FR2782148A1 - Automobile headlight for main and dipped beam functions, comprises two-filament lamp with masked dipped beam filament, and reflector configured to support both operating modes - Google Patents

Abstract

The lamp filaments are aligned with the vehicle fore-and-axis, the main beam filament behind and slightly below the other, which is located over a cup-shaped mask. The filaments are placed close to the main focus of the generally parabolic reflector (20), whose upper zone (21,23,24), exposed to the dipped beam filament, is symmetrically placed w.r.t. the vertical plane (Z) containing the filaments, while the lower zone (22) is wholly concealed from the dipped beam filament by the mask. The upper reflector zone comprises a sequence of vertical sections (21C,21D1,etc.), merging on transition lines, giving varying horizontal light deviation, each contributing part of the dipped beam. The lower zone (22) contains a similar sequence, the component sections each contributing to the main beam. The upper zone also includes two basically parabolic sections (23,24) completing the formation of the dipped beam as specified, one of these (24) also being vertically striated.

Description

The present invention relates generally to floodlights

  motor vehicles, and more particularly a crossover / road type headlamp equipped with a lamp with two filaments, one of which has a concealment cup intended to limit its field of illumination in the direction of the mirror of the headlamp. he

  may in particular be a standard lamp "114".

  In the most conventional way, such a lamp is associated with a mirror in the form of a paraboloid of revolution, the axis and the focus of which are judiciously arranged with respect to the filaments, in particular so that the lateral edges of the obscuring cup make it possible to define two half-cuts in the passing beam, one horizontal (on the left for a headlamp suitable for traffic on the right) and the other oblique by being raised by a given angle, typically 15, at

above the horizontal.

  In this type of known spotlight, the greatest difficulty in obtaining two beams of good quality resides in the striations which the glass must receive in order to give the beams appropriate widths while retaining good homogeneity and a good spot of light concentration. near the axis of the road. And this sorting is all the more difficult to achieve that the glass is, in modern vehicles, strongly inclined to match the plunging shape of

the front of the vehicle.

  Furthermore, in these known projectors, the part of the cut inclined at 15 above the horizontal is dependent on the position of the corresponding edge of the blackout cup relative to the filament, and

  unwanted deviations are often encountered.

  In addition, as soon as one seeks to achieve the lateral spreading of the beam no longer by a streaking of the glass, but by playing on the reflecting surface itself, the designer then encounters great difficulties in achieving the surface which is exposed to both the crossing filament and the road filament, knowing that it is always a question of finding a compromise between the qualities of the two beams. It is also difficult for him to suitably marry the aforementioned surface with the rest of the mirror, exposed only to the road filament and whose contours, by

  the orientation of the lamp, are asymmetrical.

  The present invention aims to overcome these drawbacks of the state of the art, and to propose a projector in which, thanks to an original arrangement of a lamp of known type, the mirror can be designed with greater flexibility as to its optical properties. Another object of the present invention is to provide a headlamp in which, contrary to recent trends, it is possible to modulate the concentration of the passing beam by playing in particular on the

height of the mirror.

  Thus the present invention provides a motor vehicle headlamp, comprising a lamp having a first axial filament for passing beam with which is associated a concealment cup having two lateral edges generally parallel to the axis of said first filament, and a second axial filament for driving beam, a mirror and a closing glass, characterized in that the cup is positioned essentially symmetrically with respect to an axial vertical plane, in that the mirror has a first essentially symmetrical zone on either side of an axial vertical plane, exposed to the first filament, and a second zone, complementary to the first zone and entirely masked from the first filament by the cup, the transitions between the first and second zones being located in regions of the mirror obscured by the cup with respect to the first filament, in that the first zone comprises a first re part capable of positioning images of the first filament in a substantially aligned manner below a horizontal cut and with a substantial width, and a second part capable of positioning images of the first filament in a substantially aligned manner below a oblique half cut raised with respect to said horizontal cut, this without the intervention of the obscuring cup, and in that the second region of the mirror is capable of generating a portion of beam having a concentration in the axis of the

  road and a predetermined width.

