EP3717828B1 - Luminous module for motor vehicle, and lighting and/or signalling device provided with such a module - Google Patents

Description

The present invention relates to a lighting and/or signaling device for a motor vehicle.

A preferred application concerns the automotive industry, for vehicle equipment, in particular for the production of devices capable of emitting light beams, also called lighting and/or signaling functions, generally meeting regulations. For example, the invention can allow the production of a light beam, preferably highly resolved, of the pixelated type, in particular for signaling and/or participation in lighting functions at the front of a vehicle. It can be used to display pictograms or variable patterns on a projection surface of the outgoing light.

• un faisceau de croisement, dirigé vers le bas, encore parfois appelé faisceau de code et utilisé en cas de présence d'autres véhicules sur la chaussée ;
• un faisceau de route dépourvu de coupure, et caractérisé par un éclairement maximal dans l'axe du véhicule ;
• un faisceau d'éclairage pour temps de brouillard, caractérisé par une coupure plate et une grande largeur d'éclairement ;
• un faisceau de signalisation pour la circulation en ville, encore appelé lampe de ville.

Signaling and/or lighting lights for motor vehicles are light devices which include one or more light sources and a lens which closes the light. Simplified, the light source emits light rays to form a light beam which is directed towards the window in order to produce an illuminating area which transmits the light to the exterior of the vehicle. These functions must meet regulations regarding light intensity and visibility angles in particular. Known lighting and signaling modules have so far been designed to emit, for example:

• a passing beam, directed downwards, also sometimes called a code beam and used in the event of the presence of other vehicles on the roadway;
• a main beam without interruption, and characterized by maximum illumination in the axis of the vehicle;
• a lighting beam for foggy weather, characterized by a flat cut-off and a large illumination width;
• a signaling beam for city traffic, also called a city lamp.

Recently, technologies have been developed making it possible to produce a high definition pixelated or segmented beam, with a definition of at least 1000 segments, in particular via micro or nano electromechanical devices called MEMS or NEMS respectively. Due to the great flexibility of shape and pattern of beams that they allow and because their price tends to decrease, these systems tend to be installed for increasingly important functions, notably in headlights at the front of vehicles. There figure 1 gives an example of the implementation of a pixelated and digital imaging system in the form of a micro-mirror matrix 13 in a beam projection module. A light source 11 generates light rays in the direction of an optical device 12 making it possible to generate a beam which will impact a reflection face 14 of a micro-mirror matrix 13. Depending on the controlled inclination of the mirrors, the light is either returned to the projection device 15, or returned to a dead zone so as not to participate in active illumination.

In certain cases, this requires significant output illumination and in particular sufficient to comply with regulatory luminous flux conditions. Achieving significant illumination is, however, difficult given the layout illustrated in figure 1 . It is easy to understand that the magnification of the lens used for the input device 12 or its proximity to the matrix of micro mirrors 13 quickly poses a problem of interference with the lens used as projection device 15. In the example shown, the the beam envelope delimited by the rays a1, a2 is at the limit of interfering with the edge of the projection device 15; likewise, the rays b1, b2 returned by the matrix 13 are transmitted by the device 15 in rays c1, c2 to the limit of interfering with the input device 12. Taking into account this limitation, the patent document WO 2017/143371 A1 discloses a headlight for a motor vehicle comprising a matrix of micro mirrors and provided with a pair of light sources with electroluminescent diodes each associated with a lens for focusing a light beam on the reflection surface of the matrix of micro mirrors. This duplication of sources obviously increases the luminous flux leaving the projector. However, it inevitably increases cost and bulk.

In other patent documents relating to video projector devices or motor vehicle lights, such as GB2418996 , CN205388665U Or US2016241819 , it has been proposed to combine two prisms or as in US2013188156 a prism with an optical element placed nearby in order to optimize the luminous flux and reduce bulk. However, these solutions generate chromatism which must be corrected via a complex and expensive optical projection system (number of lenses and type of lenses) . Furthermore, in prism combinations, in order to respect the conditions of total internal reflection, it is necessary to use materials which are expensive to produce the prisms. The document US2016/019523 A1 discloses a device according to the preamble of claim 1.

The present invention aims to remedy at least in part the drawbacks of current techniques and aims in particular to propose a simpler, more compact and more economical optical system.

