Patent Publication Number: US-6341886-B1

Title: Motor vehicle headlight having means for selectively emitting a beam for driving on the left or on the right

Description:
FIELD OF THE INVENTION 
     The present invention relates in general terms to motor vehicle headlights, and in particular to a novel dipped beam headlight which is able to be adapted in an extremely simple way for driving on the right or for driving on the left. 
     BACKGROUND OF THE INVENTION 
     Vehicle headlights of the elliptical type are well known in which the cut-off line of a dipped beam is defined by a mask or screen which is placed in the path of the light between a generally elliptical reflector and a convergent lens. In such a headlight, it has previously been proposed to make the form of the mask able to be modified selectively in such a way as to enable a beam to be produced respectively which is suitable for driving on the selected side of the road, i.e. on the right or on the left. 
     However, these arrangements are not able to be used in the case of a headlight in which the beam is formed directly by the reflector in cooperation with a light source (which may be partly masked). The above arrangements cannot be applied to a reflector of such a headlight, nor, where appropriate, to light-diverting elements such as striations or prisms formed on the cover glass of the headlight. 
     In this connection, in this type of headlight, one example of which is a light which uses a lamp of the “H4” normalised type in a parabolic reflector, the form of the reflector and/or the arrangement of the light-diverting elements is determinant to give a cut-off beam of good quality when driving on the required side of the road. In this connection, recourse to a so-called “vacation mask”, consisting of a band of opaque adhesive applied in an appropriate place on the front glass or lens of the headlight when the vehicle has to change its driving mode between the left and right hand sides of the road, is a palliative with which the modified beam is in no way satisfactory in terms of visual comfort. Thus, dipped beam headlights for driving on the left and for driving on the right must in general have reflective surfaces and/or front cover glasses (lenses) which are different from each other. 
     In addition, the Company Valeo Vision has developed, over the last few years, reflectors having reflective surfaces which are adapted to produce, by themselves, beams capable of being used both in traffic driving on the right and in traffic driving on the left, with the required photometry, in particular in terms of the cut-off line, homogeneity of the beam, and beam width. However, here again, the reflective surface is designed specifically for driving on a given side of the road, and a single surface is not suitable for use in common for driving on both the left and the right. 
     In addition, there is today a tendency to equip vehicle headlights with discharge lamps, which are well known for their substantially superior light intensity as compared with that of a filament light, but with a much smaller power consumption. 
     The high intensity of this type of light source, together with the presence, in the vicinity of the luminous arc itself, of secondary light sources which result from the accumulation of salts in certain regions of the lamp, or which result from reflections on the electrodes, do however pose particular problems, which are partly resolved by a design which is particular to the reflecting surface of the reflector itself. 
     Thus, the specific character of the reflective surfaces, related to their exclusive suitability for driving on either the left or the right, is often even more pronounced with this type of lamp. 
     One consequence of this exclusivity is the need to provide different mould parts for the two types of traffic, and (if necessary) also different designs of mould cavity, which does of course lead to high tooling costs. 
     SUMMARY OF THE INVENTION 
     In order to overcome the limitations in the state of the art as discussed above, it would be highly beneficial to design a headlight in which not only a common reflective surface, but also a common type of lamp, could be used for a headlight that would be adaptable so that by simply moving the lamp within the headlight, the setting of the latter could be changed from a setting suitable for driving on the left to a setting suitable for driving on the right. An object of the present invention is to satisfy this need. 
     Thus the present invention aims to provide a headlight which first of all has a reflective surface which is adapted to generate, according to the position of the lamp, a dipped beam for driving on the left and a dipped beam for driving on the right, and which also includes means, of particularly simple, inexpensive and reliable construction, for the purpose of ensuring suitable positioning of the lamp in its orientation corresponding to the required driving mode, i.e. on the right or left hand side of the road. 
