Lighting module and associated occupant monitoring device

Abstract

The invention relates to an illumination module comprising at least one light source (220) designed to emit a light beam (222) consisting of a set of light rays (228), each light source having a periphery, and a reflector (223) having at least one reflective surface (224R, 225R) arranged to reflect at least partially the light beam (222). According to the invention, the reflector is configured to extend only over a portion of the periphery of the light source, so as to provide a free space. The at least one reflective surface is arranged so that, after reflection on it, at least a portion of the light rays (228) of the light beam is reflected outside the light beam emitted by the at least one light source, the portion of the light rays then passing through the free space provided at the periphery of the at least one light source. Figure for the abstract: Fig. 4

Description

Title of the invention: Lighting module and associated occupant monitoring device Technical field of the invention

[0001] The present invention relates generally to an illumination module.

[0002] It relates more particularly to an illumination module comprising at least one light source adapted to emit a light beam, and a reflector adapted to reflect the light beam(s) in order to illuminate an area of ​​interest.

[0003] It also relates to a device for monitoring the occupants of a motor vehicle comprising such an illumination module. State of the art

[0004] To increase the safety of vehicle occupants, it is known to equip the vehicle with an occupant monitoring device, particularly for the driver. Using sensors, placed notably at the front of the vehicle's passenger compartment, the driver's behavior can be monitored. Signs of inattention on the part of the driver, such as signs of drowsiness or indicators of intoxication, can trigger an alert if necessary.

[0005] For example, the behavior of occupants can be monitored using an imaging system, which generally includes an illumination module, intended to illuminate an area of ​​interest, such as, for example, the face of an occupant, as well as the torso region, or more generally, the front part of the vehicle's passenger compartment.

[0006] This illumination module is accompanied by an image acquisition module, including a camera, to capture images of the area of ​​interest illuminated by the illumination module. Finally, the assembly is generally completed by an image processing module, enabling the analysis of the acquired images and the deduction of any signs of drowsiness on the part of the occupants or the driver.

[0007] Conventional illumination modules generally comprise a set of light sources, for example light-emitting diodes, each emitting a multitude of light rays forming a light beam. This light beam can be associated with an emission angle, the value of which can be estimated from the half-width at half-height of the angular distribution of the intensity of the light source.

[0008] Typically, the emission angle of most light-emitting diodes is close to 60°, here and in the rest of the description, the symbol ° denoting a unit of angle in degrees. This results in an emission field of 120°.

[0009] Each of the light sources is then surrounded by a reflector, also called a collector. This makes it possible to concentrate the emitted light flux towards the area of ​​interest, thanks to reflective surfaces oriented towards the light source.

[0010] The combination of light sources and reflectors defines an illumination field that angularly delimits an illuminated area, corresponding to the area of ​​interest. Preferably, this illuminated area has a rectangular shape, adapted to the elongated configuration of the vehicle's passenger compartment as seen from the front of the vehicle.

[0011] On the other hand, due to the limited space generally present in the passenger compartment of a vehicle, the distance between the occupant monitoring device and the area of ​​interest is limited to a few tens of centimeters, typically in the order of 60 cm to 100 cm.

[0012] Thus, in order to have a sufficiently large illuminated area, it is necessary to have a sufficiently wide angular illumination field, for example, equal to or greater than 180°.

[0013] However, the edges of the reflectors surrounding the light sources obstruct the emitted light beams, and angularly limit the illumination field.

[0014] The illumination field is therefore known to be limited to a maximum extent of approximately 160°, less than the 180° desired for the intended application. Presentation of the invention

[0015] In this context, it is proposed to use an illumination module comprising a reflector adapted to widen the illumination field compared to the emission field of the light sources alone.

[0016] More particularly, the invention proposes an illumination module, comprising at least one light source, designed to emit a light beam, for example according to an emission cone, consisting of a set of light rays, each of the sources having a periphery and a reflector having at least one reflective surface arranged to reflect at least partially the light beam, wherein the reflector is configured to extend only over a part of the periphery of the at least one light source, so as to leave a free space, the at least one reflective surface is arranged so that after reflection, for example, after specular reflection or diffuse reflection, on the reflective surface, at least a part of the light rays of the light beam is reflected outside the light beam emitted by said at least one light source,the portion of light rays reflected outside the light beam passing through the free space at the periphery of the light source.