• transmettre entre la première face et la troisième face au moins une partie des rayons lumineux de la partie transmise vers la surface d'impact ;
• former des rayons réfléchis par réflexion d'au moins une partie de rayons lumineux renvoyés par la surface d'impact, par réflexion totale interne sur la première face ;
• renvoyer au moins une partie des rayons réfléchis vers une zone de projection via la deuxième face

et caractérisé ence qu'il comprend un module additionnel configuré pour produire un faisceau de base de feu de croisement et un module additionnel configuré pour produire un faisceau de base de feu de route et dans lequel le faisceau pixélisé de sortie dudit module lumineux chevauche en partie à la fois le faisceau de base de feu de route et/ou le faisceau de base de feu de croisement.The present invention relates, according to one aspect, to a motor vehicle lighting and/or signaling device characterized in that it is equipped with at least one light module configured to produce an output beam, comprising a light source comprising at least one light-emitting diode, a pixelated and digital imaging system, and an optical input device interposed, following the path of the light rays coming from the light source, between the light source and the pixelated and digital imaging system of so as to transmit at least one part, called the transmitted part, of the light rays coming from the light source towards an impact surface of the pixelated and digital imaging system, characterized in that said light module comprises a prism, comprising a first face , a second face and a third face, and configured for:

• transmit between the first face and the third face at least part of the light rays from the transmitted part towards the impact surface;
• forming reflected rays by reflection of at least a portion of light rays returned by the impact surface, by total internal reflection on the first face;
• return at least part of the reflected rays towards a projection zone via the second face

and characterized in that it comprises an additional module configured to produce a basic low beam beam and an additional module configured to produce a basic high beam beam and in which the pixelated output beam of said light module partly overlaps both the high beam base beam and/or the low beam base beam.

Thus, the light rays are deflected during their journey from the source light towards the projection device at least in part thanks to the prism. The function of the prism includes, upstream of the imaging system, a transmission of light rays coming from the source and, downstream of the imaging system, a total internal reflection making it possible to carry out an angular modification of the rays, advantageously strong , so as to return the rays leaving the prism towards the projection device. The prism allows strong angular variations in beam direction between the beam upstream of the imaging system and the beam downstream of the latter.

We can thus easily adjust the position and the angle of the optical device located at the input, without being hindered by considerations of space relative to the optical projection device, contrary to the state of the art illustrated in figure 1 . The optical input device can advantageously be brought closer to the imaging system and/or its diameter increased (the increase in illumination is directly linked to the increase in the diameter of a lens). In doing so, the luminous efficiency of the beam impacting the imaging system is higher which makes it possible, despite the use of a light-emitting diode source, to obtain satisfactory illumination at the output.

According to another aspect, the present invention also relates to a motor vehicle lighting and/or signaling device equipped with at least one light module. This device may comprise at least one additional module comprising at least one of an additional module configured to produce a basic low beam beam and an additional module configured to produce a basic high beam beam.

Advantageously, the pixelated beam can be an effective complement to another beam, or even several. According to the invention, the device comprises an additional module configured to produce a basic low beam beam and an additional module configured to produce a basic high beam beam and in which the pixelated output beam of the module partly overlaps both the high beam base beam and/or the low beam base beam. The pixelated beam can thus be used both to perform a ground writing function in the portion overlapping with the dipped beam and to contribute to anti-glare high beam functions (Glare Free High Beam in English). ) or dynamic cornering light for the portion astride with the main beam.

The present disclosure also describes a vehicle equipped with at least one module and/or a device according to the present invention.

According to a particularly advantageous embodiment, the module is such that the second face and the third face are carried by two planes perpendicular to each other.

In addition, it preferably comprises an optical device for projecting the output beam receiving at least partially the at least part of the returned rays.

Advantageously, the optical projection device has an optical axis perpendicular to the second face.

Optionally, the optical projection device has an optical axis forming an obtuse angle with an average direction of the transmitted part. This This possibility is very useful for limiting bulk and gives great freedom in lens size for the input optical device.

In a non-limiting case, the third face is parallel to the impact surface. Advantageously and preferably, the third face includes an anti-reflective coating. This avoids the phenomena of ghost images that can be produced by strong reflections returning from the mirrors on the third face.

