EP0373065B1 - Motor vehicle headlight comprising a reflector with a complex surface including modified intermediary zones - Google Patents

Description

The present invention relates generally to motor vehicle headlamps, and it relates more particularly to improvements made to headlamps capable of emitting a cut beam, for example a European type passing beam or an anti-fog beam, and comprising for this purpose a lamp whose filament emits freely all around it and cooperates with a smooth reflector with complex surface designed to form the cut by itself.

More specifically, the invention relates to improvements to projectors of this type, the smooth surface of the reflector is further designed to give the beam, without the intervention of the closing glass, a substantial width. This avoids the well-known optical defects which appear in particular when a strong lateral deviation is required from a closing glass inclined relative to the vertical.

Projectors of this type are described in French patent application No. FR-A-2 609 148 in the name of the Applicant.

This document describes a reflector, a bottom zone of which is modified to spread the light laterally, while lateral zones are produced in a conventional manner.

However, in all these known projectors, the deviation imparted by the reflector to the light rays which it reflects takes place in a horizontal plane. This means in particular, for a dipped beam headlamp with European cut-off, the rays which normally define the inclined half-cut of this type of beam are separated from this half cut by such a deviation. In practice, this is manifested by a well defined horizontal half-cut over a large width, while the inclined half-cut relative to the horizontal is only defined over a very small extent. This is clearly illustrated in FIG. 13 of the aforementioned patent application, where it can be seen that the inclined half-cut is extended to the right by what constitutes a simple extension of the left horizontal half-cut.

Furthermore, in the headlights described in this patent application, the width of the beam is obtained by acting essentially on the bottom zone of the complex reflector. This is not always compatible with the presence of a direct light cover placed in front of the lamp. Indeed, if the beam is given the required width by strengthening the convergence of the rays reflected by the background, a large proportion of these rays will be intercepted by this mask and not participate in the beam. The light output is thereby reduced.

The present invention aims to overcome the drawbacks of the prior art and to provide a beam projector of the above type in which, by the sole intervention of the reflector, retaining an essentially continuous and smooth surface, a substantial beam widening is obtained not only horizontally, but if necessary essentially parallel to an inclined part of the cut, and in particular along the angle of raising of the cut along the inclined half-cut of a standardized European passing beam.

As a corollary, the invention aims to propose a new reflector design in which the bottom zone and the edge zone or zones are produced in a conventional manner, while intermediate zones ensure the enlargement in the aforementioned manner.

In this regard, a secondary object of the present invention, when the lamp used comprises a direct light cover placed at the front thereof, is to minimize the quantity of rays which, after reflection on the reflector, are directed towards this cover and therefore do not participate in the formation of the beam.

To this end, the present invention relates to a motor vehicle headlamp having the features of claim 1.

Preferred aspects of the projector of the invention are defined in the subclaims.

• la figure 1a est une vue de côté en coupe d'un projecteur de croisement à coupure européenne conforme à la présente invention, dont la lampe est illustrée par son seul filament;
• la figure 1b est une vue de dos du projecteur de la figure 1, dépourvu de sa glace de fermeture;
• les figures 2a à 2c sont des vues en coupe transversale schématique à travers le réflecteur, illustrant le principe de base de la présente invention;
• les figures 3a à 3g illustrent, par des ensembles d'images du filament projetées sur un écran de protection, l'éclairement fourni par diverses zones du réflecteur des figures 1a et 1b, en l'absence de la glace de fermeture ;
• la figure 4 illustre, de façon analogue, l'éclairement fourni par l'ensemble du projecteur des figures 1a et 1b, en l'absence de la glace de fermeture;
• la figure 5 est une vue de face d'un projecteur antibrouillard conforme à la présente invention, dépourvu de sa glace de fermeture et dont la lampe est illustrée par son seul filament;
• les figures 6a à 6d illustrent, par des ensembles d'images du filament projetées sur un écran, l'éclairement fourni par diverses zones du réflecteur de la figure 5, en l'absence de la glace de fermeture;
• la figure 7 illustre, par un ensemble de courbes isocandéla sur un écran de projection, l'éclairement fourni par l'ensemble du projecteur de la figure 5, dépourvu de sa glace de fermeture; et
• les figures 8a à 8c sont des vues schématiques en coupe horizontale illustrant la répartition horizontale des rayons lumineux réfléchis avec deux projecteurs de la technique antérieure et un projecteur conforme à la présente invention.

