EP0736726B1 - Motor vehicle headlamp producing a light pattern delimited by two parallel cut-off lines offset in the height - Google Patents

Description

The present invention relates generally to a motor vehicle headlight, of the type capable to emit a cut beam conforming in particular to regulations of the United States of America, and identified by the American standard SAE J 579 C.

Document US-A-3,858,040 in the name of the Applicant defines a cutoff profile which allows to respect the aforementioned regulation.

The cut is defined by two horizontal half-planes P1 and P2 shifted in height (the right half-plane being shifted upwards for a right-hand traffic direction), and by an oblique connection zone in the vicinity of the axis of the road.

We know by the same document US-A-3 858 040 in the name of the Applicant a parabolic type projector which allows to generate this cut, with a filament provided a concealment cup allowing to generate a beam cut by a horizontal plane, and a mirror provided with prisms capable of detecting the images of the filament located on one side to define the half cut plane P2 record.

We understand that, by using a cup blackout neutralizing about half the radiation, the light output of this projector is low.

We also know from document FR-A-2 583 139 a projector capable of generating, with a filament devoid of concealment cup and thanks to a specific design of the mirror, the same type of cut. In one embodiment, it is necessary to provide prisms on the closing glass to obtain the two offset half-cuts. In another form of realization, this offset is obtained by an offset angular of certain regions of the mirror with respect to others, so that the mirror has notches undesirable, and causes optical anomalies.

We finally know by the document FR-A-2 599 120 in the name of the Applicant a capable projector, also at using a reflective surface without discontinuity, to generate a beam respecting the same type of cut and whose concentration spot is offset laterally relative to the axis of the filament and the mirror.

But in these known projectors, the beam generated by the naked mirror remains relatively narrow, and a work important ice level is required.

Mention will also be made of document EP-A-735 309 which part of the state of the art under Article 54 (3) and (4) EPC.

The present invention aims to propose a new projector which allows to obtain a beam which at the same time corresponds to the cut of the aforementioned type and which, without the intervention of the closing glass, offers a wide important, while using a mirror whose reflective surface is continuous and preferably without slope breaks.

Another object is to achieve these objectives by achieving a beam of satisfactory homogeneity.

Thus the present invention provides a projector for motor vehicle as defined in claim 1.

Preferred, but not limiting, aspects of projector according to the invention are defined in dependent claims.

la figure 1 est une vue en plan de face d'un miroir d'un projecteur selon la présente invention, et d'un filament de lampe associé,

les figure 2 est une vue en coupe horizontale axiale du miroir et du filament de la figure 1, ainsi que d'une glace de fermeture,

les figures 3a et 3b, illustrent, par des courbes isocandéla, l'éclairement donné par deux zones différentes du miroir des figures 1 et 2, en l'absence de glace de fermeture,

la figure 3c illustre, par des ensembles de courbes isocandéla, l'éclairement donné par l'ensemble du miroir des figures 1 et 2, en l'absence de glace de fermeture,

la figure 4 est une vue schématique en coupe horizontale de la région avant d'un véhicule équipé de deux projecteurs selon l'invention,

les figures 5a et 5b représentent en coupe schématique deux moules destinés à fabriquer des miroirs de projecteurs pour circulation à gauche et à droite,

la figure 6 est une vue de face d'un miroir selon une autre forme de réalisation de l'invention,

les figures 7a à 7c illustrent par trois ensembles de courbes isocandéla les parties de faisceaux engendrées par trois surfaces de base, non striées, du miroir de la figure 6, en l'absence de glace de fermeture,

la figure 8 illustre un processus de réalisation de stries sur les surfaces de base du miroir de la figure 6,

les figures 9a et 9b illustrent par des ensembles de courbes isocandéla les parties de faisceaux engendrées par deux zones du miroir de la figure 6 pourvues de stries, et

la figure 9c illustre par un ensemble de courbes isocandéla la partie de faisceau engendrée par les deux zones précitées.

