FR2772883A1 - MOTOR VEHICLE PROJECTOR WITH SINGLE MIRROR AND MOVABLE SOURCE FOR GENERATING TWO DIFFERENT LIGHTING BEAMS - Google Patents

Abstract

A motor vehicle headlamp comprises a light source (15) defined by a lamp (10), a mirror and a lens, and means for relative displacement of the lamp and the mirror between two stable positions to generate in these positions respectively a first beam and a second beam of different types. The source (15) is moved by translation along an oblique path relative to the axis of the mirror. According to the invention, the lamp is oriented along an axis (AL) parallel to the direction of said oblique path. Application in particular to crossing projectors / single source road and mirror.

Description

The present invention relates generally to floodlights

motor vehicles.

  It relates more particularly to a projector capable of emitting, from a single lamp and a single mirror, two types of light beams, and this by relative displacement between the lamp and the mirror. Already known, in particular from EP-A-0 705 730, a projector which comprises a mirror and a lamp, the mirror being fixed while the lamp can be moved by

  relation to the mirror so as to allow the latter to generate two different beams.

  It is thus proposed in this document, a first concrete solution in which the lamp is pivotally mounted, under the effect of an actuator, around a horizontal axis 15 located above the lamp. This pivoting induces a lowering of the source (filament or light arc) relative to the optical axis of the mirror, as well as a movement of recoil from said source towards the bottom of the mirror.20 This document also proposes a second solution according to which the lamp is mounted in translation in an oblique direction extending in the axial vertical plane of the mirror and oriented in a rising direction towards the front.25 These technical solutions are relatively complicated and bulky, in the first case by necessity to provide an arm of relatively great height inside the headlight housing, between the pivot axis and the actuation point, and in the second case because of the need to provide special means for guiding in oblique translation at near the lamp hole. In addition, the oblique displacement of the lamp, oriented horizontally, may require providing at the bottom of the mirror an oversize of the lamp hole or other passage for the lamp, due to the fact that the lamp is at an angle to its direction of displacement. Finally, and very particularly with regard to the second embodiment described in EP-A-0 705 730, it is understood that guiding in oblique translation requires parts of very specific geometry,

  thus posing manufacturing problems. In particular, the part on which the lamp is mounted must have parts made in correlation with the horizontal axis10 of the lamp, and other parts made in correlation with the oblique direction of movement.

  The present invention aims to overcome these limitations of the state of the art and to provide a projector of the

  aforementioned type, in which the production of the lamp guiding means and their implementation are improved.

  Thus the present invention a motor vehicle headlamp, comprising a light source defined by a lamp, a mirror and a lens, and means for relative displacement of the lamp and the mirror between two stable positions to generate in these positions respectively a first beam and a second beam of different types, and in which the displacement means operate by translation along an oblique path with respect to the optical axis of the mirror, characterized in that the lamp is oriented along an axis parallel to the direction of said oblique path. Preferred, but not limiting, aspects of the projector according to the invention are as follows:

  - The mirror is fixed and the displacement means act on the lamp.

  - the lamp is mounted in a mobile cylindrical support coaxial with the lamp, and fittings

  complementary to guiding in translation are integral with the mirror.

  - Said complementary guide arrangements are made in one piece with the mirror during the manufacture of the latter by molding, and the demolding direction of the mirror is parallel to said oblique path. 5 - the direction of the path and the axis of the lamp extend obliquely to the optical axis of the mirror while being contained in an axial vertical plane of said mirror. - the direction of the path and the axis of the lamp extend obliquely both with respect to a plane - axial horizontal and with respect to an axial vertical plane

from the mirror.

