FR3073054A1 - OPTICAL SYSTEM WITH HEAD-UP DISPLAY AND INTEGRATED CAMERA - Google Patents

Abstract

The present invention relates to a vehicle optical system (1) comprising a windshield (10) or a semi-reflective plate, the optical system comprising a head-up display device, comprising: image (20), • a transparent mirror (21) adapted to reflect the image generated by the image generation unit (20) so as to produce a virtual image upstream of the windshield or the blade. semi-reflective vehicle (1), said virtual image being visible from a viewing area (9) corresponding to a predicted location of the face of a driver of the vehicle (1), characterized in that it further comprises at least a camera (31) configured to receive light from the viewing area and reflected by the transparent mirror.

Description

The invention relates to a vehicle optical system provided with a windshield, comprising optical equipment, which can typically be equipment for monitoring the drowsiness of the driver or a so-called "flight time" device, suitable for determining the position in driver's headspace.

Motor vehicles (especially cars, trucks, etc.) are increasingly equipped with equipment that aims to improve or simplify driving, and to increase vehicle safety.

Among these devices, a head-up display device is also known, also known in English as "Head-Up Display" or by the abbreviation HUD. Such a head-up display device is for example described in document US 6,359,737.

It comprises a light source adapted to generate an image which must be viewed by the driver of the vehicle, and a transparent mirror which is arranged to reflect the image generated by the light source towards the driver so as to produce a virtual image, upstream of the windshield, visible to the driver.

The transparent mirror is advantageously formed directly in the windshield, but can also be formed in an additional glazed strip positioned above the dashboard. In this way, the transparent mirror is in the driver's field of vision, and the projected image is superimposed on the road, which allows the driver to access the projected information easily and avoid loss of attention possibly dangerous.

Another type of safety equipment is a driver drowsiness monitor. An example of such equipment is for example described in document US 6,717,518.

A drowsiness monitoring device conventionally consists of a camera which is arranged to acquire images of the driver's eyes, and a processing unit which analyzes the images acquired by the camera in real time to follow the movements of the driver's eyes and determine, based on these movements, a state of drowsiness of the driver.

For cases where the ambient light is insufficient to obtain reliable images (particularly in the case of night driving), the device also includes a light source suitable for illuminating the driver's eyes. To avoid glare, the light emitted by this source is generally infrared light, and the camera used is an infrared camera.

The monitoring device then emits an alarm, which can be a sound, the display of a message or visual signal, or even a vibration, to alert the driver to his drowsy state.

Another type of security equipment is an optical matrix detection device with three-dimensional detection, known in English as the "Time Of Flight Camera" or "TOF", or also and in the following text as a device said " flight time ". This device also includes infrared lighting for illuminating the driver's face, an infrared camera, and a processing unit which is suitable for:

• synchronize the operation of the light source and the camera, • measure a time of flight between the light emitted by the source and detected by the camera, and • as a function of the time of flight and the images acquired by the camera, detect the three-dimensional position of the driver's face.

Such a device can for example be used so that the driver actuates controls by the movement of the head, without having to remove his hands from the steering wheel or to pay attention elsewhere than on the road.

Time-of-flight or drowsiness detection devices therefore require positioning an illumination source and a camera ideally in the vehicle in order to be able to provide face lighting with satisfactory intensity and vision of the face in all driver positions. The choice of the location of the camera and the source is most often made on the facade of the dashboard, also called the instrument cluster, which is visible to the driver, but installation can be difficult because the lack of space available due to the many gauges and indications which are already there.

The steering column can also be chosen to position the camera and / or the source, but this choice is also open to criticism because the camera or the source can form a troublesome or unsightly protuberance. In addition, in the case of cameras, these should preferably be concealed to avoid annoying or attracting the attention of the driver.

There is therefore a need to improve the implementation of a drowsiness monitoring device or a time-of-flight device.

An object of the invention is to at least partially overcome the drawbacks of the prior art, by improving the installation of a drowsiness monitoring device or a time-of-flight device in a vehicle comprising a windshield and a head-up display device.