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

FIG. 1 is a front plan view of a mirror of a projector according to the present invention, and of an associated lamp filament,

FIG. 2 is a view in axial horizontal section of the mirror and of the filament of FIG. 1, as well as of a closing glass,

FIGS. 3a and 3b illustrate, by isocandela curves, the illumination given by two different zones of the mirror of FIGS. 1 and 2, in the absence of closing glass,

FIG. 3c illustrates, by sets of isocandela curves, the illumination given by the assembly of the mirror of FIGS. 1 and 2, in the absence of closing glass,

FIG. 4 is a schematic view in horizontal section of the front region of a vehicle equipped with two headlights according to the invention,

FIGS. 5a and 5b show in schematic section two molds intended for manufacturing projectors mirrors for left and right circulation,

FIG. 6 is a front view of a mirror according to another embodiment of the invention,

FIGS. 7a to 7c illustrate by three sets of isocandela curves the parts of beams generated by three base surfaces, not striated, of the mirror of FIG. 6, in the absence of closing glass,

FIG. 8 illustrates a process for producing ridges on the base surfaces of the mirror of FIG. 6,

FIGS. 9a and 9b illustrate by sets of isocandela curves the parts of beams generated by two zones of the mirror of FIG. 6 provided with streaks, and

FIG. 9c illustrates by a set of isocandela curves the part of the beam generated by the two aforementioned zones.

Preliminary note that from one figure to the other, identical or similar elements or parts are designated as far as possible by the same reference signs.

It will also be noted that, on the representations of beams by isocandéla curves, the indications numerical values are given in degrees. In addition, we call HH and VV respectively the horizon line and a plane of vertical center reference.

Referring first to Figures 1 and 2, we have shown a motor vehicle headlamp comprising a mirror 20, which will be described in detail below, a lamp mounted in the bottom of the mirror and comprising a axial filament 10, and a closing glass 30.

The lamp is in this case a standard type lamp "9006", used in particular in the United States of America. His filament emits freely all around it, only a cover front of the lamp which obscures direct light.

The mirror is capable, on its own, of generating a beam delimited by a cut of the kind of that mentioned in the preamble to this description.

The following description of the mirror of Figures 1 and 2 refers to a beam for right-hand traffic, that is to say whose right half cut plane is raised in relation to the left half-cut plane.

To this end, the mirror includes a first zone 21 which consists of a surface capable of generating filament 10 images which are all located below of a horizontal cut, and preferably whose highest points are located in the vicinity of this cut, and which at the same time brings these images to one side (in this case on the right side) of the vertical reference plane VV.

We understand that, due to the position of the zone 21 relative to source 10, the images produced by the zone 21 are relatively small on the one hand small, and on the other hand reasonably slightly inclined by compared to the horizontal.

In this way, the surface 21 is capable of generating a relatively thin spot of concentration of laterally offset from the VV plane, under a horizontal half-cut.

For example, to present the above properties, the reflective surface of zone 21 is produced according to the equation indicated on page 5 of the document FR-A-2 583 139, or more preferably in accordance with to the equations on page 10 of document FR-A-2 599 120, these two documents being in the name of the Applicant.

In the first hypothesis, the surface is subjected to horizontal tilting necessary to shift the beam to the right (for a right-hand traffic direction), this offset being a function of the width of the part of beam and corresponding to about half of this width. In the second hypothesis, the surface reflective is capable in itself of bringing light on the right side of the projection plane, and none tipping is not necessary.

The lighting obtained by zone 21, with a surface conforming to the second hypothesis, is illustrated by a set of isocandela curves in FIG. 3a. he has a generally straight cut at the HH horizon line, and is located immediately to the right of the vertical reference VV.

The reflective surface of zone 22, which occupies the bottom of the mirror and its side opposite to zone 21, is a surface capable of producing a beam of a width important and defining a horizontal cut. Of preferably, the highest points of the images of the filament generated are located in the vicinity of this cut.

Advantageously, in order to obtain a large width combined with good homogeneity in the horizontal direction, this surface is produced in accordance with the equations mathematics given in document FR-A-2 639 888 (zones 210, 220 and 230 of FIG. 5), or preferably, in document FR-A-2 664 677 (zones 201, 202 and 203).

The part of the beam generated by the zone 22 is illustrated in Figure 3b. We observe that the cut generated line is slightly lower, for example by 0.7 °, that the beam cut generated by the area 21. To do this, in relation to its definition mathematical in an orthonormal coordinate system (0, x, y, z), the area 22 is tilted 1.5 ° downwards.

