EP1610057A1 - Lighting module for a vehicle headlight and headlight incorporating such a module - Google Patents

Abstract

The module has a concave reflector (2) to transform a spherical wave front from a light source (S) into a wave front restoring to an arc of circle (A) situated in a plane of a plate (4). A lens (3) located in front of the reflector and the source rotates around an axis (Z) orthogonal to the plane and passing through a center (C) of the arc of circle. The plate has an upper reflecting side for folding a beam from the reflector. An independent claim is also included for a headlight of a motor vehicle.

Description

The invention relates to a lighting module for a projector of motor vehicle, capable of giving, in particular, a beam of light to cut. It concerns in particular a module of the kind of those who have a concave reflector, at least one light source arranged in the concavity of the reflector to illuminate at least upwards, and a lens located in front of the reflector and the light source, the reflector being associated with a flat plate, in particular horizontal, whose face upper is reflective to fold the beam from the reflector, said plate having a front end edge adapted to form the cut in the lighting beam.

Such a lighting module is known for example from EP-A-1 357 334 which shows a reflector constituted by a coupled elliptical mirror with a lens of revolution around the optical axis. Front view, the lens has a circular contour located in a vertical plane, orthogonal to the optical axis. If you want to assemble several modules side by side, contour lenses circular will be tangent to a point with a space that is not used between the contours. You can insert corners between the circular contours, but these are dark areas to create an apparent surface additional unnecessary. Alternatively, we can cut or enlarge the lenses in square or hexagon to assemble them by putting in contact cut faces. By operating in this way, a surface loss is created illuminating.

A projector made with such a module assembly gives the impression of a plurality of boxes. So not only the collection of light is not optimal, but an observer will perceive the plurality of different light sources through the lenses, which is not satisfying for the style, especially when the light sources are numerous, in particular constituted by diodes.

A first object of the invention is to provide a module that can be assembled with similar modules in a continuous way, with a minimum of light loss, and without it being possible to distinguish light sources located inside a projector.

In addition, with an elliptical reflector, the lens is stigmatic. The Cutting of the lighting beam is only clear along the optical axis of the projector. This is even more noticeable with a module whose source light is constituted by a light-emitting diode, such a module having a low focal length; the cutoff of the lighting beam is blurred on edges. With a very wide lighting beam, there is no break net across the entire width. Another object of the invention is to improve the sharpness of the cut along the width of the beam.

The invention therefore aims, above all, to provide a lighting module of the defined above which no longer has, or to a lesser degree, the disadvantages mentioned above. The object of the invention is in particular to provide a lighting beam in three dimensions, with a minimum of distortions, especially in barrel.

According to the invention, a lighting module for a projector of motor vehicle, of the kind defined above, is characterized in that that the reflector is determined to transform a wave surface spherical source from a wave surface down to a arc of a circle located in the plane of the plate, and in that the lens is revolution about an axis substantially orthogonal to the plane of the plate and passing through the center of said arc.

The reflector and the lens according to the invention are designed such so that the reflector provides the horizontal distribution of the beam while the lens ensures the cutting of the beam and the vertical distribution without interfere with the horizontal distribution established by the reflector.

The reflector is determined by the choice of the radius of the arc of circle, the distance from the source to the center of the arc, and the distance from the source to the top of the reflector in the plane of the arc of circle.

Preferably, the plane of the plate passes substantially through the center of the source, which is advantageously substantially punctual.

According to another definition, the surface of the reflector is such that light rays coming from the source and falling at points located on a curve formed by the intersection of the surface of the reflector and a plane vertical passing through the center of the arc of a circle, but separated from the source, are reflected by the surface of the reflector in this vertical plane so as to converge at a point formed by the intersection of said vertical plane and the arc of circle.

Preferably, the reflective plate or "bender" is constituted by a part of disk having for edge the arc of circle.

The invention also relates to a projector formed of a assembly of several modules as defined above.

Fig. 1 est une vue schématique simplifiée en perspective d'un module selon l'invention.

