WO2019141788A1

WO2019141788A1 - Head-up display for motor vehicle and assisted-driving system including such a display

Info

Publication number: WO2019141788A1
Application number: PCT/EP2019/051186
Authority: WO
Inventors: Pierre Mermillod; François GRANDCLERC
Original assignee: Valeo Comfort And Driving Assistance
Priority date: 2018-01-17
Filing date: 2019-01-17
Publication date: 2019-07-25
Also published as: EP3740810A1; FR3076913A1; FR3076913B1

Abstract

The invention relates to a head-up display (10) for a motor vehicle (3), including a first image-generating unit (11) comprising a first laser scanner (13, 14, 15) having a laser diode emitting at a first wavelength (λ₁), this first unit being controlled by a computer (30) to generate first images (Img1); a second image-generating unit (12) controlled by the computer to generate second images (Img2), this second unit being suitable for generating a light beam in a band of wavelengths (Δλ) comprising a second wavelength (λ₄); and an optical assembly (18) for projecting images, suitable for projecting the first and second images into the field of view of a driver (2) and including a spectrally selective optical filter (19) suitable for reflecting light at the first wavelength and for transmitting light in a major portion of the band of wavelengths. According to the invention, the first and second units are placed on either side of the optical filter so that the first and second images are formed in a first image plane (P1) and in a second image plane (P2), respectively, and the computer controlling the first unit is configured to process a set of data relative to the environment facing the vehicle so as to superimpose a first image with at least one specific object of said environment.

Description

HEAD-UP DISPLAY FOR MOTOR VEHICLE AND SYSTEM

DRIVING AID HAVING SUCH A DISPLAY

TECHNICAL FIELD TO WHICH THE INVENTION REFERS

The present invention generally relates to systems for assisting the driving of motor vehicles.

It relates more particularly to a head-up display for a motor vehicle, comprising a first and a second image generation unit generating respectively first and second images; and an optical projection assembly for projecting the first and second images into the field of view of a conductor, the first and second image generation units being arranged with respect to said optical assembly so as to respectively form the first images and images. second in a first image plane and in a second image plane.

It also relates to a driving assistance system comprising such a head-up display.

BACKGROUND

To facilitate and make safer driving a motor vehicle, we want to prevent the driver is forced to look away from the road he takes.

For this, it is known to use a head-up display, suitable for projecting information (speed of the vehicle, direction to follow, malfunction of the engine, presence of obstacles, ...) in the form of images at height. the driver's gaze.

Two types of head-up displays are particularly known.

The first type of displays, called laser scanners, use an image forming device comprising a diffuser and a scanning unit designed to generate a light beam scanning an entrance face of the diffuser. The light beam at the output of the diffuser thus forms an image, which can then be projected into the field of vision of the driver of the vehicle.

The displays of the second type use a display screen that generates an image on the surface of the screen, this image then being projected into the driver's field of vision.

Document WO 2013/189808 discloses a display head-high as defined in the introduction. In this display, two image generation units are provided which are placed at different distances from a partially reflecting mirror, so that the images they generate are seen by the driver at different distances.

The major disadvantage of this device is that some of the images projected at the greater distance may sometimes become entangled with particular objects present in the traffic environment of the vehicle so that the driver may not see said particular objects of the vehicle. environment and / or misinterpret some of the information projected by the head-up display, which can be dangerous if the particular object must be distinguishable by the driver (eg a pedestrian crossing in front of the vehicle) or if the information relates to a safety indication (signboard important, oncoming vehicle with collision risk, etc ...).

OBJECT OF THE INVENTION

In order to overcome the aforementioned drawback of the state of the art, the present invention proposes a head-up display for a motor vehicle comprising:

a first image generation unit comprising a first laser scanner having at least one laser diode, which transmits at a first wavelength, said first image generation unit being computer-controlled to generate first images;

a second image generation unit, separate from the first image generation unit and computer controlled to generate second images, the second image generation unit adapted to generate a light beam in a length band wave which comprises a second wavelength distinct from the first wavelength; and

an optical image projection assembly, which is adapted to project the first and second images in the field of vision of a driver of said motor vehicle and which comprises a spectrally selective optical filter adapted to mainly reflect, respectively transmit, light to at least said first wavelength, and predominantly transmitting, respectively reflecting, the light in a major part of said wavelength band;

the first and second image generation units being placed with respect to said optical filter so that said first and second images are respectively formed in a first image plane and in a second image plane distinct from the first image plane.

