FR2761026A1 - Dual-beam motor vehicle headlamp with single source and reflector - Google Patents

Abstract

The headlamp has a single light source (11), a single reflector (20) and a front glass (30). In addition the lamp has a reflective element (50) that selectively presents an active state in front of the light source to deliver the light received in an essentially lateral direction. The reflector has a central zone (201) always exposed to the direct illumination from the source, and a lateral zone (202,203) exposed to the light returned by the reflector when the reflector is in its active state. The reflector is a prism, a prism combined with a lens, or a mirror. The reflector is tilted and part occluded to switch between high and low beam.

Description

 The present invention relates generally to motor vehicle headlamps.

 It relates more particularly to a projector comprising a single light source and a single reflector, while being capable of generating at least two different light beams.

 Many solutions are already known for varying the beam emitted from a single source / reflector assembly.

 A first solution, applicable in elliptical type projectors with image projection, consists in using a movable cover, or even a cover of fariable profile, to vary the shape and / or the size of the light spot projected on the road. . Numerous prior art documents illustrate such projectors.

 However, this solution suffers from the drawback of being applicable only to projectors of the elliptical type, without being able to be transposed to projectors of the parabolic type.

 Some solutions also exist in the context of a parabolic type projector, that is to say the beam of which is obtained after a single reflection on the reflector, and possibly adjusted using refractive elements on the ice.

 Thus the document FR-A-2 009 672 describes a headlamp in which mechanical switching means cause the reflector to tilt, to generate a passing beam or a raised beam, of driving beam.

 Furthermore, document DE-A-44 35 507 describes a projector in which, the reflector being fixed, the lamp is tilted so as to be able, by moving the filament of this lamp, to generate two different beams.

 However, none of the solutions which call for a controlled displacement of the reflector and / or of the lamp are entirely satisfactory. Indeed, if the height of the beam will be able to be adjusted in this way, there is in this case no total control of the photometry of the beams. Thus it is easy to optimize the reflector for a first type of beam, but in this case the second type of beam is generally far from satisfactory.

 Furthermore, if the lamp and the conserving reflector were moved, two beams emitted in different general directions would be obtained, but both having substantially the same contours and the same light distribution, which is generally not satisfactory, for, for example, the shape of a passing beam, in particular with a “V” cut, and the shape of a driving beam, without cut, are very different from each other.

 Furthermore, another known solution, as illustrated for example by DE-A-44 19 365, consists in varying the geometry of the reflective surface of the reflector, either mechanically or by an electrochromic screen, so as to vary selectively beam photometry.

 These solutions are however complex and imprecise in the case of mechanical displacement, and costly in the case of bringing into play a phenomenon of selective light transmission by electrochromic screen.

 Finally, document FR-A-2 699 259 discloses a projector of the parabolic type comprising, in addition to the source, the reflector and the lens, a set of mobile dioptres intended, when they are selectively brought to the right of the source, to alter the path of the rays emitted towards the reflector, to modify the beam generated.

 This known solution is however tricky to implement in the context of a headlamp / dipped beam, because the transformation of a beam cut into a suitable beam of road, without cutting, by the simple interposition of diopters is far from being obvious.

 In addition, such a known headlight, when passing from the passing beam to the driving beam, gives substantially no additional light, so that the visual comfort expected by the driver when switching to road lighting is not entirely satisfied .

 The present invention aims to overcome these limitations of the state of the art and to provide a projector of the aforementioned type which, by simple and economical means, based on the selective displacement of optically active elements, can easily generate a beam at cut-off and an uncut beam, of the road type, both of satisfactory photometry, with in particular a significant increase in light in the road position.

 Thus the present invention provides a motor vehicle headlamp, comprising a single light source, a single reflector with respect to which the source is fixed, and a lens, characterized in that it further comprises at least one reflecting element capable of selectively presenting an active state in front of the source for returning the radiation received from the latter in an essentially lateral direction, and in that the reflector comprises a central area always exposed to direct radiation from the source, and at least one lateral area exposed to the radiation returned by the source 'reflective element at least provided when the latter is in its active state, to complete the beam generated by said central area.

Preferred, but not limiting, aspects of the projector according to the invention are as follows
- The reflecting element is constituted for example by a prism, a prism combined with a lens or a. .

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 - Two reflective elements are provided in correspondence with two opposite lateral zones of the reflector.

 - the two reflecting elements share a common lens and define a one-piece assembly.

 - The projector comprises means for moving the reflecting element at least provided between a position located in front of the lamp, corresponding to its active state, and a position remote from the lamp, corresponding to an inactive state.

 - Alternatively, the projector further comprises a blackout, the reflective element at least provided being fixed and interposed between the source and the blackout, and there is further provided means for moving the blackout between an advanced position, in which the at least one reflecting element is released to be in its active state, and a retracted position, in which the at least one reflecting element is covered by said screen to be in an inactive state.

 - The concealer comprises at least one side wall capable of intercepting the radiation at the outlet of the reflecting element at least provided in the retracted position of said concealer.