Other aspects, objects and advantages of the present invention will appear better on reading the following detailed description of a preferred embodiment thereof, given by way of example and made with reference to the accompanying drawings, in which :

• FIG. 1a is a side view in section of a European cut-off headlamp according to the present invention, the lamp of which is illustrated by its only filament;
• Figure 1b is a back view of the projector of Figure 1, devoid of its closing glass;
• Figures 2a to 2c are schematic cross-sectional views through the reflector, illustrating the basic principle of the present invention;
• FIGS. 3a to 3g illustrate, by sets of images of the filament projected on a protective screen, the illumination provided by various zones of the reflector of FIGS. 1a and 1b, in the absence of the closing glass;
• Figure 4 illustrates, similarly, the illumination provided by the assembly of the projector of Figures 1a and 1b, in the absence of the closing glass;
• Figure 5 is a front view of a fog light according to the present invention, devoid of its closing glass and whose lamp is illustrated by its only filament;
• FIGS. 6a to 6d illustrate, by sets of images of the filament projected on a screen, the illumination provided by various zones of the reflector of FIG. 5, in the absence of the closing glass;
• FIG. 7 illustrates, by a set of isocandela curves on a projection screen, the illumination provided by the whole of the projector of FIG. 5, devoid of its closing glass; and
• Figures 8a to 8c are schematic views in horizontal section illustrating the horizontal distribution of the light rays reflected with two projectors of the prior art and a projector according to the present invention.

Referring firstly to Figures 1a and 1b, there is shown a dipped projector comprising a lamp (of contours not shown) provided with an axial filament 100 modeled by a cylinder of length 2 ℓ and radius r, arranged parallel to the optical axis Ox so that its lower surface is essentially tangent to this axis, a reflector with complex surface 200 and a closing glass 300.

The reflector is divided into six zones 201 to 206 each having a clearly defined role on the optical plane, these zones being themselves continuous in second order and connecting together, according to the planes as illustrated, also with continuity in second order (with the exception of connections between zones 204, 205 and 203, 206, respectively, where continuity is only achieved at first order).

A projector of this type is described in French patent applications Nos. FR-A-2 536 502 and FR-A-2 599 121 in the name of the Applicant, to which reference may be made for more details.

In accordance with an essential aspect of the invention, each of the zones 201 to 206 is produced only in part in accordance with the equations set out in the above-mentioned patent applications, being modified in certain regions with respect to these equations, as will be seen. see now with reference to Figures 2a to 2c.

Each of these figures is a view in horizontal section through the area 205, all the light rays being projected vertically in the horizontal plane of this section.

Figure 2a illustrates the case of a projector according to the French patent No. FR-A-2 536 502 cited above. As can be observed, all the rays reflected by the zone 205 circulate approximately in a vertical plane parallel to the optical axis 0x; the delivered beam is therefore relatively narrow and its width will be given to it by the closing glass, either prismably or striated.

Figures 2b and 2c illustrate the principle of the invention. The zone 205 here comprises an interior sub-zone 205i and an external sub-zone 205e whose surfaces are identical to the surface of the zone 205 in FIG. 2a, except that the basic focal distances of these two zones are different . It is further defined an intermediate zone 205m whose profile deviates from the known surface, so as to give the reflected rays either a determined convergence (FIG. 2b), or a determined divergence (FIG. 2c). According to the invention, the various sub-areas have continuous second order surfaces, and furthermore are connected to each other, in transition planes, with second order continuity. It should be noted here that the differences between the known surface and the surface modified in accordance with the invention have been greatly exaggerated for the sake of clarity.

In accordance with an essential aspect of the present invention, the large width conferred on the part of the beam generated by the area 205 is obtained on the one hand by respecting the inclined half-cut generated in itself by this area, but especially by deflecting the rays luminous at the level of the intermediate zone not horizontally, but in a plane parallel to the cut. Thus, as will be detailed later, the "V" cut of the beam is defined over a large lateral extent.

