EP1245897A1 - Compact dipped beam headlamp for vehicle - Google Patents

Abstract

Each region (31,32,33) of the reflector mirror is connected to the adjacent region without indentation. The first region (32) has a reflecting surface strongly spreads the beam in a lateral direction. The second and third regions (31,33) are situated on the same side of the light source. The second region reflecting the beam under the horizontal part of the cut, is closer to the light source than the third region which reflects the beam under the inclined part of the cut. Cross beam projector, for an automobile, having a light source (30) forming a V cut beam. The reflector mirror has at least three regions (31,32,33) laterally placed with respect to each other. The first region (32) gives the beam its width, the second (31) its range under the horizontal part of the cut and the third (33) its range under the inclined part of the cut. The reflector mirror has a fourth region which gives the beam its range along the vehicles longitudinal axis. This fourth region is adjacent to the third, but farther away from the source. At least some of the regions (31,33,34) give a slightly divergent spread to the beam.

Description

The present invention relates generally to headlamps for motor vehicles, and in particular dipped headlights.

Low beam headlights for motor vehicles conventionally consist of a reflecting mirror reflecting light rays emitted by a light source towards the front of the vehicle, a window possibly modifying the path of these rays, to obtain a light beam with photometry predetermined.

In known manner, it is necessary to have recourse to a relatively large reflective mirror, particular in width, to obtain a passing beam which respects both the regulations in force and that either performance.

These large dimensions of the reflective mirror are necessary to recover a sufficient amount of the luminous flux emitted by the source, and on the other hand generate, in some of the mirror regions, source images that are small enough to form in the beam of crossing a spot of sufficiently intense concentration to improve the range of the projector.

Conventionally, the larger the mirror, for a given base focal length, plus the solid angle covered by the mirror seen from the source is important, and therefore the better the recovery rate of light flux from the source. However, the two objectives mentioned above are contradictory: the lower the base focal length of the mirror small, i.e. the more the mirror is closed around the source for a given height and width, the better the stream recovery, but source images are found all enlarged, and the range is insufficient. On the contrary, if using a larger base focal length, the range is improved but the overall beam intensity is decreased by unwanted way.

We are then led to provide mirrors comprising areas of different focal lengths, so as to improve the times the beam range and intensity, by combining the advantages of small and large focal length areas. The surface of the mirrors thus designed then presents discontinuities and dropouts, which make it difficult to manufacture of such mirrors, their metallization and their varnishing final.

The present invention is placed in this context and aims to overcome these drawbacks of the state of the art, by proposing a projector which, while having a space requirement extremely reduced both in width, in height and in depth, or capable of generating a beam, in particular a passing beam, and more particularly a beam of European crossbreeding, presenting both a range suitable, suitable width and good uniformity, the surface of the mirror showing no stalls.

The subject of the invention is therefore a dipped headlight for motor vehicles, comprising a light source cooperating with a mirror to form a light beam with a V-cut, the mirror comprising at least three regions arranged laterally with respect to each other, a first region giving the beam its width, a second region giving the beam its range under the horizontal part of the cut, and a third region giving the beam its carried under the inclined part of the cut.

According to the invention, each region is connected to the region adjacent without detachment, the first region of the mirror has a reflective surface which strongly spreads the light in lateral direction and the second and third regions are located on the same side of the light source

• la deuxième région, conférant au faisceau sa portée sous la partie horizontale de la coupure, est plus proche de la source lumineuse que la troisième région, conférant au faisceau sa portée sous la partie inclinée de la coupure.
• le miroir comporte en outre une quatrième région conférant au faisceau sa portée dans l'axe longitudinal du véhicule.
• la quatrième région est située adjacente à la troisième région, en étant plus éloignée de la source lumineuse que cette troisième région.
• les troisième et quatrième régions sont raccordées sans décrochement.
• au moins certaines régions du miroir qui étalent la lumière réalisent un étalement faiblement divergent.

According to other characteristics of the invention:

• the second region, giving the beam its range under the horizontal part of the cut, is closer to the light source than the third region, giving the beam its range under the inclined part of the cut.
• the mirror further comprises a fourth region giving the beam its range in the longitudinal axis of the vehicle.
• the fourth region is located adjacent to the third region, being further from the light source than this third region.
• the third and fourth regions are connected without an offset.
• at least certain regions of the mirror which spread the light achieve a slightly divergent spread.

