LIGHTING MODULE FOR A DEVICE FOR LIGHTING IN LIGHT SEGMENTS OF A MOTOR VEHICLE HEADLIGHT

Abstract

The invention relates to a lighting module for a headlight for lighting in light segments of a motor vehicle, as well as to a headlight comprising modules in accordance with the invention. The modules according to the invention are characterized in that they allow the creation of headlights that have a continuous external projection surface and implement a lighting function in segments, such as in strips, through the juxtaposition of identical modules.

Claims

1: A lighting module for a lighting device producing light segments of a motor vehicle headlight, including: at least one primary optical element having a light pixel forming structure intended to cooperate with at least one light source and a corrector exit diopter, each primary optical element defining an optical axis; a projection lens; the module being configured to project light entering the primary optical element or elements and leaving via the projection lens in the form of a light segment, such as a light polygon or strip, formed of at least one light pixel; wherein the normal mounting direction the exit diopter of the projection lens has a toroidal shape.

2: The light module according to claim 1, wherein the normal mounting direction in a horizontal plane the exit diopter of the projection lens has a convex curvature with a radius of curvature R given by the formula: $R=\frac{L}{2}.Math.\left({\sin \left(\frac{\alpha }{2}\right)}^{-1}\right)$ wherein L is the width of the projection lens seen from in front; α=k(Δθ)/N, where Δθ is the angular width in degrees of a light segment projected by the module and k and N are positive integers.

3: The lighting module according to claim 1, wherein the exit diopter of the projection lens has in the normal mounting direction in a horizontal plane a convex curvature with a radius of curvature R greater than 200 mm and preferably between 400 and 1200 mm inclusive.

4: The lighting module according to claim 1, wherein the projection lens includes in the normal mounting direction in a horizontal plane an entry diopter with at least one part having a convex profile, the convexity or convexities being generally aligned to the positions of the optical axes of the primary optical elements of the module.

5: The lighting module according to claim 1, wherein an intermediate lens for each primary optical element is disposed between the exit diopter of the primary optical element and the projection lens, the intermediate lens being configured to concentrate the radiation from the exit diopter of the corresponding primary optical element on the projection lens.

6: The lighting module according to claim 1, wherein the pixel forming structures include at least one light guide and/or cushions.

7: The lighting module according to claim 1, wherein the light source or sources include(s) at least one light-emitting diode (LED) and/or one laser diode.

8: The lighting module according to claim 1, wherein the module includes lateral positioning means intended to juxtapose two identical modules horizontally in the normal mounting direction so that the exit diopters of the modules form a continuous surface.

9: The lighting module according to claim 8, wherein the positioning means include at least one notch in a first lateral face of the projection lens and at least one protrusion in the second lateral face so that the at least one protrusion of a first module can be engaged in the corresponding at least one notch of an identical module juxtaposed horizontally in the normal mounting direction.

10: The lighting module according to claim 8, wherein the module includes support means on which the light source or sources and the projection lens are disposed, the support rings including the lateral positioning means.

11: The lighting module according to claim 1, wherein the width of the module in the normal mounting direction is increasing in the direction of the light emitted by the module.

12: The lighting module according to claim 1, wherein the width of the module in the normal mounting direction is decreasing in the direction of the light emitted by the module.

13: The lighting module according to claim 11, wherein the smallest width of the module in the normal mounting direction is 5 to 50% narrower than the greatest width of the module in the normal mounting direction.

14: An assembly including a plurality of identical lighting modules according to claim 1, wherein the lighting modules are assembled in horizontal juxtaposition in the normal mounting direction so that the respective projection lenses form a continuous surface of the assembly.

15: A motor vehicle headlight wherein the headlight includes a lighting device producing light strips and including at least two lighting modules according to claim 1.

16: A motor vehicle headlight wherein the headlight includes a lighting device producing light strips and including at least one assembly as claimed in claim 14.

17: The lighting module according to claim 2, wherein the exit diopter of the projection lens has in the normal mounting direction in a horizontal plane a convex curvature with a radius of curvature R greater than 200 mm and preferably between 400 and 1200 mm inclusive.

18: The lighting module according to claim 3, wherein the projection lens includes in the normal mounting direction in a horizontal plane an entry diopter with at least one part having a convex profile, the convexity or convexities being generally aligned to the positions of the optical axes of the primary optical elements of the module.

19: The lighting module according to claim 4, wherein an intermediate lens for each primary optical element is disposed between the exit diopter of the primary optical element and the projection lens, the intermediate lens being configured to concentrate the radiation from the exit diopter of the corresponding primary optical element on the projection lens.

20: The lighting module according to claim 5, wherein the pixel forming structures include at least one light guide and/or cushions.

Description

[0031] Other features and advantages of the present invention will be understood better with the aid of the description of examples and from the drawings, in which:

[0032] FIG. 1 is an isometric view from behind of a lighting module according to the invention;

[0033] FIG. 2a is a diagrammatic top view of a module according to one preferred embodiment of the invention;

[0034] FIG. 2b shows diagrammatically light strips projected by the module from FIG. 2a;

[0035] FIGS. 3a and 3b show light strips projected by modules according to two embodiments of the invention;

[0036] FIG. 4 shows light strips projected by modules according to one embodiment of the invention;

[0037] FIG. 5 is a diagrammatic top view of an assembly of modules according to one embodiment of the invention;

[0038] FIG. 6 shows a section transverse to the optical axis through a projection lens of a module according to one embodiment of the invention;

[0039] FIGS. 7A and 7B show light strips projected by modules according to other embodiments of the invention.