In practice, each zone 201 to 206 comprises an interior sub-zone, respectively 201i to 206i, a sub-zone intermediate, respectively 201m to 206m, and an outer subzone, respectively 201e to 206e.

The interior and exterior sub-zones are produced in accordance with the above equations, however using in each zone different basic focal distances for the internal sub-zone and the external sub-zone.

In other words, the sub-areas 201i, 201e and 202i, 202e are portions of paraboloids of revolution, having either the same focal point located on the optical axis directly above the center of the filament, or two distinct focal points located respectively in the vicinity of the two axial ends of the filament, and also having different focal distances two by two. In addition, the interior zones 203i to 206i and 203e to 206e are the areas with complex surface defined mathematically in the patent applications cited above, and therefore have the properties stated therein. It may be recalled here that the purpose of such a reflector is, by zones 201 and 202, to initiate the "V" cut of the general type described in the introduction, and by zones 203 to 206 to extend this cut by generating images of the filament, all the points of which are located below the said cut.

In accordance with the present invention, each of the intermediate sub-areas 201m to 206m locally modifies the profile of the area considered to give the beam the required width, as has been seen above for the area 205m. More specifically, each intermediate subzone has the property of making a continuous second order connection between the associated interior and exterior subzones, offset from one another, by presenting a profile for two for this purpose. reverse curvatures separated by a line of inflection, as shown in Figures 2b and 2c. Each intermediate subzone also has the property of connecting with second order continuity with the intermediate subzone located immediately above or below.

From the optical point of view, each intermediate sub-zone has the function of deflecting the light rays in a direction essentially parallel to the part of the cut defined by the zone in question, so that the various parts of said cut are defined over a large area. extended in width. In particular, the intermediate sub-areas 203m and 204m of the complex surface areas 203 and 204 widen the beam portion considered horizontally below the horizontal half-cut hH of a standardized European passing beam, while the sub- intermediate zones 205m and 206m of the areas with complex surface 205 and 206 widen the portion of beam considered below the half-cut inclined at 15 °, denoted Hc, by deflecting the rays parallel to this half-cut.

In the projection in the yOz plane that constitutes FIG. 1b, the intermediate sub-areas 201m and 202m are delimited by arcs of circles centered on the center O of the reflector, while the intermediate sub-areas 203m and 204m are delimited by vertical line segments and the intermediate sub-areas 205m and 206m are delimited by line segments making an angle β with the vertical, that is to say perpendicular to the inclined half-plane of cut Hc. Furthermore, the intermediate sub-zones located on the same side of the optical axis are all located in the extension of one another as illustrated.

We will now define by a mathematical approach an embodiment of the reflector according to this first aspect of the invention, other examples being of course possible without departing from the scope of the invention.

In FIG. 1b, the following parameters have been illustrated:
y _G is the distance between the axis 0x and the inner edge of the group of intermediate sub-areas 201m, 203m and 205m located to the left of the optical axis;
y _GM is the distance between the axis 0x and the center of the said group ("center" means the vertical straight line or inclined, or the portion of a circle, where the inflection of each of the intermediate subzones is found);
y _GL is the distance between the center O and the outer edge of the group of intermediate sub-areas 201m, 203m and 205m;
y _D , y _DM and y _DL have the same meanings as y _G , y _GM and y _GL , for the intermediate sub-zones on the right in FIG. 1b, namely 202m, 204m and 206m;
f _G , f _C and f _D are the basic focal distances of the left (sub-areas 201e, 203e and 205e), central (sub-areas 201i to 206i) and right (sub-areas 202e, 204e and 206e) of the reflector;
A _GL and A _GM are parameters which characterize the extent of the deformation of the reflector at the level of the intermediate left sub-areas 201m, 203m and 205m;
A _DL and A _DM are identical parameters, but for the intermediate right sub-areas 202m, 204m and 206m.

