Photonic sensor assembly of an optical system configured for obstacle detection

Abstract

Title of the invention: Photonic sensor assembly of an optical system configured for obstacle detection. The present invention relates to a photonic sensor assembly (32) comprising an electrically insulating support (50), photonic receivers (321, 322) positioned on the electrically insulating support (50) and together forming a light-receiving zone, and a protective wall (70) disposed to cover the reception zone. The photonic sensor assembly (32) is characterized in that a means (78) for blocking stray light rays is interposed between the reception zone and the protective wall (70). Abstract figure: Figure 2

Description

Title of the invention: Photonic sensor assembly of an optical system configured for obstacle detection

[0001] The present invention relates to the fields of optics and electronics, and finds a particular application in the automotive field. It relates more precisely to an optical system integrating an obstacle detection function, which can be installed in a vehicle.

[0002] In recent motor vehicles, assemblies of light-emitting diodes are commonly used to produce external lighting devices such as dipped beam or signaling lights. These assemblies of light-emitting diodes can also be used, in addition to their lighting functions, for obstacle detection purposes.

[0003] It is notably possible to use light-emitting diodes in LiDAR (Light Detection And Ranging) type technologies. Such LIDAR technologies, which are otherwise very expensive, then involve optical systems already on board the motor vehicle for regulatory signaling and lighting applications. The optical systems already present are adapted for this purpose for obstacle detection. For example, it is known to increase the bandwidth of light-emitting diodes, these light-emitting diodes emitting light in the visible spectrum, to use equalization techniques, to use diodes smaller than 300 micrometers, or to combine these techniques. The light-emitting diodes used are, for example, blue light diodes adapted to emit white light.

[0004] In this context, it is known that optical systems have photonic reception devices capable of receiving and processing a light signal coming from outside the vehicle.

[0005] These photonic reception devices comprise, for example, photodiodes arranged on an electrically insulating support. In addition to this electrically insulating support, the photodiodes are surrounded by air, and they are also, for example, protected by a protective wall. It is then necessary to manage optical crosstalk phenomena, in which the successive crossing of the protective wall and the air by the light signal coming from outside the vehicle creates undesirable reflections, i.e. interference. This interference resulting from the successive crossing of different media having different refractive indices can distort the information received by the photodiodes and, a fortiori, the detection of obstacles by the optical system.

[0006] The present invention aims to overcome this drawback by proposing a photonic sensor assembly within which the interference due to undesirable reflections of the light signal at each change of material is limited by the presence of a means for blocking stray light rays, this blocking means being arranged in a volume between the photodiodes and the protective wall.

[0007] The main subject of the present invention is thus a photonic sensor assembly comprising an electrically insulating support, photonic receivers positioned on the electrically insulating support and together forming a light reception zone, and a protective wall arranged to cover the reception zone, the photonic sensor assembly being characterized in that a means for blocking stray light rays is interposed between the reception zone and the protective wall.

[0008] The photonic sensor assembly according to the invention is intended to equip an optical system of a motor vehicle in the context of an obstacle detection application. The photonic sensor assembly, also called a photonic sensor device, comprises photonic receivers, in particular a sensor equipped with photon avalanche photodiodes or SPAD (Single-Photon Avalanche Diode). These photonic receivers are arranged on an electrically insulating support on which they form a zone for receiving a light signal, such a light signal providing information on the presence of obstacles within a road scene around the motor vehicle. It is understood that the photonic receivers participate in forming a sensor of the light signal within the photonic sensor assembly.

[0009] The photonic sensor assembly also comprises a protective wall, which is opposite the support electrically insulating with respect to the photonic receivers. This protective wall is for example transparent or translucent. The protective wall makes it possible to protect the photonic receivers against impacts or scratches which could damage them.

[0010] The protective wall is not pressed against the reception zone and extends away from the latter so that it forms a space, originally empty and capable of being filled with air, in accordance with what exists in the photonic reception devices of the prior art, if a filling material is not interposed between the reception zone and the protective wall.

