CN112285929A

CN112285929A - Device for observing a vehicle occupant

Info

Publication number: CN112285929A
Application number: CN202010703900.8A
Authority: CN
Inventors: J.魏因加滕; R.菲斯; T.门希
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2019-07-22
Filing date: 2020-07-21
Publication date: 2021-01-29
Also published as: DE102019210817A1; FR3099095B1; FR3099095A1

Abstract

The invention relates to a device (22) for observing a vehicle occupant (24) of a vehicle (20), having a lighting unit (30) for emitting infrared radiation (44) and having an image recording unit (32), wherein the device (22) has a hologram (46) that is reflective for the infrared radiation (44, 48). The hologram (46) and the lighting unit (30) are arranged relative to one another in such a way that infrared radiation (44) emitted by the lighting unit (30) is reflected on the hologram (46) and can be directed in the direction of the vehicle occupant (24). Furthermore, the hologram (46) and the image recording unit (32) are arranged relative to one another in such a way that infrared radiation (48) radiated back by the vehicle occupant (24) is reflected on the hologram (46) and can be guided in the direction of the image recording unit (32).

Description

Device for observing a vehicle occupant

Technical Field

The invention relates to a device for observing a vehicle occupant of the type described in the independent claim. Furthermore, a method for observing a vehicle occupant is also subject matter of the invention.

Background

DE 60300919T 2 discloses an image recording device for a vehicle occupant in a vehicle.

Disclosure of Invention

A device for observing a vehicle occupant of a vehicle is proposed, which has a lighting unit for emitting infrared radiation and has an image recording unit, wherein the device has a hologram which is reflective for infrared radiation. The hologram and the lighting unit are arranged relative to one another in such a way that infrared radiation emitted by the lighting unit is reflected on the hologram and can be directed in the direction of the vehicle occupant. Furthermore, the image recording unit is arranged in such a way that infrared radiation emitted back by the vehicle occupant can be guided in the direction of the image recording unit.

The device can also be referred to as an occupant observation system and/or a driver observation system. The device can be designed, for example, for observing a vehicle occupant, for example for detecting the direction of vision of a vehicle occupant, in particular of a driver or a passenger, or the fatigue state and/or other vitality values of a vehicle occupant. Furthermore, for example, the identity of a vehicle occupant can be detected.

The hologram (Hologramm) is in particular an element with holographic-optical properties. For holograms which can also be referred to as holographic-optical elements or HOEs and which are realized as volume holograms, the radiation diversion is advantageously predefined not by refraction but by diffraction on a volume grating. HOEs can be produced in particular not only in transmission but also in reflection, and they can be realized in different structural forms by a free choice of the angles of incidence and emergence or the angles of diffraction. The holographic diffraction grating can be exposed to a photosensitive material, such as a photosensitive photopolymer or a thin photosensitive foil, for example.

The hologram can be designed, for example, as a volume reflection hologram. By means of the use of volume reflection holograms, costs and/or installation space can be saved or reduced, in particular, when arranging the components of the device. In particular, the volume reflection hologram can be used in accordance with a narrow-band filter, so that additional filters can be omitted, and thus, in particular, costs and/or installation space can be saved.

The invention has the advantage that the lighting unit and/or the image recording unit can be arranged variably. As a result, a variable arrangement is produced, in particular, in the dashboard of the vehicle, as a result of which the available installation space can be utilized, in particular, more flexibly and thus also the installation space can be saved. Furthermore, costs and/or expenditure for the specific integration of the components in the instrument panel of the vehicle and thus in the instrument cluster of the vehicle can thereby be saved or reduced.

A further advantage is that, by means of the hologram, a specific region, in particular in the region of the face of the driver, can be illuminated with infrared radiation. This makes it possible to place infrared radiation in particular in the area in which the driver should be observed. This makes it possible to save costs, in particular, since it is preferably not necessary to use additional optical elements for focusing the infrared radiation. The hologram can be used, for example, as an optical element in the beam path of infrared radiation. This enables, for example, the sensitivity to infrared radiation to be optimized. In particular, less luminous flux can thereby be used for illuminating the vehicle occupants by means of infrared radiation, as a result of which energy can be saved. This can reduce the degree of heat generation of the lighting unit.