     According to the invention, a motor vehicle headlight comprising a reflector and a lamp mounted in the said reflector is characterised in that the reflector has a reflective surface adapted to generate selectively two types of dipped beam, for driving on the left and driving on the right respectively, the reflector cooperating with a lamp occupying in a corresponding manner one of two given angular positions, in that the reflector carries a support member which is able to rotate with respect to the said reflector and on which the said lamp is mounted fixedly, and in that actuating means are provided for manually rotating the support member to one or the other of two working positions, each working position corresponding to a given one of the said angular positions of the lamp, together with locating means for locating the assembly that consists of the support member and the lamp on the one hand, and a fixed part of the headlight on the other hand, whereby to ensure stability of the position of the support member in each of the said working positions. 
     The support member preferably has a generally circular form and is guided in rotation by arrangements provided at the rear of the reflector. 
     Preferably, the headlight includes a single locking device, firstly for securing the lamp fixedly on the support member, and secondly for providing axial retention of the support member with respect to the reflector. The said locking means preferably consists of an elastic hairpin fastener or spring clip, in engagement against smooth zones of the cap of the lamp. 
     The actuating means for the support member preferably include a link which is articulated on the support member. 
     Preferably, the actuating means further include an articulated lever, pivoted on the said link and adapted to displace the said link. 
     The actuating means may comprise a screw-and-nut assembly, one of the elements (screw or nut) of which is fixed to the said link for straight line or axial movement with the said link. In that case, one of the elements comprising the screw or nut is preferably formed on a housing of the headlight. 
     Preferably, the above mentioned locating means comprise at least one finger fixed to the reflector and biased resiliently towards a notch defined on the lamp cap. There is preferably more than one of these locating fingers, and preferably, each locating finger has a rounded end, with the said notch having a width smaller than the width of each finger. 
     The locating means may consist of the screw and nut assembly, the end of travel positions of which are determined in such a way as to correspond to the two working positions of the support member. 
     The cooperation between threads of the screw and nut assembly preferably has substantially no axial clearance, and a predetermined minimal coefficient of friction. 
     Preferably, the lamp is a discharge lamp equipped with masking means. Alternatively, the lamp may be a lamp comprising at least one incandescent filament equipped with a mask of the cup type. 
     Further features and advantages of the invention will appear more clearly on a reading of the following detailed description of some preferred embodiments of the invention, which are given by way of non-limiting example only and with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 a  is a diagrammatic back view of an assembly consisting of a reflector and a lamp in a first position with respect to each other, which represents a headlight setting such that a dipped beam is obtained which is suitable for driving on the right hand side of the road. 
     FIG. 1 b  is a diagrammatic back view of the same reflector and the same lamp, in a second mutual position that represents another headlight setting, which is suitable for giving a dipped beam for traveling on the left hand side of the road. 
     FIGS. 2 a  and  2   b  are sets of isolux curves, showing the appearance of the dipped beams which are produced, by the reflector and lamp assembly in the settings shown in FIG. 1 a  and FIG. 1 b  respectively, the effect of the closure lens of the headlight being ignored. 
     FIG. 3 is a more detailed back view of a preferred embodiment of the reflector of FIGS. 1 a  and  1   b.    
     FIG. 4 is a partial back view, on an enlarged scale, of the reflector and lamp assembly of FIGS. 1 a  and  1   b.    
     FIG. 5 is a side view in elevation of an occulting member, or mask, with which the reflector and lamp assembly of FIGS. 1 a ,  1   b  and  4  is equipped. 
     FIGS. 6 a  and  6   b  are back views showing a first embodiment of a means which enable the lamp to be put selectively into the two working positions, or settings, of the headlight in accordance with the invention, in which it produces a beam for use when driving on the right and a beam for driving on the left, respectively. 
     FIGS. 7 a  and  7   b  are two detail views of means for stabilizing the position of the lamp in each of the two working positions corresponding to FIGS. 6 a  and  6   b  respectively. 