[0011] The photonic sensor assembly comprises a means for blocking stray light rays which is arranged at least partially in this space, between the reception zone of the photonic receivers and the protective wall. The blocking means is thus arranged in a volume delimited, in a direction perpendicular to the electrically insulating support, by the reception zone and the protective wall, this volume being furthermore delimited laterally, that is to say in planes parallel to the electrically insulating support, by a protective material different from the protective wall. The blocking means is for example a grid. It is notable that the blocking means is arranged in a pre-existing volume within the photonic sensor assembly and that it does not complicate the manufacturing operations of said photonic sensor assembly.

[0012] The stray light rays blocked by the blocking means are rays that have been deflected relative to a theoretical orientation that they are supposed to take to meet the reception zone. These rays are in particular deflected by a change of direction when passing between two neighboring zones of different refractive indices. These deflected rays may in particular be rays reflected several times between the reception zone and the face of the protective wall which is opposite this reception zone, once the rays have passed through the protective wall. The light received by the reception zone is for example received by a first photonic receiver, while the stray rays are received by a second photonic receiver, which distorts the information received by the photonic sensor assembly.Furthermore, when light is reflected within the photonic sensor assembly, the stray light rays formed by these multiple reflections reach the reception area in a way that is offset from the light initially received, which distorts the information received by the photonic receivers.

[0013] The presence of the blocking means makes it possible to limit the interference phenomena likely to be generated by the successive crossing of the protective wall and the air by laterally blocking the parasitic light rays which generate this interference.

[0014] According to an optional characteristic of the invention, the blocking means comprises a plurality of walls in contact with the receiving zone and in contact with the protective wall.

[0015] The walls of the blocking means extend from the receiving zone to the protective wall. These walls are for example substantially perpendicular to a main extension plane of the receiving zone and to a main extension plane of the protective wall.

[0016] According to an optional characteristic of the invention, the photonic receivers, each composed of at least one photonic element, are arranged at a distance from each other, the blocking means being arranged to cover portions of the reception zone devoid of photonic receivers.

[0017] Each photonic receiver comprises, depending on the embodiments, a single photonic element or a plurality of photonic elements. The photonic receivers are arranged within the substrate participating in forming the reception zone. so as to be spaced apart from each other by portions of said substrate. In certain embodiments, the photonic receivers are aligned in rows within the substrate to form the reception zone, the blocking means extending at least in overlapping a space between two rows of photonic receivers, i.e. in overlapping the portions of substrate separating the photonic receivers. The arrangement of the walls is such that any stray light rays cannot, when they emanate from reflection of the light intended for a given photonic receiver, be received by another photonic receiver. The walls therefore prevent the reflection of light rays on photonic receivers neighboring the photonic receiver receiving the light for the purpose of detecting obstacles.

[0018] According to an optional characteristic of the invention, the blocking means comprises openings arranged opposite the photonic receivers.

[0019] The openings are delimited by the walls of the blocking means. These openings are for example square or rectangular in shape. Each opening is arranged opposite a given photonic receiver, so that the light coming from outside the vehicle and providing information on the possible presence of obstacles can reach said photonic receiver.

[0020] According to an optional characteristic of the invention, the blocking means comprises a filling material arranged at least in the openings.

[0021] The filling material may be a resin. The filling material is intended to be engaged in the openings of the blocking means, where appropriate engaged in the grid. A refractive index of the filling material is chosen to be close to that of the receiving wall and / or that of the receiving zone. Alternatively, the blocking means comprises a liquid disposed in the openings, this liquid having a refractive index close to that of the receiving wall and / or the receiving zone. In still other embodiments, the refractive index of the resin or of the liquid corresponds to an average between that of the receiving wall and that of the receiving zone.

[0022] According to an optional characteristic of the invention, the photonic sensor assembly comprises opaque walls arranged within the reception zone between the photonic receivers.

[0023] These opaque walls may correspond to walls of another means of blocking light rays which is itself arranged in the portions of substrate used to distance the photonic receivers.

[0024] According to an optional characteristic of the invention, the walls of the blocking means are arranged opposite the opaque walls.

[0025] Both the opaque walls and the walls of the blocking means have a function of blocking stray light rays; they differ in that the means of blocking is outside the receiving area while the opaque walls are integrated into this receiving area. The opaque walls serve as a support to immobilize the blocking means within the photonic sensor assembly.

[0026] According to an optional characteristic of the invention, the blocking means comprises a light-absorbing material.