To design a reflector according to the invention, the parameters of dimensions in "y" defined above and the focal length f _G are first chosen, then the importance of the width to be given to the beam, represented, is then chosen. by the angular openings, in planes parallel to the two half-cuts, portions of the beam generated by the intermediate subzones of left and right. These angular openings are noted Θ _G and Θ _D , respectively.

et ${\text{A}}_{\text{DL}}{\text{= (tgΘ}}_{\text{D}}{\text{)/(y}}_{\text{DM}}{\text{-y}}_{\text{DL}}\text{) (2)}$

   On détermine ensuite la valeur de f_C en posant :

${\text{f}}_{\text{C}}{\text{= f}}_{\text{G}}{\text{+ Δf}}_{\text{G}}\text{ (3)}$

Δf_G étant choisi égal à la solution supérieure de l'équation du second degré suivante :

${\text{4X² + 4(AA + f}}_{\text{G}}{\text{)X - y}}_{\text{G}}{\text{.y}}_{\text{GM}}{\text{+ 4AA.f}}_{\text{G}}\text{= 0 (4)}$

où

   le paramètre A_GM est alors calculé par la formule suivante :

   Pour calculer la focale f_D, on pose de même :

${\text{f}}_{\text{D}}{\text{= f}}_{\text{C}}{\text{+ Δf}}_{\text{D}}\text{ (7)}$

où Δf_D est la solution supérieure de l'équation :

${\text{-4X² + 4(BB - f}}_{\text{C}}{\text{)X + 4f}}_{\text{C}}{\text{.BB + y}}_{\text{D}}{\text{.y}}_{\text{DM}}\text{= 0 (8)}$

où

   On calcule ensuite A_DM de la façon suivante :

   Tous les paramètres sont ainsi définis, en étant pour certains choisis par le concepteur et, pour les autres, calculés à partir des premiers comme indiqué ci-dessus.The parameters A _GL and A _DL are defined by:

${\text{AT}}_{\text{GL}}{\text{= (tgΘ}}_{\text{G}}{\text{) / (y}}_{\text{GM}}{\text{-y}}_{\text{GL}}\text{) (1)}$

and ${\text{AT}}_{\text{DL}}{\text{= (tgΘ}}_{\text{D}}{\text{) / (y}}_{\text{DM}}{\text{-y}}_{\text{DL}}\text{) (2)}$

We then determine the value of f _C by setting:

${\text{f}}_{\text{VS}}{\text{= f}}_{\text{G}}{\text{+ Δf}}_{\text{G}}\text{(3)}$

Δf _G being chosen equal to the upper solution of the following second degree equation:

${\text{4X² + 4 (AA + f}}_{\text{G}}{\text{) X - y}}_{\text{G}}{\text{.y}}_{\text{GM}}{\text{+ 4AA.f}}_{\text{G}}\text{= 0 (4)}$

or

the parameter A _GM is then calculated by the following formula:

To calculate the focal length f _D , we pose the same:

${\text{f}}_{\text{D}}{\text{= f}}_{\text{VS}}{\text{+ Δf}}_{\text{D}}\text{(7)}$

where Δf _D is the upper solution of the equation:

${\text{-4X² + 4 (BB - f}}_{\text{VS}}{\text{) X + 4f}}_{\text{VS}}{\text{.BB + y}}_{\text{D}}{\text{.y}}_{\text{DM}}\text{= 0 (8)}$

or

A _{DM is} then calculated as follows:

All the parameters are thus defined, some being chosen by the designer and, for the others, calculated from the first ones as indicated above.

We will now indicate the equations of the various zones 201 to 206 of the reflector, in the orthonormal reference frame [0, x, y, z] as illustrated in FIGS. 1a and 1b.

avec

${\text{V = (α + α ′)|y| - αy}}_{\text{L}}{\text{- α ′y}}_{\text{M}}$

   Dans cette équation, ℓ représente la demi-longueur du filament, α₁ est égal à y/|y|, et ε est égal à z/|z|. En outre, les valeurs que prennent les paramètres α, α', y_L, y_M et f₀ apparaissant pour la première fois dans cette équation varient en fonction de la valeur de la coordonnée y sur l'axe y′Oy, et sont indiquées dans le tableau I suivant :