According to the invention, said computer controlling said first image generation unit is configured to process a set of data relating to the environment facing said motor vehicle so as to superpose at least one of said first images with at least one particular object of said environment.

Thus, thanks to the computer of the thus configured display, when one wants to highlight a particular object of the vehicle environment, it is possible with the head-up display of the invention, to emphasize the presence of said object particular by projecting into the driver's field of vision a first particular image at the same location as said particular object.

In this way, it is avoided that the first images projected by the head-up display of the invention do not blur the visibility of said particular object.

Other non-limiting and advantageous features of the head-up display according to the invention, taken individually or in any technically possible combination, are as follows:

said first and second image generation units are arranged with respect to said image projection optical assembly such that said first image plane is located at a greater distance from the conductor than the second image plane;

said image projection assembly is configured so that said first images and said second images are visible by said conductor in two angular directions separated from each other;

said image projection assembly is configured so that said first images and said second images have different angular sizes;

said laser scanner of said first image generation unit comprises three laser diodes which emit at three distinct wavelengths, including said first wavelength;

said second image generation unit comprises a second laser scanner having at least a second laser diode, which emits at said second wavelength; said second image generation unit comprises a display screen;

said spectrally selective optical filter is a partially reflecting mirror, for example a dichroic mirror.

The invention finds a particularly advantageous application in the realization of a driving assistance system.

The invention thus proposes a driving assistance system for a motor vehicle comprising a head-up display as aforesaid and an environmental observation device facing said motor vehicle configured to deliver to the computer said display head- a set of data relating to said environment.

Advantageously, said observation device may for example comprise a radar or a lidar (eg an infra-red lidar) which scans the near environment (distances of between 1 and 10 meters for example) and reconstructs it in a three-dimensional way. by simple image processing.

In a variant, the observation device may comprise a camera for acquiring image sequences of the environment and a processor adapted to process these sequences in order to map the environment.

DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT

The following description with reference to the accompanying drawings, given as non-limiting examples, will make it clear what the invention consists of and how it can be achieved.

In the accompanying drawings:

FIG. 1 is a diagrammatic overall plan view of a motor vehicle traveling on a road and equipped with a driving assistance system according to a preferred embodiment of the invention comprising a head-up display and an environmental observation device; and

Figure 2 is a schematic view of the head-up display of Figure 1.

FIG. 1 diagrammatically shows, in plan view, a motor vehicle 3 traveling on a road 4, for example two opposite lanes (right lane 5 and left lane), here from right to left.

This motor vehicle 3 is equipped with a driving assistance system comprising a head-up display 10 and an observation device 21, 23, 24 for detecting the environment facing the vehicle 3.

The driving assistance system described here is particularly advantageous when the above-mentioned head-up display 10 is a head-up display of the "Augmented Reality" type.

It will be seen in the rest of the description that such a head-up display 10 augmented reality can project information (s) so that they appear, for the driver 2 of the vehicle 3, superimposed on an object (pedestrian 7 crossing on pedestrian crossing 6, road sign 8, motorcyclist on his motorcycle 9, see figure 1) located in the environment, facing the vehicle 3.

According to the example described here, the information contains, for example, a symbol or an outline which, superimposed on the pedestrian 7 or placed close to it, makes it possible to underline its presence. This information is particularly relevant in the case of objects difficult to see by the driver, for example a pedestrian in low light conditions.

Advantageously, the observation device comprises at least one sensor 21, 23 adapted to acquire a set of data relating to the environment of the vehicle 3, in particular to the environment 5 facing (see FIG. .

The sensor here comprises an image acquisition unit 21, for example a video camera. In this case, the environment data set 5 represents an acquired image and / or a sequence of images.

The camera 21 is disposed at the front of the vehicle 3, for example at the interior (central) mirror of the vehicle 3. The camera 21 has a field of view 22 which extends towards the vehicle 3.

Advantageously, the field of view 22 covers the solid angle corresponding substantially to the windshield 1 of the vehicle 3 (as seen from the driver 2) and extends beyond the solid angle corresponding to said shield. breeze 1.