     FIGS. 8 a  and  8   b  are back views of a second version of the above mentioned means in accordance with the invention. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION 
     Reference is first made to FIGS. 1 a ,  1   b ,  3  and  4 , which show an assembly consisting of a lamp  10  and a reflector  20  in a dipped beam headlight for a motor vehicle. In particular this assembly may comprise a discharge lamp  10  and a reflector  20 . With reference especially to FIG. 4, the lamp  10  comprises, in the usual way, a generally cylindrical first bulb  11  having at the level of the arc, S, a boss which is surrounded by a cylindrical second bulb  12 . Two opaque longitudinal bands,  13  and  14  respectively, are formed on the second bulb  12 . The purpose of these bands  13  and  14  is to mask certain zones  21 - 24  of the reflector from the light source, in order to prevent the reflector  20 , which has interruptions between surfaces in the said zones  21 - 24  from being able to give off any parasitic radiation above the required cut-off line. 
     Also provided, in association with the lamp, is a mask, or occulter of direct light,  15 . This has a front masking portion  16 , which is fixed to the base region of the reflector and is preferably fixed directly to the support of the lamp by means of two opaque longitudinal lugs  17  and  18 . The width of these lugs  17  and  18 , and their position in relation to the lamp  10 , are carefully determined in such a way that the lugs  17  and  18  also constitute masking bands which cooperate with the masking bands  13  and  14  of the second bulb  12  in a manner which will be described later on herein. 
     The reflector  20  in this example comprises four zones, namely a lower zone  21 , an upper zone  22 , and two side zones  23  and  24 . These zones are separated from each other by transition planes denoted P 13 , P 14  and P 23 , P 24  respectively, which pass close to, or preferably through, the optical axis of the reflector  20 . 
     The lower zone  21  of the reflector  20  is designed to produce from the light source  10  a part of the beam which is very much spread widthwise, and is also very homogeneous and bounded at the top by a generally horizontal cut-off line. To this end, the lower zone  21  preferably consists of individual striations S 21  (FIG.  3 ), which are so designed that firstly they spread the light laterally, and secondly they redirect all of the images from the light source  10  in such a way that their highest regions are essentially aligned with the above mentioned cut-off line. 
     The striations S 21  are for example formed of surfaces which are auto-generatrices of a beam with horizontal cut-off, such as are described in particular in French patent publication FR 2 536 503A. In such surfaces, the horizontal generatrices, which may or may not be parabolic, are chosen to be different from each other in such a way that they intersect, in particular along curved lines as shown, with a slight bend. These horizontal generatrices are also so chosen as to give the required horizontal distribution to the beam. 
     It will be noted here that the surface in the lower reflector zone  21  is constructed not according to the position of the main light source which consists of the arcs of the lamp  10  (see FIG.  4 ), but instead, and with advantage, as a function of the position of the secondary light source S′ which consists of an accumulation of salts in the bulb  11  of the lamp  10 , essentially below the arcs. This is illustrated in particular in FIG.  4 . 
     The upper zone  22  of the reflector is preferably constructed in the same way as the lower zone  21 , with striations S 22  which are adapted for spreading the light below a horizontal cut-off line, with, again, a high degree of homogeneity. However, as far as the upper zone  22  is concerned, the various striations S 22  are constructed as a function of the position of the main light source, which consists of the arcs of the lamp  10 . 
     As to the side or lateral zones  23  and  24  of the reflector  20 , these lie on either side of the lamp  10 , and are so designed that, according to the angular position of the lamp  10 , and therefore according to the angular position of its masking bands  13  and  14  with relation to the reflector  20 , the side zones  23  and  24  complete the beam produced by the lower zone  21  and the upper zone  22 , so as selectively to raise the cut-off line, either on the left for driving on the left, or on the right for driving on the right. 
     The side zones  23  and  24  are formed symmetrically with respect to the vertical axial plane of the reflector  20 , and therefore only one of the zones (in this case the zone  23 ) need to be described here in any detail. This zone  23  is divided into two sub-zones  231  and  232  respectively, with the first zone  231  being adjacent to the lamp  10 , while the second sub-zone  232  extends between the first and second side edges of the reflector  20 . 
