the light signal s1, the source 10 provides a square wave signal whose width l of the square waves is approximately 10ns (nanoseconds), the frequency of the signal being 50MHz. To allow the transmission of this signal having such a high frequency level, the electronic control device 3 comprises for example a pre-equalization stage, possibly associated with an amplifier stage.Instead or in addition, the light-emitting diodes 121, 122 are chosen to be smaller than 300 micrometers so as to naturally have a cut-off frequency greater than 50 MHz. Preferably, the light-emitting diodes 121, 122 of the lighting device 26 are produced in the same substrate matrix, arranged parallel to the front face of the vehicle. The light-emitting diodes 121, 122 of the lighting device 26 can be activated individually or in groups that are small enough to allow characters to be displayed by the lighting device 26.

[0037] Furthermore, the electronic control device 3 comprises, in a known manner, a device called a “bias tee” allowing the injection of a direct voltage into the signal coming from the signal source 10, possibly amplified, before the application of the sum of this direct voltage and the square wave signal coming from the signal source 10, to the terminals of the diodes 121, 122. The application of the direct voltage makes it possible to polarize the diodes 121, 122, and to allow the emission of the light signal s1 by them.

[0038] The emission means specific to the light device 26 make it possible to send the light signal 5 at a frequency of 50 MHz and at a power such that its reflection on the obstacle 6 gives rise to a reflected light signal s2 of sufficient light power to be captured by photodiodes 321, 322 of the plurality 32 of photodiodes of the light device 26.

[0039] The reception means of the lighting system 1 specific to the light device 26 comprise, in addition to the photodiodes 321, 322, a blue light filter 8 making it possible to filter the light of the reflected light signal s2 so as to allow only the blue component of this light to pass, and a lens 9 focusing this component towards the photodiodes 321, 322. The blue light emitted by the diodes 121, 122 is in fact of greater light intensity than the intensity of sunlight and its analysis therefore makes it easier to distinguish the reflected light signal s2 from external light pollution in the process of decoding this reflected light signal s2.

[0040] The light signal s1 sent by the diodes 121, 122 encodes a specific sequence of slots of width l of 10ns, this sequence repeating cyclically. The sequence of slots is defined so as to easily evaluate a time shift between its transmission and its reception as explained below. It presents for example three slots which follow one another, then after 60ns, a single slot, then after 40 ns, two slots which follow one another, etc.

[0041] The emitted light signal s1 hits the obstacle 6 and gives rise to the reflected light signal s2. The photodiodes 321 and 322 capture the blue components of the reflected light signal s2 and of the ambient light, for example sunlight, and provide an electrical signal to an electronic control device 13 which amplifies it and provides it to the decoding means 38. The electronic control device 13 optionally comprises, in addition to an amplifier stage, a post-equalization stage.

[0042] The decoding means 38 comprise a count Nb of the photons received as a function of time t by each of the photodiodes 321, 322, and thresholding means 34 of the intensity of the light signal received by the photodiodes 321, 322 relative to the light intensity of the sunlight. This thresholding corresponds to a clipping of the counting signal Nb as a function of time t, beyond a number of photons corresponding to the light intensity of the blue component of the sunlight, which gives rise to a thresholded light signal s3. Indeed, the blue component emitted by the diodes 121, 122 being of greater intensity than the blue component of the sunlight, such thresholding makes it possible to remove the component due to the sunlight from the received electrical signal. Of course, the term thresholded light signal here actually refers to an electrical or digital signal corresponding to the thresholding of the received light signal s2.

[0043] The decoding means 38 also comprise means 36 for correlating the thresholded light signal s3 with the light signal s1 sent by the diodes 121, 122. These correlation means 36 determine a time shift τ between the thresholded light signal and the light signal s1 sent, and transmit this time shift τ to the obstacle detection means 40 of the lighting system 1. The obstacle detection means 40 convert this time shift τ into a distance relative to an obstacle 6, and therefore make it possible to detect this obstacle.

[0044] In order to allow the decoding means 38 to discard, in the analysis of the light signals received by the light device 26, the signals resulting from a reflection of a light signal emitted by the front left 22 and front right 24 lighting devices, the emission means of the lighting system 1 specific to the front left 22 and front right 24 lighting devices differ from those specific to the light device 26, in the source of square wave signals used.

[0045] Indeed, the transmission means specific to the front left 22 and front right 24 lighting devices comprise, for each of these lighting devices, a source of square wave signals and an electronic device for controlling the diodes of the lighting device 22, 24, in a manner similar to the source of square wave signals 10 and the electronic control device 3. However, while the source of square wave signals 10 transmits a first sequence of square wave signals, the sources of square wave signals of the lighting devices transmit a second sequence of square wave signals different from that transmitted by the source 10 of square wave signals. In other words, the sequence of square wave signals that constitutes this second sequence differs from the sequence of square wave signals that constitutes the first sequence, for example the second sequence has 2 square wave signals that follow one another, then after 80 ns, a single square wave signal, then after 60 ns, three square wave signals that follow one another, etc.

[0046] The square wave signal sources of the lighting devices possibly transmit this second sequence at a frequency different from the transmission frequency of the square wave signal source 10. For example, the square wave signal source 10 transmits at 50 MHz and the square wave signal sources of the lighting devices transmit at 100 MHz.