[0040] In the following description, similar reference numbers are used to describe similar concepts through different embodiments of the invention.

[0041] Unless specifically indicated otherwise, technical features described in detail for a given embodiment may be combined with the technical features described in the context of other embodiments described by way of nonlimiting example.

[0042] FIG. 1 shows in simplified form a lighting module 1 according to the invention. The headlight is generally represented in the lighting direction. The headlight is partly represented by its diopters.

[0043] The lighting module 1 includes, in the lighting direction, a primary optical element 6 and a projection lens 4. The primary optical element has an optical axis 10 along which it illuminates and along which it concentrates and generally bends its rays.

[0044] The lighting module includes at least one light source 12, such as a light-emitting diode (LED) or a laser diode, which produces light rays entering the optical system via the primary optical element 6. The module 1 may further include a casing which is not shown for clarity. The light sources of the module are supplied with power in a known manner by a device for controlling the supply of power to the light sources that will not be described in detail in the context of the present invention. Such devices are known to the person skilled in the art and generally include a converter for converting a voltage supplied by a current source of a motor vehicle, such as a car battery, into a charging voltage suitable for supplying power to the light source or sources. The device controlling the supply of power makes it possible, in a manner known for ADB systems, to supply selectively and independently with power each group of light sources participating in the creation of a projected pixel.

[0045] In the FIG. 1 example the primary optical element 6 includes at least one light guide 14, four of them here, and a body with a curved exit diopter 16. The body of the primary optical element forms a correction portion with a domed, for example, hemispherical, surface 16. Each light guide 14, also referred to as a waveguide or optical guide, is associated with a primary light source 12; it conducts light through the material of the element. It has a lengthwise extent, possibly its main lengthwise extent, along the optical axis 10. The material constituting the light guides 14 and the body is transparent. Here it is an optical lens material, such as an organic material or possibly glass and is in one piece. An optical element of this kind is well known to the person skilled in the art and can be produced as described in the document EP2743567A1. Alternatively, the primary optical element may include microlenses or cushions for guiding the light emitted by the light sources.

[0046] The projection lens 4 has an entry diopter 22 facing the exit diopter 16 of the primary optical element and an exit diopter 24. Each of these diopters is continuous. The projection lens 4 forms a continuous strip of material. The surface of the exit diopter 24 follows the geometry of a toroidal surface produced by rotating a circle about an axis offset from its center. Two identical modules therefore have two identical surface elements of the same torus and can be assembled horizontally in the normal mounting direction to form a continuous surface element of the same torus having a double surface. The surface created in this way by the exit diopters 24 can be widened by adding identical modules.

[0047] According to a preferred embodiment of the invention, the radius of curvature R of the exit diopter 24 of the projection lens 4 is given by the following equation:

[00002]$\begin{array}{cc}R=\frac{L}{2}.Math.\left({\sin \left(\frac{\alpha }{2}\right)}^{-1}\right)& \left(1.1\right)\end{array}$

[0048] in which L is the width of the projection lens seen from in front and α=k(Δθ)/N. Δθ is the angular width in degrees of a light segment projected by the module and k and N are positive integers.

[0049] The light segment width is substantially equal to the mid-height width of the intensity profile.

[0050] The quantities operative in equation 1.1 are illustrated diagrammatically in FIG. 2a, which is a diagrammatic top view of a lighting module according to the invention in the situation where α=Δθ.

[0051] L is the width of the projection lens seen from in front; in the instance shown, this is the length of a chord of a circle of radius R the center of which is the location of the single light source 12 of the module, the chord subtending an angle Δθ.

[0052] Δθ is the angular width in degrees of a light segment projected by the module.

[0053] The radius of curvature R is preferably greater than 200 mm and preferably between 400 and 1200 mm inclusive. The angle Δθ is preferably between 1.5° and 3° inclusive.

[0054] The entry face 22 of the projection lens 4 preferably has a convex geometry in the horizontal direction, as shown in FIG. 2a. The convexity is preferably centered on the optical axis 10 of the primary optical element.

[0055] FIG. 2b shows diagrammatically a light segment in the form of a light strip that the module 1 from FIG. 2a is able to project onto the road in front of the vehicle equipped with the module. The single light source 12 creates a single strip of angular width Δθ. Similar modules capable of creating a plurality of parallel strips of identical width (contiguous or spaced by an angular width Δθ) using a plurality of light sources and/or primary optical elements can be produced by the person skilled in the art using a projection lens conforming to the formula according to the invention.

