FR3156187A1 - Illumination module and associated occupant monitoring device - Google Patents

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 of the light sources being provided with a periphery and a reflector (223) having at least one reflective surface (224R, 225R) arranged to at least partially reflect 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 thereon, at least a portion of the light rays (228) of the light beam are 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 abstract: Fig. 4

Description

Illumination module and associated occupant monitoring device Technical field of the invention

The present invention generally relates to an illumination module.

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

It also relates to a device for monitoring the occupants of a motor vehicle comprising such an illumination module.

State of the art

To increase the safety of vehicle occupants, it is common practice to equip the vehicle with a device for monitoring occupants, particularly the driver. Using sensors, located in particular at the front of the vehicle's passenger compartment, the driver's behavior can be monitored. Signs of a driver's lack of vigilance, such as drowsiness or signs of drunkenness, can trigger an alert if necessary.

For example, occupant behavior may be monitored using an imaging system, which typically includes an illumination module, intended to illuminate an area of interest, such as, for example, an occupant's face, as well as the torso region, or more generally, the front portion of the vehicle's passenger compartment.

This illumination module is accompanied by an image acquisition module, in particular a camera, in order to capture images of the area of interest illuminated by the illumination module. Finally, the assembly is generally completed by an image processing module, allowing the acquired images to be analyzed and possible signs of lack of vigilance on the part of the occupants or the driver to be deduced.

Conventional lighting 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 assessed at the half-width at half-height of the angular distribution of the intensity of the light source.

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

Each of the light sources is then surrounded by a reflector, also called a collector. This allows the emitted light flux to be concentrated towards the area of interest, thanks to reflective surfaces oriented towards the light source.

The combination of light sources and reflectors defines an illumination field angularly delimiting 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 seen from the front of the latter.

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.

Therefore, 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 even greater than 180°.

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

The illumination field is therefore known to be limited to a maximum extent of approximately 160°, below the 180° desired in the context of the targeted application.

Presentation of the invention

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.

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 being provided with a periphery and a reflector having at least one reflective surface arranged to at least partially reflect the light beam, in which it is provided that the reflector is configured to extend only over a part of the periphery of the at least one light source, so as to provide 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 reflecting 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 part of the light rays reflected outside the light beam crossing the free space provided at the periphery of the light source.

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

Thus, thanks to the invention, it is possible to illuminate a large and close area of interest, thanks to a sufficiently wide angular illumination field. Indeed, the reflector is thus configured to obstruct as little as possible the light beams emitted by the light sources, and the reflective surfaces of the reflector adopt a shape adapted to angularly deflect the light beams in order to have the widest possible illumination field.

Other advantageous and non-limiting (i.e. optional) characteristics of the illumination module according to the invention, taken individually or in all technically possible combinations, are the following:
- The at least one reflective surface is at least partially non-planar.
- The at least one reflective surface is convex relative to the at least one light source for which it is arranged to at least partially reflect the light beam.
- The at least one light source emits towards a direction called the illumination direction, 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 illumination direction.
- 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 further 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 then advantageously reduced, since a reflector can be used for a multitude of light sources. This can simplify the assembly of the module, in addition to reducing the weight and/or the cost of the assembly.
- Each of the reflector's reflective surfaces is oriented toward at least one of the light sources. For example, a reflector's reflective surface may be oriented toward one, two, or even more light surfaces. The number of sources to be used may, for example, be chosen according to the lighting requirement.
- The illumination module comprises a printed circuit board, and the plurality of light sources is fixed on the printed circuit board. The module in this case comprises 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.

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

The invention also proposes an occupant monitoring device for a motor vehicle 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 optional characteristics, which may be taken individually, or in any technically possible combination:
- The acquisition module is placed in the central region of the illumination module.
- The acquisition module is at least partly surrounded by the reflector; in particular by the side walls that compose it, the plurality of light sources is arranged around the acquisition module, so as to surround it. This configuration then allows space saving, and offers greater compactness to the occupant monitoring device.
- The motor vehicle comprises a passenger compartment and the area of interest for the occupant monitoring device at least partially comprises a space in front of the passenger compartment of the motor vehicle.

Of course, the various features, variants and embodiments of the invention may be combined with each other in various combinations to the extent that they are not incompatible or mutually exclusive.

Detailed description of the invention

The description which follows with reference to the attached drawings, given as non-limiting examples, will make it clear what the invention consists of and how it can be implemented.