[0017] In other words, the reflector has a shape such that it does not surround at least one light source, and it reflects a part of the light rays that the latter emits in a direction that deviates from that of the light beam initially emitted by the light source.

[0018] Thus, thanks to the invention, it is possible to illuminate a large and close area of ​​interest, thanks to a sufficiently wide angular field of illumination. Indeed, the reflector is configured to minimize obstruction of the light beams emitted by the light sources, and the reflector's reflective surfaces adopt a shape adapted to deflect the light beams angularly in order to obtain the widest possible field of illumination.

[0019] Other advantageous and non-limiting (i.e., optional) features of the illumination module according to the invention, taken individually or in all technically possible combinations, are as follows: - At least one reflective surface is at least partially non-planar. - The at least one reflective surface is convex with respect to the at least one light source for which it is arranged to reflect at least partially the light beam. - Where at least one light source emits towards a direction called the direction of illumination, the light rays corresponding to the part of the rays reflected outside the light beam form an angle greater than or equal to 90° with the direction of illumination. The illumination module comprises a plurality of light sources, and / or the reflector comprises a plurality of reflective surfaces. The illumination module may then have a central region where the plurality of reflective surfaces of the reflector are arranged. The central region may also be surrounded by a peripheral region where the plurality of light sources are arranged so that the reflector is surrounded by the plurality of light sources. Thus, the number of elements within the illumination module is advantageously reduced, as one reflector can be used for a multitude of light sources. This can simplify the assembly of the module, in addition to reducing the overall weight and / or cost. Each of the reflector's reflective surfaces is oriented towards at least one of the light sources. For example, a reflector's reflective surface can be oriented towards one, two, or even more light sources. The number of light sources to use can be chosen, for example, according to the lighting requirements. The illumination module comprises a printed circuit board, and the plurality of light sources is fixed to the printed circuit board. The module in this case includes a a single printed circuit board, rather than a plurality, which is possible when the emission axes of the different sources are collinear rather than inclined in order to maximize the illumination field.

[0020] - The reflector is a single piece. In other words, the reflective surfaces can be joined, possibly connected by reflective or non-reflective surfaces. - At least one light source includes at least one light-emitting diode.

[0021] The invention also provides an occupant monitoring device for motor vehicles comprising an acquisition module adapted to image an area of ​​interest illuminated at least partially by an illumination module according to the invention. This monitoring device may optionally have the following features, which may be taken individually or in any technically feasible combination: - The acquisition module is placed in the central region of the illumination module. The acquisition module is at least partially surrounded by the reflector; specifically, by its side panels, the multiple light sources are arranged around the acquisition module, effectively encircling it. This configuration saves space and makes the occupant monitoring system more compact. - The motor vehicle includes a passenger compartment and the area of ​​interest for the occupant monitoring device includes at least partially a front space of the passenger compartment of the motor vehicle.

[0022] Of course, the various features, variants, and embodiments of the invention can be combined with one another in various ways, provided they are not incompatible or mutually exclusive. Detailed description of the invention

[0023] The following description with regard to the attached drawings, given by way of non-limiting examples, will make it clear what the invention consists of and how it can be carried out.

[0024] On the attached drawings:

[0025] [Fig.1] is a schematic view of a motor vehicle equipped with an occupant monitoring device comprising an illumination module according to the invention;

[0026] [Fig.2] is a schematic representation of an illumination module included in an occupant monitoring device as described in [Fig.1], representing in particular the light beams emitted by the light sources of the illumination module;

[0027] [Fig.3] is a schematic front view of the illumination module of [Fig.2], where a reflector surrounded by two light sources is notably shown; and

[0028] [Fig.4] is a schematic profile view of the illumination module of [Fig.2].

[0029] In [Fig.1], a motor vehicle 1 is shown here in the form of a car, but it could be a completely different type of motor vehicle 1 (truck, ship, plane...).

[0030] This motor vehicle 1 includes a passenger compartment, where occupants 4 are located. These occupants 4 can refer to several groups of people, such as for example, the driver alone, the driver and the front passenger, the driver, the front passenger, and the rear passenger(s), etc.