In one embodiment, the hologram and the image recording unit can be arranged relative to one another in such a way that infrared radiation emitted back by a vehicle occupant can be deflected on the hologram and can be guided in the direction of the image recording unit. In one exemplary embodiment, the hologram and the image recording unit can be arranged relative to one another in such a way that infrared radiation emitted back by a vehicle occupant can be reflected on the hologram and can be guided in the direction of the image recording unit. The advantage of this is the possible variable arrangement of the lighting unit and/or the image recording unit, as a result of which, in particular, the installation space, for example in the dashboard of a vehicle, can be used more flexibly and thus also saved. Furthermore, costs and/or expenditure for the specific integration of the components in the instrument panel of the vehicle and thus in the instrument cluster of the vehicle can thereby be saved or reduced.

In an advantageous embodiment, the hologram can have a first surface, wherein the first surface is embodied as a reflective structure for infrared radiation. The use of a reflective surface for reflecting infrared radiation makes it possible in particular to reflect infrared radiation into a defined area. In particular, the face of the driver or the observer to be observed can thereby be directly illuminated by means of infrared radiation. Infrared radiation reflected by the illuminated driver or observer or radiated back is likewise reflected and thus reflected again on the hologram and is thus guided to the image recording unit. In particular, overhead, such as, for example, costs and/or installation space, can thereby be saved. The components of the device can be arranged in a flexible manner in particular in the dashboard of a vehicle.

Furthermore, the infrared radiation impinging on the first surface of the hologram can have an angle of incidence with respect to the normal of the first surface and the light beam reflected by means of the hologram can have an angle of exit with respect to the normal of the first surface, wherein the angle of incidence and the angle of exit can be the same or different. It is an advantage that the components can be flexibly arranged with respect to each other. This makes it possible to make optimum use of the installation space, in particular in the dashboard or instrument panel of the vehicle, which makes it possible to save installation space in particular. In this way, a defined area of the driver or the observer can be advantageously illuminated by means of infrared radiation. In other words, the infrared radiation can be directed directly into a predefined specific area, in particular in the area of the face of the driver. In this way, the entire surface does not have to be illuminated, which makes it possible to save costs, for example.

In an advantageous embodiment, the image recording unit and/or the illumination unit can be arranged behind a flap arranged in the dashboard of the vehicle. Thereby, the image capturing unit and/or the illumination unit can be protected from external influences. Furthermore, these components are not directly visible to the viewer.

Furthermore, the hologram is capable of reflecting infrared radiation and substantially incapable of reflecting a beam in the visible range. For example, the hologram is capable of reflecting infrared radiation in a spectral range between 1 μm and 780 nm. For this purpose, in particular selective holograms can be used. As a result, in particular, no disturbing light can reach the image recording unit, which influences in particular the infrared radiation returning from the driver. In other words, the influence of disturbance light can be reduced, whereby the function of the device can be improved.

In an exemplary embodiment, the hologram can have at least two regions with different optical functions. For example, light beams incident on the hologram at different angles can be reflected differently, in particular at different angles. This enables, for example, two different regions, for example two observers or two regions of an observer, to be illuminated. Alternatively or additionally, light beams of different wavelengths can be reflected differently by means of the different optical functions. In this way, different regions can likewise be illuminated, in particular with different light beams. For example, differently illuminated regions can be recorded and evaluated, in particular, by means of one image recording unit or by means of two image recording units. Thus, by using two different optical functions, construction space and/or expenditure, such as for example costs for different optical elements, can be saved or reduced.

In one development, the infrared radiation can be guided by means of the hologram into a defined spatial angular range in the direction of the vehicle occupant. In this way, the infrared radiation can be guided in particular into the defined region, whereby only specific regions, for example the face of the driver, can be illuminated. This enables, in particular, savings in terms of costs and energy.

In an advantageous embodiment, the device can have a display unit for displaying pictures. By means of the display unit, in particular, a picture can be displayed for the driver. For example, information about the vehicle, such as speed, rotational speed, filling level of the fuel tank, temperature, information of the navigation system and/or information of the entertainment system, can be displayed to the driver. By the use of a hologram for reflecting an infrared beam, it is possible to arrange the display unit and the image taking unit and the illumination unit, in particular, independently of each other. In particular, thermal interactions between the components, in particular the image recording unit and the illumination unit, can thereby be avoided. Preferably, the display surface can thereby be utilized to the full extent for displaying information and/or pictures to an observer.

