VEHICLE LIGHTING DEVICE WITH PRESENTATION OF DRIVING ASSISTANCE INFORMATION

Abstract

A lighting device of a vehicle includes at least one lighting device for a road scene in front of the vehicle arranged to form a first light beam defined by a first lighting. A device for generating a second light beam defined by a second lighting is configured to superimpose the second beam on the first light beam. A sum of the first lighting and of the second lighting is greater than the first lighting, the second light beam forms driving assistance information.

Claims

1: Lighting device of a vehicle comprising at least one lighting means for a road scene in front of the vehicle, arranged to form a first light beam defined by a first lighting, and a device for generating a second light beam defined by a second lighting configured to superimpose the second beam on the first light beam, in which a sum of the first lighting and of the second lighting is greater than the first lighting and in which the second light beam forms driving assistance information.

2: Device according to claim 1, wherein the lighting of the first beam in a portion of the road scene lying between three meters and fifteen meters in front of the vehicle lies between 20 lux and 50 lux.

3: Device according to claim 1, wherein the lighting of the first beam is equal to 30 lux.

4: Device according to claim 1, wherein the lighting means is arranged with the lighting of the first beam to be constant in a portion of the road scene lying between three meters and fifteen meters in front of the vehicle.

5: Device according to claim 1, wherein a contrast between the first and the second light beams lies between zero exclusive and five.

6: Device according to claim 1, wherein the lighting of the second beam in a portion of the road scene lying between three meters and fifteen meters in front of the vehicle lies between 30 lux and 150 lux.

7: Device according to claim 1, wherein the lighting means and the device for generating the second beam share at least one same light source which generates the first light beam and the second light beam.

8: Device according to claim 7, wherein the light source is pixelated.

9: Device according to claim 8, in which the light source is formed by a matrix of individual light sources which extend in a same plane (π).

10: Device according to claim 1, wherein the lighting means comprises at least one optical system whose focal plane coincides with the plane (π) in which the individual light sources extend.

11: Device according to claim 8, wherein the light intensity of a plurality of light sources can be controlled individually.

12: Device according to claim 1, wherein the lighting means and the device for generating the second beam are formed by at least one same assembly comprising at least one light source emitting a beam of light rays, a scanning system receiving the beam of light rays and distributing it over a surface of a wavelength conversion device.

13: Device according to claim 1, wherein the lighting means and the device for generating the second beam are formed by at least one same assembly comprising a uniform light source and an LCD screen.

14: Device according to claim 1, wherein the lighting means and the device of the second beam are formed by at least one same assembly comprising a uniform light source and micro-mirrors.

15: Device according to claim 1, wherein the second light beam is configured to be superimposed on the first light beam in at least a part of the first light beam, this part corresponding to an area of the road scene.

16: Device according to claim 1, wherein the second lighting of the second light beam is greater than the first lighting of the first light beam.

17: Headlight of a motor vehicle comprising a lighting device according to claim 1.

Description

[0031] Other features, details and advantages of the invention will emerge more clearly on reading the description given hereinbelow by way of indication in relation to the drawings in which:

[0032] FIG. 1 is a perspective view of a vehicle provided with a lighting device according to the present invention,

[0033] FIG. 2 is a schematic view of an exemplary embodiment of a light source used by the present invention,

[0034] FIG. 3 represents the image of the light beam produced by the lighting device according to the present invention projected onto a screen situated at 25 meters in front of the vehicle and at right angles to the main axis of the beam,

[0035] FIG. 4 is a side view of a road and of a vehicle positioned on this road, provided with a lighting device according to the present invention,

[0036] FIG. 5 is a graph representing the lighting of a lighting device according to the prior art compared to the lighting provided by a lighting device according to the invention, as a function of the distance separating the lighting device according to the invention and the point of ground impact on the road.

[0037] It must first of all be noted that the figures explain the invention in detail to implement the invention, said figures naturally being able to be used to better define the invention if necessary.

[0038] FIG. 1 schematically represents a motor vehicle 1 provided with at least one lighting device 2, each comprising at least one lighting means 4 for a road scene 5 situated in front of the vehicle 1. “Front of the vehicle” defines the front part thereof situated facing the road scene when the vehicle is moving forward.

[0039] The lighting means 4 are arranged so as to form a first light beam 6. Advantageously, the first beam 6 is regulatory. A beam is considered to be regulatory when it meets a national or a community regulation setting a photometric grid to be observed. By way of example for a headlight, the first light beam may observe the European regulations ECE R98, ECE R112, ECE R113 or ECE R123, in their latest amendments coming into force on Dec. 9, 2015 at the latest and/or the American regulations like the “Federal Motor Vehicle Safety Standard 108” (FMVSS 108) whose latest amendment came into force on Dec. 15, 2015. According to these regulations, the first light beam can notably be a high beam or a low beam.