Fig. 2 est un schéma en perspective, sous un autre angle, avec parties coupées ou arrachées, et à plus grande échelle, du module selon l'invention, avec représentation de trajets de rayons lumineux.

Fig. 3 est un schéma en perspective simplifié, à échelle différente, illustrant principalement la plieuse.

Fig. 4 est une coupe schématique verticale passant par l'axe optique illustrant la section transversale de la lentille.

Fig. 5 est une vue schématique en plan d'un projecteur avec trois modules juxtaposés d'axes optiques parallèles.

Fig. 6 est une vue schématique en plan d'un projecteur avec quatre modules juxtaposés, avec des axes optiques à inclinaison progressive.

Fig. 7 est une vue schématique en plan d'un projecteur avec trois modules juxtaposés d'axes optiques parallèles, dans lequel la lentille du module central présente une courbure en sens inverse de celle des lentilles latérales.

Fig. 8 est un schéma en plan de deux modules juxtaposés avec courbure en sens inverse.

Fig. 9 montre un réseau de courbes isolux obtenu avec un module selon l'invention, dont le rayon de l'arc de cercle est infini.

Fig. 10 montre un réseau de courbes isolux obtenu avec un module convexe selon l'invention et

Fig. 11 montre un réseau de courbes isolux obtenu avec un module concave selon l'invention.

The invention consists, apart from the arrangements described above, in a certain number of other arrangements which will be more explicitly discussed hereinafter with regard to exemplary embodiments described with reference to the appended drawings, but which are not in no way limiting. On these drawings:

Fig. 1 is a simplified schematic perspective view of a module according to the invention.

Fig. 2 is a perspective diagram, from another angle, with cut or torn parts, and on a larger scale, of the module according to the invention, with representation of light ray paths.

Fig. 3 is a simplified perspective diagram, on a different scale, mainly illustrating the folder.

Fig. 4 is a vertical schematic section through the optical axis illustrating the cross-section of the lens.

Fig. 5 is a schematic plan view of a projector with three modules juxtaposed parallel optical axes.

Fig. 6 is a schematic plan view of a projector with four juxtaposed modules, with optical axes gradually inclined.

Fig. 7 is a schematic plan view of a projector with three modules juxtaposed parallel optical axes, wherein the lens of the central module has a curvature in the opposite direction to that of the side lenses.

Fig. 8 is a plan diagram of two juxtaposed modules with curvature in opposite direction.

Fig. 9 shows a network of isolux curves obtained with a module according to the invention, the radius of the arc of which is infinite.

Fig. 10 shows a network of isolux curves obtained with a convex module according to the invention and

Fig. 11 shows a network of isolux curves obtained with a concave module according to the invention.

Referring to Fig. 1, we can see, schematically shown, a lighting module 1 for a motor vehicle headlight, clean to give a light beam cut. This module 1 includes a concave reflector 2, at least one light source S arranged in the concavity of the reflector to illuminate at least upwards, and a lens 3 located in front of the light source S and the reflector 2, in the direction of propagation of the light beam.

The reflector 2 is associated with a flat plate 4 in particular horizontal as shown in FIG. 1. The plan of this plate 4 goes from preferably, but not necessarily, substantially by the center of the light source S. The reflector 2 is located above the plate 4 and the upper face of the plate 4 is reflective to fold the beam of rays coming from the reflector 2, as explained in particular in EP-A-1 357 334. The reflective plate 4 is frequently called "folding" and it has a clean front end edge to form the cut in the lighting beam. When the plate 4 is horizontal, the cut is horizontally and the area illuminated by the beam from the spotlight 1 is located below a horizontal line. By tilting the plane of the plate 4, or a part of this plate, relative to the horizontal plane can be tilt the cut line with respect to a horizontal direction in tilting the lens at the same angle.

The light source S is advantageously substantially punctual, especially formed by a light emitting diode wrapped by a globe or hemispherical capsule, this diode presenting a light distribution axis substantially orthogonal to the flat plate 4, and lighting up.