In particular, an object of the invention is to take advantage of the head-up display device of the vehicle to integrate an illumination source and / or a camera of a drowsiness monitoring device or of a time-out device. flight.

In this regard, the subject of the invention is a vehicle optical system comprising a windshield or a semi-reflecting blade, the optical system comprising a head-up display device, comprising:

• an image generation unit, • a transparent mirror adapted to reflect the image generated by the image generation unit so as to produce a virtual image upstream of the windshield or of the semi-reflecting blade of the vehicle said virtual image being visible from a viewing area corresponding to a planned location on the face of a driver of the vehicle.

The optical system is remarkable in that it further includes at least one camera, configured to receive light from the viewing area and reflected by the transparent mirror.

Advantageously, the camera is sensitive to infrared light.

In one embodiment, the optical system comprises a device for monitoring the driver's drowsiness, comprising the infrared camera, an infrared light source, and a control and processing unit adapted to follow the movements of at least one eye. of the driver of the vehicle from the images acquired by the infrared camera, and to deduce therefrom a degree of drowsiness of the driver.

Alternatively, the optical system includes a time-of-flight device, comprising the infrared camera, an infrared light source, and a control and processing unit adapted to synchronize the infrared light source and the infrared camera, for measuring a time of flight between the light emitted by the infrared light source and detected by the infrared camera, and for detecting the position in space of the driver's face from the time of flight and images acquired by the infrared camera.

Advantageously, the optical system further comprises a dichroic filter interposed between the image generation unit and the transparent mirror, said dichroic filter being adapted to transmit light coming from the image generation unit to the transparent mirror, and to reflect infrared light from the transparent mirror to the camera.

The head-up display device may further comprise an optical assembly adapted to propagate the light between the image generation unit and the transparent mirror, and in which the dichroic filter can then be interposed between the generation unit image and the optical assembly.

In embodiments, the head-up display device comprises an optical assembly adapted to propagate the light between the image generation unit and the transparent mirror, said optical assembly comprising at least one fixed mirror and one rotating mirror. adapted to reflect light from the fixed mirror to the transparent mirror, and in which the camera is positioned behind the fixed mirror, and the fixed mirror is covered with a dichroic filter so as to reflect the light emitted by the generation unit image to the rotating mirror, and transmit infrared light to the camera.

The control and processing unit of a drowsiness monitoring device or of a time-of-flight device can then be adapted to control the position of the rotating mirror as a function of the position of the driver's eye or face.

Advantageously, the optical system further comprises at least one infrared light source adapted to illuminate the viewing area. The infrared light source can be configured so that the infrared light it generates is reflected by the transparent mirror to the viewing area.

Advantageously, the transparent mirror is integrated into the windshield or the semi-reflecting blade.

The invention also relates to a motor vehicle comprising a windshield or a semi-reflecting blade, and an optical system according to the above description.

The optical system according to the invention makes it possible to integrate at least the infrared camera, and possibly also the infrared light source, of a device for monitoring the state of drowsiness of the driver or of a time-of-flight device for the journey. optics that already exist for a head-up display device.

However, this device being designed so that the driver always sees the projected information, it guarantees that the infrared camera, using the same optical path, is at all times able to acquire images of the driver's face. Likewise, it ensures that the infrared light source always illuminates the driver's face.

In addition, the invention makes it possible to facilitate the integration of the infrared camera and advantageously of the infrared light source, and to reduce its bulk.

The infrared camera and / or the infrared light source are preferably advantageously integrated into the dashboard of the vehicle, which makes it possible to conceal them while preserving the space of the instrument cluster.

Other characteristics, objects and advantages of the invention will emerge from the description which follows, which is purely illustrative and not limiting, and which should be read with reference to the appended drawings in which:

- Figure 1 schematically shows an example of a head-up display device in a vehicle,

FIG. 2 schematically represents the installation of a transparent mirror of a head-up display device in a vehicle,

FIGS. 3a to 3c represent different alternative embodiments of an optical system according to the invention,

- Figures 4a and 4b show different possible locations of an infrared light source according to the invention.