[0031] This motor vehicle 1 is equipped with an occupant monitoring device 2. The role of this device is to ensure that the occupants 4 of the motor vehicle 1 do not engage in risky behavior. In the example presented here, the case of a monitoring device 2 for the driver and the front passenger is considered.

[0032] Thus, in this example, an area of ​​interest 3 for the monitoring device 2 designates a region, preferably rectangular in shape, extending in the direction of the width of the motor vehicle 1, indicated by an axis GD, which extends from the driver to the front passenger.

[0033] Such an area of ​​interest 3, represented schematically on [Fig.1], includes in particular the face of the driver and front passenger, a portion of the torso, and the arms of the driver, when the latter adopts a classic driving posture.

[0034] Typically, the monitoring device 2 is placed at the front of the passenger compartment of the motor vehicle 1, for example in a region near an upper or lower part of the windshield of the motor vehicle 1, at the level of the dashboard of the motor vehicle 1 or in the rearview mirror.

[0035] The monitoring device 2 here relies on visual information, via the recording and analysis of images.

[0036] The monitoring device 2 thus comprises an illumination module 22, an acquisition module 20, adapted here for image acquisition and a computer 24.

[0037] According to the representation in [Fig. 1], it is assumed here that the three aforementioned elements are contained within the same dedicated housing. According to one possible variant, the computer 24 is located at a distance from the illumination module 22 and the image acquisition module 20, in which case it would be suitable for exchanging data with these two other modules, for example via an embedded network.

[0038] The acquisition module 20 acquires, at given time intervals, images of the area of ​​interest 3, and these are then analyzed by the computer 24, in order to trigger an alert if necessary.

[0039] The acquisition module 20 includes a photosensitive sensor, and imaging optics, adapted to image the area of ​​interest 3 on the photosensitive sensor located downstream of the imaging optics.

[0040] Imaging optics may in particular refer to a lens, as well as bandpass optical filters intended to eliminate any parasitic radiation emitted outside a spectral range of interest.

[0041] The photosensitive sensor comprises a set of photosensitive pixels arranged in a table. These pixels are photosensitive to a spectral range that at least partially overlaps that of the illumination module 22. This may include the visible range, or the infrared range (in particular the near-infrared range). These spectral ranges will be defined in more detail later in this description.

[0042] In order to actively illuminate the area of ​​interest 3, an illumination module 22 is used to illuminate an illumination zone corresponding at least partially to the area of ​​interest 3. Here, these two zones are represented as coinciding in Figures 1 and 2.

[0043] The spectral range chosen for the lighting is typically located in the infrared range, in particular the near-infrared, in the context of "surveillance device" type applications. Indeed, this spectral range has the advantage of being invisible to the human eye, and thus avoids dazzling the occupants. However, a spectral range of lighting in the visible range is also possible.

[0044] Thus, in this example, the illumination module 22 emits radiation within a spectral range between 700 nm and 2000 nm, or even within a spectral range extending into the visible spectrum, and therefore from 400 nm to 2000 nm. This radiation can be monochromatic, or polychromatic.

[0045] In particular, in the embodiment presented, the wavelength of illumination is 940 nm.

[0046] Next, in order to illuminate the whole area of ​​interest 3, the illumination module 22 optimally comprises a plurality of light sources 220. In particular, in the embodiment shown, the illumination module 22 comprises two light sources 220.

[0047] According to possible variants, the illumination module 22 can also include one, four, six or eight light sources 220.

[0048] These light sources 220 may refer, for example, to a light-emitting diode (also commonly referred to as an LED, or LED according to the Anglo-Saxon designation) of any type, or a vertical cavity surface-emitting laser diode (“VCSEL”, according to the Anglo-Saxon designation), or any other light source suitable for emitting radiation in the spectral range chosen for lighting.

[0049] Here, in the embodiment considered, the described illumination module 22 comprises two LEDs. It is further assumed that these two light sources 220 are identical. The use of light sources 220 with different characteristics according to variants of the invention is nevertheless conceivable.

[0050] These two LEDs can in particular emit light radiation at a wavelength around 940 nm, with a spectral width of several tens of nanometers.