[0027] In particular, the walls forming the means for blocking stray rays may be formed by such a light-absorbing material. The role of this light-absorbing material is to prevent the reflection of stray light rays. It may in particular be made of opaque material. It makes it possible to prevent the light dedicated to a given photonic receiver from reaching another photonic receiver.

[0028] According to an optional characteristic of the invention, the blocking means is made of a black-colored polymer.

[0029] According to an optional feature of the invention, the blocking means comprises a coating configured to absorb light.

[0030] The blocking means is for example metallic with a coating configured to absorb light which is obtained by anodizing the metallic blocking means. The coating then corresponds to a surface treatment of the blocking means. In other embodiments, a coating having light absorption properties is deposited on another material forming a support within the blocking means.

[0031] The invention further relates to an optical obstacle detection system for a motor vehicle comprising a photonic transmitter configured to emit a high-frequency coded light signal, the light signal being at least within a predefined range of wavelengths in the visible spectrum, preferably a range of wavelengths between 420 and 460 nanometers, a photonic sensor assembly according to any one of the preceding claims configured to receive a reflected light signal resulting from a reflection on an obstacle of the light signal emitted by the photonic transmitter, means for demodulating the reflected light signal, and obstacle detection means comprising means for calculating a distance to the obstacle as a function of a demodulated signal provided by the demodulation means and the light signal emitted by the photonic transmitter.

[0032] The optical obstacle detection system according to the invention is integrated within a motor vehicle. In addition to the obstacle detection function, the optical system is also configured to perform lighting and / or signaling light functions. The optical system comprises a photonic transmitter and a photonic sensor assembly respectively configured to transmit and receive a light signal. Depending on a delay between the light signal received by the photonic sensor assembly and the light signal emitted by the photonic transmitter, the optical system is capable of detecting the presence of obstacles and, if applicable, their distance from the motor vehicle.

[0033] Other characteristics, details and advantages of the invention will emerge more clearly on reading the description which follows on the one hand, and examples of embodiment given for informational and non-limiting purposes with reference to the appended drawings on the other hand, in which:

[0034] [Fig-1] illustrates, schematically, an optical obstacle detection system of a motor vehicle according to the invention, comprising in particular a photonic transmitter and a photonic sensor assembly;

[0035] [Fig.2] illustrates, schematically, a perspective view of the sensor assembly photonics of [Fig.l], a portion of a protective wall of this sensor assembly having been partially removed;

[0036] [Fig.3] illustrates, schematically, a sectional view of the sensor assembly photonics of [Fig.l] as a whole;

[0037] [Fig.4] illustrates, schematically, a sectional view of a part of the assembly photonic sensor of [Fig.l];

[0038] [Fig.5] illustrates, schematically, a top view of part of the assembly photonic sensor of [Fig.l], the protective wall having been removed.

[0039] The features, variants and different embodiments of the invention may be combined with each other, in various combinations, provided that they are not incompatible or mutually exclusive. In particular, variants of the invention may be imagined comprising only a selection of features described below in isolation from the other features described, if this selection of features is sufficient to confer a technical advantage and / or to differentiate the invention from the prior art.

[0040] In the figures, the elements common to several figures retain the same reference.

[0041] [Fig.l] illustrates, schematically, the operation of an optical obstacle detection system 1. This optical system 1 is integrated within a motor vehicle in order to perform on the one hand an obstacle detection function, and on the other hand at least one lighting function such as a lighting function or a signaling function.

[0042] The obstacle detection uses, on the face of the vehicle integrating this function, at least one photonic emitter 12, for example in each optical unit of the vehicle when the optical system 1 is intended to detect frontal obstacles, and at least one photonic sensor assembly 32, also in each optical unit of the vehicle. The photonic emitter 12 comprises for example two light-emitting diodes with blue light 121, 122, adapted to emit white light. The light-emitting diodes 121, 122 are, for example, adapted to produce a light beam of a daytime running light.

[0043] The photonic sensor assembly 32, which will be described in more detail below, is for example a sensor comprising photonic receivers 321, 322, here in the form of photon avalanche photodiodes or SPAD photodiodes (from the English Single-Photon Avalanche Diode) such as the SPAD photodiodes referenced 321, 322. For the purposes of illustration, [Fig. 1] only comprises two light-emitting diodes 121, 122 and two photodiodes 321, 322 for simplicity. Many more photodiodes are preferably used, and the daytime running lights can use many more diodes.