  Preferred, but not limiting, aspects of this projector are the following: - the lamp is arranged in the mirror so that the first filament overhangs an optical axis of the first zone while being essentially tangent to said axis. - The second part of the first zone consists of a surface capable of generating by itself images of the first filament essentially concentrated and aligned below said oblique half-cut. - the second part of the first zone is located

  in an upper corner region of the mirror.

  - The first part of the first zone consists of a set of streaks joining along transition lines along which the horizontal deflection of the light varies, each of these streaks being capable of generating a part of the beam located under

a horizontal cut.

  - The second zone is constituted by a set of streaks joining along transition lines along which the horizontal deflection of the light varies. said streaks of the second zone have reference axes tilted upward to varying degrees relative to a reference axis common to the streaks

  of the first part of the first zone.

  Other aspects, aims and advantages of the present invention will appear better on reading the

  following detailed description of an embodiment

  preferred thereof, given by way of nonlimiting example and made with reference to the accompanying drawings, in which: FIG. 1 illustrates in rear view the position of the two filaments and of the concealment cup in a conventional headlamp equipped of a "H4" type lamp, FIG. 2 is a back view of the position of the two filaments and of the cup of this same lamp in a headlight according to the present invention, FIG. 3 illustrates in side view the position of the two filaments and of the cup as shown in FIG. 2, FIG. 4 is a geometric view, from the back, of a mirror intended to cooperate with the lamp in its position as illustrated in FIGS. 2 and 3, FIG. 5 illustrates by a set of isocandela curves the appearance of the part of the beam generated by certain areas of the mirror with the crossing filament lit, without intervention of the lens of the projector, FIG. 6 illustrates in the same way the appearance of the part of the beam generated by another zone of the mirror, still with the crossing filament and without the intervention of the glass, and FIG. 7 illustrates the appearance of the crossing beam overall obtained, again without

ice intervention.

  Note that the description which

  follows refers to an orthogonal reference trihedron (0, X, Y, Z) where 0X is the horizontal direction transverse to the optical axis of the projector, 0Y is the direction of this

  optical axis, and OZ is the vertical.

  Referring first to Figure 1, there is shown the crossing filament 11 and its concealment cup 13, as well as the road filament 12, of a standard lamp of type "H4" designated by the reference 10 and whose other components (bulb, base, etc.), well known and useless for the understanding of

  the present invention have not been shown.

  The cup 13 has a left edge 131 and a right edge 132 generally rectilinear and parallel to the axes of the filaments 11 and 12, which are generally cylindrical. In the conventional position of the lamp, as illustrated in FIG. 1, the axis of the crossing filament 11 is placed on the axis OY and the straight edge 132 of the cup is contained in the horizontal plane XOY, while the left edge 131 of the cup and the base of the filament 11 are contained in an inclined plane of an angle c for example equal to 7.5 with respect to the horizontal, the geometry of the cup being such that, in this case , the plane passing through the axis of the crossing filament 11 and the left edge 131 of the cup makes an angle 5 for example of 15 relative to the horizontal. Also conventionally, the lamp thus oriented is arranged in a mirror not shown in the form of a paraboloid of revolution whose axis is

confused with the OY axis.

  It is well known that this arrangement makes it possible to generate, with this kind of mirror, a standardized European passing beam with a "V" cut, with a horizontal half cut defined by the straight edge 132 of the cup, and a half - cut raised to 15

  defined by the left edge 131 of said cup.

  According to one aspect of the present invention, and now with reference to FIGS. 2 and 3, the two filaments and the cup of this same lamp "H4" are shown, but in a position in which the cup 13 is oriented symmetrically relative to the vertical axial plane YOZ passing through the axis of the filament 11, so that its edges 131 and 132 and the base of the filament 11 pass through a common horizontal plane and are each offset, relative to the axis of the filament 11, by 7.5 down, and from the top of the

  filament 11, about 15 down.

  The aforementioned common horizontal plane is also in this case the XOY plane, since the reference trihedron (0, X, Y, Z) (from which the surface of the mirror will be designed as will be seen in detail below) is shifted downwards so that the axis OY is tangent to the surface of the filament 11 at its lower end. The filament 11 is somehow "laid"

on the OY axis.

  In practice, compared to a conventional "H4" lamp position, the new position according to the present invention is obtained by rotating the lamp 7.5 clockwise from the rear view, and by a lamp offset of the order of 0.6 mm upwards, knowing that the diameter of the filament

  crossing 11 is typically 1.2 mm.