According to one aspect of the present invention, in order to avoid a separation between the surfaces of the two zones, normally due to such a tilt, we determine the parameters of these, and especially their basic focal length, so that the intersection of the two surfaces, previously tilted one in relation to the other thanks to the adjustment of their equations, is located along a transition line, noted LT in Figure 1, which generally extends vertically between the top and bottom edges of the mirror 20. In this way, the mirror has no continuity solution. It only presents a very slight bend at the LT transition line, this bend which can practically be eliminated during polishing operations of the mold piston used to realize the optically active side of the mirror.

The overall beam obtained is illustrated by isocandela curves in Figure 3c. We observe the offset between the half-planes defining the cut at left and right of the vertical reference VV. We also observe that the beam has a large width, great homogeneity and a stain of concentration located immediately below the cut and slightly shifted to the right.

In this way, the closing glass of the projector can be practically devoid of amenities (streaks, prisms, ...) of deflection of light, and be smooth.

In addition, although illustrated in the figures 1 and 2 a mirror in which, in front view, the zone 21 is located on the left, the reverse layout may well heard to be withheld.

In particular, and as illustrated on the Figure 4 of the drawings, we can predict that the mirror of a left projector presents zone 21 on the left (in view of face) and that the mirror of a right projector has the zone 21 on the right (always in front view). this provision is particularly advantageous when, as shown in figure 4, the mirror presents, because rounded shapes of the front of the vehicle, an edge interior extending substantially more forward than its outer edge. In this way, we can give each zone 21 a large area while now at a relatively large distance from the source, in favor of the intensity of the stain beam concentration.

Although we have described above a mirror adapted to a right-hand traffic direction, i.e. with raising the cut to the right and shifting the spot of concentration to the right, the skilled person will know make the necessary changes to make a identical beam for left-hand traffic direction (for example the regulations in force in Japan). Concretely, the mirror for left-hand traffic is the mirror image of the mirror for right-hand traffic.

However, if it is desired to produce, by molding plastic material using the same bottom (or pocket) of mold, mirrors indifferently for a sense of left and right traffic, we run into the difficulty linked to the asymmetry of the mirror. So we have shown schematically in Figures 5a and 5b, with an exaggeration of the dimension along the optical axis xx by for clarity, a mold with a mold pocket common 100 and two movable mold parts (pistons) distinct 102a and 102b, defining the surfaces respective reflective for a beam for right-hand traffic and for a beam for traffic to the left.

We observe, due to the asymmetry of the surface reflecting from the optical axis xx, deviations significant deflection (distances f1 to f4 illustrated on the Figures 5a and 5b), undesirable both in terms of behavior of the mirror brought to its temperature of functioning (risk of irregular deformation and malformations in the bundle), that in terms of the economy (significant consumption of plastic). In fact, these constraints lead to design and build two separate mold pockets.

To overcome these drawbacks, the present invention also offers to make beams of the type mentioned, that is to say with two half-cuts offset in height and respectively for right-hand traffic and for left-hand traffic, performing the functions assigned to zones 21 and 22 of the embodiment of the Figures 1 and 2 using a specific streak of certain areas of the reflective surface.

More specifically, and now with reference to Figure 6, there is shown a mirror 40 which is separate in three zones 41, 42 and 43.

The central zone 42 has, over its extent, the same surface as the central area 22 of the mirror 20 of the Figures 1 and 2 on the same extent.

The lateral zone 41 has a base surface identical to the reflective surface of zone 21 of Figures 1 and 2. The lateral zone 43 presents a surface symmetrical to that of zone 41. We realize so a mirror with a symmetrical base surface, which will, as we will see below, resolve the problem discussed above with reference to Figures 5a and 5b. It will be noted here that the surfaces of zones 41, 42 and 43 are not tilted vertically relative to each other to others, that is to say that the horizontal cuts generated by these surfaces are aligned.

Figure 7a shows the light distribution which would be obtained with the base surface of zone 41. This distribution is naturally substantially identical to that of FIG. 3a.

Figure 7b shows the light distribution obtained with the surface of zone 42, which has large similarities to that illustrated in Figure 3b the fact that the area of area 42 corresponds to a substantial part of the surface of zone 22 of Figures 1 and 2.

Finally Figure 7c shows that, due to the symmetry areas 41 and 43, the light distribution which would be given by area 43 is symmetrical to that which would be given by zone 41.