According to the invention, the reflector 2 is determined to transform a spherical wave surface from the source into a surface wavelength reducing to an arc A in the plane of the plate 4, and the lens 3 is of revolution about an axis Z orthogonal to the plane of the plate 4 and passing through the center C of the arc A.

A suitable reflector 2 satisfying the stated conditions previously, is unique for a given choice of the radius R of the arc of circle A, the distance from the source S to the center C of the arc A, and the distance f from S to the vertex 5 of the reflector in the plane of the arc of a circle A. The top 5 of the reflector corresponds to the point of intersection of the axis Y-Y optical module with the reflector, which optical axis is confused with the line passing through C and S.

The spherical wave surface from the source can be reduce to a point S as illustrated in FIG. 2.

The characteristics of the reflector 2 are exposed with reference at Fig. 2 on which the reflector 2 has only been partially represented. We considers a vertical plane V passing through the point C and the Z axis but separated from the source S, which is outside the plane V. The intersection of the reflector 2 by the plane V is constituted by a curve 6 partially shown. Two points m1 and m2 of this curve 6 constitute common points, any of the surface of the reflector 2.

We consider two light rays i1, i2 coming from the source S and falling respectively in m1 and m2 against the inner surface reflection of the reflector 2. The rays i1 and i2 are not in the plane V since S is out of this plane.

With the reflector 2 as defined above, the radii incidents i1 and i2 are reflected along rays k1 and k2 which are all two located in the vertical plane V. In addition, the reflected rays k1 and k2 converge at a point P formed by the intersection of the vertical plane V and the arc circle A.

These properties are preserved regardless of the m point considered on the curve 6, and regardless of the angular orientation of a vertical plane V passing through CZ.

Each point P of the arc A will behave like a new light source giving rise to a wave surface whose cut by the plane V is a circle 7 of radius r which increases proportionally with time.

The optical path from the source S to the point P passing through the current point m1, or m2 of the curve 6 is constant: Sm1 + m1P = Sm2 + m2P = constant.

The lens 3 constitutes a volume of revolution around the axis vertical Z. The intersection of the plane of the arc A with the entrance surface 3E1 of the lens 3 is formed by a portion of circumference 8 likewise center C as the arc A, but whose radius is greater than R.

The light rays k1, k2 returned by the reflector 2 fall in P on the edge of the reflective plate 4 or "folder", and are therefore returned in directions q1, q2 remaining in the vertical plane V impact. The rays q1, q2 fall in n1, n2 on the input surface 3E1 of the lens. Normals at the surface 3E1 at points n1, n2 are in the vertical plane V which contains the light rays q1, q2. The Rays refracted t1, t2, in the lens, remain in the same plane V, as well as the rays u1, u2 which exit through the output face 3ES of the lens.

The reflective plate 4 or "folding" is formed by a part of a disc having the edge of the arc of circumference A. This plate reflecting reflector extends under the concave mirror forming the reflector 2. The limit 9 (Fig.3) to source S only depends on practical considerations of passage of the light from the source S. This limit 9 is formed by example, on both sides of an angle whose concavity is turned towards the center C, this angle generally admitting as bisecting plane the plane vertical passing through the optical axis CS.

The light source S is preferably constituted by a diode electroluminescent emitting upwards in the upper half-sphere.

In reality, the source S is not perfectly punctual and light rays (not shown between the source S and the vicinity of P) will be shifted beyond the edge A and continue their journey straight on q'1, q'2 without being folded by the plate 4 they do not meet.

Fig.4 is a lens section of the 3 by a plane containing the vertical axis Z and the CS optical axis intersecting point to the arc A.

The curve E1 of the input face of the lens in the plane of section of Fig.4 has an influence on the sharpness of the cut. This curve E1 is chosen so that the cutoff of the lighting beam is made clear and the best possible, even for a wide beam. This curve E1 is advantageously formed by a portion of circumference whose center is situated on the right joining source S and center C; this portion of circumference E1 turns its convexity inwards that is to say towards the center C as shown in Fig.4. The ends of the curve E1 can to be curved in a more pronounced way. The section of the lens is limited to the outside by a curve ES substantially in hat constable, that is to say having a central rounded hump whose convexity is turned outwards, which is extended on each side by an inflected zone becoming concave towards the outside.