  the mirror comprises a zone with a parabolic base capable of generating a portion of concentration of a first beam situated below a given cut-off when the source is in front of a focal point of said parabolic base, and the displacement of the source includes a retreat thereof towards said focus. - the recoil movement of the source is accompanied by a lowering and a lateral offset of the source, so as to redirect said concentration part of the first beam upwards and in an opposite lateral direction, to form the part of the second beam. 25 - the first beam is a dipped beam with concentration shifted towards the side of the road and the second beam is a beam of road with axial concentration. Other aspects, purposes and advantages of this

  invention will appear better on reading the following detailed description of an embodiment

  preferred thereof, given by way of example: <example and made with reference to the appended drawing, in which: FIG. 1 is a schematic back view of an optical assembly, consisting of a mirror and a lamp, of a headlamp of the present invention, FIG. 2 is a schematic side view and partially in section of the optical assembly of FIG. 1, FIG. 3 is a schematic view from above and partially in section of the optical assembly of Figures 1 and 2, Figure 4 is a schematic front view of a mirror suitable for use in a projector of the present invention, Figure 5 is a schematic top view of a - part of the mirror Figure 4 and the associated light source, Figure 6 is a rear view of an optical assembly according to another embodiment, Figure 7 is a schematic side view and partially in section of the optical assembly of the Figure 6, Figure 8 is a schematic top view and partial nt in section of the optical assembly of Figures 6 and 7, Figure 9 is a schematic side view and partially in section of an optical assembly according to another embodiment of the invention, Figure 10 is a partial view front view of the optical assembly of FIG. 9, FIG. 11 illustrates the general appearance of the concentration zone of a passing beam obtained with a headlight according to the present invention, and FIG. 12 illustrates the general appearance of the area of

  concentration of a driving beam obtained with a headlamp according to the present invention.

  It will be noted at the outset that, from one figure to another, identical or similar elements or parts are designated as far as possible by the same reference signs, and will not be described again in

every time.

  Referring firstly to Figures 1 to 3, there is shown an optical assembly of a vehicle headlamp

  automobile, which conventionally is housed in a housing closed by a crystal (these elements not being shown for the sake of simplification).

  The optical assembly includes a mirror 20 in which a lamp 10 is mounted.

  The lamp in this case is a conventional discharge lamp, with a connector 11, a support flange 12, a bulb 13 and an external electrode 14, and is capable of forming a luminescent arc 15 of generally elongated shape depending on the AL axis of the lamp. The mirror 20, a concrete embodiment of which will be described in more detail below, has a reflecting surface capable by itself, and if necessary with the help of opaque zones provided on the lamp, of a cut-off beam, and in this case a passing beam conforming to European standards. The lamp 10 is movably mounted relative to the mirror 20 so that, in a first position, its arc occupies a first location such that the

  reflecting surface of the mirror 20 generates the aforementioned passing beam, and that, in a second position, its arc occupies a second different location, chosen so that the mirror then produces a beam with a longer range, and in this case a road beam.

  This behavior can be obtained in particular the second location of the arc 15 is offset on the one hand towards the rear (that is to say towards the bottom of the mirror), and on the other hand towards the bottom, by relative to the first location, as well as to the side if necessary. Thus, whether the movement of the source recedes only downwards or both downwards and to the side, this source must be moved in a direction of oblique translation relative to the optical axis Y of the mirror 20. According to a characteristic of the invention, the lamp is oriented so that its own axis AL coincides with this direction, that is to say adopts an oblique orientation. In the embodiment of Figures 1 to 3, it is a double obliquity, the orientation of the axis AL being descending towards the bottom of the mirror and

  gradually shifted to the right also towards the bottom of the mirror.

  To carry out such a mounting of the lamp, the latter is secured, for example using a pin or the like (not shown), on a mobile support 16 which comprises a radial part 16a having a central opening traversed by the lamp 10, the flange of said lamp resting on the periphery of this opening, and a cylindrical outer part 16b with an axis coinciding with the axis AL of the lamp. 20 a guide structure 30 is attached to the rear of the mirror which includes a support plate 31 applied and

  fixed against the rear of the mirror 20, and a cylindrical guide sleeve 32 whose internal diameter and very slightly greater than the external diameter of the part 16b of the support 16 and whose axis defines the orientation of the axis AL.