[0040] Thus, the first light beam 6 exhibits a first lighting corresponding to a light intensity less than 12 000 Candelas (Cd), according to an angle β of less than four degrees relative to a reference straight line situated at the height of the headlight. This reference straight line forms the optical axis of the lighting device 2. The vertical angle β extends in a vertical plane passing through the optical axis. This optical axis for example crosses the lighting means 4 of the vehicle 1. According to this vertical angle, a distance D of at least fifteen meters in front of the vehicle is lit by the first light beam 6, when the lighting means 4 generates a low beam.

[0041] The lighting device 2 also comprises at least one device 7 for generating a second light beam 10. This device 7 for generating the second beam 10 is configured to superimpose the second light beam 10 on the first light beam 6. The second beam 10 exhibits a second lighting and forms a driving assistance information 9. Advantageously, the superimposition of the light beams 6, 10 is regulatory.

[0042] The driving assistance information 9 concerns, for example, the speed of the vehicle, signaling information or even information guiding the driver of the vehicle 1. The driving assistance information 9 exhibits a lighting greater than the lighting of the first light beam 6. In other words, the sum of the lightings of the first beam 6 and of the second beam 10 is greater than the lighting of the first beam 10. A contrast between the background formed by the first light beam 6 and the information 9 formed by the second light beam 10 is provided by the different lighting values generated between the device 7 for generating the second beam 10 and the lighting means 4.

[0043] According to an exemplary embodiment illustrated in FIG. 2, the lighting means and the device for generating the second beam 10 here share a same light source 12 which generates at the same time the first light beam and the second light beam. FIG. 2 shows an embodiment of the light source 12 which takes the form of a matrix of pixelated light sources. This matrix comprises a multitude of pixels P located in a plane π which extends here in two directions (y, z). The pixels P are horizontally aligned according to the y axis and vertically according to the z axis. In this exemplary embodiment, a first group of pixels G1 of the matrix is intended to form the first beam 6 and a second group of pixels G2 is intended to form the second beam 10. Thus, here, the second group of pixels G2 is likened to the generation device 7. According to this embodiment, each pixel P can be controlled individually and so the light intensity and the lighting can be controlled in on or off mode or linearly.

[0044] According to a variant embodiment, the light source 12 can be of DMD type (“digital mirror device”) in which the rotational modulation of micro-mirrors makes it possible to obtain a desired light intensity in a given direction.

[0045] According to another variant embodiment, the light source 12 can be of LCD type (liquid crystal display) comprising a surface light source in front of which liquid crystals are placed. The movement of the liquid crystals allows or prevents the passage of light and thus forms a pixelated light source 12.

[0046] According to yet another embodiment of the invention, the light source 12 is of laser type sending a beam of light rays to a scanning system which distributes it over the surface of a wavelength conversion device, such as a plate comprising a luminophor.

[0047] The light source 12 can be associated with an optical system 14 for projecting light onto the road scene. In an embodiment using the matrix of pixels as a light source 12, the optical system 14 exhibits a focus area coinciding with the plane π of the matrix of pixels, that is to say coinciding with the light source 12.

[0048] When it is possible, the light intensity of the road scene as the lighting device 2 according to the invention makes it possible, it also becomes possible to optimize the uniformity of the lighting of the first beam 6 and of the second beam 10. Homogeneity or uniformity of the beam should be understood to mean that the lighting of the beam is constant over a given lighting distance measured on the ground.

[0049] FIG. 3 represents an example of the image of the first light beam 6 and of the second light beam 10 obtained from the lighting means 4 projected onto a screen 16 placed at right angles to the optical axis at 25 meters in front of the vehicle 1. An image I of the pixel of the light source exhibits a lighting proportional to the luminance of the pixel, and the same applies for the information 9 formed by the second beam 10.

[0050] The lighting means is arranged so that the lighting of the first beam 6 and the lighting of the second beam 10 are constant in a portion of the road scene 5 lying between three meters and fifteen meters in front of the vehicle. The light intensity follows the following law in a given direction for each light beam 6, 10:

I(α,β)=E×D.sup.2

where E corresponds to the lighting of the beam expressed in lux, D corresponds to the distance separating the light means 4 and the point of ground impact associated with the direction (α, (β).

[0051] In this way, the light intensity makes it possible to ensure a uniform lighting of the ground by the first beam 6. The lighting of the first beam 6 in a portion of the road scene 5 lying between three and fifteen meters in front of the vehicle 1 then lies between 20 lux and 50 lux, which corresponds to a light intensity lying between 2000 Cd and 5000 Cd at ten meters. Preferably, the lighting of the first beam 6 is equal to 30 lux. Furthermore, the lighting of the first beam 6 in a portion of the road scene 5 situated at 300 meters in front of the vehicle lies between 0.5 lux and 2 lux.