[0051] As mentioned previously, in the context of a monitoring device 2, the area of ​​interest 3 ideally takes the form of a rectangle extending along the axis GD. Thus, it is desirable to illuminate an area of ​​similar shape, in order to illuminate both the driver and the front passenger.

[0052] Thus, in this embodiment, the two light sources 220 of the illumination module 22 are considered to be arranged horizontally, along the axis GD.

[0053] The two light sources 220 considered here can be separated by a few to a few tens of millimeters. For example, here, the distance between the two light sources 220 is 13 mm.

[0054] Other arrangements of the light sources 220 are possible depending on the lighting requirements or the characteristics of the light sources 220 used.

[0055] Each of the light sources 220 of the illumination module 22 emits a set of light rays 228 which forms a light beam 222. This light beam 222 is three-dimensional, and has a spatial distribution which may be inhomogeneous and devoid of rotational symmetry.

[0056] For the sake of simplicity in the following description, and in accordance with all the figures, the light beam 222 emitted by each of the light sources 220 is described as a rotationally symmetric emission cone, which corresponds to a reasonable model of the situation described. This emission cone is represented by a vertex and an angle at the vertex with respect to an axis defined as the emission axis A1, A2.

[0057] Preferably, the two emission axes Al, A2 of the two light sources 220 are collinear, so that the two light sources 220 illuminate in a common direction, called the direction of illumination. This direction of illumination is parallel to the emission axis Al, A2, and oriented towards the area of ​​interest 3. Thus, the two emission axes Al, A2 are parallel to an axis AA' describing the front-to-rear axis of the motor vehicle 1.

[0058] However, other embodiments where the emission axes A1, A2 of the different sources are not collinear can also be considered, the sources being able to be inclined with respect to the axis AA'. The direction of illumination would then remain parallel to the axis AA', and oriented towards the area of ​​interest 3.

[0059] However, the collinearity of the emission axes Al, A2 offers the advantage of being able to fix the different light sources 220 on the same printed circuit board 221. In one example of a possible embodiment, a single printed circuit board 221 serves as a support for all the light sources 220 of the illumination module 22, and also serves for the control of the different light sources 220 which are fixed to it.

[0060] Due to the spatial arrangement of the area of ​​interest 3 in relation to the passenger compartment of the motor vehicle 1, only angles measured in a plane containing the axis GD and the axis AA' will be considered in the remainder of this description, again for the sake of simplification.

[0061] For a light beam 222, the apex of the emission cone is located at the level of the light source 220, assumed to be a point source, and the angle at the apex in the plane containing the axis GD and the axis AA' corresponds to an emission angle 0e of the light source 220. This emission angle 0e can, for example, be defined as the half-width at half maximum (FWHM) of the angular distribution of the intensity of the light source 220. The value of the emission angle 0e is measured in absolute value with respect to the emission axis A1, A2. Other possible definitions for the emission angle of a light source can be used.

[0062] Such light beams 222, according to an emission cone are represented in figures 2, 3 and 4. In particular, figures 2 and 4 represent the emission angle 0e described previously.

[0063] The emission angle 0e of the light source 220 is between 0° and 90°, and varies depending on the light source 220 considered. Usually, the emission angle 0e is less than 80°.

[0064] In the embodiment considered, two light beams 222 are emitted along two distinct emission cones, each by a light source 220.

[0065] The set of light sources 220 of the illumination module define an emission field, the value of which along the GD axis of the vehicle, i.e. in the plane containing the GD axis and the AA' axis, is represented by an angle, corresponding to twice the emission angle 0e of the light sources 220, these being identical here.

[0066] The emission field of the light sources 220 is between 0° and 180°, being less than 180°. For example, in the described embodiment, the emission field of the light sources 220 is equal to 160°.

[0067] Furthermore, to prevent the edges of the printed circuit board 221 from limiting the emission field by partially obstructing the light beams 222, the light sources 220 of the illumination module 22 are placed at the end of an edge of the printed circuit board 221.

[0068] Here, the different light sources 220 are each placed a few micrometers from the end of an edge of the printed circuit 221, for example between 100 and 500 pm from the edge.