     The sub-zone  231  preferably consists of a reflective surface such as is described in French patent publication No. FR 2 609 146A, in the name of the Company Valeo Vision. Such a reflective surface has the property that it can behave, in cooperation with a mask which limits the angular field of radiation from the source as a paraboloid of revolution, while at the same time spreading the light below the cut-off line, whether the latter be horizontal or inclined. The light source is of the filament type in front of a normalised “H4” lamp. If any further details of such a surface are required, reference should be made to the above mentioned French patent specification. Preferably, a surface is chosen which gives convergence of the radiation, although this convergence is adjusted in such a way that the mask  15  of the lamp does not intercept an excessive quantity of light. 
     The sub-zone  232  of the reflector side region  23  consists of a base surface in the form of a paraboloid of revolution, on which there are projected striations S 232   b  and S 232   h  for spreading the light along the cut-off line. Such projected striations are described in the literature, in particular in French patent publication No. FR 2 710 393A in the name of the Company Valeo Vision. 
     Preferably, and with particular reference to FIG. 3, these striations comprise upper striations S 232   h  which extend vertically above the horizontal axial plane of the reflector, together with lower striations S 232   b  which extend below the same horizontal axial plane, and which are inclined to the vertical by an angle γ, which is preferably equal to about 15°. With this arrangement, the upper striations S 232   h  are adapted to spread the light horizontally, while the lower striations S 232   b  are adapted to spread the light in an inclination of 15° approximately with respect to the horizontal. 
     It will be noted here that the dimensioning of the side sub-zone  231  and that of the striations in the sub-zone  232  is such that these surfaces provide lateral spreading of the light to a substantially smaller degree than the zones  21  and  22  described earlier herein. 
     As has already been said, the other side or lateral zone  24  is made symmetrical with the zone  23 , and has two sub-zones  241  and  242  with respective striations S 242   h  and S 242   b.    
     With particular reference to FIG. 4, in preferred arrangements the half planes of separation between the various zones  21 - 24  of the reflector  20  are inclined to each other as follows. Each of the transition planes, or half planes, P 13  and P 14  is inclined through an angle β of 28° below the horizontal. Each of the half planes P 23  and P 24  is inclined above the horizontal by an angle α of 25°. 
     The arrangement of the lamp  10  and its various masking bands  13 ,  14  will now be described, still with reference in particular to FIG.  4 . In a manner which is conventional per se, the lamp  10  includes the two opaque longitudinal bands  13  and  14  on its outer bulb  12 . In the position shown, which corresponds to a beam suitable for driving on the left, the masking band  13 , situated on the left, has its upper edge contained in the vertical plane which passes through the base of the arc of light, while the other band  14  has its upper edge contained in a plane which passes through the base of the arc and is inclined at 15° downwards. 
     These two upper edges perform a function which is similar to that of the two opposed edges of a masking cap for a normalised “H4” filament lamp. 
     From their upper edge, the two masking bands  13  and  14  extend downwards over an angular gap of about 25° about the axis of the cylindrical second bulb  12 , and are thus disposed symmetrically with respect to a plane of symmetry PS which is inclined by 7.5° with respect to the vertical axial plane. 
     As to the two masking lugs  17  and  18 , the angular extent of these is such as to place them, in relation to that of the bands  13  and  14 , in the following way. Still considering the attitude shown in FIG. 4, each masking lug  17  and  18  has an upper edge which is so situated that it does not mask any radiation from the arc passing above the upper edge of the associated band  13  or  14 , so as to leave the arc and these upper edges to define the required half cut-off lines. In addition, the masking lugs  17  has a lower edge such that no radiation emitted from the lamp, and in particular from the region S′ of its salts, is able to reach the lateral zone  23  of the reflector. 
     The upper edge of the lugs  17  and  18  and the lower edge of the lug  17  having been defined as above, the lugs  17  and  18  are dimensioned in such a way that they are symmetrical with respect to the plane of symmetry PS. In this way, when the lamp  10  occupies a position which is offset angularly by 15°, so as to produce a beam suitable for use when driving on the right, the lower edge of the masking lug  18  will perform the same masking function that the lower edge of the masking lug  17  performed in the case described above. 