On the attached drawings:

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

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;

FIG. 3 is a schematic front view of the illumination module of the FIG. 2 , where a reflector surrounded by two light sources is represented; and

FIG. 4 is a schematic profile view of the illumination module of the FIG. 2 .

On the FIG. 1 , a motor vehicle 1 has been shown here in the form of a car, but it could be a completely different type of motor vehicle 1 (truck, ship, plane, etc.).

This motor vehicle 1 comprises a passenger compartment, in which occupants 4 are located. These occupants 4 can designate 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.

This motor vehicle 1 is equipped with a monitoring device 2 for the occupants 4. 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.

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.

Such an area of interest 3, represented schematically on the FIG. 1 , includes in particular the face of the driver and front passenger, a portion of the torso, and the driver's arms, when the latter adopts a classic driving posture.

Typically, the monitoring device 2 is placed at the front of the passenger compartment of the motor vehicle 1, for example in a region close to 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 even in the rearview mirror.

Surveillance device 2 here relies on visual information, via the recording and analysis of images.

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

According to the representation of the FIG. 1 , it is considered here that the three aforementioned elements are included within the same dedicated box. According to a 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 adapted to exchange data with these two other modules, for example via an on-board network.

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

The acquisition module 20 comprises a photosensitive sensor, and imaging optics, adapted to image the area of interest 3 on the photosensitive sensor located downstream of the imaging optics.

Imaging optics can include a lens, as well as optical bandpass filters intended to eliminate any stray radiation emitted outside a spectral range of interest.

The photosensitive sensor groups together a set of photosensitive pixels arranged according to a table. These pixels are photosensitive to a spectral range which at least partially covers that of the illumination module 22. Here, this may in particular be 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.

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 merged in Figures 1 and 2.

The spectral range chosen for lighting is typically located in the infrared range, particularly the near infrared range, 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 4. However, a spectral range of lighting in the visible is also possible.

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

In particular, in the embodiment presented, the illumination wavelength is 940 nm.

Then, in order to illuminate the entire 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.

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

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

Here, in the embodiment considered, the illumination module 22 described 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.

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

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

Thus, in this embodiment, it is considered that the two light sources 220 of the illumination module 22 are arranged horizontally, along the GD axis.

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.

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

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 symmetry of revolution.

For the sake of simplification in the remainder of the description, and in accordance with all the figures, the light beam 222 emitted by each of the light sources 220 is described as an emission cone with rotational symmetry, which corresponds to a reasonable modeling of the situation described. This emission cone is represented by a vertex and an angle at the vertex relative to an axis defined as the emission axis A1, A2.

Preferably, the two emission axes A1, A2 of the two light sources 220 are collinear, so that the two light sources 220 illuminate in a common direction, called the illumination direction. This illumination direction is here parallel to the emission axis A1, A2, and oriented towards the area of interest 3. Thus, the two emission axes A1, A2 are here parallel to an axis AA’ describing the front-rear axis of the motor vehicle 1.

However, other embodiments where the emission axes A1, A2 of the different sources are not collinear can also be envisaged, the sources being able to be inclined relative to the axis AA’. The illumination direction would then remain parallel to the axis AA’, and oriented towards the area of interest 3.

However, the collinearity of the emission axes A1, A2 offers the advantage of being able to fix the different light sources 220 on the same printed circuit 221. In an example of a possible embodiment, a single printed circuit 221 serves as a support for all the light sources 220 of the illumination module 22, and also serves for controlling the different light sources 220 which are fixed there.

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

For a light beam 222, the apex of the emission cone is located at the level of the light source 220, assumed to be point-like, and the angle at the apex in the plane containing the axis GD and the axis AA', corresponds to an emission angle of the light source 220. This emission angle 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 is measured in absolute value relative to the emission axis A1, A2. Other possible definitions for the emission angle of a light source can be used.

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 described previously.

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

In the embodiment considered, these are two light beams 222 according to two distinct emission cones which are each emitted by a light source 220.

All the 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 220 light sources, these being identical here.

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

Furthermore, to prevent the edges of the printed circuit 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 221.

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

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 comprises a reflector 223. This reflector 223 plays several functions, including that of shaping the illuminated area so that it best corresponds to the geometry of the area of interest 3, but also, for example, of adequately distributing the luminous flux over this area.

After reflection on 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.