[0047] Furthermore, the light signal emitted by the light device 26 is preferably of lower power than the light signal emitted by the lighting devices 22, 24, since the light device 26 is dedicated to obstacle detection in the zone z only.

[0048] Of course, the invention is not limited to the examples which have just been described and numerous adjustments can be made to these examples without departing from the scope of the invention.

Claims

Lighting system (1) for a vehicle, the lighting system (1) comprising an optical assembly (22, 24, 26) comprising a left front lighting device (22) and a right front lighting device (26) each capable of projecting a lighting beam (222, 242), the optical assembly (22, 24, 26) further comprising means (10, 12) for transmitting a high-frequency coded light signal (s1) to the outside of the vehicle (2), comprising photonic transmitters (121, 122), and means (32) for receiving such a light signal arriving from the outside of the vehicle (2), comprising photonic receivers (321, 322), characterized in that the optical assembly (22, 24, 26) further comprises a light device (26) intended to be arranged on the vehicle (2) between the devices lighting (22, 24), the light device (26) comprising at least part of the photonic emitters (121, 122) and at least part of the photonic receivers (321, 322),and in that the lighting system (1) further comprises obstacle detection means (40), and decoding means (38) for a light signal (s2) received by one of the photonic receivers (321, 322) of the lighting device (26), capable of providing at least one value representative of a time shift (τ) between on the one hand the light signal received (s2) by the photonic receiver (321, 322) of the lighting device (26) and on the other hand a light signal (s1) sent by at least one of the photonic transmitters (121, 122) of the lighting device (26), to the obstacle detection means (40)., Lighting system (1) according to claim 1, in which the transmission means (10, 12) comprise means for coding a high-frequency signal (s1) intended to be transmitted by photonic transmitters (121, 122) of the lighting device (26), at a frequency between 5 and 200 MHz. Lighting system (1) according to claim 1 or 2, wherein the light device (26) is capable of performing a display or signaling function. Lighting system (1) according to one of the preceding claims, wherein said at least a portion of the photonic emitters (121, 122) of the light device (26) are configured to emit wavelengths in the visible spectrum. Lighting system (1) according to any one of claims 1 to 4, wherein at least one of the lighting devices (22, 24) comprises another part of the photonic emitters of the emission means (10, 12) and another part of the photonic receivers of the reception means (32). Lighting system (1) according to the preceding claim, wherein said another part of the photonic emitters of the emission means (10, 12) is of the same type as said at least one part of the photonic emitters (121, 122) of the lighting device (26). Lighting system (1) according to the preceding claim, wherein said another part of the photonic emitters of the emission means (10, 12) is configured to emit wavelengths in the visible spectrum. Lighting system (1) according to any one of claims 4 to 7, in which the decoding means (38) are capable of decoding a light signal received by one of the photonic receivers of the lighting device (22, 24), and of providing at least one value representative of a time shift between the light signal received by the photonic receiver of the lighting device (22, 24) and a light signal sent by at least one of the photonic transmitters of the lighting device (22, 24), to the obstacle detection means (40). Lighting system (1) according to any one of claims 4 to 8, wherein the transmission means (10, 12) are configured to transmit to the photonic emitters of the lighting device (22, 24), an electrical signal encoding a first sequence of slots, and to transmit to the photonic emitters (121, 122) of the lighting device (26) an electrical signal encoding a second sequence of slots. Lighting system (1) according to claim 9, wherein the first sequence of slots is different from the second sequence of slots. Lighting system (1) according to claim 9, wherein the first sequence of slots is identical to the second sequence of slots. A lighting system (1) according to any one of claims 9 to 11, wherein the electrical signal encoding the first sequence of square waves is of a lower electrical power than an electrical power of the electrical signal encoding the second sequence of square waves. Lighting system (1) according to any one of claims 9 to 12, wherein the first sequence of slots is sent at a frequency different from a sending frequency of the second sequence of slots. Lighting system (1) according to any one of claims 1 to 13, in which the decoding means (38) comprise means (34) for thresholding a light signal received (s2) by one of the photonic receivers (321, 322) of the lighting system (1), providing a thresholded light signal (s3), and means (36) for correlating the thresholded light signal (s3) with a light signal sent (s1) by at least one of the photonic transmitters (121, 122) of the lighting system (1), the correlation means (36) providing a value representative of a time shift (τ) between the thresholded light signal (s3) and the light signal sent (s1) by the photonic transmitter (121, 122) of the lighting system (1), and in which the obstacle detection means (40) comprise means for converting the representative value from the correlation means (36) into a distance from an obstacle (6). Vehicle (2) comprising a lighting system (1) according to any one of claims 1 to 14, wherein the left front lighting device (22) is arranged on a left front part of the vehicle (2), the right front lighting device (24) is arranged on a right front part of the vehicle (2), and the light device (26) is arranged on a front face of the vehicle (2) between the left front lighting device (22) and the right front lighting device (24). Vehicle (2) according to the preceding claim, in which the emission surface of the photonic emitters of the light device and the reception surface of the photonic receivers of the light device are mounted fixed parallel to the front face of the vehicle. Vehicle (2) according to claim 15 or claim 16, the light device (26) is arranged at least partially offset downwards relative to the lighting devices.

Images