  FIG. 2 also shows the half-planes PG and PD which correspond to the limits of the illumination of the crossing filament 11, as defined by the

  left and right edges of the cup 13.

  We will now describe the construction of the mirror capable of cooperating with the filaments 11 and 12 and the cup 13 in the new position described above, observing beforehand in FIG. 3 a certain number of reference points used for this.

construction.

  Thus the point FO designates a "reference focus", which is located on the axis OY at a certain distance behind the crossing filament 11, the point Fh designates a "high focus" which in this case is confused with FO but which, in practice, can also be located somewhere on the OY axis between the point FO and the rear end of the crossing filament 11, the point Fb designates a "low focus" and is located on the OY axis at the front end of the crossing filament 11, and finally the point FR, also located on the axis OY, designates a "focal point of the road" and is placed in the middle, in the direction of the axis OY, of the road filament 12. Now with reference to FIG. 4, there is shown in rear view a mirror 20 intended to cooperate with the lamp in its position illustrated in the figures

2 and 3.

  The mirror is separated into two main zones 21 and 22, the zone 21 occupying the upper part of the mirror

  while zone 22 occupies its lower part.

  Zones 21 and 22 meet in half-planes

  of radial transition Pl and P2 both inclined above

  below the horizontal, for example symmetrically and

at an angle of 18.

  The half-planes PG and PD described above and corresponding to the emission limits of the crossing filament 11 are also illustrated, and it is understood that the entirety of the zone 22, as well as of the border regions of the zone 21 , are hidden when the filament

light is on.

  From there, the zone 21 is designed, as will be described in detail, so as to be able to cooperate with the passing filament 11 to generate a passing beam

  European standards, here for right-hand traffic.

  When the road filament 12 is lit, on the other hand, the entire surface of the mirror is exposed at the source, and the zone 22 is designed to complete the part of the beam resulting from the cooperation between the road filament. 12 and zone 21 of the mirror

  to form a satisfactory route beam.

  Each of zones 21 and 22 is defined by the juxtaposition of sub-zones or ridges, produced as will be explained below, with in particular: - in zone 21, a central streak 21C, six streaks 21G1 to 21G6 located in its left part, and three streaks 21D1 to 212D3 located in its right part; - in zone 22, a central streak 22C, two streaks 22G1 and 22G2 located on its left side, and

  three streaks 22D1 to 22D3 located in its right part.

  There is also in the upper zone 21 a lateral region 21D4 of particular geometry, intended, as will be seen below, to generate in the beam the cut-off ascent specific to the

European beams.

  We will now describe with reference to FIGS. 5 and 6 a preferred embodiment of the streaks of the zones.

  upper and lower 21 and 22 of the mirror.

  Referring first to Figure 5, we illustrated the orthonormal reference frame indicated above, 0X being horizontal and perpendicular to the optical axis, 0Y

  being the optical axis and 0Z being vertical.

  The sub-zones or stripes of each zone 21 and 22 of the mirror are juxtaposed laterally with one another, that is to say delimited by border lines extending between the upper and lower edges of

each of the zones.

  The reflecting surface Sn of a sub-area Zn is generated by first defining at this area a horizontal generator GHn which is designed to ensure a predetermined lateral spread of light, contained between two limits, symmetrical or not. This horizontal generator can in particular be a hyperbola portion, an ellipse portion, even a straight line segment, etc. The reflecting surface is constructed from this generator, so that it has in its vertical sections a predetermined defocus. Defocusing here means the variation in position of the place from which a ray emitted by the center of the source S is reflected in a horizontal plane parallel to the axis 0Y of the mirror. Thus, in FIG. 5, the upper half of the surface Sn has a "high focus" Fhn different from the focus F of purely parabolic sections Pn, Pn 'illustrated in dashed lines for comparison purposes, while its lower half has a " low focal point "Fbn also different from F. The term" high defocusing "means the distance, measured along the axis 0Y, between the focal point F and the" high focal point "Fh, while the" low defocusing "

  corresponds to the distance between F and Fb.

  Documents FR-A-2 536 502 and FR-A-2 536 503, both in the name of the Applicant. describe in particular

  surfaces exhibiting the aforementioned defocus.