The observation device also comprises an electronic processing unit 24 which is programmed to process the acquired images transmitted by the video camera 21 of the observation device.

The electronic processing unit 24 here includes a memory unit (not shown) for storing a plurality of image processing algorithms able to obtain information on the acquired image, for example:

detect the presence or absence of an "object" (eg pedestrian 7); identifying the object 7 or tracking the object 7 on a sequence of acquired images;

predicting the evolution of the position of the object 7 in time, or extracting characteristics of the object 7, such as, for example, its distance D1 (see Fig. 1) from the vehicle 3, its orientation, its size , its displacement (sense and speed), etc ...;

calculating the remaining time (eg in seconds) before a potential collision between the object 7 and the vehicle 3.

In the embodiment shown in FIG. 1, the observation device of the driver assistance system is a hybrid device comprising, in addition to the observation camera 21, other sensors such as, for example, here a telemetry device 23 for measuring a distance D1 between an object, here the pedestrian 7, and the vehicle 3.

The telemetry device 23 comprises for example a radar, or a lidar, here a lidar using an infrared laser (IR) scanning. The telemetry device 23 is able to emit an electromagnetic wave (an IR laser pulse) and to acquire the electromagnetic wave reflected by the pedestrian 7 present in a detection field of the telemetry device 23. The distance between the pedestrian 7 and the Vehicle 3 is then calculated by measuring a flight time between the emission of the laser pulse and the reception of the reflected pulse (echo signal) by the pedestrian 7.

FIG. 2 schematically shows in greater detail an exemplary embodiment of the head-up display 10 of the driver assistance system fitted to the motor vehicle 3.

This head-up display 10 comprises two separate image generation units 11, 12 controlled by a computer 30, and an optical projection assembly 18.

The projection optical assembly 18 is designed to project the images emitted by the two image generation units 11, 12 into the field of view of the conductor 2.

It comprises for this purpose a partially reflecting mirror 19, on the one hand and on the other side of which are placed the two image generation units 1 1, 12, so that its two front and rear faces are respectively illuminated by the beams emitted by the two image generation units 1 1, 12.

According to a particularly advantageous characteristic of the invention, this partially reflecting mirror is a spectrally selective optical filter 19, adapted to mainly reflect the light at least at a first wavelength λ, and mainly to transmit the light in a major part of the light. an AK band of wavelengths comprising at least a second wavelength ₁₄ distinct from the first wavelength li.

In practice, this spectrally selective optical filter 19 will be designed here to reflect light in a finite number of wavelengths λ1, λ2, 13, and to transmit light in several bands of wavelengths AK which do not include these wavelengths li, z, K3 (l ₄ being then any wavelength belonging to one of these wavelength bands Dl).

To better understand the invention, the embodiment of the head-up display 10 shown in FIG. 2 can be described in more detail.

According to the invention, the first image generation unit 11 is of the "emissive" type and comprises a laser scanner having at least one laser diode, which emits at the first wavelength K1.

The laser scanner comprises a diffuser 15 and a scanning unit which generates a light beam of variable direction so as to be able to scan the rear face of the diffuser 15. The scanning unit more precisely comprises a beam forming module 13 and one or several mobile mirror (s) 14, for example made in the form of an electromechanical microsystem (or MEMS for "MicroElectroMechanical System" in English).

The beamforming module 13 could comprise a single monochromatic light source (laser diode) at the first wavelength li.

However, in order to be able to generate color images, it preferentially comprises three monochromatic light sources, here three laser diodes emitting in three distinct colors. He thus understands more precisely:

a red laser diode emitting at the wavelength λ of about 650 nanometers (in practice in a very narrow wavelength band, for example less than 10 nm wide),

a green laser diode emitting at the wavelength K2 of about 530 nm (in practice in a very narrow color band, less than 10 nm wide), and

a blue laser diode emitting at a wavelength K3 around 470 nm (in practice in a very narrow color band, less than 10 nm wide).

The respective light beams of these three laser diodes (monochromatic) are combined (for example using partially reflecting mirrors) to form a single polychromatic light beam (here laser) emitted at the output of the beam forming module 13. light beam generated by the beam forming module 13 is directed towards the (or) mobile mirror 14, whose orientation is controlled by a control module (not shown) so that the reflected light beam sweeps the face rear of diffuser 15.