     It will be understood that the lamp  10 , with its mask  15 , may be mounted within the reflector  20  in such a way that they can assume either one of two stable orientations, the first being the one shown in FIG. 1 a,  and the other being the one shown in FIGS. 1 b  and  4 . 
     Reference will now be made in particular to FIGS. 6 a  and  6   b,  to describe the means which enable the position of the assembly consisting of the lamp and mask to be varied between the two angular positions corresponding to two modes of emission of the headlight, and to ensure stability of this assembly in each of those two positions. 
     FIGS. 6 a  and  6   b  are two representations showing a first embodiment of these positioning and stabilising means. FIG. 6 a  shows the position in which the headlight produces a beam suitable for driving on the right, while in FIG. 6 b,  the headlight is set for driving on the left. These FIGS. 6 a  and  6   b  also show the outline of the reflector  20 . The positioning and stabilising means are mounted in the base of the reflector  20 . 
     With reference firstly to FIG. 6 a,  a generally circular support member  30  is mounted for pivoting movement about the optical axis of the headlight, concentrically with a lamp hole in which the lamp  10  and its mask  15  (which are not shown in this Figure) can be mounted. The lamp  10  and its mask  15  are arranged to be fixed on the support member  30  in a reference position which is defined in the axial and transverse directions and angularly. The broken line  31  shows the outline of the trap for giving access to the lamp. 
     A lug  32  is fixed to the support member  30  and projects radially outwards from the perimeter of the support member  30 , extending substantially horizontally in the configuration shown in FIG. 6 a.    
     The lower end of a vertical link  34  is articulated on a pivot pin  320  which is formed in the free end region of the lug  32 . The upper end of the link  34  is pivoted on a central point of a control arm  35 , one end of which (that is to say the one on the left in the Figures) is articulated on a pivot pin  320  fixed to the reflector  20 . The other end of the link  34  constitutes a working region which is accessible to the finger of the user through the lamp access trap  31 . 
     The movements of the support member  30  and its lug  32 , together with those of the link  34  and the arm  35 , all take place in a plane which is transverse to the optical axis of the reflector  20 . 
     A crown  36  is arranged concentrically around the pivoted support member  30 , The crown  36  consists for example of a rear collar portion which is formed integrally on the reflector  20  by moulding. 
     A conventional spring steel clip  37  of the hairpin type is articulated on the rear of the reflector  20 , and can be locked in order to retain in the axial direction, firstly the lamp  10  on the support member  30 , and secondly the support member  30  on an engagement surface which is formed on the rear of the reflector and which is bounded by the crown  36 . This fastening, which holds the lamp  10  against any rotation with respect to the support member  30  (by means of suitable conventional angular indexing means), does not however prevent rotational movement of the support member  30  about the optical axis of the reflector. This rotational movement is also guided by the crown  36 . The freedom of the support member  30  to be rotated is for example ensured by engaging the curved bearing zones of the spring clip  37  against the smooth zones of the collar portion of the lamp  10 . The spring clip  37  ensures that the lamp  10  can be easily removed for replacement. 
     As can be seen best in FIG. 7 a , the lamp has a collar portion or lamp cap, which includes, in a clearly defined angular position, a substantially hemispherical notch  300  of a given diameter which is open on the outer periphery of the lamp cap facing towards the crown  36 . As to the crown  36  itself, this has two respective blind holes  361  and  362  which are spaced apart by a predetermined angle, in this example 15°, and which are open radially inwardly on the lamp  10 . 
     Movable locating fingers  3610  and  3620 , mounted in the blind holes  361  and  362  respectively, are biased radially against the periphery of the lamp by means of springs  3611  and  3621  respectively, these spring being compressed between the base of the respective blind holes  361  and  362  and an internal engagement face of the associated finger. The fingers  3620  and  3610  have substantially hemispherical free ends and a diameter which is slightly greater than that of the notch  300 . 
     When the notch  300  in the lamp cap is aligned with one of the two fingers  3610  or  3620 , the spring  3611  or  3621  associated with that finger is then in partial engagement with the rounded end of that finger in the notch. This cooperation of the finger with the notch  300  of the lamp accordingly ensures stability of the lamp and of the support member  30  to which it is fixed, in the required angular position. 