  Of course, the mobile support 16 is connected to an actuator (not shown) capable of bringing it selectively into one or the other from two positions corresponding respectively to the two working positions of the lamp. Appropriate stop means are further provided, not shown, to ensure the stability of the lamp in each of its positions. In FIGS. 2 and 3, the lamp is shown in its advanced position, corresponding to the passing beam, in which case the arc 15 is located in the vicinity of the reference center of the three-dimensional coordinate system X, Y, Z on the basis of which the surface reflective of the mirror 20 is designed. The retracted position of the arc is designated by the reference 15 '. Thanks to the oblique mounting of the lamp as described above, the lamp holder 16 can be coaxial with the lamp, which makes its design and manufacture easier and economical. Furthermore, it is possible optionally to produce the guide piece 30 in one piece with the mirror 20 when

  this is produced by injection of thermosetting material, by simply adapting the release direction so that it is parallel with the axis of the cylindrical guide sleeve 32.

  We will now briefly describe with reference to Figures 4 and 5 an example of a mirror that may be suitable for the above application. The mirror 20, as mentioned above, is capable of ensuring by itself the desired light distribution for a standard European type passing beam, that is to say that the front lens of the headlight (not shown) is smooth or very slightly deviating. It is subdivided into three distinct zones 21, 22 and 23 which are connected to each other continuously or not, and is intended to cooperate with a known discharge lamp of the type incorporating two occulters, in this case strips of opaque paint provided on the bulb 13.30 These opaque bands are formed so as to obscure the radiation from the arc 15 in two well-defined angular sectors, in order to facilitate the formation by the mirror of the beam with European standard cut-off, delimited by a horizontal half-plane (on the side of traffic in the opposite direction) and by a half-plane going up to 15 above the horizontal (on the side of the side of the road). According to one aspect of the invention, two of the three radial half-planes of transition between the three zones 21, 22, 23 of the mirror are located in the aforementioned obscured sectors. In particular, the transition half-plane P12 between zone 21 and zone 22 of the mirror is in this case inclined at +25 above the horizontal, while the transition half-plane P23 between zones 22 and 23 is tilted by

    below the horizontal, on the side opposite the lamp.

  In addition, a transition half-plane P31 is inclined at -30 below the horizontal, on the same side as the

P12 half-plane.

  Of course, these values are in no way limiting. In particular, in order to increase the

  symmetry of the surface with respect to the axial vertical plane y0z, and to facilitate the adaptation of the headlamp for a 20 direction of left-hand traffic.

  We will now describe the structure and the optical role of each of the zones 21, 22, 23 of the mirror 20.

  Zone 21 The essential vocation of this zone is to ensure the reach of the crossing beam in a region located

  below and in the vicinity of the inclined right half-cut, this in order to satisfactorily illuminate the right shoulder of the road at distances of the order of 30 to 40 meters and more.

  This area is defined by a base surface on which light spreading streaks are applied. The process for applying these streaks will be

  preferably that described in document EP-A-0 645 578 in the name of the Applicant.

  The base surface is advantageously a portion of a modified bottom dish, which is described in detail in

  Document FR-A-2 609 148 in the name of the Applicant, to which reference will be made for more details.5 It will nevertheless be recalled here that these surfaces have vertical sections which are parabolas.

  The focal point F of these parabolas is preferably located on the axis Y and offset rearward relative to the center, along Y, of the arc 15. This axial offset is preferably between 10 and 6 mm.

  The horizontal generator of such a base surface, for its part, is a parabola with the same focal length and the same focal point F, but the central part (bottom) of which is modified to ensure convergence of the rays reflected. The setting of this background part is determined so that the half-angle of this convergence, and

  therefore the divergence which follows in the distance, preferably around 20. The transition between the modified part and the unmodified part is preferably located at a lateral distance of the order of 50 mm relative to the optical axis.

  The modified central subzone of zone 21 is used as it is, i.e. it is a

  smooth, continuous and driftable surface (without indentations25 or elbows).

  The outer, purely parabolic sub-zone of zone 21 extends between the central sub-zone 111 and the lateral edge of the mirror, and preferably receives a certain number of slightly marked striations intended to ensure controlled spreading. of light in particular along the inclined part of the standardized cut-off and to favor the illumination in the vicinity of the standardized measurement points 75R and 50R of the projection screen. In this regard, some of the ridges may have a non-symmetrical profile with a part of radius of curvature intended to ensure a large spreading of the light towards the outside and a part of radius of

  greater curvature intended to spread the light little inward.