 - Said side wall extends towards the bottom of the reflector to a distance such that it also obscures direct radiation from the source to the corresponding lateral zone of the reflector.

 - The central zone of the reflector is able to generate a cut-off beam, and the lateral zone (s) in cooperation with the reflective element (s) are capable of completing the cut-off beam to form an uncut beam.

Other aspects, aims and advantages of the present invention will appear better on reading the following detailed description of a preferred embodiment thereof, given by way of example and made with reference to the appended drawing, in which
FIG. 1a is a schematic view in axial horizontal section of a headlight according to a first embodiment of the invention, in a first state,
FIG. 1B is a view similar to FIG. 1a, of the projector in a second state,
FIG. 2 is a partial view in axial horizontal section of a reflecting element according to an embodiment of the invention,
FIG. 3 is a partial view in axial horizontal section of a reflecting element according to another embodiment of the invention, corresponding to the case of FIGS. 1a and 1b,
FIG. 4 is a partial view in axial horizontal section of a reflecting element according to another embodiment of the invention, and
Figures Sa and 5b are partial side views of a projector according to another embodiment of the invention, in two different states.

 Referring firstly to FIGS. 1a and 1b, a headlamp has been shown which comprises a light source 11, a reflective reflector 20, a lens 30, for example mounted on a front opening of a housing (not shown), and a concealer 40 forming a kind of bell covering the front end of the lamp.

 The source 11 can for example be the single filament of an incandescent lamp 10, or even the arc of a discharge lamp.

 Between the lamp 10 and the shield 40 is interposed an optical element 50 intended to reflect the incident radiation from the source 11 towards certain well-defined zones of the reflector 20.

 In this case, this optical element is constituted by two prisms 501, 502 made of glass or the like, the sections of which are in the form of right isosceles triangles, oriented so as to return the light coming from the filament 11, by internal reflection on their large face, respectively towards two lateral zones 202, 203 of the reflector.

 In the present example, the large faces of the prisms are oriented in vertical planes inclined at 450 on either side of the optical axis of the projector, but it is understood that other orientations can be adopted, in particular for modifying the position of the areas of the reflector covered by the radiation returned by the prisms.

 Furthermore, the shield 40 can be moved in translation, by appropriate means such as an electromagnetic actuator, along the optical axis between two positions illustrated in FIGS. 1a and 1b.

 The first position, illustrated in FIG. 1 a, is an advanced position in which the optical element 50 is released from the occultor 40, which allows the radiation to reach the areas 202, 203 of the reflector after having passed through the prisms, as described above.

 The second position is a retracted position in which the shield 40 covers the optical element 50, so as to prevent the light leaving the prisms 501, 502 from reaching the reflector 20.

 Of course, the cross section of the shield 40 is chosen slightly larger than the cross section of the assembly of the optical element 50. In addition, its side walls 401, 402 define two rear edges 403, 404 positioned in such a way so that these side walls obscure, in this remote position, the zones 202 and 203 of the reflector.

 We will now describe the optical behavior of the headlamp as described above, in the specific case of a dipped / main beam headlamp.

 First of all, it will be noted that the reflecting surface of the central zone 201 of the reflector is preferably a surface capable of cooperating with a bare source, that is to say one devoid of a concealment cup, to generate by itself a dipped beam, for example a European V-shaped dipped beam. Numerous previous patent publications, in the name of the Applicant, describe such surfaces in detail. it is moreover preferably a surface capable of emitting such a beam with a substantial width, so that the glass 30 can be smooth or slightly deflecting.

In this way, when the shield 40 occupies the position illustrated in FIG. 1b, the projector emits, by cooperation of the source 11 with the only central zone 201 of the reflector, a passing beam
In addition, the two lateral zones 202, 203 of the reflector preferably comprise surfaces constituted by parts of paraboloids of revolution, the focal points of which are located in the vicinity of the images of the source 11 created by the oblique faces of the two prisms, respectively 501 and 502, and whose axes are parallel to the axis xx of the central area 201.

 In this way, when the shield 40 is brought into its advanced position, the central zone 201 of the reflector projects the light as described above and, in addition, the lateral zones 202, 203 are exposed to the radiation of the source deflected by the prisms. respective. The beam obtained therefore results from the superimposition of the aforementioned passing beam and a "pointed" beam, that is to say having a high intensity concentrated in the axis of the road, generated by the zones 202 and 203.

 Overall, this results in a beam which is entirely suitable for the road function.

 Of course, by playing on the shape and dimensions of the optical element 50, the blackout 40 and the reflector 20, one can easily modify the amount of light added to the beam in the position of FIG.

 FIGS. 2 to 5 illustrate three possible embodiments for the optical element 50.

 In the case of FIG. 2, the prisms 501, 502 of FIGS. 1a, 1b are replaced by two plane mirrors 511, 512 oriented respectively for example at 450 on either side of the optical axis x-x.

 This solution has the advantage of minimizing the loss of light at the level of the optical element. On the other hand, the solid angle covered by the two plane mirrors with respect to the source, a solid angle whose horizontal component is designated by a, remains relatively reduced for a given width of the optical element and for a given distance of l optical element 50 at source 11.