[0069] To guide the light beams 222 emitted by the light sources 220 so as to illuminate the area of ​​interest 3 optimally, the illumination module 22 also includes a reflector 223. This reflector 223 plays several functions, among which is to shape the illuminated area so that it corresponds as closely as possible to the geometry of the area of ​​interest 3, but also, for example, to distribute the light flux adequately over this area.

[0070] After reflection from the reflector 223, the light beams 222 define an illumination field, defined angularly. This illumination field differs from the emission field defined by the light sources 220 alone. This reflection corresponds, for example, to a specular reflection or a diffuse reflection, depending on the reflector 223 considered.

[0071] The illumination field is shown in Figures 1 and 2, and underlies in particular the area of ​​interest 3. It is angularly represented by twice an angle, corresponding to an illumination angle 0r. This angle is also measured in a plane containing the axis GD and the axis AA', with respect to the axis AA', or equivalently to the emission axis Al, A2 of the light sources 220, in the case where these three axes are collinear.

[0072] The reflector 223 is shown in more detail in [Fig. 3], by way of a front view.

[0073] It has a plurality of lateral walls 224, 225, 226, 227, here four in number, forming a parallelepiped-shaped volume. These lateral walls 224, 225, 226, 227 extend substantially vertically along the axis AA', in order to reflect the light rays 228 emitted by the light sources 220.

[0074] The four lateral walls 224, 225, 226, 227 of the reflector 223 are joined along the axis AA', so that the four lateral walls 224, 225, 226, 227 thus joined form a border, opening onto two ends along the axis AA'.

[0075] One end is in contact with the printed circuit board 221, or even embedded in it to a depth of 1 mm to 10 mm, thus fixing the reflector 223 onto the illumination module 22. Alternatively, the reflector 223 and the printed circuit board 221 are held by a housing 26. This housing 26 is specifically designed so as not to obstruct the passage of the light rays 228 reflected from the reflector 223. For example, the light sources 220 can be placed a few micrometers from an edge of the housing 26. This then presents a wall of low thickness and / or the wall of the housing is at least partially transparent to the spectral range of lighting.

[0076] According to variants, other solutions for retaining the reflector 223 on the printed circuit board 221 and / or the housing 26 are possible, for example by providing fixing tabs protruding from one end of the reflector 223. These tabs can then be screwed, soldered or glued onto the printed circuit board 221 and / or the housing 26.

[0077] The second end of the reflector 223, opposite the end in contact with the printed circuit 221, is left open.

[0078] In the described embodiment, the reflector 223 is thus in one piece.

[0079] According to other possible embodiments, non-contiguous side walls 224, 225, 226, 227 can also be envisaged, and the reflector 223 would then be made by means of several disjointed parts.

[0080] In the described embodiment, the dimensions of the reflector 223 are contained within a parallelepiped 10 mm wide by 3 mm high, the height being described along the axis AA'.

[0081] Here, a single reflector 223 is used to reflect all the light beams 222 generated by the plurality of light sources 220 of the illumination module 22.

[0082] The illumination module 22 comprises two distinct regions, a central region where the reflector 223 is fixed, surrounded by a peripheral region where the light sources 220 are arranged. In other words, the single reflector 223 of the illumination module 22 is placed in the center, surrounded by the various light sources 220.

[0083] Various geometric arrangements of the light sources 220 can be considered. For example, here, the two light sources 220 are aligned along the axis GD, and the reflector 223 is placed between the light sources 220. Ideally, the reflector 223 is placed equidistant from the two light sources 220, straddling an axis connecting the two light sources 220.

[0084] Thus, the two light sources 220 are diametrically opposed to each other with respect to the reflector 223.

[0085] Thus, the reflector 223 is configured so as to minimize obstruction of the passage of the light beams 222. Indeed, positioned in this way with respect to the light sources 220, that is to say, at the center of them, the reflector 223 and all of its lateral walls 224, 225, 226, 227, extend only over a part of a periphery defined around each of the light sources 220. In other words, the reflector 223 borders only one of the sides of each of the light sources 220. A free space is thus formed on the rest of the periphery of each light source 220. The light beams 222 reflected by the reflector 223 then propagate through this free space provided on the periphery of each of the light sources 220, without being obstructed by the reflector 223.