  Zone 22 The double purpose of this zone is to generate the part of the cut beam located below the half-cut of

  left (horizontal) and to carry out a very large horizontal spreading of the light, to give the beam the great width contributing to visual comfort.

  It preferably comprises a base surface which is constituted either by a portion of a self-contained surface.

  horizontal cut generator, as defined in particular in FR-A-2 536 503, or by a portion of a self-generating horizontal cut surface with modified bottom, as defined in document FR-A-2 609 148, either by a portion of a self-generating horizontal cutoff surface, with intermediate zones

  modified, as defined in one or other of the documents FR-A-2 639 888 and FR-A-2 664 677. Reference is made to the description of these documents for more

  details about the construction of the surfaces. In the first case, the vertical sections of the surface are portions of parabolas with evolving foci, so as to place all the images of the source below and flush with a horizontal cut defined by the horizontal axis of the projection screen. In the second or third case, the vertical sections of the surface are parabolas. Their home is

  advantageously found offset towards the rear with respect to the arc generated by the lamp.

  As regards the horizontal generator of such a surface, it is in the first case a parabola, in the second case a parabola whose background area is modified to ensure convergence of the reflected radiation, and therefore at a large distance a spread, and in the third case of a parabola modified in its central zone by a set of successively divergent and / or convergent and / or parabolic zones.5 In the present example, it is a base surface produced in accordance with the configuration illustrated in FIG. 11b of document FR-A-2 664 677. In other words, the base surface of zone 22 comprises, in its left part and from left to right on FIG. 5 a first sub-zone whose horizontal generator is parabolic, a second sub-zone whose horizontal generator is modified so, from outside to inside, starting from a zero horizontal deviation, passing through a point of converges nce horizontal maximum15 and return to a point of zero horizontal deviation, and a third sub-area including the horizontal generator

  is modified for, from the outside to the inside, starting from said zero horizontal deviation, passing through a point of maximum horizontal divergence and returning to a point of zero horizontal deviation situated in the vertical axial plane YZ.

  These different profiles of the horizontal generator of the base surface together constitute a line

  continuous and differentiable (i.e. without breaking the slope).

  The right part of the generator of this base surface is produced symmetrically or not, but with the same evolutions in terms of horizontal deviation. Zone 22 also includes a specific streak,

which we will describe below.

  First of all, the intermediate subzones with modified horizontal generator are left as they are; they are smooth (continuous and differentiable) over their entire extent. 35 On the other hand, the two border sub-zones, whose base surfaces are parabolas, each include a set of grooves with vertical guide intended to ensure a

  large horizontal spread of light.

  Furthermore, in accordance with the teachings of EP-0 645 578 cited above, these ridges can have progressive profiles so that vertically aligned ridges can be connected to each other

  without discontinuity, which avoids optical anomalies such as dazzling parasitic radiation.

  Alternatively, one can streak not only the border subareas, but also portions of the

  intermediate zones which are adjacent to them, so as to reinforce the horizontal spreading of the light. Generally, we make sure when designing this area, that its part farthest from the source, that is to say close to the lateral edge of the mirror, generates the spreading beam part moderate horizontal located below the left half-cut, while the other parts of this zone, and mainly its upper part, generate a light diluted significantly the light in width. In this way, the displacement of the source relative to the mirror to pass from the crossing function to the road function, displacement whose effect is all the more sensitive as the point of reflection is close to the latter, will generate a rather large, but not very annoying, displacement of the light diluted horizontally by the upper part of the area, and a less significant, but well controlled displacement, of the light located under the left half-cut, generated by the lateral part of the area to raise it slightly and bring it towards the a:.: e of the road. Zone 23 This zone, located in the lower part of the mirror between the transition planes P23 and P31, is advantageously a surface constructed like the base surface of zone 22, namely in accordance with the teachings of FR-A-2 664 677 and more particularly of its figure llb. 5 However, unlike zone 22, zone 23 has no streaks, so as to leave a spot of significant concentration in the axis of the road in the beam portion generated. In this example, the equation for area 23 is

  performed with parameters of identical or different values to those of the parameters in zone 22.