In addition, the display unit can be arranged on the side of the hologram opposite to the image capture unit and the illumination unit. In this way, it is possible in particular to arrange the image recording unit and the illumination unit with respect to the display unit decoupled from one another, thereby avoiding thermal interactions of the different components. This makes cooling easier, which makes it possible to save costs, in particular. Furthermore, the thermal influence of the different components, in particular of the image recording unit and the illumination unit, on each other can be reduced. This allows a more flexible use of the installation space, which makes it possible in particular to save installation space.

In an exemplary embodiment, the hologram can be arranged on the display unit with a second surface opposite the first surface. This results in particular in a saving of installation space.

The picture of the display unit can be made visible to the vehicle occupant particularly advantageously by means of a hologram. This has the advantage that installation space can be saved by the arrangement of the holograms of the display unit. Furthermore, a flexible arrangement of the components in the device can be achieved.

Furthermore, a method for observing a vehicle occupant of a vehicle is proposed, having the following steps:

-emitting infrared radiation by means of a lighting unit of the device in the direction of a hologram of the device, wherein the infrared radiation is reflected on the hologram in the direction of a vehicle occupant;

-capturing infrared radiation radiated back by the vehicle occupant and reflected on the hologram in the direction of the image capturing unit by means of an image capturing unit of the device.

The advantage of the invention is that the driver can be observed, whereby, for example, specific functions in the vehicle can be activated or deactivated. Furthermore, the vehicle occupant can be observed, whereby, for example, the display device can be made to follow the direction of the observer's line of sight. Furthermore, it can be detected whether the driver has noticed a particular message or a particular graphic representation on the display device. In one development, for example, a vital value of the driver can be ascertained, so that for example it can be ascertained whether the driver is too tired to fulfill the driving task.

A further advantage is that, by means of the hologram, a specific region, in particular of the region of the driver's face, can be illuminated with infrared radiation. This makes it possible to place infrared radiation in particular in the area in which the driver should be observed. This makes it possible to save costs, in particular, since it is preferably not necessary to use additional optical elements for focusing the infrared radiation.

In a further development, in a further step, the vehicle occupant can be identified by means of an image recognition algorithm. In other words, by means of the method, a vehicle occupant can be identified, so that, for example, a specific function can be activated or deactivated. For example, it is thereby possible to allow only the vehicle occupant to start the vehicle and travel with the vehicle.

Drawings

Embodiments of the invention are illustrated in the drawings and are explained in detail in the following description. The same reference numerals are used for elements which are shown in different figures and which perform a similar function, wherein repeated descriptions of said elements are dispensed with. Wherein:

FIG. 1 shows a schematic view of a vehicle having a device for viewing a vehicle occupant;

FIG. 2 shows a schematic view of a vehicle having a display unit;

FIG. 3 shows a schematic view of a vehicle having a display unit;

FIG. 4 shows a schematic view of an apparatus according to an embodiment of the invention;

FIG. 5 shows a schematic view of an apparatus according to an embodiment of the invention;

FIG. 6 shows a schematic view of an apparatus according to an embodiment of the invention;

FIG. 7 shows a schematic view of an apparatus according to an embodiment of the invention;

FIG. 8 shows a schematic diagram of a graph relating angle and wavelength dependence according to an embodiment of the invention;

fig. 9 shows a schematic diagram of a method according to an embodiment of the invention.

Detailed Description

Fig. 1 shows a schematic illustration of a vehicle 20 with a device 22 for observing a vehicle occupant 24, wherein the vehicle 20 is shown in this embodiment, in particular, in a simplified side view. The vehicle 20 has an interior 26, in particular, wherein one or more seats 28 for one or more vehicle occupants 24 can be arranged in the interior 26. Furthermore, the vehicle 20 has a device 22 for observing a vehicle occupant 24, wherein the device 22 can also be referred to as an occupant observation system and/or a driver observation system. The device 22 can be designed, for example, to detect the direction of vision of a vehicle occupant 24, in particular of the driver 24 or of a co-worker, or the fatigue state and/or other activity values of the vehicle occupant 24. Furthermore, for example, the identity of the vehicle occupant 24 can be detected.