In one embodiment, the prism is made of a material whose Abbe number is greater than or equal to 50. Good conditions for total internal reflection are guaranteed over the entire visible light range.

Advantageously, the prism is made of PMMA or Crown glass. These materials are particularly economical.

Optionally, a window is placed between the impact surface and the third face.

According to an example, a first face of the window is located opposite the impact surface and includes an anti-reflective coating. This avoids the phenomena of ghost images that can be produced by strong reflections returning from the mirrors on the window.

Advantageously, the anti-reflective coating is configured to reflect less than 4%, preferably less than 2% of light rays in the visible range.

Preferably, the average direction of the transmitted part forms, with a normal to the third face, an angle between -20° and +20°.

Preferably, the distance separating the impact surface and the third face is less than or equal to 2 mm, and preferably less than or equal to 1 mm.

In one embodiment, the pixelated and digital imaging system includes an array of micro-mirrors.

Optionally, the output beam is configured to project at least one pictogram pattern.

In a preferred embodiment, the module is configured to project a light beam at the front of a motor vehicle.

• la figure 1 montre une schématisation d'une projection d'un faisceau pixélisé selon l'état de la technique ;
• la figure 2 représente un exemple de réalisation de l'invention.

Other characteristics and advantages of the present invention will be better understood with the help of the exemplary description and the drawings including:

• there figure 1 shows a schematization of a projection of a pixelated beam according to the state of the art;
• there figure 2 represents an example of embodiment of the invention.

Unless specifically indicated otherwise, technical characteristics described in detail for a given embodiment may be combined with technical characteristics described in the context of other embodiments described by way of example and not limitation.

In the characteristics set out below, the terms relating to verticality, horizontality and transversality, or their equivalents, are understood in relation to the position in which the lighting module is intended to be mounted in a vehicle . The terms “vertical” and “horizontal” are used in this description to designate directions, following an orientation perpendicular to the plane of the horizon for the term “vertical”, and following an orientation parallel to the plane of the horizon for the term “horizontal”. They must be considered in the operating conditions of the device in a vehicle. The use of these words does not mean that slight variations around the vertical and horizontal directions are excluded from the invention. For example, an inclination relative to these directions of the order of + or - 10° is considered here as a minor variation around the two preferred directions.

The device of the invention incorporates at least one module making it possible to generate a pixelated type beam, but also preferably ensures the projection of at least one other beam, via at least one other module. The device of the invention can therefore be complex and combine several modules which can also possibly share components.

In the context of the invention, the term passing beam is understood to mean a beam used when there are crossed and/or followed vehicles and/or other elements (individuals, obstacles, etc.) on the roadway or nearby. . This beam has an average downward direction. It can possibly be characterized by an absence of light above a plane inclined by 1% downwards on the side of traffic in the other direction, and another plane inclined by 15 degrees compared to the previous one of the side of traffic in the same direction, these two plans defining a cutoff in compliance with European regulations. This upper downward cutoff aims to avoid dazzling other users present in the road scene extending in front of the vehicle or on the sides of the road. The low beam, formerly derived from a simple headlight, has undergone developments, the low beam function being able to be coupled with other lighting characteristics which are still considered as low beam functions within the meaning of the present invention.

• faisceau AFS (abréviation pour « Advanced Frontlighting System » en anglais), qui propose notamment d'autres types de faisceaux. Il s'agit notamment de la fonction dite BL (Bending Light en anglais pour éclairage de virage), qui peut se décomposer en une fonction dite DBL (Dynamic Bending Light en anglais pour éclairage mobile de virage) et une fonction dite FBL (Fixed Bending Light en anglais pour éclairage fixe de virage) ;
• faisceau dit Town Light en anglais, pour éclairage de ville. Cette fonction assure l'élargissement d'un faisceau de type feu de croisement tout en diminuant légèrement sa portée ;
• faisceau dit Motorway Light en anglais, pour éclairage d'autoroute, réalise quant à elle la fonction autoroute. Cette fonction assure une augmentation de la portée d'un feu de croisement en concentrant le flux lumineux du feu de croisement au niveau de l'axe optique du dispositif projecteur considéré ;
• faisceau dit Overhead Light en anglais, pour feu de portique. Cette fonction assure une modification d'un faisceau de feu de croisement typique de telle sorte que des portiques de signalisation situés au-dessus de la route soient éclairés de façon satisfaisante au moyen des feux de croisement ;
• faisceau dit AWL (Adverse Weather Light en anglais, pour feu de mauvais temps).