In the exemplary embodiment of FIG. 2, the second image generation unit 12 is here of the "light modulation" type. It comprises a display screen 17, here a liquid crystal display (or LCD for "Liquid Crystal Display") thin film transistors (or TFT for "Thin-Film Transistor"). It also comprises here a backlighting device 16 located at the rear of the screen 17. This backlighting device 16 comprises a plurality of light-emitting diodes (or LEDs for "light-emitting diode") distributed behind the liquid crystals of the light-emitting diode. display screen 17.

These light-emitting diodes are here designed to emit white light. In this way, the second image generation unit 12 is adapted to emit light - to generate a light beam - in a large band of wavelengths, for example between 400 and 800 nanometers (nm).

It may be noted here that this band of wavelengths comprises the three wavelengths li, l2, KΆ.

In an alternative embodiment, the display screen 17 may be an OLED screen (for "Organic Light-Emitting Diode") with an active matrix (AM-OLED screen for "Active Matrix-OLED"), an LCoS screen (for "Liquid Crystals on Silicon") or even a DLP type screen (for "Digital Light Processing"). In another embodiment, the second image generation unit could be of the "emissive" type and comprise a second laser scanner with at least a second laser diode generating a light beam in a wavelength band (for example 1 nm or less) around the wavelength l ₄ , different from the first wavelength li.

The first image generation unit 11 and the second image generation unit 12 are controlled by two different computers or, as in the embodiment of FIG. 2, controlled by the same and single computer 30, which is for example part of the electronic control unit (ie the computer or ECU for "Electronic Control Unit") of the vehicle 3.

The two image generation units 1 1, 12 make it possible, under the control of the computer 30, to generate two distinct images Img1, Img2 (see Fig. 2) that the projection optical assembly 18 will be able to project into the field of view. driver's vision 2 when the driver's gaze is turned towards route 4 (see figure 1).

The optical projection assembly 18 is more specifically designed to project first images Img1 and second images Img2 (which are all virtual) in the field of view of the driver 2 of the vehicle 3 at distances D1, D2 of the driver 2 which are greater than that separating the driver 2 from the windshield 1 (so that the eyes of the driver do not have to perform accommodation work to perceive the projected information).

In other words, and as shown in FIG. 2, the first image generation unit 11 and the second image generation unit 12 are placed respectively with respect to the spectrally selective optical filter 19 so that the first images Img1 and the second images Img2 are respectively formed by projection in a first image plane P1 and in a second image plane P2 distinct from the first image plane P1.

The optical projection assembly 18 comprises for this purpose a combiner 20 placed in the field of view of the driver 2 of the vehicle 3.

Here, this combiner 20 is formed by a partially reflecting blade which is arranged in the passenger compartment of the motor vehicle 3, between the windshield 1 of the vehicle 3 and the eyes 2 of the driver, and which is curved so as to enlarge the size images Img1, Img2 generated by the two units of In a variant, the combiner could be formed by the windshield itself.

Thus, in the embodiment shown in FIG. 2, the blade forming the combiner 20 is here a plane blade with parallel faces. In this rudimentary optical configuration, the combiner 20 plays as a simple optical element (semi-transparent mirror) for a conjugation between the diffuser 15 and the first virtual image Img1 for different projection distances D1: there is more or less efficiency in this conjugation over a wide range of distance. However, for first distances D1 projection too high, for example greater than twice the optical distance between the diffuser 15 and the combiner 20, the optical distortion is too strong, and the eye of the driver 2 can not compensate, so that the first image Img1 can become fuzzy.

In a first embodiment, a combiner 20 formed by a concave blade (i.e. with a curvature facing the driver) could be used.

In a second embodiment improvement, the conjugation between the diffuser and the first image plane (and also between the screen and the second image plane) can be improved by adding, in addition to the combiner 20:

a complex optical surface between the combiner (plane or curved) and the partially reflecting mirror to have a zoom optics: we then seek to optimize the quality of conjugation according to the two desired image planes P1, P2; and or

an optical system between the diffuser and the partially reflecting mirror to shape the beam and correct the aberrations (especially the distortion).

The optical projection assembly 18 also comprises the spectrally selective optical filter 19, which makes it possible to direct the images generated by the two image generation units 11, 12 to the combiner 20.

Although this is not the case, it could possibly also include one or more other mirror (s), said (s) folding.