For fields 203 and 204, the equation is as follows:

with

${\text{V = (α + α ′) | y | - αy}}_{\text{L}}{\text{- α ′ y}}_{\text{M}}$

In this equation, ℓ represents the half-length of the filament, α₁ is equal to y / | y |, and ε is equal to z / | z |. In addition, the values taken by the parameters α, α ', y _L , y _M and f₀ appearing for the first time in this equation vary according to the value of the y coordinate on the y′Oy axis, and are indicated in the following table I:

$\text{Z = -y.sinβ + z.cosβ}$

   La nouvelle équation obtenue, non écrite afin d'éviter d'alourdir la description, sera notée (12).The reflecting surfaces of the zones 205 and 206 are defined by equation (11) above, but by replacing the coordinates x, y and z by coordinates X, Y and Z defined as follows:

$\text{Y = y.cosβ + z.sinβ}$

$\text{Z = -y.sinβ + z.cosβ}$

The new equation obtained, unwritten in order to avoid adding to the description, will be noted (12).

It can be noted that this change of coordinates amounts in practice to rotating the surface defined by equation (11) around the axis Ox, by an angle β which is the angle of bearing of the half-cut of beam right.

ou

$\text{ρ = √(y² + z²)}$

   Les valeurs prises par les paramètres apparaissant dans cette équation varient ici encore en fonction de la position de la coordonnée y sur l'axe y′Oy, conformément au tableau II ci-dessous.

Finally, the reflective surfaces of zones 201 and 202 are defined by the following equation:

or

$\text{ρ = √ (y² + z²)}$

The values taken by the parameters appearing in this equation vary here again as a function of the position of the y coordinate on the y′Oy axis, in accordance with Table II below.

FIGS. 3a to 3g show, in the form of images of the filament 100 on a standardized projection screen [H, h, v], the light distribution obtained with the various sub-areas of the reflector as described in detail below the correspondence between each of these figures and the sub-area (s) considered. Figure Sub-area (s) 3a 201i to 206i 3b 201m, 205m 3c 202m, 206m 3d 204m 3rd 203m 3f 201st, 202nd, 205th, 206th 3g 203rd, 204th

As can be seen in FIG. 3b, the intermediate zones 201m and 205m widen the considered portion of the beam not laterally along hh, but indeed along the inclined half-cut Hc. It is therefore extended on the side with a substantial extent and a definition which remains excellent. In practice, this translates into an increase in the range of the dipped headlight at the level of the lower side, for greater driving comfort, as well shown in FIG. 4, which illustrates the light distribution given by the whole of the reflector, also in the form of images of the filament projected on [H, h, v].

FIG. 5 shows a front view of a reflector according to the present invention, capable of emitting an anti-fog beam, that is to say limited by a cut defined by two horizontal half-planes both located at the same level.

The reflector 200 comprises a central zone 210, two intermediate zones 220, 230 and two external zones 240, 250.

The central and external zones are produced in accordance with the teachings of French patent No 2,536,503 to which reference will be made for more details. We can simply indicate that this document teaches a smooth surface reflector whose shape is designed to that it generates by itself the above-mentioned horizontal cut. The only difference from this patent is that different basic focal lengths are used for each of these three areas.

The intermediate zones 220, 230 are constructed in the same way as the sub-zone 205m in FIGS. 2b and 2c. More precisely, using the same parameters as for the surface of the reflector of FIGS. 1a and 1b, the equation of the entire surface of the reflector according to this second embodiment is identical to equation (11) set out above. .

In this case, the two half-cuts being horizontal, the deviation imparted to the spokes by the intermediate zones takes place in horizontal planes.

FIGS. 6a to 6d have illustrated, by images of the filament generated by the bare reflector and projected on a standardized screen [H, h, v], the light distribution obtained with each of the zones of this reflector.

FIG. 6a corresponds to the central part 210 of the reflector, FIG. 6b corresponds to the left intermediate zone 220, FIG. 6c corresponds to the right intermediate zone 230 and FIG. 6d corresponds to the external zones 240 and 250.

FIG. 7 illustrates, for its part, by a set of isocandela curves in this same projection screen, the light distribution obtained with the whole of the reflector.