[0044] The photonic transmitter 12 is capable of emitting a high-frequency coded light signal s towards the exterior of the vehicle, and the photonic sensor assembly 32 is capable of receiving a corresponding reflected light signal s2, arriving from the exterior of the vehicle.

[0045] In order to form the light signal si coded at high frequency, each optical block comprises a source 10 of electrical signals in voltage square waves and a control unit 3, connected upstream of the light-emitting diodes 121, 122. To send the light signal si, the source 10 provides a square wave signal of width 1.

[0046] The light signal si sent by the diodes 121, 122 of the photonic transmitter 12 encodes a specific sequence of “slots” or light peaks of width 1, this sequence repeating cyclically. In other words, the light signal si is modulated according to a specific data sequence, called modulating. The sequence of slots is defined so as to easily evaluate a time shift between its transmission and its reception as explained below.

[0047] The reflection of the light signal s on an obstacle 6 gives rise to the reflected light signal s2 of sufficient light power to be captured by the photodiodes 321, 322 of the photonic sensor assembly 32.

[0048] The photonic sensor assembly 32 comprises, for example, in addition to the photodiodes 321, 322, a blue light filter 8 for filtering 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 generally has a light intensity lower than that of the illumination of the sun, but approaches it for wavelengths close to 460 nm. The modulation of the reflected signal s2 makes it possible to distinguish it from external light pollution in a process of demodulation of this reflected light signal s2. The demodulation process makes it possible in particular to eliminate, in the reflected light signal s2, parasitic light signals emitted by other vehicles.

[0049] More precisely, the photodiodes 321, 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 demodulation means 38. The photodiodes 321 and 322 being SPAD photodiodes, the electrical signal that they provide is equivalent to a count Nb of the photons received as a function of time t by each of the photodiodes 321, 322. Thresholding means 34 adjust the detection level of these photodiodes so as to separate in the intensity of the light signal received by the photodiodes 321, 322, the portion of light intensity due to sunlight.This thresholding corresponds to keeping in the counting signal Nb as a function of time t only the values ​​extending beyond a number of photons corresponding to the luminous intensity of the blue component of sunlight, which gives rise to a thresholded light signal s3. Such thresholding makes it possible to remove the component due to sunlight from the received electrical signal. Here, we call "thresholded light signal" an electrical or digital signal actually corresponding to the thresholding of the received light signal s2.

[0050] The demodulation means 38 comprise the thresholding means 34 which are produced in software or analog manner from a non-thresholded electrical signal coming from the photodiodes 321, 322.

[0051] The demodulation means 38 also comprise means 36 for correlating the thresholded light signal s3, once demodulated, with the light signal si sent by the diodes 121, 122 of the photonic transmitter 12. These correlation means 36 determine a time shift r between the demodulated thresholded light signal s3 and the light signal si sent, and transmit this time shift r to obstacle detection means 40 of the vehicle. The obstacle detection means 40 convert this time shift r into a distance relative to the obstacle 6, and therefore make it possible to detect this obstacle. Described otherwise, the demodulation means 38, from the reflected light signal 2 received by the photodiodes 321, 322, are capable of providing the obstacle detection means 40 with at least one value representative of a time shift r between, on the one hand, the reflected light signal s2 and, on the other hand, the light signal s1 emitted by the photonics 121, 122.

[0052] The photonic sensor assembly 32 of the optical system 1 will now be detailed in relation to FIGS. 2 to 5.

[0053] The photonic sensor assembly comprises an electrically insulating support 50 which is here a printed circuit board or PCB, for example made of an epoxy resin. This electrically insulating support 50 comprises a first face 52 and a second face 54 opposite in a direction perpendicular to the axis of the photonic sensor assembly. dicular to a main extension plane of the electrically insulating support 50. The first face 52 receives a plurality of electrical connection terminals 56, which take the form of solder points. The second face 54 carries an electronic chip 58 consisting of different layers of semiconductors and metal deposits. The electronic chip 58 is secured to the electrically insulating support 50, for example by gluing.