The path of a light ray q3 from point a is shown. This ray q3 falls at a point n3 on the curve E1 and is refracted at t3 to exit by the next ES face u3.

The angle Ω (Fig.2) of opening of the reflector 2, symmetrical by vertical plane passing through the optical axis CS, has a maximum value determined by the angle formed between the straight lines joining point C to intersections of the arc A with the reflector 2 in the plane of the plate 4.

The width of the light beam coming out of the module depends mainly from this angle Ω but also from other parameters, especially the source-to-vertex distance, because of their influence on the size of the images.

When the radius R of the arc A reaches infinity, the lens 3 tends to a cylindrical lens and the beam (everything else being equal) tends towards the most intense spot allowed by the luminance of the source and the apparent surface. We are then optically equivalent to the combination of an ellipsoid and a stigmatic point infinite lens, but with lower aberrations in the field according to the invention.

The particular example of circumference portion given for the curve E1 is not limiting. E1 can be any curve.

The ES curve of the exit face is constructed so that, in the plane considered (plane passing through the axis of revolution CZ), the lens 3 is stigmatic between the point a and infinity; in other words, a beam of diverging light rays coming from the point a becomes, at the output of the curve ES, a beam parallel to the optical axis CS.

The distance between the point a and the vertex of the curve E1 on the optical axis CS is a parameter; this distance is called the draw T of the lens. For a given reflector 2, the height H of the lens depends on it, on the assumption that the lens is constructed so as to recover all the possible luminous flux.

According to the embodiment of FIGS. 1 to 4, the center C of the arc circle A is located behind the source S according to the direction of propagation the light beam from the module; in this case, the curvature of the edge of the Folder 4, formed by the arc A circle turns its convexity forward following the direction of propagation of the light beam.

If the center C1 (Fig.8) of the arc A1 is located beyond the light source S1 in the direction of propagation of the beam, the curvature A1 edge of the folder changes sign and turns its concavity forward. All explanations provided previously remain true.

The end faces 3Ld, 3Lg (FIG. 1) of the lens 3 are flat and located in the extreme planes passing through CZ, with opening angle Ω.

It is possible to assemble several modules, without any edge or recess, placing the right or left end face of the lens one module against the left or right end face of another module.

Fig.5 illustrates the realization of a projector L by assembly side to coast of identical modules 1a, for example three modules, for which the radius R is infinite so that the arc becomes a rectilinear segment. The lenses 3a of each module are in the extension of one another to form a kind of rectilinear bar orthogonal to the optical axes parallel represented by arrows.

Fig.6 is a diagram of an Lb projector obtained by assembling several modules, in particular four, having a positive radius R (FIGS. 1 to 4), but whose value decreases in one direction, from right to left on Fig.6.

The first module 1b has an infinite radius R; the following module 1 c a a smaller radius R and the center Cc of the module 1c is located on a boundary (left in the example) of module 1b, and so on: the next module 1 d has a radius R lower than that of the module 1 c and the center Cd of the module 1 d is located on the left angular boundary of module 1c. Finally, the module 1 e extreme has the smallest radius R and its center This is located on the boundary left angle of module 1d. The optical axes of the successive modules, represented by arrows, have a progressive inclination with respect to the optical axis of the first module 1 b.

The surface formed by the assembly of the lenses 3b, 3c, 3d, 3e is continuous and differentiable.
The Lb projector of Fig.6 can be a DBL ("Dynamic Bending Light" or "dynamic cornering light") with a successive ignition of the light sources of the modules 1 b ... 1 e to follow a turn.

Fig.7 shows another type of Lc projector obtained by assembly of three modules 1f, 1g, 1h. The two side modules 1f, 1g have a positive radius of curvature in the sense of the embodiment of FIGS. 1 to 4, while the middle module 1 h has a negative radius R which leads to a reverse curvature of the lens 3h. The curve formed by the assembly lenses then have a wavy shape. The optical axes of the three Fig.7 modules are parallel, always represented by arrows.