It can be seen that the horizontal cut is defined with good sharpness over a large width.

We will now explain, with reference to FIGS. 8a to 8c, another advantage of the present invention over the headlights of the prior art, in the case where the headlight, whether it is a dipped headlight or an anti-fog headlight, has a screen or direct light cover.

Projectors comprising a lamp (not shown), a reflector 200 and a front lens 300, in this case a lens arranged at an angle, have been illustrated in the horizontal sections of FIGS. 8a to 8c. At the front of the lamp is provided a direct light cover 110 arranged so that no light ray emitted by the filament can directly reach the lens 300. Such a cover, in the general form of a cylinder closed at its end remote from the lamp, has as its object, so known, to prevent rays from coming out of the projector above the cut-off. Any dazzling of oncoming conductors is thus avoided.

In FIGS. 8a and 8b, the reflector is produced in accordance with French patent application No. 2 609 148, that is to say that it has a background different from that of a projector with a conventional complex surface and intended to modify the convergence of the light rays reflected by said background. In the case of FIG. 8a, the bottom F is divergent, which causes at the level of the closing glass large mixtures between the images generated by the background and those generated by the edges B of the reflector (more precisely in the area 300a of ice). It is thus impossible to ensure using said glass a selective treatment of the various parts of the beam, for example large images (coming from the background) giving the beam its width and thickness and small images (coming from the edges). defining the beam concentration spot.

When, on the other hand, a convergent background F is used, this advantageously avoids the mixing of images at the level of the glass. However, a non-negligible proportion of the rays reflected by the background, due to this convergence, is now intercepted by the direct light mask 110. This results in a reduction in the light output as well as a reduction in the width of the beam, since it is the rays which are the most laterally inclined which are intercepted.

A reflector according to the present invention is illustrated in Figure 8c. It can be observed that, since the reflector is modified not at the bottom F but in intermediate regions I between the bottom F and the edges B. Such a solution combines the advantages of the solutions known in FIGS. 8a and 8b, without having any the disadvantages: there is practically no mixing between large images of the filament generated by the background and the intermediate zones and the small images generated by the edges, and at the same time the mask of direct light does not obscure substantially any ray. More precisely, the converging rays reflected by the modified zones I are sufficiently distant from the cover to bypass the latter (rays R _I in FIG. 8c).

Of course, the present invention is not limited to the embodiments described above and shown in the drawings, but a person skilled in the art will know how to make any variant or modification in accordance with his spirit.

In particular, it is clear that the invention is applicable to headlights whose reflector does not have the same lateral extent on one side and the other of the lamp, as in the case of FIG. 8c. And in a borderline case, the reflector may have only one edge zone (for example, in FIG. 1b, the sub-zones 201e, 203e and 205e or else the opposite external sub-zones may not exist, and in FIG. 5, one of the zones 240 and 250 may not exist.

In addition, a person skilled in the art will know how to adapt the invention to the case of a standard cut-off headlamp in force in the United States of America, defined by two horizontal half-planes offset in height.

Claims (9)