In the different figures, the same references designate identical or similar elements.

Head-up display

FIG. 1 schematically represents an example of a head-up display device arranged in a vehicle 1 comprising a windshield 10 or a semi-reflective blade, for example in the case where the vehicle 1 does not have a windshield 10. The blade semi-reflective can in this case be mounted on the dashboard 11 of the vehicle 1. By dashboard 11 is meant the part which extends in front of the driver and the front passenger and which comprises the instrument cluster on the front for vehicle navigation 1.

The head-up display device 2 comprises an image generation unit 20, which can be called in English "Picture Generation Unit" or with the abbreviation PGU, which is suitable for generating images intended to be viewed by the vehicle driver 1.

For this, a perception reference point marked 9 is defined, which is determined by the median position of the eyes of the median user. Around this reference point is defined a viewing area 90, which takes into account the variations in size and behavior of the conductors with respect to the perception reference point.

The image generation unit 20 typically includes one or more light sources, a liquid crystal display and an electronic control card, housed in a housing.

The light source may include a light-emitting diode module comprising a plurality of light-emitting diodes (called "LEDs"), which can be arranged in one or more parallel rows to form a matrix arrangement. Alternatively, the light source of the image generation unit 20 may be a matrix of liquid crystal displays (LCDs) or fluorescent displays. Optionally, the image generation unit 20 can also include a filter making it possible to protect the light source, in particular from sunlight which can reach the light source by the principle of reverse light return, in order to avoid overheating of the light source.

The head-up display device 2 also includes a transparent mirror 21 which is adapted to reflect the image generated by the image generation unit 20 in order to produce a virtual image V upstream of the windshield 10 or of the semi-reflecting plate, this virtual image being visible from the viewing area 90 (also called “eye box” in English). For this, the transparent mirror 21 is advantageously positioned between the route observed by the driver and the latter, in the direction of his gaze X, as shown in FIGS. 1 and 3. This mirror being transparent, it therefore allows the driver to '' simultaneously observe the road and the image projected through it.

According to an advantageous embodiment, the transparent mirror 21 is arranged in the windshield 10 or the semi-reflecting blade of the vehicle 1, as is the case in FIGS. 1 and 3. As a variant, in the case of a vehicle 1 provided with a windshield 10, the transparent mirror 21 can be distinct from the windshield 10 of the vehicle 1, and be formed from a semi-reflective glazed strip mounted on the dashboard 11.

The image generation unit 20 is advantageously integrated into the dashboard 11, which may locally include a through hole or a transparent blade 12 to allow the passage of light from the image generation unit 20 to the mirror transparent 21 and vice versa.

In an embodiment shown for example in Figures 3 and 4, the head-up display device 2 can also include an optical assembly 22 adapted to propagate the image generated by the image generation unit 20 from that -this to the transparent mirror 21, depending on the location of the image generation unit 20. This optical assembly 22 can also be adapted to magnify the image. In the example shown in FIGS. 3 and 4, it typically comprises a magnifying fixed mirror 23 and a rotating mirror 24 whose geometry makes it possible to compensate for the curvature of the transparent mirror 21 (in particular in the case where it is integrated into the windshield 10). The rotary mirror 24 can advantageously pivot about a horizontal axis, orthogonal to the direction of progression of the vehicle 1, to adapt the head-up display device 2 to the variations in size of the conductors.

The optical assembly 22 can be integrated into the dashboard 11 of the vehicle 1, as is the case in FIGS. 3b and 3c.

With reference to FIGS. 3a to 3c and 4, the vehicle 1 also comprises a device for monitoring the drowsiness of the driver, and / or a device of the time of flight type, also known by the acronym TOF for “Time Of Flight” >, adapted to detect the position in space of the driver's face. These two devices are designated by the same reference in the figures.