[0054] This electronic chip 58 is made of a substrate 59 within which the photonic receivers 321, 322 are inserted, these photonic receivers 321, 322 corresponding to SPAD photodiodes as mentioned previously. As is particularly visible in FIGS. 4 and 5, the photonic receivers 321, 322 are arranged at a distance from each other within the substrate 59. In other words, portions of substrate 59 separate the photonic receivers 321, 322 from each other. The photonic receivers 321, 322 are for example arranged in rows within the substrate 59, several rows of photonic receivers 321, 322 being arranged side by side on the electronic chip 58. Electronic equipment may be arranged within these portions of substrate 59 between the photonic receivers 321, 322.

[0055] The photonic receivers 321, 322 form a light reception area which is configured to receive the reflected light signal s2 arriving from outside the motor vehicle and comprising information on the presence of possible obstacles. This reception area comprises both the photonic receivers 321, 322 which receive and react to the light and the substrate portions 59 which are interposed between the rows of photonic receivers 321, 322.

[0056] On an edge of the reception zone formed by the photonic receivers 321, 322, the photonic sensor assembly 32 comprises cathode connection terminals 60. These cathode connection terminals 60 are connected to the electrical connection terminals 56 by means of metal wires 62, which pass through the electrically insulating support 50 for this purpose. The metal wires 62 are, for example, gold wires.

[0057] As is particularly visible in Figures 2 and 3, the electronic chip 58 does not extend over the entire second face 54 of the electrically insulating support 50. The electronic chip 58 is in fact arranged in a central zone 64 of the electrically insulating support 58, that is to say at a distance from its end edges connecting the first face 52 and the second face 54. The electrically insulating support 50 comprises, between the central zone 64 and its end edges, a peripheral zone 66. The metal wires 62 pass through the electrically insulating support 50 at the level of this peripheral zone 66, that is to say around the electronic chip 58.

[0058] The metal wires 62 being very thin and therefore easily tearable, the assembly photonic sensor 50 comprises a protective material 68 arranged to cover these metal wires 62. More generally, the protective material 68 covers the peripheral zone 66 of the electrically insulating support 50, and extends around the electrical chip 58 and therefore the reception zone formed by the photonic receivers 321, 322. The protective material 68 is for example a thermosetting resin.

[0059] The protective material 68 also extends around a protective wall 70 which covers the reception zone. This protective wall 70, for example a window, is configured to allow the light rays to pass through to the reception zone formed by the photonic receivers 321, 322, and it is for example transparent. The protective wall 70 protects the photonic receivers 321, 322 from external aggression or from dust.

[0060] The protective wall 70 has an internal face 72 facing the reception zone and an external face 74 oriented towards an exterior of the photonic sensor assembly 32. If the internal face 72 faces the reception zone, it is however at a distance from the latter so that there is a non-zero distance between the internal face 72 of the protective wall 70 and the electronic chip 58 carrying the photonic receivers 321, 322 which form the reception zone. It is thus understood that there is a space 76 between the protective wall 70 and the reception zone, this space 76 being delimited laterally by the protective material 68.

[0061] In [Fig.4], the light arriving from outside the motor vehicle, and in particular here light comprises the reflected light signal s2, is represented by a solid black arrow. The main trajectory of these light rays, carrying the reflected light signal s2, is such that the light rays successively pass through each of the layers of the stack formed by the protective wall 70, the space 76 and the reception zone. More particularly, the light carrying the light signal s2 enters the protective wall 70 via its external face 74, exits via the internal face 72, passes through the space 76 and then reaches the reception zone formed on the electronic chip 58, the light signal s2 then reaching the photonic receivers 321, 322.

[0062] Each of the layers of the stack formed by the protective wall 70, the air-filled space 76 and the receiving zone has a given refractive index. The passage from one layer to the other, depending on the refractive index differential between the two successive layers, is likely to generate reflected light rays. In other words, reflected light rays are likely to be generated at various levels, namely at an interface between the exterior of the vehicle and the protective wall 70, i.e. at the external face 74, at an interface between the protective wall 70 and the space 76, i.e. at the internal face 72 and finally at an interface between the space 76 and the receiving area, i.e. at a surface of the electronic chip 58. Such reflected light rays are illustrated in [Fig.4] by white arrows.