  Advantageously, the basic focal distance of the surface of the area 23 (parameter f0 in the document

  FR-A-2 664 677) is less than that used for zone 22.

  In addition, it is advantageous for the axis of this surface, corresponding to the axis 0x in FR-A-2 664 677, to be shifted downwards by a distance d relative to the axis Y common to the surfaces of the zones 21 and 22.20 It is observed in fact that, in an arc lamp, the salts present in the lower part of the lamp, below the arc 15, generate a certain amount of light which constitutes a source of parasitic secondary light . By shifting the axis of the surface of zone 23 downwards so that it extends in the vicinity of this secondary source, one avoids generating images of this

  last which extend well above the cut and which are likely to dazzle the drivers of vehicles traveling in the opposite direction. Preferably, with the discharge lamps currently available on the market, an offset c close to 1.5 mm is chosen.

  The base focal point of the surface of zone 23 is preferably located, on the abovementioned offset axis, immediately in front of said secondary source.35 Furthermore, the parameters of the surface of zone 23 are preferably chosen such that so that from the center to the side edges of this area the deviation

  horizontal spread progressively goes from a zero value to a maximum divergence, then to a maximum convergence, then to a deviation again zero at level5 of the lateral parts with parabolic profile.

  With this behavior, the part of the beam generated by the zone 23 has both a high concentration along the axis and a large spread contributing to the visual comfort.10 It has been observed that with a mirror 20 as described in detail above. above, and with an arc displacement presenting

  the double obliquity described with reference to FIGS. 1 to 3, it was possible to obtain, in the remote position of the arc, a completely satisfactory driving beam.

  More precisely, the fact of moving the arc 15 back has the first effect of bringing it closer to the focal point F of the zone 21 of the mirror, so that the parabolic-based sub-zone of this zone 21 will be able to generate a portion of more concentrated beam in the distance, so as to create the range of the driving beam. At the same time, the cut generated by this area in the first

  location of the arc is destroyed, since the images of the arc will be projected in positions no longer respecting this cutoff (and being typically straddling this one).

  In addition, the fact of shifting the arc slightly downwards results in a general rise of the light

  emitted by zone 21, so that it is at a suitable height in the axis of the road.

  Finally, the fact of shifting the arc slightly to the right results in a shift to the left, that is to say towards the axis of the road, of the light emitted by said zone 21. Figures 11 and 12 roughly illustrate the areas of concentration of the passing beam and of the driving beam thus obtained. We observe that, while the concentration of the passing beam is

  shifted to the side of the road, and situated below the inclined half-cut c, the road beam is suitably centered on the axis of the road, materialized by the point H in a standardized projection screen.

  Of course, a lamp displacement with a simple obliquity, that is to say with a direction of displacement of the arc 15 extending obliquely relative to the axis Y in the vertical axial plane YZ of the mirror, can also prove to be satisfactory in certain cases, and - mainly in the case where the light of the two types of beams is each time centered horizontally on

the axis of the road.

  Thus, in both cases, the source remains located in the axial vertical plane of the mirror, so that, during movement, the main beam concentration zone

  emitted will generally move vertically.

  It will be observed here that the oblique orientation of the axis AL of the lamp has the effect of tilting so

  corresponding to the elongated luminescent arc generated by it.

  However, this inclination is limited enough not to cause a perceptible defect in the

  beam formed, all the more so since, conventionally, an arc has a greater thickness in the center than at its ends.

  Such an inclination will not be bothersome in the case where the source is constituted by an incandescent cylindrical filament. 30 We will now describe other embodiments making it possible to move the light source in a direction having a double obliquity . First of all, FIGS. 6 to 8 illustrate the case where the lamp 10 remains oriented in the conventional manner, that is to say with a lamp axis AL parallel to the axis Y of the mirror. the mobile support 16 ′ is in this case adapted and

  has a radial part 16a 'extending in a plane perpendicular to the axis AL of the lamp, and a cylindrical external part 16b' whose axis AG is inclined at an angle oblique to said axis AL and determines the direction of movement of the arc.