In both cases, the device comprises an infrared light source 30, which is adapted to illuminate the driver's face (in particular the eyes in the case of drowsiness monitoring) and a camera 31 sensitive to infrared light, which is suitable for acquiring an image of the driver's face (in particular the eyes in the case of drowsiness monitoring). Advantageously, the infrared light emitted by the source is detected by the camera 31 is located in the near infrared, that is to say that it has a wavelength between 800 and 1,200 nm.

The camera 31 can have one or more sensors, for example three to four sensors in the case of a camera 31 used for a time-of-flight device.

According to one embodiment, each sensor of the camera 31 is only sensitive to infrared. Alternatively, each sensor may have a wider sensitivity band and the camera 31 may further include a filter passing for infrared light and blocking for visible light. The sensor (s) of the camera 31 can typically be of the CCD or CMOS type.

The presence of the head-up display device 2 is used to better integrate the infrared light source 30, the infrared camera 31, or both.

Indeed, the optical components provided for the head-up display device 2 are designed so that the image generated by the image generation unit 20 is always visible to the driver. The optical path provided for the head-up display device 2 can therefore be used at least in part to route the light emitted by the infrared light source 30 towards the driver's face, and / or, according to the principle of reverse light return, to route light from the driver's face to the infrared camera 31.

Infrared camera

In this regard, the infrared camera 31 is advantageously positioned so as to take advantage of the configuration of the head-up display device 2, that is to say that it is positioned so as to receive light from the viewing area 90 and reflected by the transparent mirror 21.

In one embodiment, as in the example shown in FIG. 3a, a dichroic filter 41 is interposed between the image generation unit 20 and the transparent mirror 21, and adapted for:

• transmit the light emitted by the image generation unit 20 to the transparent mirror 21, and to • reflect the infrared light reflected by the transparent mirror 21 to the infrared camera 31.

This dichroic filter 41 has the additional advantage of reducing the quantity of infrared light reaching the image generation unit 20, for example infrared light from the sun, and therefore limits the heating of this unit.

In the case where the head-up display device 2 comprises an optical assembly 22 for propagating the light between the image generation unit 20 and the transparent mirror 21, the dichroic filter 41 can advantageously be interposed between the unit of image generation 20 and the optical assembly 22, as is the case in FIG. 3b.

According to another variant not shown, the dichroic filter 41 can also be positioned between the optical assembly 22 and the transparent mirror 21. This variant is however less advantageous because, unlike the previous ones, it does not allow the rotary mirror 24 to be used. which also makes it possible to compensate for the curvature of the windshield 10, and therefore makes it necessary to provide a separate correction optic for the infrared light source 30.

According to another variant still shown in FIG. 3c, in the case where the head-up display device 2 comprises an optical assembly 22 comprising a fixed mirror 23 and a movable mirror 24, the infrared camera 31 can be positioned behind the fixed mirror 23 of the optical assembly 22, and in this case this mirror can be coated with a dichroic filter 42 which is provided on the one hand for the fixed mirror 23 to transmit infrared light, so that the reflected infrared light coming from the viewing area and reflected by the transparent mirror 21 reaches the infrared camera 31, and provided on the other hand for reflecting visible light, in particular light coming from the image generation unit 20 towards the mirror.

Face lighting device

The vehicle 1 also comprises a device for lighting the driver's face, which includes the infrared light source 30. The infrared light source 30 can be that of a drowsiness monitoring device or a time-of-flight device. It can be placed on the instrument cluster or above the windshield 10 of the vehicle 1, being oriented towards the driver so that images of the driver's face can be continuously obtained.

According to an advantageous variant, the driver's face lighting device is configured so as to take advantage of the configuration of the head-up display device 2, that is to say it is configured so as to illuminate the driver's face by reflection on the transparent mirror 21 of the head-up display device 2.

In an embodiment shown diagrammatically in FIG. 4a, the infrared light source 30 is integrated into the image generation unit 20. For example, the light source of this unit can be adapted to generate infrared light in addition visible light. The light source can then be controlled to alternately generate infrared light and visible light.