This includes the following functions:

• AFS beam (abbreviation for “Advanced Frontlighting System” in English), which notably offers other types of beams. These include the so-called BL (Bending Light) function, which can be broken down into a so-called DBL (Dynamic Bending Light) function and a so-called FBL (Fixed Bending) function. Light in English for fixed cornering lighting);
• beam called Town Light in English, for city lighting. This function ensures the widening of a low beam type beam while slightly reducing its range;
• beam called Motorway Light in English, for highway lighting, performs the highway function. This function ensures an increase in the range of a low beam by concentrating the luminous flux of the low beam at the optical axis of the headlamp device in question;
• beam called Overhead Light in English, for gantry light. This function ensures a modification of a typical low beam beam such that signal gantries located above the road are satisfactorily illuminated by means of the low beam;
• beam called AWL (Adverse Weather Light in English, for bad weather light).

The basic main beam has the function of illuminating the scene in front of the vehicle over a large area, but also over a significant distance, typically around 200 meters. This light beam, due to its lighting function, is mainly located above the horizon line. It may have a slightly ascending optical axis of illumination, for example.

The device can also be used to form other lighting functions via or beyond those described above.

As indicated previously, one aspect of the invention relates to a module allowing the generation of an output beam of the pixelated type, that is to say processed by a pixelated and digital imaging system offering great flexibility, by the control of the imaging system, in terms of beam configurations actually projected. The terms "pixelated and digital imaging system", "pixelated ray imaging system" or their equivalents have the definition of a system emitting a light beam, said light beam being formed of a plurality of light sub-beams , each sub-light beam can be controlled independently of the other sub-light beams. These systems can be for example micro-mirror matrices 23 as shown, liquid crystal devices, digital light processing technology (Digital Light Processing (DLP) in Anglo-Saxon terms). Micro-mirror matrices are also called, in English terms, “Digital Micromirror Device” (DMD).

Each independently controllable sub-beam forms a pixelated ray. The control of the micro-mirror matrices is carried out by control electronics. Each micro-mirror preferably has two operating positions. A so-called active position corresponds to an orientation of the micro-mirrors allowing the reflection towards an output diopter of an incident light beam. A so-called passive position corresponds to an orientation of the micro-mirrors allowing the reflection towards an absorbing surface of an incident light beam, that is to say towards a direction different from that of the output diopter. Generally speaking, this type of imaging system is implemented in mechanical micro-electronic systems known under the term MEMS, which also includes in the present application nano systems called NEMS.

In a manner known per se, a light source 21 is used to illuminate an impact surface 24 of the pixelated imaging system, for example the reflective face of the micro-mirrors of a micro-mirror matrix 23, and the rays treated by the pixelated imaging system are returned to be projected, generally via an output optical element such as a projector glass or a projection lens. Generally speaking, the present invention can use light sources of the light-emitting diode type, also commonly called LEDs. These may possibly be organic LED(s). In particular, these LEDs can be equipped with at least one chip capable of emitting light of advantageously adjustable intensity according to the lighting and/or signaling function to be performed. Furthermore, the term light source here means a set of at least one elementary source such as an LED capable of producing a flow leading to generating at least one light beam at the output of the module of the invention. In an advantageous mode, the output face of the source is of rectangular section, which is typical for LED chips. HAS non-limitatively, the light source 21 is configured to produce a luminous flux greater than 3000 Im and for example of the order of 4000 lm.

We understand the interest of pixelated beams in the automotive field and the multiplication of functionalities that they allow. However, their integration into vehicles concomitantly with other beam projection systems is still largely unexplored and leads to strong space constraints.

There figure 2 presents an exemplary embodiment of the present invention which allows relative placement of the light source and the optical input device improved relative to the state of the art.

From upstream to downstream following the path of the light rays, we note the presence of a light source 21, which can be of the type previously indicated. Preferably, the light source 21 is configured to emit in a half-space from an emissive zone of rectangular shape. At least part of the rays emitted by the source 21 is optically processed by an optical device 22. The latter may comprise one or more lenses of more or less complex shape.