For observing the vehicle occupant 24, the device 22 has an illumination unit 30 for emitting infrared radiation and an image recording unit 32. The device 22 can be arranged in particular in an instrument panel 34 and/or an instrument panel 34 of the vehicle 20. In an advantageous embodiment, the device can be arranged in particular in a cluster in the instrument panel 34. Alternatively or additionally, the device 22 can also be arranged elsewhere in the interior 26 of the vehicle 20, for example on the roof of the vehicle 20, on one of the side mirrors or pillars, i.e. on the a-pillar and/or on the B-pillar.

The lighting unit 30 is directed in particular in the direction of the vehicle occupant 24 and thus in the direction of the vehicle seat 28 for illuminating the vehicle occupant 24 with infrared radiation. In other words, infrared radiation is emitted in the direction of the vehicle occupant 24 by means of the lighting unit 30. The illumination unit 30 can be designed, for example, as a light-emitting unit, a light-emitting element, a light-emitting diode and/or as an LED, laser diode.

The image recording unit 32 can be embodied, for example, as a camera, in particular as an infrared camera module, wherein the image recording unit 32 points in the direction of the vehicle occupant 24 and thus in the direction of the vehicle seat 28 for visually detecting the vehicle occupant 24 of the vehicle 20. By virtue of the infrared camera module being designed, it is also possible to carry out observation at night without the vehicle occupant 24 being illuminated and thus dazzled. Furthermore, the device 22 has a control unit 37 or evaluation unit 37 for controlling the illumination unit 30 and/or the image recording unit 32 and for processing the data recorded by means of the image recording unit 32.

Fig. 2 shows a schematic representation of a top view of a vehicle 20, such as a motor vehicle, such as a passenger car, having a display device 36 for displaying or displaying a picture for a vehicle occupant 24. The display device 36 has a display unit 38 for displaying pictures and can be arranged, for example, in the dashboard 34 or in the dashboard 34 of the vehicle 20. Alternatively or additionally, the display device 36 can be arranged elsewhere in the dashboard 34 of the vehicle 20.

The display unit 38 can have a display surface or be designed as a display surface, for example. By means of the display unit 38, information about the vehicle, such as vehicle state information or information about the vehicle mode, such as, for example, speed and/or rotational speed and/or temperature and/or filling level of the fuel tank and/or navigation instructions and/or information of the vehicle entertainment system and/or further information which can be used for operating the vehicle, can be displayed.

The display device 36 is arranged in the vehicle 20 in such a way that the observer 24 can observe the information shown by means of the display unit 38 of the display device 36. The observer 24 can be, inter alia, a vehicle occupant 24, such as a driver and/or a co-occupant of the vehicle 20.

Fig. 3 shows a schematic view of a cut-out of the vehicle 20 from the side with the display device 36. The vehicle 20 according to fig. 3 can be designed according to the vehicle 20 according to fig. 2. The display device 36 according to fig. 3 can be designed in particular according to the display device 36 according to fig. 2 and is arranged in the vehicle 20 according to fig. 2.

Fig. 4 shows a schematic illustration of a device 22 for observing a vehicle occupant 24 of a vehicle 20 according to an exemplary embodiment of the present disclosure. The device 22 according to fig. 4 can be arranged in the vehicle 20 according to the device 22 according to fig. 1. In this advantageous embodiment according to fig. 4, an instrument panel 34, a windshield 40 and a steering wheel 42 are shown in the vehicle 20. In this advantageous embodiment, the device 22 is arranged in or on the dashboard 34.

The device 22 for observing a vehicle occupant 24 of the vehicle 20 has an illumination unit 30 for emitting infrared radiation 44 and an image recording unit 32. In this advantageous embodiment, the image recording unit 32 and the illumination unit 30 are arranged behind a flap 45 provided in the dashboard 34 of the vehicle.

Furthermore, the device 22 has a hologram 46 which is reflective for the infrared radiation 44. In an advantageous embodiment, the hologram 46 can be designed, for example, as a volume reflection hologram. The hologram 46 has in particular a first surface 50, wherein the first surface 50 is designed in a reflective manner for the infrared radiation 44. By means of the hologram 46, in particular infrared radiation 44 can be reflected and light beams in the visible range cannot be substantially reflected. In an exemplary embodiment, infrared radiation 44 in the spectral range between 1 μm and 780nm can be reflected by means of the hologram 46.