  Thus the reflecting surface Sn which will be obtained in the zone Zn is a surface capable of generating images of the source which are all located below a cut, and which at the same time ensures a controlled spreading of the images above. below this cut, the horizontal generator is preferably chosen so that this spreading is also homogeneous. In addition, if the defocusing is such that the top and bottom focal points Fhn and Fbn of the vertical top and bottom sections of the surface are respectively at the posterior end and at the anterior end of the source S, then the images are found essentially

  aligned below and flush with the cut.

  Now with reference to FIG. 6, the construction of zones 21 and 22 is carried out in successive stages. We start by defining a central subzone, as explained above. Preferably, it is the sub-zone located vertically of the lamp, and the parameters are defined, and mainly the shape of the horizontal generator and the high and low defocuses of the vertical sections of the reflecting surface, depending on the size of the mirror and the photometry sought for the part

wide of the beam.

  Then, the adjacent subzones, to the left and to the right of the background subzone, are defined with their own parameters (here again mainly the shape of the horizontal generator and the high and low defocuses of its vertical section), d on the one hand as a function of the desired positioning of the light projected by these sub-zones, and on the other hand and above all so that the reflecting surface of these adjacent zones intersects the reflecting surface of the bottom sub-zone along a line of transition which has two essential characteristics: - on the one hand it must extend from top to bottom between the upper and lower edges of the zone 21 or 22 considered, - on the other hand, the lateral deviation provided by each of the surfaces reflecting at this transition line should not be constant but should

  on the contrary vary regularly along this line.

  FIG. 6 precisely illustrates the case where a reflective surface S1 was initially defined intended to define a bottom subzone Z1, and the reflective surface of which rests on a horizontal generator GH1, with high and low defocusings

Fhl and Fbl appropriate.

  The reflective surface S2 of a subzone Z2 is then defined, this surface resting on a horizontal generator GH2 and having

  high and low defocus Fh2 and Fb2.

  We understand that by playing in particular on the position of the horizontal generator GH2 along the 0Y axis, we can ensure that, in the X0Y plane, the two reflecting surfaces intersect at a point with a dimension X12 well determined for define the border common to the two subzones Z1 and Z2 in this same plane. Insofar as the other parameters of the subzone Z2 remain within certain limits, the two subzones will in fact intersect along a transition line LT12 passing through the dimension X12 at the level of the section plane X0Y and joining the edges top and bottom of zone 21 or 22 considered. Optionally, one can play on the exact trajectory of the transition line LT between the subzones Z1 and Z2 on the height of the zone considered by playing on the values of the high and low defocuses in

each of these areas.

  Several approaches, and mainly two, can be adopted to do this: - the first consists in varying the high and low focal points, respectively Fh and Fb of the upper and lower parts of the reflecting surface so that they have two first positions identical for the entirety of one of the sub-zones, and two identical second positions, but different from

  first positions, for the entire other sub-

  zoned; this makes it possible to gradually bend the transition line LT12 in a controlled manner, as we move up and down the plane XOY, to the left or to the right when this transition line is observed in projection in the plane

vertical XOZ.

  - the second approach consists in varying the position of the high and low hearths no longer sub-zone by sub-zone, but continuously within the same sub-zone; so you can adjust independently

  from each other the depth offsets of a sub-

  zone with respect to its two neighboring zones, and therefore inflect the corresponding transition lines independently of one another; preferably, the evolution of the high and / or low foci within the same sub-zone is such that the defocus evolves linearly as a function of the dimension along X. It will further be observed that, each transition between sub-zones being produced by the intersection of two generally non-tangent surfaces, it does not create zero order discontinuity between the reflective surfaces of the two zones, but there is an elbow at its level which, when the spotlight is off, allows the observer to clearly differentiate the different sub-zones, which can be interesting

aesthetically.

  We also note that, thanks to the variations made to defocusing, the transition line LT12 between the subzones Z1 and Z2 will generally follow a more or less curved and sinuous trajectory which has the property of not being confused with a lateral isodeviation line of zone Z1, nor with a lateral isodeviation line of zone Z2. It follows that the width of each sub-area will vary gradually as a function of the dimension along Z, and that the maximum lateral spread provided at the level of the transition line LT12 will gradually vary when one moves along this line. In this way, any phenomenon of sudden stop of the beam part

  generated by each of the subzones is avoided.