To the figure 2 , the optical device 22 takes the form of a lens having an entry face 22a making it possible to admit the light rays coming from the source 21 and an exit face 22b ensuring projection towards the rest of the module. At the output of the optical device 17, at least one part referenced "a" called the transmitted part of the processed rays is intended to impact the surface of the pixelated and digital imaging system, here a matrix of micro-mirrors 23. However, according to the invention, the light rays first enter through a prism 26, via a first face 26a of the latter.

Preferably, the angle formed between the first face 26a and the third face 26c is between 40 and 50°, preferably between 44 and 46°, more preferably it is 45°, within manufacturing tolerances. This avoids generating field curvature aberrations in the rays reflected by the impact surface 24 towards the internal side of the first face 26a and therefore reduces the cost of the projection system because it will not require a correction element. these aberrations.

In a configuration of the module dedicated to a ground writing function; preferably, the first face 26a forms an acute angle with the average direction of the transmitted part “a” of the light rays coming from the source 21. More preferably, the average direction and the normal to the first face 26a forms an angle between -20° and + 20°. We thus favor the quantity of flow retransmitted.°.

In a configuration of the module including an anti-glare high beam function; preferably, the third face 26c forms an acute angle with the average direction of the transmitted part “a” of the light rays coming from the source 21. More preferably, the average direction and the normal to the third face 26c forms an angle between -20° and + 20°. This greatly reduces the generation of parasitic rays during reflection on the impact surface 24 and promotes the emission of a pixelated beam with high contrast, which is desirable for an anti-glare function.

Generally speaking, it is desirable to use for the prism 26 a transparent material and advantageously having a high Abbe number, preferably greater than or equal to 50. It may be Crown glass or even polymethacrylate. methyl (PMMA).

In order to optimize the pixelated module for use both for writing functions on the ground and for anti-glare high beam functions, we will favor a prism material with an Abbe number greater than or equal to 50, an angle between the first face 26a and the third face 26c ideally of 45° and illumination of the prism by the source 21 such that the average direction and the normal to the third face 26c forms an angle between -20° and + 20° , ideally confused with normal.

The light rays entering the prism 26, referenced “a” in figure 2 , are directed towards a third face 26c of the prism 26 facing which the imaging system is located, which is in the example shown a matrix of micro-mirrors 23. Advantageously, the impact surface 24 (corresponding to the exposed surface of the micro-mirrors) is parallel to the third face 26c, the latter being preferably planar. Advantageously, the impact surface 24 is protected by a window 27, a first face 27a of which is located facing the impact surface 24. A second face 27b of the window 27 is located opposite, and in contact or not, of the third face 26c. Advantageously, the distance separating the impact surface 24 and the third face 26c is limited and can for example be less than 2 mm or even 1 mm, and preferably 0.5 mm. The presence of the window 27 can be used to adjust this spacing without risk of damaging the impact surface 24.

In the illustrated embodiment, we also seek to eliminate, or at least limit, the parasitic effects that could be produced by a reflection on the third face 26c of the prism 26 or the first face 27a of the window of the rays having reached the impact surface 24 and having been reflected. To this end, it is advantageous to provide at least the third face 26c of the prism 26, advantageously also the window 27, with an anti-reflective coating 28 which may be of standard design and in particular be configured to produce a maximum reflection of 4%. , or even a maximum of 2% in the visible spectrum. Preferably the anti-reflective is chosen with a maximum reflection of 1% in the visible spectrum. In the context of use with a need for high contrast, we will favor a maximum reflection of 0.2%, more preferably 0.1% in the visible spectrum.

Preferably, the impact surface 24 defined by all of the micro-mirrors is of rectangular shape. It preferably extends in a plane perpendicular to a plane carrying the second face 26b of the prism 26 and/or parallel to the optical axis of the projection device 25.

Depending on the orientation of the mirrors, the rays are reflected, either so as to participate in the projected beam, or so as to be inactive. This is how the configuration of the pixelated beam can be controlled as desired. In the case shown, the active rays “c” are directed so as to re-enter the prism 26 via the third face 26c. This ray path is configured so that the active rays “c” reach the first face 26a again. However, this time, the angle of the rays relative to the first face 26a is such that it produces a total internal reflection in the prism 26 so as to form reflected rays “d” which are directed towards the second face 26b of the prism 26.