As noted, the base surface described above is modified by appropriate striations, and more precisely by two types of striations in zones 41 and 43, so as to selectively obtain either a cutoff adapted to left-hand traffic direction (by example for Japan), a cut adapted to a direction traffic on the right (for example for the United States of America). In both cases, the central zone 42 remains smooth.

In the following description, we will consider the case a mirror for left-hand traffic.

All the streaks shown in this example the same width and the same height, and are separated, projection in a plane perpendicular to the optical axis, by horizontal and vertical boundaries.

With reference to FIG. 8, we have illustrated the fact that each streak S (M, N) is characterized on the one hand by radii of curvature R1 and R2 at the ends respectively upper and lower and secondly by two values of levels N1 and N2 at the ends compared to a base surface. The mathematical method used for design the reflecting surface of the mirror from equations of the base surfaces of zones 41 and 43 and streak parameters will not be described in detail, simply an increase in the coordinate at x of each point of the equation, calculated as a function of the position of the point on the streak considered and streak parameters (height, width, radius of curvature and levels).

• assurer un certain étalement latéral de la lumière engendrée par les zones 41 et 43, et
• assurer un relèvement de cette même lumière, en l'occurrence dans la zone 43, de manière à obtenir la demi-coupure relevée à gauche (aucun relèvement dans la zone 41).

The streak for the left-hand traffic direction is shown in Figure 6. It includes a first network of 15 x 5 streaks S (1,1) to S (15,5) in zone 41, and a second network of 15 x 5 streaks S (16.1) to S (30, 5) in zone 43. The streaks are provided so as to:

• ensure a certain lateral spreading of the light generated by the zones 41 and 43, and
• ensure a bearing of this same light, in this case in zone 43, so as to obtain the half-cut noted on the left (no bearing in zone 41).

Zone 41

In the example considered, the levels of the streaks in zone 41 are therefore all zero, which means that none significant vertical shift is not suffered by the light. In addition, the ten streaks S (14.1) to S (15.5) are inoperative (hatched area), i.e. they have been modeled with an infinite radius or that can be considered infinite.

The other streaks have radii of curvature which preferably vary between 20 and 40 mm, with a regular distribution for example on values of 20, 25, 30, 35 and 40 mm, for widths of the order of 3 to 5 mm.

In this way, we ensure a horizontal spreading of the light that would normally be generated by the surface of base of area 41, and Figure 8a illustrates the result of this spread.

Zone 43

Zone 43 includes, in the present example, a a number of streaks that do not work, as in the case of zone 41 (mainly streaks located in the lateral parts of zone 43). These streaks are indicated by tight hatching.

It is also expected (streaks S (26.2) to S (30.2)) of streaks, indicated by wide hatching, which have property of evolving gradually, from bottom to top, a large radius of curvature, similar to a flatness of the streak, towards a reduced radius of curvature, typically 35 to 40 mm.

Zone 43 also includes a number of streaks with a fixed radius of curvature or evolutionary, which have the property of presenting a level to their upper end (relative to the surface of base) which is below their level at the end lower.

In this way, these streaks provide a certain degree of light spreading, but above all a straightening the light upwards, so that form the highest half-cut of the beam.

In the present example, the streaks S (17,1) to S (30.1), S (21.2) to S (30.2), S (19.3) to S (30.3), S (20.4), S (29.4), S (30.4), S (29.5) and S (30.5) have this property. As an indication, the differences in levels between the top and bottom edges of each streak included preferably between 0.20 and 0.50 mm.

In addition, in addition to the streaks indicated by tight hatching, the streaks in area 43 have radii of curvature, fixed or progressive, which are preferably distributed in a range from 20 to 60 mm.

Finally, we will observe that both in zone 41 and in zone 43, the levels and radii of curvature of two adjacent overlapping streaks at their horizontal transition, are very preferably identical. In this way, it does not exist in the surface, at least vertically, no solution of continuity likely to give rise to faults optics.

FIG. 9a illustrates the appearance of the part of beam generated with the region 41 of the striated mirror 40 as shown above. We observe that the beam is spread in width significantly, without damaging the horizontal cut, located at the horizon, produced by the surface which would be striated.

Figure 9b shows the beam portion generated with zone 43 of the ribbed mirror also as indicated. Due to the differences in level of the streaks between their upper and lower ends, the cut is offset upwards relative to that of FIG. 9a, and at the same time, a certain width is given to the beam. We also observe that, thanks to a judicious arrangement of the streaks, the cut off beam extends almost entirely to the left of the plane vertical vertical VV of the projection screen.