1. A motor vehicle headlight of the type comprising a lamp having a filament (100), a reflector (200) defining an optical axis (Ox), and a closure glass (300), the filament emitting light freely in all radial directions thereabout and the reflector having a smooth and essentially continuous reflecting surface which reflects the rays emitted by the filament in such a manner as to cause the majority of them to be situated beneath a cut-off (hHc; hh) constituted by two half-planes of given height and slope, the headlight being characterized in that the reflecting surface comprises a central zone (201i- 206i; 210), two intermediate zones (201m, 203m, 205m; 202m, 204m, 206m; 220, 230) situated on either side of the central zone and connected thereto with continuity, which intermediate zones reflect the light rays from the filament by imparting a substantial deflection thereto in planes essentially parallel to the cut-off half-plane with the rays participating in defining said cut-off, and at least one peripheral zone (201e, 203e, 205e; 202e, 204e, 206e; 240, 250) situated beyond one or both intermediate zones and being connected thereto with continuity, the peripheral zone(s) reflecting the rays from the filament so that they propagate in planes which are essentially vertical and parallel to the optical axis.
2. A headlight according to claim 1, characterized in that it includes two peripheral zones (201e, 203e, 205e; 202e, 204e, 206e; 240, 250) situated beyond respective ones of the two intermediate zones (201m, 203m, 205m; 202m, 204m, 206m; 220, 230).
3. A headlight according to claim 1 or 2, in which the cut-off is constituted by a horizontal half-plane (hH) and a half-plane (Hc) sloping above the horizontal by a cut-off lift angle (β) and corresponding to a European dipped beam, the headlight being characterized in that the filament (100) is disposed parallel to the optical axis (Ox) and above the optical axis so that its light-emitting surface is substantially tangential to said optical axis, in that the reflector is additionally subdivided into two first zones (201, 202) based on portions of paraboloids extending symmetrically on either side of the optical axis between two planes including the optical axis, one of said planes being horizontal and the other sloping relative to the horizontal at the cut-off lift angle, two second zones (203, 206; 204, 205) extending said first zones respectively above and below said zones and forming images of the filament in which the topmost points lie in the vicinity of the cut-off, and in that the central zone, the intermediate zones, and the peripheral zone(s) are respectively constituted by inner subzones (201i-206i), intermediate subzones (201m-206m), and outer subzones (201e-206e) in each of said first and second zones.
4. A headlight according to any one of claims 1 to 3, characterized in that the central zone and the peripheral zone(s) have different design focal lengths (f_C; f_G; f_D).
5. A headlight according to claim 4, as dependent on claim 3, characterized in that when projected onto a plane perpendicular to the optical axis, the intermediate subzones (201m, 202m) of said first zones of the reflector are laterally delimited by portions of circles, whereas the intermediate subzones (203m-206m) of said second zones are laterally delimited by segments of straight lines perpendicular to the cut-off half-planes in question, with the straight lines being tangential to the ends of the associated portions of circles.
6. A headlight according to claim 5, characterized in that the surfaces of the first zones (201, 202) of the reflector are defined by equation (13), whereas the surfaces of the second zones (203, 206; 204, 205) are defined by the following equations:
      for the second zones (203 and 204):

   

   where
   
   ${\text{V = (α + α')|y| - αy}}_{\text{L}}{\text{- α'y}}_{\text{M}}$

   

   
   
      where l represents the half length of the filament, α₁ is equal to y/|y|, ε is equal to z/|z| and α, α', y_L, y_M, and f₀ vary as a function of the Y coordinate along the axis y'Oy, as given below:

   

      for the second zones (205 and 206): the same equation as (11) but replacing the coordinates x, y, and z by coordinates X, Y, and Z defined as follows:
   
   $\text{Y = y.cosβ + z.sinβ}$

   

   
   $\text{Z = -y.sinβ + z.cosβ}$

   
7. A headlight according to claim 1 or 2, in which the cut-off is constituted by two horizontal half-planes (hH, Hh) at the same level, and corresponding to the beam from a foglight, the headlight being characterized in that the filament (100) is disposed parallel to the optical axis and above the optical axis in such a manner that its light-emitting surface is substantially tangential to said optical axis, and in that the surface of the reflector (200) is defined by the following equation:

   

   where
   
   ${\text{V = (α + α')|y| - αy}}_{\text{L}}{\text{- α'y}}_{\text{M}}$

   

   
   
      where l represents the half length of the filament, α₁ is equal to y/|y|, ε is equal to z/|z| and α, α', y_L, y_M, and f₀ vary as a function of the Y coordinate along the axis y'Oy, as given below:

   
8. A headlight according to any preceding claim, further including a direct light mask (110) disposed in front of the lamp, the headlight being characterized in that the distance (y_G, y_D) between the center (O) of the reflector and the beginnings of the intermediate zones is selected to be large enough to prevent the rays that are deflected inwards by the intermediate zones being intercepted by said mask.
9. A headlight according to claim 1, characterized in that when projected onto a plane perpendicular to the optical axis, the intermediate zones are laterally delimited at least in part by segments of straight lines perpendicular respectively to the cut-off half-planes in question.

Images