The illumination field is shown in Figures 1 and 2, and notably underlies the area of interest 3. It is angularly represented by twice an angle, corresponding to an illumination angle This angle is also measured in a plane containing the GD axis and the AA' axis, relative to the AA' axis, or equivalently to the emission axis A1, A2 of the light sources 220, in the case where these three axes are collinear.

Reflector 223 is shown in more detail on the FIG. 3 , thanks to a front view.

It has a plurality of side walls 224, 225, 226, 227, here four in number, forming a volume of parallelepiped shape. These side walls 224, 225, 226, 227 extend substantially in height along the axis AA', in order to be able to reflect the light rays 228 emitted by the light sources 220.

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

A first end is in contact with the printed circuit 221, or even sinks into it to a depth ranging from 1 mm to 10 mm, to thus fix the reflector 223 on the illumination module 22. Alternatively, the reflector 223 and the printed circuit 221 are held by a housing 26. This housing 26 is notably made so as not to obstruct the passage of the light rays 228 reflected on the reflector 223. For example, the light sources 220 can be placed a few micrometers from an edge of the housing 26. The latter then has a thin wall and/or the wall of the housing is at least partially transparent to the spectral range of lighting.

According to variants, other solutions for holding the reflector 223 on the printed circuit 221 and/or the housing 26 are possible, for example by providing fixing tabs protruding from one of the ends of the reflector 223. These tabs can then be screwed, welded or glued onto the printed circuit 221 and/or the housing 26.

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

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

According to other possible embodiments, non-joining side walls 224, 225, 226, 227 can also be envisaged, and the reflector 223 would then be produced using several separate parts.

In the embodiment described, the dimensions of the reflector 223 are contained in a parallelepiped 10 mm wide by 3 mm high, the height being described along the axis AA’.

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

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 different light sources 220.

Various geometric arrangements of the light sources 220 may be considered. For example, here, the two light sources 220 are aligned along the GD axis, 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 linking the two light sources 220.

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

Thus, the reflector 223 is configured so as to obstruct the passage of the light beams 222 as little as possible. Indeed, thus positioned relative to the light sources 220, that is to say, at the center thereof, the reflector 223 and all of its side walls 224, 225, 226, 227, extend only over a portion 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 remainder of the periphery of each light source 220. The light beams 222 reflected by the reflector 223 then propagate through this free space provided at the periphery of each of the light sources 220, without being obstructed by the reflector 223.

In order to at least partially reflect 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 side walls 224, 225 of the reflector 223, towards the light sources 220.

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

To reflect the light beams, the reflector 223 is at least partially metallized, or may be at least partially covered 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 be treated so as to limit parasitic reflections, by anodization for example.

In the embodiment described, the reflector 223 has two reflective surfaces 224R, 225R. These two reflective surfaces 224R, 225R are diametrically opposite one another, and are each oriented towards one of the two light sources 220. In particular, these two reflective surfaces 224R, 225R are here 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 and matt coating can for example cover the two reflective surfaces 224R, 225R.

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 . As mentioned before, 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.

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

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.

This means in particular that after reflection on the reflective surfaces 224R, 225R of the reflector 223, at least a portion of the light rays 228 coming from the light beam 222 of one of the light sources 220 is deflected away from the light beam 222 initially incident on the reflective surface 224R, 225R.

In other words, after reflection on the reflecting 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 outside the light beam 222 following reflection on the reflector 223 thus makes it possible to enlarge the illumination field compared to the emission field of the light sources 220 alone.

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

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

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

Such a reflective surface 224R, 225R, suitable for enlarging the illumination field compared to the emission field of the light sources 220 alone, has an exact shape which can be determined experimentally, or by means of ray tracing simulation processes, well known to those skilled in the art. A simplified explanation for establishing an adequate reflective surface shape 224R, 225R, based on geometric optics concepts will be proposed in the remainder of this description.

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

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

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’.

This first convex curvature of the reflecting surface 224R, 225R along the axis AA’ has a vertex.

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

The degree of curvature as well as the exact shape of the surface along this axis AA’ can be specified experimentally, or using ray tracing simulation processes, well known to those skilled in the art.

Here, along the axis AA’, the reflective surface 224R, 225R considered has 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.

Then, each of the reflecting surfaces 224R, 225R can also have a second convex curvature along the GD axis.