For example, for a drowsiness monitoring device, the light source can generate pulses of infrared light synchronized with the camera frame which can vary from 25 images per second to 100 images per second, and generate visible light on the rest of the period.

In the embodiment in which the light source of the image generation unit 20 comprises light-emitting diodes, this source may comprise additional light-emitting diodes, housed in the same housing, adapted to generate light in the infrared . These additional light-emitting diodes integrated into the image generation unit 20 form the infrared light source 30. All of the light-emitting diodes are then advantageously controlled by the same electronic card.

As a variant, the infrared light source 30 can be separated from the image generation unit 20. In this case the facial lighting device advantageously comprises a dichroic filter 40, represented in FIGS. 3a to 3c, interposed between the image generation unit 20 and the transparent mirror 21, and the infrared light source 30 is positioned so as to illuminate the dichroic filter 40, the latter being adapted for:

• on the one hand, transmitting the light emitted by the image generation unit 20 to the transparent mirror 21, and • on the other hand, reflecting the light emitted by the infrared light source 30 towards the transparent mirror 21.

In the case where the head-up display device 2 comprises an optical assembly 22 for propagating the image generated by the image generation unit 20 towards the transparent mirror 21, the facial lighting device is advantageously configured so that the light emitted by the infrared source enters the optical assembly 22, that is to say through the same entry point as that of the light generated by the image generation unit 20. This can be obtained by integrating the infrared light source 30 with the image generation unit 20 as previously, or by positioning the dichroic filter 40 between the image generation unit 20 and the optical assembly 22, as this is the case in Figure 3b.

Alternatively, the infrared light generated by the source 30 can enter the optical assembly 22 through a separate entry point. For example, with reference to FIG. 4b, when the optical assembly 22 comprises a magnifying fixed mirror 23 and a rotating mirror 24, the infrared light source 30 can advantageously be positioned behind the magnifying fixed mirror 23, which is then transparent to infrared light.

According to another variant not shown, the dichroic filter 40 can also be positioned between the optical assembly 22 and the transparent mirror 21. This variant is however less advantageous because, unlike the previous ones, it does not allow the rotary mirror 24 to be used. which also makes it possible to compensate for the curvature of the windshield 10, and therefore makes it necessary to provide a separate correction optic for the infrared light source 30.

The infrared camera 31 can advantageously, but not limited to, be positioned adjacent to the infrared light source 30, in particular in the case where these two elements are part of a time-of-flight device, which simplifies the calculation of the flight time of flight. light from the infrared light source 30 to the conductor and then back to the infrared camera 31. In this case, the dichroic filters 40 and 41 mentioned above can be confused. For this reason, FIGS. 3a and 3b show, by identical symbols, the infrared light source 30 and the infrared camera 31 on the one hand, and the dichroic filters 40 and 41 on the other hand.

Alternatively, the different configurations described above for the infrared camera 31 and the infrared light source 30 can be combined with one another.

The device, whether it is a device for monitoring a drowsy state of the driver, or whether it is a time-of-flight device, also comprises a control and processing unit 32 which comprises at least one computer (for example a processor) and a memory storing code instructions to be executed by the computer. This control and processing unit 32 is adapted to control the infrared light source 30 and the infrared camera 31 in a synchronized manner. For example, the control and processing unit 32 can control the acquisition of images simultaneously with the emission of light pulses by the infrared light source 30.

The control and processing unit 32 is also suitable for processing the images acquired by the infrared camera 31 in order to deduce therefrom:

• in the case of a device for monitoring a drowsy state of the driver, the position of the driver's eyes and a conclusion on his state of drowsiness, • in the case of a time-of-flight device, the position in the space of the driver's face, deduced from the images and from a time of flight information of the light between the infrared light source 30 and the infrared camera 31.

Those skilled in the art can refer to publication FR 3 048 111 for the processing of the light signal acquired by the camera in a time-of-flight device.