Here, the spectrally selective optical filter 19 is a partially reflecting mirror, for example a dichroic mirror, which is adapted to:

reflect the light around the three wavelengths li, Kz, KΆ (ie in wavelength bands centered on the three wavelengths li, l2, KΆ of the three laser diodes of the laser scanner 11 and of very narrow width, less than 10 nm, here considered equal to 2 nm), and

transmitting the light in the remainder of the visible range (for example in AK wavelength bands between 400 and 469 nm, between 471 and 529 nm, between 531 and 649 nm, and between 651 and 800 nm).

This dichroic mirror 19 will preferably be chosen in such a way that, for each of the three wavelengths li, l2, KΆ of the first image generation unit 11, it has a reflection coefficient of greater than or equal to 90%. . This coefficient will preferably be greater than 95%. For best results, this coefficient will be between 99% and 100%.

The dichroic mirror 19 will also preferably be chosen such that, in each of the four bands of wavelengths AK (see above), it has a transmission coefficient of greater than or equal to 90%. This coefficient will preferably be greater than 95%. For best results, this coefficient will be between 99% and 100%.

It will thus be understood that, thanks to the spectrally selective optical filter 19, the light emitted by the first image generation unit 11 will be almost completely reflected towards the combiner 20. The light emitted by the second image generation unit 12 (ie by the screen 17 here) will also be almost entirely transmitted to the combiner 20, except around the three wavelengths li, l2, KΆ.

As has been explained above, the first and second image generation unit 1 1, 12 are controlled by the same computer 30, which can now be described in more detail.

It will be specified in advance that if here one and the same computer 30 will drive here the two image generation units 1 1, 12, the latter could alternatively be controlled each by a calculator of their own.

Here, the computer 30 conventionally comprises a processor (CPU), a random access memory (RAM), a read only memory (ROM), and different input and output interfaces.

Thanks to its input interfaces, the computer 30 can receive input signals, such as images to be generated. These images will be developed in such a way that the information they contain is not superimposed. Thanks to its read-only memory, the computer 30 stores useful data in the context of controlling the two image generation units 1 1, 12.

Finally, thanks to its output interfaces, the computer 30 transmits control signals to the image generation units 1 1, 12 so that they generate the desired images Img1, Img2.

Moreover, and according to a particularly advantageous characteristic of the invention, the computer 30 is programmed to process a set of data relating to the environment facing the motor vehicle 3 so as to superpose at least one of the first images Img1 with at least one particular object of the environment.

For this purpose, the observation device of the driver assistance system is configured to deliver to the computer 30 of the head-up display 10 this set of data relating to the environment.

The environmental data here comes from the electronic processing unit 24 (see Fig. 1) of the observation device.

In the embodiment described here, it is the pedestrian 7 which crosses the studded passage 6 (see Fig. 1) which is highlighted by the head-up display 10 by superimposing on the pedestrian 7 an outline of its determined silhouette. by the electronic processing unit 24 (with, for example, an edge detection algorithm). In other embodiments, it may be the outline of a tree or the white bands of a zebra crossing. It may also be the contours of a traffic sign or the figures of the authorized speed limit value. It may still be the contours of a motor vehicle arriving in the opposite direction and with which there is a risk of impending collision.

In an alternative embodiment, it is possible to use the information available from a navigation system (based for example on a geolocation or GPS system) to highlight elements of the path, for example the limits of the currently circulated route.

In another variant embodiment, a fixed point in space (such as a beacon) may be added to indicate a particular position on the path, such as for example the exact position of the destination of arrival.

Preferably, the first images Img1 are projected by the head-up display 10 at a projection distance D1 (determined from the driver's eye 2 of the vehicle 3, see Fig. 2) larger than the distance D2 Projection to which are projected the second images Img2.

In practice, the distance D1 projection is for example between 10 and 20 meters and / or the distance D2 projection is between 2 and 2.5 meters.

More preferably, it is provided - as is the case in FIG. 2 - that the first images Img1 and the second images Img2 are disjoint and visible by the conductor 2 in two angular directions 1X1, IX2 separated one from the other. 'other.

For this purpose, the diffuser 15 of the first image generation unit 11 and the display screen 17 of the second image generation unit 12 are shifted laterally (here in the direction of the height) so that they are centered on two axes OX1, OX2 (see Fig. 2) which do not intersect.