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

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

The invention is nevertheless in no way limited to the reflective surfaces 224R, 225R described above, and other surfaces can easily be selected by those 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.

The definition of a non-planar reflective surface 224R, 225R allowing a light ray 228 to be reflected 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 explained simply using the rules of geometric optics. These are well known to those skilled in the art, in particular the Snell-Descartes laws.

By defining a normal N at each point of the reflecting 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 each incident at a point of the reflecting surface 224R, 225R. An angle of incidence i can then be defined between the normal N and the incident light ray 228.

The incident light ray 228 is then reflected by the reflecting 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.

An example of a normal N at a point on the reflecting surface 224R is plotted in Figures 3 and 4, as well as the light ray 228 incident on this reflecting surface 224R and the corresponding reflected light ray 228.

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 width greater than the emission field associated with the light sources 220 alone.

The above explanation presents a possible way of proceeding in order to obtain the reflective surfaces 224R, 225R of the embodiments according to the invention. More sophisticated modeling and various optimizations of the reflective surfaces 224R, 225R via commercial or non-commercial ray tracing algorithms and software can also be used within the scope of the invention.

The reflector 223 can be manufactured in various ways, such as by casting a metallic material, in particular aluminum, or by injection of plastic, followed by deposition of a metallic layer, for example by vacuum evaporation of a metal, such as aluminum.

According to a possible embodiment for the occupant monitoring device 2 described above, the acquisition module 20 can be fitted within the reflector 223.

In this embodiment, the acquisition module 20 nests between the side walls 224, 225, 226, 227 of the reflector 223, preferably centered within the parallelepiped volume formed by the reflector 223.

The photosensitive sensor of the acquisition module 20 is then fixed on the printed circuit 221, overlooked by the imaging optics.

Thus, in the embodiment described, the acquisition module 20 is centered between the different light sources 220, here two in number. Along the GD axis, the sequence of 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 side wall 224, then the acquisition module 20, a second side wall 225 on which rests on its outer face the second reflective surface 225R, oriented in the direction of the second light source 220.

The arrangement described above offers the advantage of a compact occupant monitoring device.

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 to the wavelength used in the illumination device 22.

Other examples of integration of the acquisition module 20 and the illumination module 22 in order to form the monitoring device 2 can also be envisaged.

The present invention is in no way limited to the embodiments described and shown, but those skilled in the art will be able to provide any variation in accordance with the invention.

For example, depending on the 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.

According to a first variant, 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.

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

Claims (12)

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) being provided with a periphery,
- a reflector (223) having at least one reflecting surface (224R, 225R) arranged to at least partially reflect 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 reflecting surface (224R, 225R) is arranged so that after reflection on said at least one reflecting 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). The illumination module (22) of claim 1, wherein said at least one reflective surface (224R, 225R) is at least partially non-planar. 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 at least partially reflect the light beam (222). Illumination module (22) according to any one of claims 1 to 3, wherein, said at least one light source (220) emits towards a direction called the illumination direction, said light rays (228) corresponding to said part of said light rays (227) reflected outside of said light beam (222) form an angle greater than or equal to 90° with said illumination direction. An illumination module (22) according to any one of claims 1 to 4, wherein said illumination module (22) comprises a plurality of light sources (220), and wherein said reflector (223) comprises a plurality of reflective surfaces (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). The illumination module (22) of claim 5, wherein said illumination module (22) comprises a printed circuit board (221), and wherein said plurality of light sources (220) are attached to said printed circuit board (221). An illumination module (22) according to any one of claims 1 to 6, wherein said reflector (223) is in one piece. Illumination module (22) according to any one of claims 1 to 7, wherein said at least one light source (220) comprises at least one light-emitting diode. Device (2) for monitoring the occupants (4) 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 one of claims 1 to 8. Monitoring device (2) according to claim 9, comprising an illumination module (22) according to any one of claims 5 or 6, wherein said acquisition module (20) is placed in said central region of the illumination module (22). Monitoring device (2) according to any one of claims 9 or 10, comprising an illumination module (22) according to any one of claims 5 or 6, wherein said acquisition module (20) is at least partly surrounded by the reflector (223) and said plurality of light sources (220) is arranged around said acquisition module (20). Monitoring device (2) according to any one of claims 9 to 11, wherein said motor vehicle (1) comprises a passenger compartment, said area of interest (3) at least partially comprises a space in front of said passenger compartment of said motor vehicle (1).