The hologram 46 and the lighting unit 30 are arranged relative to one another in such a way that the infrared radiation 44 emitted by the lighting unit 30 is reflected on the hologram 46 and can be directed in the direction of the vehicle occupant 24. In other words, the infrared radiation 44 emitted by the lighting unit 30 is reflected at the hologram 46 and is thereby guided in the direction of the vehicle occupant 24. The infrared radiation 44 impinging on the vehicle occupant 24 is now scattered or guided back or reflected at the vehicle occupant 24. In other words, the infrared radiation 44 impinges on the vehicle occupant 24 and is then guided or scattered or reflected from the vehicle occupant 24 back in the direction of the hologram 46. A portion of the infrared radiation 44 does not impinge on the vehicle occupant 24 and is therefore not guided back in the direction of the hologram 46. In particular, the position of the vehicle occupant 24 can thereby be determined by evaluating the infrared radiation 48 radiated back. The image recording unit 32 is arranged in such a way that infrared radiation 48 radiated back by the vehicle occupant 24 can be guided in the direction of the image recording unit 32. For this purpose, in this advantageous embodiment, the infrared radiation 48 radiated back or guided back by the vehicle occupant 24 is reflected again in particular on the hologram 46 and guided in the direction of the image recording unit 32. The hologram 46 and the image recording unit 32 are arranged relative to one another in such a way that infrared radiation 48 radiated back by the vehicle occupant 24 is reflected at the hologram 46 and can be guided in the direction of the image recording unit 32. By means of the infrared radiation 48 radiated back and thus the infrared radiation 48 recorded by the image recording unit 32, the position of the vehicle occupant 24 can be determined. For this purpose, the captured infrared radiation 48 can be evaluated, in particular, by means of an evaluation unit.

In an advantageous embodiment, the

infrared radiation

44, 48 impinging in particular on the first surface 50 of the hologram 46 can have an angle of incidence 52 with respect to a normal 54 of the first surface 50. Preferably, the

infrared radiation

44, 48 reflected by means of the hologram 46 can have an exit angle 56 relative to a normal 54 of the first surface 50, wherein the entrance angle 52 and the exit angle 56 can be identical or different. The

infrared radiation

44, 48 can advantageously be guided into a defined spatial angular range by means of the hologram 46, for example, in the direction of the vehicle occupant 24 by the infrared radiation 44. In other words, by means of the hologram 46, a specific spatial angular range can be defined into which the

infrared radiation

44, 48 is guided, in particular not only the infrared radiation 44 guided in the direction of the vehicle occupant 24 but also the infrared radiation 48 radiated back by the vehicle occupant 24 and re-reflected by the hologram 46.

In one development, the hologram 46 can have in particular at least two regions with different optical functions. For example, light beams incident on the hologram at different angles can be reflected differently, in particular at different angles. This enables, for example, two different regions, for example two observers or two regions of an observer, to be illuminated. Alternatively or additionally, light beams of different wavelengths can be reflected differently by means of different optical functions. In this way, different regions can likewise be illuminated, in particular with different light beams. For example, the differently illuminated regions can be recorded and in particular analyzed by means of one image recording unit or by means of two image recording units.

Furthermore, in this distributed embodiment, the device 22 has a display unit 38 for displaying pictures. Alternatively, the display unit 38 can also be arranged in a display device. The display unit 38 is preferably arranged on the opposite side of the hologram 46 with respect to the image recording unit 32 and the illumination unit 30. The display unit 38 can be designed according to the display unit 38 according to fig. 2 and/or 3 and/or be arranged in the vehicle 20. Furthermore, the display unit 38 can display or display information, in particular, according to the display unit 38 according to fig. 2 and/or 3.

The hologram 46 can be arranged in particular on the display unit 38. In a further development, the hologram 46 can be arranged, in particular, directly on the display surface. In other words, the hologram 46 can be arranged on the display unit 38, in particular on the display surface of the display unit 38. In particular, the hologram 46 can be arranged on the display unit 38 with a second surface 58 opposite the first surface 50. A picture is shown to the vehicle occupant 24 by means of the display unit 38. The display unit 38 can be designed in particular as a display surface, wherein a picture 60 is shown on the display surface. Such as being at least partially visible through the display surface. The image 60 of the display unit 38 can be in particular radiated through the hologram 46 and can thus be seen by the vehicle occupant 24 through the hologram 46.