• la Figure 1 est une vue schématique de dos d'un miroir pour projecteur de croisement européen du côté gauche d'un véhicule, selon une conception connue ;
• la Figure 2 est une vue schématique de dos d'un miroir pour projecteur de croisement européen du côté gauche d'un véhicule, selon la présente invention ;
• la Figure 3 est une vue schématique en coupe horizontale axiale du miroir de la figure 2, et de la source avec laquelle il coopère ;
• la Figure 4 est une vue analogue à la Figure 3, illustrant les trajets de certains rayons lumineux réfléchis par les différentes régions du miroir, et
• les figures 5A à 5C illustrent, par des ensembles de courbes isolux sur un écran de projection, l'allure de différentes parties de faisceau engendrées par l'ensemble source/miroir des Figures 2 à 4.

Others, aims, characteristics and advantages of the present invention will appear better on reading the following description of a preferred embodiment thereof, given by way of nonlimiting example and made with reference to the accompanying drawings, on which ones :

• Figure 1 is a schematic rear view of a mirror for European low beam projector on the left side of a vehicle, according to a known design;
• Figure 2 is a schematic rear view of a mirror for European dipped headlight on the left side of a vehicle, according to the present invention;
• Figure 3 is a schematic view in axial horizontal section of the mirror of Figure 2, and the source with which it cooperates;
• FIG. 4 is a view similar to FIG. 3, illustrating the paths of certain light rays reflected by the different regions of the mirror, and
• FIGS. 5A to 5C illustrate, by sets of isolux curves on a projection screen, the appearance of different parts of the beam generated by the source / mirror assembly of FIGS. 2 to 4.

There is shown in Figure 1 a mirror 20 of art anterior, intended to cooperate with a light source 10, like an axially oriented filament of a lamp incandescent such as a standard lamp "H1" or "H7", or again like the electric arc of a discharge lamp.

By convention, we define an orthonormal coordinate system Oxyz centered on the light source 10, the axis Oy being horizontal and parallel to the longitudinal axis of the vehicle, the Ox axis being horizontal and perpendicular to the Oz axis, and the Oz axis being vertical and perpendicular to the first two.

The mirror 20 is intended to generate by itself a passing beam without the need to use other optical component, such as streaks or prisms formed on a closing glass arranged in front of the mirror 20. The latter may then be smooth or slightly diverter.

The mirror 20 is subdivided into three regions 21, 22, 23, separated by substantially vertical planes parallel to the plane median yOz passing through source 10, these three regions having extent and geometry different from each other.

The central region 22 is intended to ensure spreading important light, to give the light beam its width. It can for example be of the type which is described in patents FR-B-2 760 067 and FR-B-2 760 068 at name of the Applicant

Region 21 located on the right in Figure 1 is intended mainly to confer on the beam to be generated (here a standard European passing beam, cut-off known as "V") its scope, that is to say that a substantial fraction of the region 21 is intended to generate light in the axis of the road or in the vicinity of this axis, below the cut horizontal.

The region 23 located on the left in Figure 1 is suitable for generate, by its upper part, a beam part to horizontal cut, and has rows of streaks or slightly deflecting vertical prisms, while the region 23 is suitable, by simply tilting the surface of for example 15 °, to generate a part of the beam inclined at 15 °, to define the inclined half-cut of the beam of European crossing, and has rows of streaks or slightly deflecting prisms inclined at 15 ° to the vertical.

Such a design of mirrors, if it gives entirely satisfaction, is difficult to apply when necessary to make small mirrors, which then impose that region 21 has only a reduced lateral extent in the direction Ox. Indeed, in this case, the horizontal cut does not can no longer be frank. On the one hand, this results in a clear degradation of the photometric performance of the beam, which may no longer comply with regulations, and on the other hand greater difficulty in adjusting the beam in elevation, since the adjustment systems are based on position detection of the horizontal cut.

The present invention provides a solution to this problem to obtain a European passing beam, presenting to the times a suitable span, a suitable width and a good homogeneity with a space-saving projector, and whose mirror itself has reduced dimensions.

FIG. 2 shows a mirror 30, intended to cooperate with an axial light source 10, such as the filament of a standard filament lamp "H1" or "H7", or the electric arc of a discharge lamp.

The mirror 30 is subdivided into four regions 31, 32, 33 and 34, thus identified by their intersection with the horizontal plane xOy. These three regions have extents and geometries different from each other.

Region 32, analogous to region 22 of the headlamp of Figure 1, is capable of generating a large spread of light, thus giving the light beam its width. It comprises a series of zones 321, 322, 323, 324 and 325, the configuration of which, in terms in particular of horizontal generator, can be similar to what is practiced for a mirror of usual dimensions. In the present example, the region 32 has zones constituting streaks capable of imparting to the reflected light a predetermined degree of spreading, with lateral limits 32 _G and 32 _D (FIG. 4) preferably blurred to avoid defects of homogeneity of the beam, and capable of entirely locating this light below the normalized horizontal cut-off. To make these streaks, the teachings of documents FR-A-2 760 067 or FR-A-2 760 068 mentioned above in the name of the Applicant are advantageously used.