Fig. 8 is a schematic plan view of a projector comprising at least one assembly of two modules 1 g and 1 h juxtaposed. The module 1 g has a positive radius of curvature and the other 1 h has a radius of negative curvature with inverse curvature of the lens 3h. Reflectors 2g, 2h and the folders 4g, 4h were schematized. The arc of circle A for the module 1 g has its center in C, on the left of the figure while the arc of concave circle A1 has its center in C1 on the right of Fig.8. The assembly Fig.8 is a basic motif that can be repeated several times by juxtaposition.

The 3h lens which is concave on its exit face ensures the spot that is, the concentrated area of the light beam, while the 3g lens forward convex ensures lateral spreading, as does the 3f lens of Fig.7.

The lighting modules according to the invention therefore offer opportunities for complex associations that favor the creation of original style, and the implementation of a plurality of modules.

When an observer watches a module or a projector the invention does not distinguish juxtaposed modules or sources light-emitting diodes, in particular light-emitting diodes modules. The observer therefore has the impression of a unique whole.

Fig.9 shows a network of isolux curves obtained on a screen with determined distance of a module according to the invention having an infinite radius R. he appears that the curves are all located below a line horizontal cut particularly sharp.

Fig. 10 corresponds to a convex lighting module such as that of Fig.1 to 4 or such that the modules 1f, 1g of Fig.7. The cut is also sharp with all curves below a horizontal line; the luminous flux is a little more spread down and on both sides of the plane median vertical.

Fig.11 illustrates the isolux curves obtained with a radius module Negative R, such as the 1 h module of Fig.7 and Fig.8. Cutoff sharpness is retained. The isolux are a little less angularly spread than on Fig.10.

To check if a lighting module is in accordance with the invention, it just place a point source at point S, this point source may be constituted by a laser dot or a very small side diode. Because it is a verification, it is not necessary to use a power source of larger dimensions. By placing a sheet of paper on (or instead of) the reflective plate 4, one must see appear, on the sheet of paper, a corresponding luminous arc at the arc A.

For a verification concerning the lens 3, a vertical light strip converges at a. We must then obtain a vertical light segment on the other side of the lens.

In spherical coordinates, an equation of the surface of the reflector 2.

f is the distance from source S to vertex 5 of the reflector (pseudo-focal). The origin of the marker is placed in S, the y-axis is CS, the axis x is located in the plane of the plate 4 and is orthogonal to the y-axis. The z axis is orthogonal to the plane of the plate 4 and passes through the point S.

The coordinates of the center C, in the reference are, according to the axes of x, y and z: Cx, Cy, 0.

The current point m of the surface 2 of the reflector is located on a direction defined by a longitude  and a latitude φ. The absolute value of the The vector radius of the point m is denoted by μ.

ϕ et  sont les variables de l'équation paramétrique de la surface.
Soient : α = 4{(K - ν y C y )2 - R 2(ν2 y + ν2 x )} β = -4{(K 2 - R 2 - C 2 y )(K - ν y C y )-2R 2ν y C y } χ = (K 2 - R 2 - C 2 y )2 - 4R 2 C 2 y µ = -β+β2 - 4αχ 2α Alors M = S + µ · ν appartient à la surface du réflecteur recherché. In the calculations that follow α, β and χ are intermediate variables.
We pose:

φ and  are the variables of the parametric equation of the surface.
Are: α = 4 {( K - ν there VS there ) 2 - R 2 (ν 2 there + ν 2 x )} β = -4 {( K 2 - R 2 - VS 2 there ) ( K - ν there VS there ) -2 R 2 ν there VS there } χ = ( K 2 - R 2 - VS 2 there ) 2 - 4 R 2 VS 2 there μ = -β + β 2 - 4αχ 2α So M = S + μ · ν belongs to the surface of the desired reflector.

l = T + ep 0(n-1) - d + C fe (1-cosη) n-cos σ ρ = R + d · cos ω + l · cos σ Alors

appartient à la surface de sortie de la lentille.We give the equation of the curve ES of the exit face of the lens, when the entrance face admits as curve E1 a convex circle inwards.
We put: T = d ( a , El ), draw of the lens
C _fe , radius of the entrance face
ep ₀ , thickness in the center of the lens
n , refractive index of the material
η and α are the variables of the parametric equation of the surface.
Are: h = C fe sin η d = h 2 + ( T + VS fe (1 - cosη)) 2 ω = arcsin h d

l = T + ep 0 ( not -1) - d + VS fe (1-cosη) not -cos σ ρ = R + d · Cos ω + l · Cos σ So

belongs to the exit surface of the lens.