In this advantageous embodiment, the image recording unit 32 and the illumination unit 30 are arranged behind a flap 45 provided in the dashboard 34 of the vehicle, so that the image recording unit 32 and the illumination unit 30 are arranged above the display unit 38 relative to the vehicle occupant 24 looking toward the display unit 38. Furthermore, the image recording unit 32 and the illumination unit 30 are concealed by a screen in such a way that they are not visible to the vehicle occupant 24. In other words, the image capturing unit 32 and the illumination unit 30 are disposed above the display unit 38 along the line of sight direction of the vehicle occupant 24.

In other words, in this advantageous embodiment, the image recording unit 32, which can be embodied in particular as a camera, is arranged above the display surface of the display unit 38. Furthermore, the illumination unit 30 and the image recording unit 32 are arranged outside the housing of the display device and are thus arranged in particular separately from the display unit 38. The hologram 46, which can also be embodied as a holographic foil, for example, can in particular form an optical function corresponding to an Off-Axis mirror (Off-Axis-Spiegel) which functions in the near infrared range or NIR range and in particular does not function in the visible spectrum of light. Furthermore, the hologram 46 can be configured, for example, as a photopolymer film that is highly transparent to visible light. The image recording unit 32 views the vehicle occupant 24 via the hologram 46 and also uses this path for illumination by means of infrared radiation 44. The off-axis angle can be adjusted in particular flexibly for a corresponding positioning of the camera relative to the display surface. In one embodiment, the image recording unit 32 and the illumination unit 30 can also be arranged laterally with respect to the display surface of the display unit 38, for example to the right or to the left of the display unit 38.

Such a hologram 46 can be produced, for example, by means of a holographic printer, such as an exposure machine. The hologram 46 can be exposed in the visible light by a corresponding angular advance. The hologram 46 is then designed in such a way that it functions in the NIR wavelength range in the desired optically targeted function when reconstructed. The achievable large angular range of the holographic wavefront printer (wellenfronttdruger) enables holograms to be recorded by angular advance, for example in red wavelengths, which can later be imaged in the NIR range at flatter angles. This is possible because for holography a three-dimensional refractive index modulation is produced. Thereby, a photopolymer film highly transparent to visible light can be produced.

Fig. 5 shows a schematic illustration of a device 22 for observing a vehicle occupant 24 of a vehicle according to an exemplary embodiment of the present invention. The device 22 according to fig. 5 can be formed according to the device 22 according to fig. 4. The device 22 according to fig. 5 can be arranged in a vehicle according to the device 22 according to fig. 1.

In contrast to the device 22 according to fig. 4, in the device 22 according to fig. 5 the image recording unit 32 is arranged behind the display unit 38 in the viewing direction of the vehicle occupant. The image recording unit 32 is arranged in such a way that infrared radiation 48 radiated back by the vehicle occupant 24 can be guided in the direction of the image recording unit 32. In this advantageous embodiment, the infrared radiation 48 radiated back or guided back by the vehicle occupant 24 is thus guided from the side of the hologram 46 and in the direction of the image recording unit 32. The hologram 46 and the image recording unit 32 are arranged relative to one another in such a way that infrared radiation 48 radiated back by the vehicle occupant 24 can be guided from the side of the hologram 46 and in the direction of the image recording unit 32. The position of the vehicle occupant 24 can thus be determined by means of the infrared radiation 48 captured by the image capture unit 32. For this purpose, the captured infrared radiation 48 is evaluated, in particular, by means of an evaluation unit. The separate arrangement of the image recording unit 32 and the illumination unit 30 enables a robust and/or reliable temperature adjustment of the assembly.

Fig. 6 shows a schematic illustration of a device 22 for observing a vehicle occupant 24 of a vehicle according to an exemplary embodiment of the present invention. The device 22 according to fig. 6 can be formed according to the device 22 according to fig. 4 and/or according to fig. 5. The device 22 according to fig. 6 can be arranged in a vehicle according to the device 22 according to fig. 1.