The region 31, located to the left of the region 32 in Figures 2 to 4, is able to generate the portion of the beam with horizontal cut, to give it its range under this horizontal cut. The region 31 is thus shaped so as to reflect the light rays emitted by the source 10 only in slightly diverging directions, for example comprised between the rays 31 _G and 31 _D in FIG. 4. This region 31, considered alone, thus gives a contribution to the beam represented by the isolux curves of Figure 5A.

The region 33, located to the left of the region 31 in FIGS. 2 to 4, is capable of generating the part of the beam located under the 15 ° cut-off of the passing beam. It is constructed from a parabolic base surface, while being self-generating of the beam cut-off, as for example according to the teachings of document FR-A-2 536 502, in the name of the Applicant, streaks and / or prisms, in accordance with the teachings of document FR-A-2 710 393, also in the name of the Applicant, which can be applied to this base surface, while being inclined by 15 ° to the horizontal. The region 33 is therefore shaped so as to reflect the light rays emitted by the source 10 only in slightly divergent directions, for example between the rays 33 _G and 33 _D in FIG. 4. The region 33 thus contributes to forming the part of beam represented by the isolux curves of Figure 5B.

Region 34, located to the left of region 33 in Figures 2 to 4, is capable of generating the light rays giving the beam its range in the longitudinal axis of the vehicle, and it is shaped so as not to reflect the light rays emitted by the source 10 only in slightly diverging directions, for example comprised between the radii 34 _G and 34 _D in FIG. 4, and contributing to forming the beam part represented by the isolux curves of FIG. 5C. It is understood that such a surface, in its part furthest from the source 10, will thus generate images of this source which are small enough to give the beam a satisfactory range. In addition, the beam generated by the region 34, superimposed on those generated by the regions 31 and 33, contributes to making the connection between these two beams and giving greater homogeneity to the beam.

Because regions 31, 33 and 34 of the mirror are significantly more closed around the source than its region 32, the mirror is expected to be highly asymmetrical in terms of extent on either side of the lamp, like the clearly show Figures 2 to 4.

This therefore makes it possible to produce a mirror whose width is weak, and which generates a completely satisfactory beam in terms of scope, width, overall flow and homogeneity. The the height of the mirror is advantageously close to its width. We therefore realizes a very small overall mirror and in height, and which does not present a setback.

This has the advantage that the mirror emits no stray radiation that could be generated by such setbacks.

It will be understood from the above description that, when the lamp / mirror off assembly is observed from the outside, through a glass which will be typically smooth, the observer finds that the lamp is strongly offset laterally by compared to the middle of the mirror.

To maintain a symmetry of appearance of the vehicle, it is therefore advantageous to design the lamp / mirror assembly intended for be used in the right headlamp in such a way that the lateral offset of the lamp in the mirror is reversed by relative to the offset in the left projector.

Of course, the present invention is in no way limited to the embodiments described and shown, but the man of the trade will bring many variations or changes.

Claims (6)

Low beam headlamp for a motor vehicle, comprising a light source (10) cooperating with a mirror (30) to form a light beam with a V cut, the mirror comprising at least three regions (32, 31, 33) arranged laterally relative to each other, a first region (32) giving the beam its width, a second region (31) giving the beam its range under the horizontal part of the cut, a third region (33) giving the beam its bearing under the inclined part of the cut, characterized in that each region (31, 32, 33) is connected to the adjacent region without detachment, in that the first region (32) of the mirror has a reflecting surface which spreads strongly the light in the lateral direction, and in that the second and third regions (31, 33) are located on the same side of the light source (10). Projector according to claim 1, characterized in that the second region (31), giving the beam its range under the horizontal part of the cut, is closer to the light source (10) than the third region (33), giving the beam its range under the inclined part of the cut. Headlamp according to one of claims 1 to 2, characterized in that it further comprises a fourth region (34) giving the beam its range in the longitudinal axis of the vehicle. Projector according to claim 3, characterized in that the fourth region is adjacent to the third region (33), being further from the light source (10) than this third region (33). Projector according to one of claims 3 or 4, characterized in that the third and fourth regions (33, 34) are connected without a step. Projector according to one of Claims 1 to 5, characterized in that at least certain regions of the mirror (31, 33, 34) which spread the light produce a slightly divergent spread.

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