 The solution illustrated in Figure 3 corresponds to that of Figures la and lb. Thanks to a certain degree of refraction on the entry faces of the two prisms 501, 502, the solid angle of useful light intercepted by the optical element, the horizontal component of which is designated by a ′, is greater.

 FIG. 4 illustrates another embodiment of the optical element 50, the latter being obtained by taking as starting point two prisms similar to those of FIG. 3, to which a lens has been juxtaposed at the level of the entry face plano-convex to form a one-piece optical element.

 Thus, the optical element 50 of FIG. 4 comprises a common convex entry face 521, of axis coinciding with x-x, two oblique faces 522, 523 for returning light, and two lateral faces 524, 525 for light exit.

 Thanks to this embodiment, the optical convergence created by the input face 521 makes it possible to increase the solid angle of the useful light cone intercepted by the element 50, the horizontal component of which is noted a ".

 It will further be observed that, from FIG. 2 to FIG. 4, the opening, in a horizontal plane, of the beams of light reflected by the two parts of the optical element is progressively smaller. Thus, the choice of a particular optical element can be made in conjunction with the extent which it is desired to give to the lateral zones 202, 203 of the reflector, which itself determines, with other parameters, the intensity of the beam portion added in the disengaged position of the optical element.

Furthermore, and now with reference to the figures
Sa and 5b, an alternative embodiment of the invention is shown in which the optical element 50 can selectively occupy an active position, in line with the lamp 10, in which it deflects the radiation received from the source 11 towards the zones 202, 203 of the reflector 20 (see FIG. 5a), and an inactive position, raised for example above the upper cheek of the reflector 20.

 It will be observed that, in this case, the lateral zones 202, 203 of the reflector remain permanently exposed to direct radiation from the source 11, the interposition of the optical element 50 in line with the source then complementing the light flux at which these zones are exposed, to modify the photometry of the beam.

 Furthermore, the projector of FIGS. 5a and 5b advantageously comprises, in a manner not illustrated, a cache of direct light interposed in front of the lamp 10, and the optical element, in the active position, comes to be inserted between the lamp and this streak. direct light.

 Of course, the present invention is in no way limited to the embodiment described above and shown in the drawing, but a person skilled in the art will know how to make any variant or modification in accordance with his spirit.

 In particular, it is understood that a headlight according to the invention can be easily adapted to emit different types of beam, and in particular an anti-fog beam and a driving beam, a wide driving beam and such a beam supplemented by long range, etc ...

Claims (11)

 1. Motor vehicle headlamp, comprising a single light source (11), a single reflector (20) relative to which the source is fixed, and a lens (30), characterized in that it further comprises at least one element reflective (50) capable of selectively presenting an active state in front of the source to return the radiation received from the latter in an essentially lateral direction, and in that the reflector comprises a central zone (201) always exposed to direct radiation from the source, and at least one lateral zone (202, 203) exposed to the radiation returned by the reflecting element at least provided when the latter is in its active state, to complete the beam generated by said central zone.  2. Projector according to claim 1, characterized in that the reflecting element is constituted by a prism (501; 502).  3. Projector according to claim 2, characterized in that the reflecting element consists of a prism combined with a lens (521).  4. Projector according to claim 1, characterized in that the reflecting element is constituted by a mirror (511; 512).  5. Projector according to one of claims 1 to 4, characterized in that two reflective elements (501, 502; 511, 512) are provided in correspondence with two opposite lateral zones (202, 203) of the reflector.  6. Projector according to claims 3 and 5 taken in combination, characterized in that the two reflecting elements share a common lens (521) and define a monobloc assembly (50).  7. Projector according to one of claims 1 to 6, characterized in that it comprises means for moving the reflecting element at least provided between a position located in front of the lamp, corresponding to its active state (fig. 5a), and a position remote from the lamp, corresponding to an inactive state (fig. 5b).  8. Projector according to one of claims 1 to 6, characterized in that it further comprises a concealer (40), in that the reflecting element at least provided (50) is fixed and interposed between the source (11) and the screen, and in that means are further provided for moving the screen between an advanced position, in which the reflective element at least provided is released to be in its active state, and a retracted position, in which the at least one reflecting element is covered by said concealer to be in an inactive state.  9. Projector according to claim 8, characterized in that the screen (40) comprises at least one side wall (401; 402) capable of intercepting the radiation at the outlet of the reflecting element at least provided in the retracted position of said screen .  10. Projector according to claim 9, characterized in that said side wall (401; 402) extends towards the bottom of the reflector up to a distance such that it also obscures direct radiation from the source (11) towards the corresponding side zone (202, 203) of the reflector.  11. Projector according to one of claims 1 to 10, characterized in that the central zone (201) of the reflector is capable of generating a cut-off beam, and in that the lateral zone or zones (202, 203) in cooperation with the reflective element (s) (501, 502; 511, 512) are able to complete the cut-off beam to form an uncut beam.