In the embodiment in which the head-up display device 2 comprises a rotary mirror 24, the control and processing unit 32 can be adapted to control the position of the rotary mirror 24 as a function of the position of the eyes or of the driver's face, detected from the images acquired by the camera 31. This can therefore improve the operation of the device, whether it is a time-of-flight device or a flight monitoring device. drowsiness, at the same time as it improves the visibility of the image projected by the head-up display device 2.

The control and processing unit 32 can advantageously control the intensity of the infrared light source 30 as a function of the ambient brightness. Indeed, in broad daylight the quantity of infrared light illuminating the face with the sun may be sufficient to acquire a clear image of the driver's eyes. The brightness measurement can be carried out by a dedicated sensor (not shown).

Claims (12)

1. Vehicle optical system (1) comprising a windshield (10) or a semi-reflecting blade, the optical system comprising a head-up display device (2), comprising: • an image generation unit (20), • a transparent mirror (21) adapted to reflect the image generated by the image generation unit (20) so as to produce a virtual image upstream of the screen breeze (10) or of the semi-reflecting blade of the vehicle (1), said virtual image being visible from a viewing area (9) corresponding to a planned location of the face of a driver of the vehicle (1), characterized in which further comprises at least one camera (31), configured to receive light from the viewing area and reflected by the transparent mirror (21). 2. The optical system of claim 1, wherein the camera (31) is sensitive to infrared light. 3. Optical system according to claim 2, comprising a device for monitoring the drowsiness of the driver, comprising the infrared camera (31), an infrared light source (30), and a control and processing unit (32) suitable for follow the movements of at least one eye of the driver of the vehicle (1) from images acquired by the infrared camera (31), and to deduce therefrom a degree of drowsiness of the driver. 4. Optical system according to claim 2, comprising a time-of-flight type device, comprising the infrared camera (31), an infrared light source (30), and a control and processing unit (32) adapted to synchronize the infrared light source (30) and the infrared camera (31), for measuring a time of flight between the light emitted by the infrared light source (30) and detected by the infrared camera (31), and for detecting the position in the space of the driver's face from the time of flight and from the images acquired by the infrared camera (31). 5. Optical system according to any one of the preceding claims, further comprising a dichroic filter (41) interposed between the image generation unit (20) and the transparent mirror (21), said dichroic filter (41) being adapted to transmit light from the image generating unit (20) to the transparent mirror (21), and to reflect infrared light from the transparent mirror (21) to the camera (31). 6. Optical system according to the preceding claim, wherein the head-up display device (2) further comprises an optical assembly (22) adapted to propagate the light between the image generation unit (20) and the transparent mirror (21), and in which the dichroic filter (41) is interposed between the image generation unit (20) and the optical assembly (22). 7. An optical system according to any one of claims 2 to 6, the head-up display device (2) further comprising an optical assembly (22) adapted to propagate the light between the image generation unit ( 20) and the transparent mirror (21), said optical assembly (22) comprising at least one fixed mirror (23) and a rotary mirror (24) adapted to reflect light from the fixed mirror (23) to the transparent mirror (21 ), and in which the camera (31) is positioned behind the fixed mirror (23), and the fixed mirror (23) is covered with a dichroic filter (42) so as to reflect the light emitted by the generation unit image (20) to the rotating mirror (24), and transmit infrared light to the camera (31). 8. An optical system according to claim 7 in combination with claim 3 or claim 4, wherein the control and processing unit (32) is further adapted to control the position of the rotating mirror (24) according to the position of the driver's eye or face. 9. Optical system according to any one of claims 2 to 8, further comprising at least one infrared light source (30) adapted to illuminate the display area (9). 10. Optical system according to the preceding claim, wherein the infrared light source (30) is configured so that the infrared light that it generates is reflected by the transparent mirror (21) towards the viewing area (9). 11. Optical system according to any one of the preceding claims, in which the transparent mirror (21) is integrated into the windshield (10) or into the semi-reflective strip. 12. Motor vehicle (1) comprising a windshield (10) or a semi-reflective strip, and an optical system according to any one of the preceding claims.