[0086] In order to reflect at least partially the light beams 222 emitted by the light sources 220 towards the area of ​​interest 3, the reflector 223 has a plurality of reflective surfaces 224R, 225R. These reflective surfaces 224R, 225R rest on the outer side of the lateral walls 224, 225 of the reflector 223, in the direction of the light sources 220.

[0087] In particular, each light beam 222 emitted by a light source 220 encounters on its optical path a single and unique reflective surface 224R, 225R.

[0088] To reflect light beams, the reflector 223 is at least partially metallized, or may be at least partially coated with a coating having a high albedo. Certain external surfaces of the reflector 223, such as those resting on the walls 226 and 227, may nevertheless be non-reflective, or even treated to limit unwanted reflections, for example by anodizing.

[0089] In the described embodiment, the reflector 223 has two reflective surfaces 224R, 225R. These two reflective surfaces 224R, 225R are diametrically opposed to each other and are each oriented towards one of the two light sources 220. In particular, these two reflective surfaces 224R, 225R are at least partially metallized in order to reflect the light beams 222 by specular reflection. Alternatively, in order to reflect the light beams 222 by diffuse reflection, a white, matte coating can, for example, cover the two reflective surfaces 224R, 225R.

[0090] After reflection on the reflective surfaces 224R, 225R of the reflector 223, the light beams 222 define the illumination field, described earlier in the description, as being equal to twice the illumination angle 0r. As mentioned previously, the reflection can be specular or diffuse on the reflective surfaces 224R, 225R of the reflector 223. Here, given that these two reflective surfaces 224R, 225R are at least partially metallized, the description focuses on the case of specular reflection.

[0091] The reflective surfaces 224R, 225R of the reflector 223 are at least partially non-planar.

[0092] Preferably, the reflective surfaces 224R, 225R of the reflector 223 have shapes configured so that the illumination field has an angular value greater than the emission field of the light sources 220 considered alone, in the absence of the reflector 223.

[0093] This means in particular that after reflection on the reflective surfaces 224R, 225R of the reflector 223, at least part of the light rays 228 from the light beam 222 of one of the light sources 220, is deflected out of the light beam 222 initially incident on the reflective surface 224R, 225R.

[0094] In other words, after reflection on the reflective surfaces 224R, 225R, a portion of the light rays 228 is deflected outside the emission cone initially defined for the emission of each of the light sources 220, and propagates through the free space provided around each of the light sources 220. This deflection of a portion of the light rays 228 out of the light beam 222 following reflection on the reflector 223 thus makes it possible to enlarge the field of illumination compared to the field of emission of the light sources 220 alone.

[0095] Here, in the described embodiment, the reflective surfaces 224R, 225R are chosen to be identical. According to variants, non-identical reflective surfaces 224R, 225R can also be chosen, depending on the area of ​​interest 3 and / or the location of the illumination module 22 relative to it.

[0096] For example, in the embodiment described here, the reflector 223 has two reflective surfaces 224R, 225R designed to obtain an illumination field greater than or equal to 180° about the axis GD. In other words, after reflection on one of the reflective surfaces 224R, 225R of the reflector 223, at least a portion of the light rays 228 forming the light beam 222 is reflected at an angle greater than or equal to 90° with respect to the emission axis A1, A2, in absolute value.

[0097] In particular, the half-field of illumination corresponding to the resulting illumination angle 0 can be 97°, for example, with at least a portion of the light rays 228 forming an angle of 97° with the emission axis A1, A2 of the associated light source 220. This results in an illumination field of 194°.

[0098] Such a reflective surface 224R, 225R, adapted to enlarge the illumination field compared to the emission field of the light sources 220 alone, has an exact shape that can be determined experimentally, or alternatively through ray-tracing simulation processes well known to those skilled in the art. A simplified explanation for establishing a suitable reflective surface shape 224R, 225R, based on concepts of geometric optics, will be provided later in this description.

[0099] The reflective surfaces 224R, 225R of the reflector 223 may, for example, have a convex shape with respect to the light sources 220 towards which they are oriented.

[0100] In particular, reflective surfaces 224R, 225R may be convex along several axes, and / or have a complex topography.

[0101] According to one embodiment, shown in figures 3 and 4, each of the reflective surfaces 224R, 225R has a first curvature along the axis AA'.