  It will also be noted that the variation of the high and low defocuses leads to a shift in the position of the source images on a projection screen, either upwards or downwards. In the present case where the beam portion to be formed by the upper zone 21 of the mirror must essentially respect a horizontal cut, the defocusing changes are of course chosen so that this cut continues to be respected and defined with a certain sharpness. We can take advantage of this controlled defocus to adjust the light distribution in the direction of the thickness of the beam, as

we will see it below.

  The construction of each of the zones 21 and 22 is continued by defining, in the same manner as above, a subzone Z3 adjacent to the subzone Z2 and configured so as to obtain a bent transition line LT23 extending to the desired X dimension

in the XOY plane.

  These steps can be repeated for as many areas as necessary, in the left and right parts

from the mirror.

  The beam components generated by the different sub-zones created in zone 21 and in zone 22 will thus merge with good homogeneity into a beam part of controlled width and respecting, as regards zone 21, a cut-off. horizontal. This construction principle being described, the zone 21 of the mirror is constructed with high and low defocusings corresponding to the high and low focal points Fh and Fb

illustrated in figure 3.

  It will be observed that, if the mirror must have a greater height above the lamp, then it may be advantageous to play on the position, in axial direction, of the high focus Fh relative to the crossing filament 11, this in order to play on the height of the small images of this filament compared to

  the horizontal cut in the beam formed.

  It will also be observed that, taking into account the fact that the streaks of the zone 21 extend only very slightly in the part of the mirror situated lower than the filament 11, the focal point could be placed between the center, according to OY, of the crossing filament and its front end, without encountering any image feedback problems

  above the horizontal cut.

  As indicated above, the main zone 21 of the mirror also comprises a part formed by two regions 23 and 24 intended in particular to form the

beam portion raised by 15.

  Thus the region 23, which extends to the right of the last streak 21D3 of the zone 21 and above a plane P3 raised by 15 above the horizontal, is constructed according to the teachings of the document FR-A -2 536 502 in the name of the plaintiff. It is essentially a surface capable of generating images of the filament 11 essentially aligned below a rectilinear cut. As indicated in the aforementioned document, by turning this surface by 15 by a simple reference frame conversion operation, a part of the beam is produced located under a half-cut inclined at 15. Furthermore, the fact that the generator along the plane P3 used for this surface is a parabola, focused

  preferentially at point F0, makes it possible to carry out

  below this half-cut, a relatively concentrated portion of the beam, conducive to visual comfort. It is observed here that the zone 23, located in the upper part of the mirror, is far from the place where the cup 13 obscures the mirror (plane PD), and that the cup therefore does not in any way participate in obtaining the half inclined cut-off of the passing beam. We also observe that the zone 23 being adjacent to the upper edge of the mirror, we can easily play on the amount of light produced by this zone, which directly determines the light concentration under the inclined half-cut near the axis of the road. , by adjusting the height of the mirror above the optical axis. Region 24 is in turn formed by a parabolic base surface, focused for example at point F0, on which light spreading streaks have been applied according to the principle described in in particular in document FR-A-2,710 393 in the name of the Claimant. These streaks comprise circular director streaks 241 extending in the zone 0-15 and

  designed to spread a certain amount of light

  below the inclined half-cut, and in the extension of the streaks 241, vertical streaks 242 and 243, for example having slightly different sections and if necessary varying from one streak to another. The purpose of these streaks 242 and 243 is to spread the light horizontally, both in the passing beam and in the driving beam, in

  respecting however - for the passing beam -

the horizontal cut.

  Zone 22 of the mirror is constructed according to the same principle as zone 21, with however the absence of high and low defocusing because no cut is to be observed. In addition, the sections of zones 21 and 22 in the transition planes Pl and P2, and in particular the number of ridges in each zone, can be

identical or different.

  In addition, we choose the average focal length of the streaks of zone 22 slightly longer than that of the streaks of zone 21, so that the entire surface of zone 22 is set back from the surface of the zone 21. This makes it possible to avoid the presence in the surface, at the level of the planes Pl and P2, of an upwardly turned draft and therefore capable of generating

dazzling stray rays.