In contrast to the device 22 according to fig. 4 and/or 5, in the device 22 according to fig. 6 the image recording unit 32 and the illumination units 30 are arranged behind a screen arranged in a dashboard 34 of the vehicle in such a way that the image recording unit 32 and the illumination units 30 are arranged below the display unit 38 relative to the vehicle occupant 24 looking toward the display unit 38. Furthermore, the image recording unit 32 and the illumination units and 30 are concealed by a screen in such a way that they are not visible to the vehicle occupant 24. In other words, the image capturing unit 32 and the illumination unit 30 are disposed below the display unit 38 along the line of sight direction of the vehicle occupant. The image recording unit 32 and the illumination unit 30 can also be concealed, for example, by a steering wheel 42, so that the vehicle occupant 24 does not notice these units. By reflection of the

infrared radiation

44, 48 on the hologram 46, said infrared radiation is guided, although possibly masked, in the direction of the vehicle occupant 24 and back to the image recording unit 32.

Fig. 7 shows a schematic illustration of a device 22 for observing a vehicle occupant 24 of a vehicle according to an exemplary embodiment of the present invention. The device 22 according to fig. 7 can be formed according to the device 22 according to fig. 4 and/or according to fig. 5 and/or according to fig. 6. The device 22 according to fig. 7 can be arranged in a vehicle according to the device 22 according to fig. 1.

In contrast to the device 22 according to fig. 4 and/or 5 and/or 6, the hologram 46 of the device 22 according to fig. 7 is not arranged directly on the display unit 38. In this advantageous embodiment, the hologram 46 is arranged in particular at a defined angle 62 relative to the display unit 38, in particular relative to the display surface of the display unit 38. In particular, the hologram 46 can be arranged in such a way that the hologram 46 is tilted or tilted relative to the display unit 38 toward the vehicle occupant 24.

FIG. 8 shows a schematic diagram of a graph 70 relating angle dependence and wavelength dependence according to an embodiment of the invention. In other words, the angle dependence and the wavelength dependence of the diffraction efficiency are shown for a reflection hologram by means of the diagram 70. The reconstruction angle in degrees is shown on the X-axis 72 and the wavelength in nm of the light beam is shown on the Y-axis 74. The reconstruction angle is calculated here in particular within the material of the hologram. The curve 76 shows, in particular, the angular dependence and the wavelength dependence of the hologram.

The hologram was photographed at 640nm with an angle of incidence having a value of 55 ° for the reference wave and having a value of 0 ° for the object wave, which was reconstructed in an analogous manner for the reference wave in the wavelength range 400nm to 2000nm (this is shown on the Y-axis 74) and in the angular range 0 ° to 60 ° (this is shown on the X-axis 72). Preferably, the holograms used here are efficient for smaller angles in terms of larger wavelengths. Thus, for example, for an angle of about 40 °, efficiencies of over 95% can be achieved at 900nm in the near infrared range or NIR range. The angle specification relates to a medium with a refractive index n =1.5, since exposure can be carried out by means of an immersion objective in a holographic material, here a photopolymer, without prior conversion of the recording wave from air to the medium (Belichten), the abovementioned angle of 40 ° in an immersion solvent corresponding to an angle of 75 ° in air. In this way, almost any optical function can be formed in the NIR range by means of the hologram. For example, the hologram can be designed as a 0 ° to 75 ° deflector or as a short-focal lens, in particular as a concave mirror with an open cone or a focal cone having a value of +/-75 ° and thus a value of 150 °, or as an oblique off-axis arrangement.

In addition or alternatively, the optical function of the hologram is formed by individual sub-holograms, in particular holographic elements. Each individual holographic element can be defined in particular with regard to its optical function. In other words, a single holographic element can have its own optical function. In this way, the angular advance can be adjusted locally. In other words, the angle with which the infrared radiation should be reflected can be specifically defined or adjusted. Thereby, the optical function can be reliably and easily optimized for the later reconstructed wave, whereby the imaging quality or the optical function of the NIR hologram can be improved and/or achieved. Thus, for example, holographic NIR lenses, such as NIR concave mirrors, with very short focal lengths can also be manufactured in an off-axis configuration. In this way, the infrared radiation can be guided, in particular, into a targeted spatial angular range, in particular in the direction of the vehicle occupant.

Fig. 9 shows a schematic illustration of a method 80 for observing a vehicle occupant of a vehicle with an apparatus for observing the vehicle occupant according to an embodiment of the invention. The device can be formed according to the device according to fig. 4 and/or 5 and/or 6 and/or 7.