     On the other hand, the fact that the fingers are not able to be engaged totally in the notch  300  enables the lamp and the support member  30  to be released easily by exertion of no more than a reasonable amount of effort to act on the linkage described above which includes the link  34 . 
     The stiffness of the springs  3611  and  3621  is, in this connection, quite large, so that, in the absence of any force exerted from the link  34 , the support member can be retained reliably in its position despite, in particular, vibrations arising from operation of the vehicle. At the same time, the stiffness of these springs is low enough to enable the position of the support member  30  to be changed quite easily. 
     The two fingers  3610  and  3620 , which are spaced apart by 15° on the periphery of the crown  36 , define the two working positions of the lamp  10  and therefore the two headlight settings, so that the headlight can selectively give a dipped beam for driving on the left and a dipped beam for driving on the right, respectively. In another version, it is of course possible to provide a single finger which is then able to cooperate with two notches  300 . 
     The operator displaces the lamp  10  towards one or the other of these two reference or working positions by maneuvering the control arm  35  using his (or her) finger inserted through the lamp access trap  31 . In particular, by lifting the free end of the control arm  35  from the position of the latter shown in FIG. 6 a,  this arm raises the link  34  and the lug  35 , and this causes the support member  30 , and therefore the lamp  10 , to be rotated to the other stable position. 
     It will be appreciated that FIG. 6 b  and FIG. 7 b  are views similar to those in FIGS. 6 a  and  7   a,  but that they show the support member  30  in its second position corresponding to driving on the left. 
     Conversely, by pushing the control arm  35  downwards, the support member  30  is put into the position shown in FIGS. 6 a  and  7   a.    
     Reference is now made to FIGS. 8 a  and  8   b,  which show a second version of an arrangement according to the invention. In these Figures, the support member  30  and its lug  32  are substantially identical to those in FIGS. 6 a  and  6   b.  However, the means for displacing and locating the support member  30  are different. In FIGS. 8 a  and  8   b,  those elements or parts which are identical or similar to those in FIGS. 6 a  and  6   b  are designated by the same reference signs. 
     In this second embodiment, the displacement of the lug  32  is provided by a link  41  which is articulated on the lug  32  at the lower end of the link  41 . The link  41  is fixed at its upper end to a screw  40  for axial movement with the latter. The link  41  is mounted for free rotation on the screw  40 , but coupled to the latter for straight line movement with it, by any known type of mating coupling, such as a ball joint (not shown). 
     The screw  40  is in cooperation with a nut  42  which is formed for example in the top wall of the headlamp housing (not shown), and has a maneuvering portion  401  which is situated on the outside of the headlamp housing. Manual rotation of the screw  40 , by means of its maneuvering portion  401 , enables the support member  30  to be put selectively into either one of two reference positions, which in this example are preferably determined by the end of travel of the screw action of the screw  40  in its nut  42 , resulting from appropriate design of these elements. 
     Stability of the support member  30  and lamp  10  in each of the reference positions is also ensured by appropriate design of the screw  40  and nut  42 , by minimizing the axial clearances of the threads and ensuring at the same time a sufficiently high coefficient of friction to avoid, especially having regard to vibrations in operation of the vehicle, any unwanted relative rotation between the screw and the nut. 
     One advantage of this second embodiment of the invention lies in the fact that changing the position of the lamp can be carried out directly from outside the headlamp housing, without having to open the lamp access trap. In this connection, the first embodiment described earlier can easily be adapted so that maneuvering can in that case also be carried out from outside the housing. 
     As has been indicated above, the present invention is applicable to a headlight with a discharge lamp, in particular of the type described herein. However, it can also be applied to a headlight which is equipped with a lamp having a filament cooperating with a mask of the cup type, such as a lamp of the “H4” normalized type, cooperating either with a parabolic reflector or with a reflector having surfaces which are specifically designed to give rise to dipped beams for traffic on the left and for traffic on the right according to the position of the mask.