[0102] This first convex curvature of the reflective surface 224R, 225R along the axis AA' has a vertex.

[0103] Preferably, the light source 220 can be positioned at the apex of this first convex curvature, as illustrated in [Fig.3].

[0104] The degree of curvature and the exact shape of the surface along this axis AA' can be determined experimentally, or through ray tracing simulation processes, which are well known to those skilled in the art.

[0105] Here, along the axis AA', the reflective surface 224R, 225R under consideration exhibits a convex curvature with a radius of curvature that can be between a few and a few tens of millimeters. Here, the radius of curvature is chosen to be equal to 10 mm.

[0106] Next, each of the reflective surfaces 224R, 225R can also exhibit a second convex curvature along the GD axis.

[0107] Here, in the embodiment presented, each of the two reflective surfaces 224R, 225R considered has a curvature along the two axes AA' and GD.

[0108] Along the GD axis, the reflective surface 224R, 225R first follows a curve of suitable radius; for example, in the described embodiment, the curvature has a radius of a few to a few tens of millimeters, here chosen to be 1.5 mm. The reflective surface 224R, 225R is then extended by a planar section towards the printed circuit board 221.

[0109] The invention is by no means limited to the reflective surfaces 224R, 225R described above, and other surfaces can easily be selected by a person skilled in the art, so as to adapt to the different constraints, such as the size of the area of ​​interest, its shape, its distance from the illumination module, the need, or not, to obtain homogeneous lighting, etc.

[0110] The definition of a non-planar reflective surface 224R, 225R capable of reflecting a light ray 228 with a reflection angle greater than or equal to 90°, in order to have an illumination field greater than or equal to 180°, can be simply explained using the rules of geometric optics. These are well known to those skilled in the art, in particular Snell's law.

[0111] By defining a normal N at each point of the reflective surface 224R, 225R of the reflector 223, a portion of the light rays 228 included in the light beam 222 emitted by a light source 220 is incident, each at a point on the reflective surface 224R, 225R. An angle of incidence i can then be defined between the normal N and the incident light ray 228.

[0112] The incident light ray 228 is then reflected by the reflective surface 224R, 225R in a plane of incidence, containing the normal N and the incident light ray 228. The reflected light ray 228 has an angle of reflection r equal to the angle of incidence i.

[0113] An example of normal N at a point on the reflective surface 224R is drawn on figures 3 and 4, as well as the light ray 228 incident on this reflective surface 224R and the corresponding reflected light ray 228.

[0114] Thus, a reflective surface 224R, 225R of suitable shape makes it possible to partially deflect the light beams 222 following their reflection, so as to obtain an illumination field of greater width than the emission field associated with the light sources 220 alone.

[0115] The preceding explanation presents one possible method for obtaining the reflective surfaces 224R, 225R of the embodiments according to the invention. More sophisticated modeling and various optimizations of the reflective surfaces 224R, 225R using commercial or non-commercial ray-tracing algorithms and software can also be employed within the scope of the invention.

[0116] The reflector 223 can be manufactured in various ways, such as by casting a metallic material, in particular aluminium, or by injecting plastic, followed by the deposition of a metallic layer, for example by vacuum evaporation of a metal, such as aluminium.

[0117] According to one possible embodiment for the occupant monitoring device 2 4 described above, the acquisition module 20 can be fitted within the reflector 223.

[0118] In this embodiment, the acquisition module 20 is nestled between the lateral walls 224, 225, 226, 227 of the reflector 223, preferably centered within the parallelepiped volume formed by the reflector 223.

[0119] The photosensitive sensor of the acquisition module 20 is then fixed on the printed circuit board 221, surmounted by the imaging optics.

[0120] Thus, in the described embodiment, the acquisition module 20 is centered between the different light sources 220, here of which there are two. Along the axis GD, the sequence of the elements of the illumination module can be described as follows: a first light source 220, then the first of the reflective surfaces 224R resting on a lateral wall 224, then the acquisition module 20, a second lateral wall 225 on which rests on its outer face the second reflective surface 225R, oriented in the direction of the second light source 220.

[0121] The arrangement described above offers the advantage of a compact occupant monitoring device 2 4.