Thus, the two images Img1, Img2 generated by the first and second image generation units 1 1, 12 are offset laterally with respect to each other.

In practice, the angle between the horizon and these angular directions AX1, AX2 (line which passes through the eyes of the driver 2 and the center of the virtual image Img1, Img2) has a value between 0 and 5 °, of preferably between 1 and 3 °, for example equal to about 2 ° for the first images Img1 (first image Img1 "high" in the driving position) and a value between 5 and 10 °, preferably between 5 and 7 °, by example equal to about 6 ° for the second images Img2 (second image Img2 "low" in the driving position).

Advantageously also, the first images Img1 and the second images Img2 have different angular sizes, the angular size of the first images Img1 being greater than or equal to 4 ° and that of the second images img2 being less than or equal to 2 °.

The advantage of the present invention is therefore to provide in the same optical chain (ie a single set of mirrors) a very suitable display for a conventional TFT display with an excellent quality / price ratio, and a very suitable display for a display augmented reality with a laser scan with excellent optical performance for a wide-field display.

The present invention is not limited to the embodiment described and shown, but the skilled person will be able to make any variant according to the invention. In particular, provision could be made for the first and second image generation units to be inverted with respect to the partially reflecting mirror, in which case the latter would be provided to reflect light in the AK wavelength bands and to transmit the light. around the emission wavelengths li, l2, KΆ of the laser diodes.

Claims

Head-up display (10) for a motor vehicle (3), comprising:

a first image generation unit (1 1) comprising a first laser scanner (13, 14, 15) having at least one laser diode, which emits at a first wavelength (li), said first generation unit image (1 1) being controlled by a computer (30) for generating first images (Img1);

a second image generation unit (12), separate from the first image generation unit (1 1) and controlled by a computer (30) to generate second images (Img2), the second generation unit of image (12) being adapted to generate a light beam in a wavelength band (DI) which comprises a second wavelength (l ₄₎ distinct from the first wavelength (li); and

an optical image projection assembly (18), which is adapted to project the first and second images (Img1, Img2) into the field of view of a driver (2) of said motor vehicle (3) and which comprises a filter spectrally selective optical system (19) adapted to mainly reflect, respectively transmit, the light at least said first wavelength (li), and to mainly transmit, respectively reflect, the light in a major part of said band of lengths; wave {AK),

the first and second image generation units (11, 12) being placed with respect to said optical filter (19) so that said first and second images (Img1, Img2) are respectively formed in a first image plane and in a second image plane distinct from the first image plane, and characterized in that said computer (30) controlling said first image generation unit (1 1) is configured to process a set of data relating to the environment facing said auditing motor vehicle (3) so as to superpose at least one of said first images (Img1) with at least one particular object of said environment.

A head-up display (10) according to claim 1, wherein the first and second image generation units (11, 12) are arranged with respect to said image projection optical assembly (18) for said first image plane is located at a greater distance from the driver (2) than the second image plane.

A head-up display (10) according to claim 1 or 2, wherein said image projection assembly is configured to have said first images (Img1) and said second images (Img2) visible to said driver (2). in two angular directions separated from each other.

The head-up display (10) according to one of claims 1 to 3, wherein said image projection assembly is configured so that said first images (Img1) and said second images (Img2) have different angular sizes. .

The head-up display (10) according to one of claims 1 to 4, wherein said laser scanner (13, 14, 15) of said first image generation unit (11) comprises three laser diodes (13). ) which emit at three distinct wavelengths (li, λ2, K3), including said first wavelength (li).

The head-up display (10) according to one of claims 1 to 5, wherein said second image generation unit (12) comprises a second laser scanner having at least a second laser diode, which transmits to said second wavelength (l ₄ ).

The head-up display (10) according to one of claims 1 to 5, wherein said second image generation unit (12) comprises a display screen (17).

The head-up display (10) according to one of claims 1 to 7, wherein said spectrally selective optical filter (19) is a dichroic mirror.

Driving assistance system for a motor vehicle (3) comprising a head-up display (10) according to one of claims 1 to 8 and an observation device (21, 23, 24) of the environment facing said motor vehicle (3) configured to deliver to the computer (30) of said head-up display (10) a set of data relating to said environment.