[0063] Each of these light rays reflected within the stack can generate, by successive reflections, parasitic light rays, directed towards the reception zone, which are responsible for optical crosstalk phenomena.

[0064] More particularly, the presence of stray light rays which are successively reflected between the different layers of materials forming the photonic sensor assembly 32 increases the time lag r between the light signal s2 received by this photonic sensor assembly 32 and the light signal si emitted by the photonic emitter 12, which risks disturbing the analysis of this time lag T.

[0065] According to the invention, the photonic sensor assembly 32 comprises a means 78 for blocking these parasitic light rays. The blocking means 78 is interposed between the reception zone on the one hand and the protective wall 70 on the other hand, in the space 76 which is in the illustrated example filled with air. Thus, this blocking means 78 extends from the electronic chip 58 in which the photonic receivers 321, 322 are inserted to form the reception zone to the protective wall 70.

[0066] As is particularly visible in Figures 3 and 5, the blocking means 78 here takes the form of a grid. Thus, the blocking means 78 comprises walls 80 defining openings 82 between them. The walls 80 comprise, for example, first walls 80A and second walls 80B arranged perpendicular to each other so as to form a grid which covers the receiving zone. The openings 82 of the blocking means 78 are then square or rectangular in shape.

[0067] The first walls 80A and the second walls 80B are in contact with both the receiving zone and the protective wall 70. More precisely, the walls 80 extend from the internal face 72 of the protective wall 70 to the electronic chip 58, without however being inserted within the protective wall 70 or the electronic chip 58. In other words, the walls 80 are flush with the internal face 72 of the protective wall 70 and with the electronic chip 58. As can be seen in particular in [Fig. 4], the walls 80 are perpendicular to the protective wall 70 and to the surface of the electronic chip 58.

[0068] The blocking means 78 is arranged on the electronic chip 58 in such a way that its openings 82 are opposite the photonic receivers 321, 322 while its walls 80 are opposite portions of the reception zone devoid of such photonic receivers 321, 322. More precisely, the walls 80 are arranged to cover the portions of substrate 59 interposed between the rows of photonic receivers 321, 322. It is thus understood that a shape of the blocking means 78, where appropriate of the grid, is dependent on an arrangement of the photonic receivers 321, 322 within the substrate 59 and on the dimensions of these photonic receivers 321, 322.

[0069] In certain embodiments and as illustrated in [Fig. 4], trenches are formed within the reception zone of the photonic sensor assembly 32. These trenches are more precisely formed between the photonic receivers 321, 322, within the substrate portions 59 which separate them. The walls 80 of the blocking means 78 are arranged in alignment with these trenches 84. In certain variants, opaque walls 84 are arranged within the trenches 84. It is understood that the opaque walls 84 are arranged within the electronic chip 58, unlike the walls 80 of the blocking means which are in turn covering this electronic chip 58. The walls 80 of the blocking means 78 are arranged in alignment with the opaque walls 84. The trenches, and where appropriate the opaque walls 84 which they accommodate, participate in limiting the passage of the light signal s2 from one photonic receiver 321, 322 to another.

[0070] The presence of the walls 80 of the blocking means 78 in alignment with the substrate portions 59 which separate the photonic receivers 321, 322 from each other has the effect of limiting optical crosstalk phenomena. Indeed, the walls 80 make it possible to absorb the light rays likely to be reflected at each interface between neighboring layers of the stack formed by the protective wall 70, the air-filled space 76 and the reception zone. In this way, it is possible to avoid stray light rays which would otherwise be redirected towards the reception zone and which could either reach a photonic receiver 321, 322 different from that initially targeted by the light signal s2, or alter an analysis of the time shift r.

[0071] Such absorption of the light rays reflected by the walls 80 is facilitated by the presence of a light-absorbing material within the blocking means 78. In certain embodiments, the blocking means 78 is thus made of a black-colored polymer. In other embodiments, the blocking means 78 is equipped with a coating which is configured to block the reflection of light. This coating results, for example, from a surface treatment of the blocking means 78 such as anodization.