[0056] The example described hereinafter shows the impact of the factor N involved in the calculation of the radius of curvature of the exit diopter of the projection lens according to the invention. When a plurality of identical modules, which therefore have the same radius of curvature R, are placed side by side, the integer factor N defines a factor of multiplication of the resolution obtained by the juxtaposition of the modules. This is illustrated by way of example in FIGS. 3a and 3b. In FIG. 3a, two identical modules (N=1) similar to that shown in FIG. 2a are juxtaposed horizontally in the normal mounting direction. The two light strips created by the light source 12 of the first module and the light source 12b is of the second module both have an angular width equal to Δθ and do not overlap laterally. The angle Δθ between the optical axes of the two continuous modules is therefore substantially equal, ignoring cut-off blurring effects, to the angular width of a light strip. This angle defines the resolution of the beam obtained.

[0057] In FIG. 3b the factor N is equal to 2. This results in a lateral superposition of the projected light strip halves. The horizontal angle between the optical axes of the two contiguous modules is, ignoring blurring effects, substantially half the angular width of a light segment. The resolution is therefore doubled. As N increases, the resolution of the overall beam produced by an assembly of identical modules increases, while the overall width of the beam decreases.

[0058] The factor k operative in the calculation of the radius of curvature of the exit diopter of the projection lens according to the invention is a predefined integer.

[0059] It corresponds to the choice to produce the overall light beam with segments generated by a lighting device including at least two modules according to the invention.

[0060] The factor k is the number of pixels constituting a light group coming from a single module up to encountering a pixel coming from another module of the lighting device in a particular widthwise direction of the overall beam (from left to right or vice versa). The term luminous group therefore denotes a set of contiguous or overlapping pixels produced exclusively by a module, each module projecting at least one light group, which groups can be contiguous or spaced. The light group contains at least one pixel.

[0061] The overall beam of a lighting device producing light segments consists of a succession of light groups coming from at least two identical modules according to the invention, which groups can be contiguous or overlap depending on the chosen factor N.

[0062] For practical reasons of modular design and compactness of the module of the invention, k will be chosen to be less than or equal to 50, more generally less than or equal to 20 and preferably less than or equal to 10.

[0063] Similarly, N will advantageously be between 1 and 4 inclusive.

[0064] In the following examples, the light segment is formed of a single pixel and takes the form of a vertically oriented rectangular light strip.

[0065] A first example is shown diagrammatically by FIG. 4, which shows two sets of k=2 pixels 112 projected by a first module and two sets of pixels 112b is projected by a second module identical to the first module. In the situation shown the curvature according to equation 1.1 uses the factors k=2 and N=1. The pixels projected by the two identical modules are interleaved to create a beam consisting of contiguous pixels.

[0066] FIGS. 7A and 7B show other examples of possible configurations of overall beams with light strips generated by at least two modules according to the invention associated with a lighting device producing light segments in the form of strips. To make this easier to understand, in these two figures the pixels in the form of strips coming from each of the modules are not shown superposed, it being understood that the overall beam results from the summation of the pixels. In FIG. 7A, N=1 and k=1, each module generating two spaced pixels. In FIG. 7B, k=1 and N=2, each module generating three distinct and contiguous pixels, the pixels of the first module and the second module then overlapping.

[0067] In all the embodiments, in order to facilitate the horizontal juxtaposition of the modules, it is preferable for the width of the module or its casing in the normal mounting direction to increase or decrease in the direction of the light emitted by the module. The width of the rear part is preferably strictly less than that of the front part accommodating the projection lens. The rear part is advantageously at least five times less wide than the front part. The rear part is preferably 5% to 50% less wide than the front part. This is shown by the FIG. 5 diagram, which is a top view of an assembly of eight identical modules according to the invention disposed laterally in contact.

[0068] Alternatively, the width of the front part is strictly less than that of the rear part. In this case the front part is advantageously at least five times less wide that the rear part. The front part is preferably 5% to 50% less wide than the rear part.

[0069] In all the embodiments of the invention, the module may include lateral positioning or alignment means to facilitate the juxtaposition of two identical modules horizontally in the normal mounting direction so that the exit diopters of the modules form a continuous toroidal surface element. The alignment means can be in the projection lens or in the support means for retaining the various components of the module at their intended location. Alternatively, the alignment means may be in a heatsink element of the module that is not shown.

[0070] FIG. 6 shows by way of example an internal section of a projection lens according to one embodiment of the invention. The section is taken in a vertical plane transverse to the optical axis. The alignment means include notches 26 and protrusions 25 on the lateral edges of the projection lens. The location of the notches and protrusions is chosen so that the protrusions of a first module according to the invention can be engaged in the corresponding notches of an identical horizontally juxtaposed module in the normal direction of mounting of the module. Other notch and protrusion geometries can obviously be envisaged without departing from the scope of the invention.

[0071] It is clear that the invention is not limited to the modular embodiment of motor vehicle lighting devices producing light segments including a single pixel in the form of vertically oriented rectangular light strips, as shown in the examples, and that other segment shapes may be arrived at by the person skilled in the art without departing from the scope of the present invention.

[0072] The present description and the examples shown in the figures enable the person skilled in the art to create a panoply of lighting modules according to the invention by using different parameters in equation 1.1. The assemblies of such modules can then be used to create headlights producing light segments for motor vehicles having different optical signatures.