[0052] As is shown in FIG. 4, the direction (α, β) is defined by the angles α et β. The horizontal angle α corresponds to the angle formed by the beam measured in a horizontal plane relative to the optical axis of the beam. In other words, the angle α makes it possible to light a greater or lesser portion of the road. Preferably, the angle α takes a value lying between −40° and 40°. The vertical angle β corresponds to the angle formed by the beam relative to the reference straight line V situated at the height of the headlight, forming the optical axis of the headlight. The angle β makes it possible to light a portion of road more or less distant from the headlight. The angle β can take a value lying between −10° and −4°.

[0053] The light intensity of the first light beam 6 and of the second light beam 10 can be controlled as a function of the vertical angle β. In effect, as FIG. 4 shows:

tan (β)=H/D

where β corresponds to the vertical angle as previously defined, H corresponds to the height of the headlight on the vehicle 1 relative to the ground, and D corresponds to the distance between the point of impact of the first beam 6 or of the second beam 10 on the ground for a given vertical angle β.

[0054] Thus, between three and fifteen meters in front of the vehicle, the law I (α, β)=E×D.sup.2 becomes

I(α,β)=E×(H/tan (β)).sup.2.

[0055] In these conditions, the lighting on the ground becomes E=I/D.sup.2 and corresponds to a constant for a given intensity and distance. The lighting is therefore uniform for each of the beams 6, 10.

[0056] In order to observe the regulatory standards, it is best to not exceed a light intensity of the first beam 6 of 6000 Cd maximum in order to allow the creation of the driving assistance information 9 by the second beam 10 by positive contrast with the contrast lying between 0 and 5, 0 being excluded. The outline contrast formula corresponds to:

(LMAX−LMIN)/LMIN

where LMAX corresponds to the luminance resulting from the sum of the first beam 6 and the second beam 10, and LMIN corresponds to the luminance of the first beam 6. In other words, LMAX corresponds to the luminance of the driving assistance information 9.

[0057] Since the luminance is directly proportional to the light intensity, a contrast of one is obtained corresponding to a first beam 6 of 6000 Cd and a second beam of 6000 Cd, and the luminance of the sum of the beams 6 and 10 is equal 12 000 Cd. A contrast of two corresponds to a first beam 6 of 4000 Cd and a second beam 10 of 8000 Cd, and thus the luminance of the sum of the beams 6 and 10 is equal to 12 000 Cd. A contrast of three corresponds to a first beam 6 of 3000 Cd and a second beam 10 of 9000 Cd, and the luminance of the sum of the beams 6 and 10 is equal to 12 000 Cd. A contrast of four corresponds to a first beam 6 of 2400 Cd and a second beam 10 of 9600 Cd, and the luminance of the sum of the beams 6 and 10 is equal to 12 000 Cd. A contrast of five corresponds to a first beam 6 of 2000 Cd and a second beam 10 of 10 000 Cd, and the luminance of the sum of the beams 6 and 10 is equal 12 000 Cd.

[0058] Thus, the contrast is situated between 0 exclusure and 5, and ideally between 2 and 4 in order to obtain information 9 exhibiting sharp outlines relative to the first beam 6. A contrast between 2 and 4 corresponds substantially to an intensity of the first beam 6 of 4000 Cd with an intensity of the second beam 10 between 8000 and 9600 Cd, while observing the regulatory standards.

[0059] These light intensities correspond to a lighting of the second beam 10 in a portion of the road scene 5 lying between 3 meters and 15 meters in front of the vehicle 1 lying between 30 lux and 150 lux. The lighting of the second beam 10 can be greater than the lighting of the first beam 6 which makes it possible to have information 9 that is particularly easy to distinguish while retaining a beam which lights the road taken by the vehicle equipped with the invention. Such a contrast between the background formed by the first light beam 6 and the information 9 formed by the second light beam 10 is provided by the lighting difference generated by the device 7 for generating the information 9 and the lighting means 4.

[0060] As the graph of FIG. 5 shows, a curve passing through a lighting Emax illustrates the lighting generated by a lighting device of the prior art. This curve is a bell curve with a maximum lighting substantially at fifteen meters. On the other hand, the lighting E0 generated by a lighting device according to the invention is constant up to fifteen meters then decreases gradually for longer distances. This makes it possible to provide, firstly, a controlled and uniform lighting for near light and, secondly, a reduced level of light on the ground which limits the glare effects for the users in case of a wet road. An electrical consumption of the lighting device is also optimized in as much as there is no excess light in areas of the road scene that do not require strong lighting.