[0072] In certain embodiments, the formation of stray light rays is further avoided by providing a filling material between the walls 80 of the blocking means 78. The blocking means 78 may thus comprise a resin or a liquid disposed in the openings 82. This resin or this liquid is intended to fill the entire space 76 between the protective wall 70 and the receiving zone which is not already occupied by the blocking means 78.

[0073] As previously mentioned, each of the layers of the stack formed by the protective wall 70, the space 76 and the receiving zone has a given refractive index. The filling material arranged within the openings 82 of the blocking means 78 makes it possible to reduce the difference in refractive index between the protective wall 70 and this filling material on the one hand, and between the filling material and the receiving zone on the other hand. This limits a quantity of light rays reflected within the photonic sensor assembly 32. In this way, the quantity of stray light rays likely to propagate within this photonic sensor assembly 32 by successive reflections is limited.

[0074] In order to limit stray light rays as much as possible, the refractive index of the filling material, whether it is the resin or the liquid, is chosen so as to be between the refractive index of the protective wall 70 and the refractive index of the receiving zone, i.e. the refractive index of the electronic chip. In certain embodiments, the refractive index of the filling material corresponds to an average between the refractive index of the protective wall 70 and the refractive index of the receiving zone. In other embodiments, the refractive index of the filling material is substantially equivalent to the refractive index of the protective wall 70 and / or to the refractive index of the receiving zone. Here, the term "substantially equivalent" means a refractive index different by at most 10%.

[0075] The present invention thus proposes a photonic sensor assembly of an optical obstacle detection system within which the presence of a means for blocking stray light rays arranged between photonic receivers of the photonic sensor assembly and a protective wall thereof makes it possible to limit erroneous obstacle detections.

[0076] The present invention cannot, however, be limited to the means and configurations described and illustrated here and it also extends to any equivalent means and configuration as well as to any technically effective combination of such means.

Claims

Claims

1. Photonic sensor assembly (32) comprising an electrically insulating support (50), photonic receivers (321, 322) positioned on the electrically insulating support (50) and together forming a light reception zone, and a protective wall (70) arranged to cover the reception zone, the photonic sensor assembly (32) being characterized in that a means (78) for blocking stray light rays is interposed between the reception zone and the protective wall (70).

2. Photonic sensor assembly (32) according to the preceding claim, in which the blocking means (78) comprises a plurality of walls (80, 80A, 80B) in contact with the receiving zone and in contact with the protective wall (70).

3. Photonic sensor assembly (32) according to any one of the preceding claims, in which the photonic receivers (321, 322, each composed of at least one photonic element,) are arranged at a distance from each other, the blocking means (78) being arranged to cover portions of the reception zone devoid of photonic receivers (321, 322).

4. A photonic sensor assembly (32) according to any preceding claim, wherein the blocking means (78) comprises openings (82) disposed opposite the photonic receivers (321, 322).

5. A photonic sensor assembly (32) according to the preceding claim, wherein the blocking means (78) comprises a filler material disposed in the openings (82).

6. A photonic sensor assembly (32) according to any preceding claim, comprising opaque walls (84) disposed within the receiving area between the photonic receivers (321, 322).

7. Photonic sensor assembly (32) according to the preceding claim in combination with claim 2, in which the walls (80, 80A, 80B) of the blocking means (78) are arranged opposite the opaque walls (84).

8. A photonic sensor assembly (32) according to any preceding claim, wherein the blocking means (78) comprises a light absorbing material.

9. Photonic sensor assembly (32) according to the preceding claim, wherein the locking means (78) is made of a black colored polymer.

10. The photonic sensor assembly (32) of claim 8, wherein the blocking means (78) comprises a coating configured to absorb light.

11. Optical system (1) for detecting obstacles of a motor vehicle comprising a photonic transmitter (12) configured to emit a high-frequency coded light signal (si), the light signal (si) being at least included in a predefined range of wavelengths included in the visible spectrum, a photonic sensor assembly (32) according to any one of the preceding claims configured to receive a reflected light signal (s2) resulting from a reflection on an obstacle of the light signal emitted by the photonic transmitter, and means (38) for demodulating the reflected light signal (s2), and obstacle detection means (40) comprising means for calculating a distance to the obstacle as a function of a demodulated signal provided by the demodulation means (38) and the light signal (si) emitted by the photonic transmitter (12).

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