  The mirror and the guide structure 30 are identical to those of FIGS. 1 to 3, the guide sleeve 32 being aligned along the guide axis AG.10 As can be seen in FIGS. 7 and 8, the - direction of movement of the source, parallel to the axis of movement AG, is oblique not only relative to the horizontal plane XY, but also relative to the vertical axial plane YZ, with consequently the optical behavior as described above.

  Figures 9 and 10 illustrate another embodiment of the invention, in which the movement of

  the source is not real (the lamp therefore being fixed), but produced by creating an image source offset during the interposition of one or more mobile diopters between said source and at least part of the mirror 20.

  In the present case, a diopter is arranged so as to selectively intercept the radiation emitted

  by the source 15 towards the zone 21 of the mirror, the vocation of which is to generate the most concentrated part of the beam.

  This diopter 40 has a plane entry face 41, oriented vertically and parallel to the plane YZ, and a

  convex outlet face 42, determined so as to achieve the desired displacement of the arc.

  The diopter 40, in a conventional manner in itself, is guided by appropriate guide means and moved by an appropriate actuator, these means not being shown. The face 42 is calculated so that the interposition of the diopter 40 creates an image source of the real source, designated by the reference 15 ′, which occupies a position identical to or close to the position occupied by the arc in the retracted position of the lamp in the previous embodiments, as shown in Figures 9 and 10. 5 Such a solution has the advantage of not having to move the lamp, which is likely to

  decrease its lifespan. It is understood from the foregoing description that the present application also relates, so

  independent of the essential characteristic according to which the axis of the lamp corresponds to its direction of oblique translation, the fact of giving the source, whatever the proper orientation of the lamp, a movement, real (or by imagery if the 'dioptres are used), according to a double obliquity both with respect to the axial horizontal plane and with respect to the axial vertical plane, with the aforementioned advantages in terms of beam positioning. Of course, the present invention is not limited to the embodiments described and shown, but those skilled in the art will be able to make any variant or modification in accordance with his spirit. In particular, the invention applies both to discharge lamp headlamps and to filament lamp headlamps. It also applies to generate beams other than a passing beam and a

road beam.

Claims (9)

  1. Motor vehicle headlamp, comprising a light source (15) defined by a lamp (10), a mirror (20) and a lens, and means for relative displacement of the lamp and the mirror between two stable positions to generate in these positions respectively a first beam and a second beam of different types, and in which the displacement means 10 operate by translation along an oblique path relative to the optical axis of the mirror, characterized in that the lamp is oriented along an axis ( AL) parallel to the direction of said oblique path.   2. Projector according to claim 1, characterized in that the mirror (20) is fixed and in that the means   displacement act on the lamp (10).   3. Projector according to claim 2, characterized in that the lamp (10) is mounted in a cylindrical mobile support (16) coaxial with the lamp, and in that   complementary translational guidance arrangements (30) are integral with the mirror (20).   4. Projector according to claim 3, characterized in that said additional guide arrangements (30) are made in one piece with the mirror (20) during the manufacture thereof by molding, and in that   that the demolding direction of the mirror is parallel to said oblique path.   5. Projector according to one of claims 1 to 4, characterized in that the direction of the path and the axis (AL)   of the lamp extend obliquely to the optical axis (Y) of the mirror being contained in an axial vertical plane (YZ) of said mirror.   6. Projector according to one of claims 1 to 4, characterized in that the direction of the path and the axis (AL)   of the lamp extend obliquely both with respect to an axial horizontal plane (XY) and with respect to an axial vertical plane (YZ) of the mirror.   7. Projector according to claim 6, characterized in that the mirror (20) comprises a zone (21) with a parabolic base capable of generating a portion of concentration of a first beam located below a cut   given when the source (15) is in front of a focal point (F) of said parabolic base, and in that the displacement of the source (15) includes a retraction of the latter in the direction of said focal point.   8. Projector according to claim 7, characterized in that the recoil movement of the source (15) is accompanied by a lowering and a lateral offset of the source, so as to redirect said concentration portion of the first beam up and in a   opposite lateral direction, to form the concentrating part of the second beam.   9. Projector according to one of claims 7 and   8, characterized in that the first beam is a passing beam with concentration shifted towards the   road side and the second beam is an axially concentrated road beam.