  In addition, the surface 22 is constructed so that the axes of reference of the individual ridges are tilted slightly upwards (typically by 1) relative to the axis OY of the zone 21 used for the passing beam, this in order to raise the maximum area of

  light to bring it in line with the road.

  Advantageously, in order to ensure a homogeneous mixture in the main beam between the parts of the beam generated by the different streaks of the zone 22 and by the zone 21, the tilting upwards is carried out with a certain progressiveness. For example, the axis of the central streak 22C is tilted up by 1, the axes of the adjacent streaks 22G1 and 22D1 are tilted up by 0.5, the axes of the following streaks 22G2 and 22D2 are tilted up by 0.25, and finally the axis of the extreme streak 22D3 is

flipped up 0.12.

  It will be noted here that the fact that the transition half-planes between the parts 21, 23, 24 dedicated to the crossing function and the part 22 dedicated to the road function are located in the occultation zone of the cup 13 makes it possible to conceive zone 22 relatively independently of the other zones, so as to be able to "work" efficiently the photometry of the

road beam.

  Finally, the headlight according to the invention comprises a closing glass, not shown, which can be essentially smooth or very slightly deflecting, or have inoperative patterns on the

optical plane.

  In this respect, the naked mirror is capable of generating beams having both a spot of concentration in the axis of the road or in its vicinity, an appropriate width as well as - in the case of the passing beam - a definition satisfactory cutoff. Thus, FIG. 7 illustrates by a set of isocandela curves the photometry of the part of the passing beam generated by the area 21 of the bare mirror, while FIG. 8 illustrates the photometry of the part of the passing beam generated by the area 23 and by the streaks 241. FIG. 9 represents the photometry of the whole of the passing beam. Of course, the present invention is in no way limited to the embodiment 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.

Claims (7)

  1. Motor vehicle headlamp, comprising a lamp having a first axial filament (11) for passing beam, with which is associated a concealment cup (13) having two lateral edges (131, 132) generally parallel to the axis of said first filament, and a second axial filament (12) for driving beam, a mirror (20) and a closing glass, characterized in that the cup (13) is positioned essentially symmetrically with respect to an axial vertical plane (Y0Z) , in that the mirror has a first zone (21, 23, 24) essentially symmetrical on either side of an axial vertical plane, exposed to the first filament, and a second zone (22), complementary to the first zone and entirely masked from the first filament by the cup, the transitions (Pl, P2) between the first and second zones being located in regions of the mirror obscured by the cup from the first filament, in this that the p The first zone comprises a first part (21) capable of positioning images of the first filament in a substantially aligned manner below a horizontal cut and with a substantial width, and a second part (23) capable of positioning the images of the   first filament essentially aligned with   below an oblique half-cut raised with respect to said horizontal cut, this without the intervention of the concealment cup, and in that the second region (22) of the mirror is capable of generating a portion of beam having a concentration in the axis of the   road and a predetermined width.   2. Projector according to claim 1, characterized in that the lamp (10) is arranged in the mirror so that the first filament (11) overhangs an optical axis (OY) of the first zone in   being essentially tangent to said axis.   3. Projector according to claim 2, characterized in that the second part (23) of the first zone is constituted by a surface capable of generating by itself images of the first filament (11) essentially concentrated and aligned below of said oblique half-cut.   4. Projector according to claim 3, characterized in that the second part (23) of the first zone is located in a corner region top of the mirror.   5. Projector according to one of claims 1 to   4, characterized in that the first part (21) of the first zone is constituted by a set of grooves (21G, 21C, 21D) meeting along transition lines along which the horizontal deflection of the light varies, each of these streaks being able to generate a portion of the beam located under a horizontal cut.   6. Projector according to one of claims 1 to   5, characterized in that the second zone (22) is constituted by a set of grooves (22G, 22C, 22D) meeting along transition lines along   from which the horizontal deflection of the light varies.   7. Projector according to claims 5 and 6   taken in combination, characterized in that said streaks (22G, 22C, 22D) of the second zone (22) have reference axes tilted upward in varying degrees relative to a reference axis common to the striations (21G, 21C, 21D) of the first part (21) of the first zoned.