The beam generated by zones 41 and 43 is illustrated in Figure 9c. This shows that a beam with two half-cuts offset in height, with the half-cut on the left raised in relation to the half-cut of right (beam for left-hand traffic) is generated very satisfactorily. The beam represented on the figure 9c will be further enriched by that of figure 7b, generated by the central zone 42, so it give an even greater width, for the benefit of visual comfort.

We understand that by reversing the arrangement of streaks, i.e. by placing streaks in area 41 of zone 43 of figure 6 and vice versa, we obtain a beam symmetrical to that generated by the mirror of FIG. 6, that is to say a beam adapted to a right hand traffic.

We also observe that, during this inversion, the dimension deviations along the X axis between the surface of the Figure 6 and the symmetrical surface will be a maximum of about 1 mm, value corresponding to the difference between the maximum level and the minimum level of the streaks, at which we add the deviations due to the convexity of streaks.

In this way, we can use for mirrors to left and right traffic the same pocket of mold, only the piston part being different for the two types of mirrors. The mold is therefore less expensive to make.

It will be observed here that, although the projector of the invention has been described as comprising a lamp standard type "9006", the invention applies to any type of axial filament lamp, and in particular a lamp type "9005".

In addition, a mirror according to the invention can also be used with a "9007" type lamp characterized by two axial filaments intended to form a bundle of crossing and a beam of road. In this case, we designs the mirror mainly according to the beam crossover to be obtained, and it is adjusted if necessary certain regions of the mirror or of the ice so as to obtain a satisfactory driving beam.

Of course, the present invention is by no means limited to the embodiments described and represented, but those skilled in the art will be able to bring it all variant or modification according to its spirit, in the extent that the invention remains that defined by the claims.

Claims (7)

1. Headlight for a motor vehicle, of the type comprising a lamp having an axial filament (10) emitting freely all around it, a mirror (20; 40) and a closure glass (30), the mirror being able to generate, in cooperation with the filament, a beam delimited by a cutoff defined essentially by two half-planes offset in height and situated on each side of a vertical reference plane (VV), characterised in that it comprises, in a first zone (21, 43) of the mirror, extending along a lateral edge thereof and over all its height, a reflective surface capable of forming a concentrated beam delimited by a first generally straight and horizontal cutoff and situated overall on one side of the said vertical reference plane, and in a second zone (22; 41, 42) of the mirror, extending at the bottom thereof and as far as the opposite lateral edge, a reflective surface capable of producing a broad beam delimited by a second generally straight and horizontal cutoff, in that the mirror comprises arrangements (S(16,1)-S(30,5)) for vertical beam offsetting able to position the said first cutoff at the highest cutoff half-plane, and in that the two zones are connected continuously at the intersection of the respective surfaces, along a continuous line (LT) extending between the top and bottom edges of the mirror.
2. Headlight according to Claim 1, characterised in that each reflective surface generates images of the filament whose highest points are situated close to the respective cutoff.
3. Headlight according to Claim 1 or 2, characterised in that the arrangements for vertical beam offsetting consist of a tilting of the said first zone (21) at a given vertical angle.
4. Headlight according to Claim 1 or 2, characterised in that the arrangements for vertical beam offsetting comprise a set of serrations (S(16,1)-S(30,5)) formed on a smooth base surface of the first zone, at least some of these serrations exhibiting an offset in level with respect to the said base surface between their top end and their bottom end.
5. Headlight according to Claim 4, characterised in that the mirror comprises an overall base surface formed by a first base surface (43) of the said first zone, the surface (42) of the said second zone at the bottom of the mirror and a second base surface (41) essentially symmetrical with the said first base surface with respect to an axial vertical plane, in that a first set of serrations (S(16,1)-S(30,5)) forms the said arrangements for vertical beam offsetting at the first or second base surface and in that a second set of serrations (S(1,1)-S(15,5)) forms arrangements for horizontal beam spreading at the second or first base surface, so that the beams for travelling on the right and left can be generated with the same global base surface.
6. Headlight according to Claim 5, characterised in that the mirror is produced by plastic moulding using a mould having the said mould ladle (100) for mirrors for travelling on the left and right.
7. Headlight according to one of Claims 1 to 6, characterised in that the glass (30) is smooth or slightly deviating.

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