[0122] The assembly formed by the acquisition module 20 and the illumination module 22 (which contains a plurality of light sources 220, a printed circuit 221 and the reflector 223) can be contained in the housing 26, topped with a dome 28 made of a material optically transparent at the wavelength used in the illumination device 22.

[0123] Other examples of integrating the acquisition module 20 and the illumination module 22 to form the monitoring device 2 can also be considered.

[0124] The present invention is in no way limited to the embodiments described and represented, but a person skilled in the art will be able to make any variation in accordance with the invention.

[0125] For example, depending on lighting requirements, particularly in terms of light intensity or geometry of the area to be illuminated, more than 220 light sources can be used in the illumination module 22.

[0126] According to a first embodiment, with eight light sources 220, the reflector 223 also has eight reflective surfaces 224R, 225R arranged along the sides of an octagon. Each of the reflective surfaces 224R, 225R is then oriented towards one of the light sources 220, in order to reflect the light beam 222 that it emits.

[0127] According to a second embodiment, still with eight light sources 220, the reflector 223 has four reflective surfaces 224R, 225R, arranged along the sides of a parallelepiped. Each of the reflective faces 224R, 225R would then be oriented towards two light sources, and would thus each reflect two light beams 222.

Claims

Demands

1. Illumination module (22) comprising: - at least one light source (220) designed to emit a light beam (222) consisting of a set of light rays (228), each of the light sources (220) having a periphery, - a reflector (223) having at least one reflective surface (224R, 225R) arranged to reflect at least partially the light beam (222), characterized in that said reflector (223) is configured to extend only over a portion of said periphery of said at least one light source (220), so as to provide a free space, said at least one reflective surface (224R, 225R) is arranged so that after reflection on said at least one reflective surface (224R, 225R), at least a portion of said light rays (228) of said light beam (222) is reflected outside of said light beam (222) emitted by said at least one light source (220),said portion of said light rays (228) passing through said free space provided at the periphery of said at least one light source (220), and in which said at least one light source (220) emits towards a direction called the direction of illumination, said light rays (228) corresponding to said portion of said light rays (227) reflected outside said light beam (222) form an angle greater than or equal to 90° with said direction of illumination.

2. Illumination module (22) according to claim 1, wherein said at least one reflective surface (224R, 225R) is at least partially non-planar.

3. Illumination module (22) according to claim 2, wherein said at least one reflective surface (224R, 225R) is convex with respect to the at least one light source (220) for which it is arranged to reflect at least partially the light beam (222).

4. Illumination module (22) according to any one of claims 1 to 3, wherein said illumination module (22) comprises a plurality of light sources (220), and wherein said reflector (223) comprises a plurality of surfaces reflective (224R, 225R), said illumination module (22) has a central region where said plurality of reflective surfaces (224R, 225R) of said reflector (223) is arranged, said central region being surrounded by a peripheral region where said plurality of light sources (220) is arranged so that said reflector (223) is surrounded by said plurality of light sources (220).

5. Illumination module (22) according to claim 4, wherein said illumination module (22) comprises a printed circuit board (221), and wherein said plurality of light sources (220) is fixed on said printed circuit board (221).

6. Illumination module (22) according to any one of claims 1 to 5, wherein said reflector (223) is of one piece.

7. Illumination module (22) according to any one of claims 1 to 6, wherein said at least one light source (220) comprises at least one light-emitting diode.

8. Occupant monitoring device (2) of a motor vehicle (1) comprising an acquisition module (20) adapted to image an area of ​​interest (3) illuminated at least partially by an illumination module (22) according to any one of claims 1 to 7.

9. Monitoring device (2) according to claim 8, comprising an illumination module (22) according to any one of claims 4 or 5, wherein said acquisition module (20) is placed in said central region of the illumination module (22).

10. Monitoring device (2) according to any one of claims 8 or 9, comprising an illumination module (22) according to any one of claims 4 or 5, wherein said acquisition module (20) is at least partially surrounded by the reflector (223) and said plurality of light sources (220) is arranged around said acquisition module (20).

11. Surveillance device (2) according to any one of claims 8 to 10, wherein said motor vehicle (1) comprises a passenger compartment, said area of ​​interest (3) comprises at least partially a front space of said passenger compartment of said motor vehicle (1).

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