The outgoing rays “e” are directed towards a projection device 25, which is or which typically comprises a projection lens. In the case illustrated, it is a planar convex lens, the entry face 25a of which is planar and the exit face 25b is convex. The reference “f” represents an example of a projected ray.

Advantageously, the prism 26 is configured, in terms of angle and choice of materials, so that all of the light rays coming from the input device 22 are transmitted to the matrix of micro mirrors 23 and so that all of the light rays reflected by the latter is reflected by the first face 26a. Note that the area of the first face 26a through which the rays "a" enter the prism 26 and the area of the first face 26a through which the rays "c" again reach the first face 26a to be reflected, can overlap.

REFERENCES

11.

Light source

12.

Optical device

13.

Micro-mirror array

14.

Reflection Face

15.

Optical projection device

21.

Light source

22.

Optical input device
22a. Entrance face
22b. Exit face

23.

Micro-mirror array

24.

Impact surface

25.

Optical projection device
25a. Entrance face
25b. Exit face

26.

Prism
26a. First side
26b. Second side
26c. Third side

27.

Window
27a. First side
27b. Second side

28.

Anti-reflective coating

29.

Optical axis

Claims (16)

1. Motor-vehicle lighting and/or signalling device equipped with at least one luminous module configured to produce an output beam, comprising a light source (21) comprising at least one light-emitting diode, a pixelated digital imaging system, and an optical input device (22) inserted, along the path of the light rays coming from the light source (21), between the light source (21) and the pixelated digital imaging system so that it transmits at least a portion, known as the transmitted portion, of the light rays coming from the light source (21) towards an impact surface (24) of the pixelated digital imaging system, characterized in that said luminous module includes a prism (26), comprising a first face (26a), a second face (26b) and a third face (26c), and configured to:

   - transmit between the first face (26a) and the third face (26c) at least one portion of the light rays of the transmitted portion towards the impact surface (24);

   - form reflected rays by reflecting at least one portion of the light rays returned by the impact surface (24), by total internal reflection on the first face (26a);

   - return at least one portion of the reflected rays towards a projection zone via the second face (26b)

   and characterized in that it comprises an additional module configured to produce a basic low beam and an additional module configured to produce a basic high beam and in which the pixelated output beam of said luminous module partially overlaps both the basic high beam and/or the basic low beam.
2. Device according to the previous claim, wherein the second face (26b) and the third face (26c) are held by two planes perpendicular to each other.
3. Device according to one of the previous claims, also including an optical device (15) for projecting the output beam at least partially receiving the at least one portion of the returned rays.
4. Device according to the previous claim, wherein the optical projection device (15) has an optical axis (29) perpendicular to the second face (26b).
5. Device according to one of the two previous claims, wherein the optical projection device (15) has an optical axis (29) forming an obtuse angle with a mean direction of the transmitted portion.
6. Device according to one of the previous claims, wherein the third face (26c) is parallel to the impact surface (24).
7. Device according to one of the previous claims, wherein the prism (26) is made from a material the Abbe number of which is greater than or equal to 50.
8. Device according to one of the previous claims, wherein the prism (26) is made from PMMA or crown glass.
9. Device according to one of the previous claims, including a glass sheet (27) arranged between the impact surface (24) and the third face (26c).
10. Device according to the previous claim, wherein a first face (27a) of the glass sheet situated facing the impact surface (24) comprises an anti-reflective coating (28) .
11. Device according to the previous claim, wherein the anti-reflective coating (28) is configured to reflect less than 40, preferably less than 2% of the light rays in the visible range.
12. Device according to one of the previous claims, wherein the mean direction of the transmitted portion forms an angle of between -20° and +20° with a normal to the first face.
13. Device according to one of the previous claims, wherein the distance separating the impact surface (24) and the third face (26c) is less than or equal to 2 mm, and preferably less than or equal to 1 mm.
14. Device according to one of the previous claims, wherein the pixelated digital imaging system comprises a micromirror array (23).
15. Device according to one of the previous claims, wherein the output beam is configured to project at least one pictogram pattern.
16. Device according to one of the previous claims, configured to project a light beam in front of a motor vehicle.

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