Claims (13)

Motor vehicle headlamp lighting module, providing a cut-off light beam, having a concave reflector (2), at least one light source (S) disposed in the concavity of the reflector to illuminate at least upward, and a lens (3) located in front of the reflector and the light source, the reflector being associated with a flat plate (4), in particular horizontal, whose upper surface is reflective to fold the beam from the reflector, said plate having an edge of front end adapted to form the cut in the illumination beam, characterized in that the reflector (2) is determined for transforming a spherical wave surface from the source (S) into a wave surface which is reduced to a arc of circle (A) located in the plane of the plate (4), and in that the lens (3) is of revolution about an axis (Z) substantially orthogonal to the plane of the plate and passing through the center ( VS) of said arc. Lighting module according to Claim 1, characterized in that the surface of the reflector (2) is such that light rays (i1, i2) originating from the source and falling at points (m1, m2) situated on a curve ( 6) formed by the intersection of the surface of the reflector (2) and a vertical plane (V) passing through the center (C) of the arc of a circle, but separated from the source, are reflected by the surface of the reflector in this vertical plane (V) so as to converge at a point (P) formed by the intersection of said vertical plane and the arc. Lighting module according to claim 1 or 2, characterized in that the reflector (2) provides the horizontal distribution of the beam while the lens (3) ensures the cutting of the beam and the vertical distribution without interfering with the horizontal distribution established by the reflector. Lighting module according to one of claims 1 to 3, characterized in that the reflector (2) is determined by the choice of the radius (R) of the arc (A), the distance from the source ( S) in the center (C) of the arc, and the distance from the source (S) to the top (5) of the reflector in the plane of the arc. Lighting module according to one of claims 1 to 4, characterized in that the plane passing through the plate (4) substantially passes through the center of the source (S). Lighting module according to one of the preceding claims, characterized in that the reflecting plate (4) consists of a disc portion having an arc (A) at its edge. Lighting module according to one of the preceding claims, characterized in that the light source (S) is constituted by a light-emitting diode. Motor vehicle headlight, characterized in that it is formed of an assembly of several modules according to one of the preceding claims, in particular without any edge or recess, by placing the right or left end face of the lens of a module against the left or right end face of the lens of another module. Motor vehicle headlamp according to Claim 8, characterized in that the headlamp (L) is obtained by side-by-side assembly of identical modules (1a) for which the radius (R) is infinite, the lenses (3a) of the modules being in the extension of one another to form a kind of rectilinear bar orthogonal to parallel optical axes. Motor vehicle headlamp according to claim 8, characterized in that the headlamp (Lb) is obtained by assembling modules having a radius (R) positive but whose value decreases in one direction. Motor vehicle headlight according to claim 10, characterized in that a first module (1b) has an infinite radius (R), the next module (1c) has a smaller radius, the center (Cc) of the module 1c being located on a limit of the module (1b) and so on, the optical axes of the successive modules having a progressive inclination with respect to the optical axis of the first module (1 b), the surface formed by the assembly of the lenses being continuous. Motor vehicle headlight according to claim 11, characterized in that it constitutes a DBL ("dynamic cornering light") with a successive ignition of the light sources of the modules to follow a turn. Motor vehicle headlight according to claim 8, characterized in that the headlamp (Lc) comprises at least one assembly of two modules (1g, 1h), one of the modules (1g) having a positive radius of curvature while the other module (1 h) has a negative radius with a reverse curvature of the lens (3h).

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