In a first step 82 of the method 80, infrared radiation is emitted by means of a lighting unit of the device in the direction of a hologram of the device, wherein the infrared radiation is reflected on the hologram in the direction of a vehicle occupant.

In a second step 84 of the method 80, infrared radiation which is radiated back by the vehicle occupant and is reflected on the hologram in the direction of the image recording unit is recorded by means of the image recording unit of the device.

In one development, the vehicle occupant can additionally be identified in a third step 86 of the method 80 by means of an image recognition algorithm. For this purpose, the information acquired by means of step 84 about the infrared radiation radiated back can be evaluated by means of an evaluation unit.

Claims

1. Device (22) for observing a vehicle occupant (24) of a vehicle (20), having a lighting unit (30) for emitting infrared radiation (44) and having an image recording unit (32), characterized in that,

the device (22) has a hologram (46) that is reflective for infrared radiation (44, 48),

the hologram (46) and the lighting unit (30) are arranged relative to one another in such a way that infrared radiation (44) emitted by the lighting unit (30) is reflected on the hologram (46) and can be directed in the direction of the vehicle occupant (24), and

the image recording unit (32) is arranged in such a way that infrared radiation (48) radiated back by the vehicle occupant (24) can be guided in the direction of the image recording unit (32).

2. The device (22) according to claim 1, characterized in that the hologram (46) and the image recording unit (32) are arranged relative to one another in such a way that infrared radiation (48) radiated back by a vehicle occupant (24) can be deflected on the hologram (46) and can be guided in the direction of the image recording unit (32).

3. The device (22) according to one of the preceding claims, wherein the hologram (46) and the image recording unit (32) are arranged relative to one another in such a way that infrared radiation (48) radiated back by the vehicle occupant (24) can be reflected on the hologram (46) and can be guided in the direction of the image recording unit (32).

4. The device (22) according to any one of the preceding claims, wherein the hologram (46) has a first surface, wherein the first surface is configured as a structure that is reflective for infrared radiation (44, 48).

5. The device (22) according to claim 3, characterized in that the infrared radiation (44, 48) impinging on the first surface of the hologram (46) has an angle of incidence (52) with respect to a normal (54) of the first surface and the light beam reflected by means of the hologram (46) has an angle of exit (56) with respect to the normal of the first surface, wherein the angle of incidence (52) and the angle of exit (56) can be the same or different.

6. The device (22) according to one of the preceding claims, characterized in that the image recording unit (32) and/or the lighting unit (30) are arranged behind a flap (45) provided in the dashboard of the vehicle (20).

7. The device (22) according to any one of the preceding claims, wherein the hologram (46) reflects infrared radiation (44, 48) and substantially no beam in the visible range.

8. The device (22) according to any one of the preceding claims, wherein the hologram (46) has at least two regions with different optical functions.

9. The device (22) according to one of the preceding claims, characterized in that the infrared radiation (44, 48) can be directed into the defined spatial angular range by means of the hologram (46) in the direction of the vehicle occupant (24).

10. The device (22) according to any one of the preceding claims, wherein the device (22) has a display unit (38) for displaying pictures.

11. The device (22) according to claim 10, characterized in that the display unit (38) is arranged on the opposite side of the hologram (46) with respect to the image recording unit (32) and/or the illumination unit (30).

12. The device (22) according to any of the preceding claims 10 to 11, wherein the hologram (46) is arranged on the display unit (38) with a second surface opposite the first surface.

13. The device (22) according to any one of the preceding claims 10 to 12, characterized in that the picture of the display unit (38) is visible to the vehicle occupant (24) through the hologram (46).

14. Method (80) for observing a vehicle occupant (24) of a vehicle (20) with a device (22) for observing a vehicle occupant (24) of the vehicle (20), having the following steps:

emitting infrared radiation (44) by means of a lighting unit (30) of the device (22) in the direction of a hologram (46) of the device (22), wherein the infrared radiation (44) is reflected on the hologram (46) in the direction of the vehicle occupant (24),

infrared radiation (48) radiated back by the vehicle occupant (24) and reflected on the hologram (46) in the direction of the image recording unit (32) is recorded by means of an image recording unit (32) of the device (22).

15. Method (80) for observing a vehicle occupant (24) of a vehicle (20) according to claim 14, wherein in a further step the vehicle occupant (24) is identified by means of an image recognition algorithm.