EP1139011B1 - Space saving infrared projection type motor vehicle headlamp - Google Patents

Description

The present invention relates to motor vehicle headlamps of type comprising a filter opaque to visible radiation but transparent to infrared.

Document FR-A-2 756 237 discloses such projectors which are furthermore arranged to allow the filter to move between an active position and a retracted position. These projectors have a large surface on the front face.

The object of the present invention is to solve this drawback, that is to say to propose a projector having such a mobile infrared filter but which has a small surface on the front face.

This object is achieved according to the invention by means of a motor vehicle headlamp comprising a light source, a reflector with two focal regions, the source being placed in one of the two focal regions so as to produce a reflected light spot in the another focal region, and a filter opaque to visible radiation and transparent to infrared radiation, movable between a position away from the reflected reflector light and a position where it is traversed by a substantial portion of the light reflected by the reflector to the lens, characterized in that it comprises a lens designed to transform the task of reflected light into a beam projected onto the road, the lens being placed in front of the reflector.

• il inclut une pièce de maintien du filtre adaptée pour se déformer sous l'effet de dilatations thermiques du filtre ;
• la source est placée dans la région focale interne du réflecteur et le filtre est placé en aval de la tâche de lumière réfléchie ;
• les moyens de maintien du filtre sont prévus pour autoriser un déplacement de ce dernier jusqu'à une position où il se trouve substantiellement dans une zone d'ombre correspondant à l'image optique d'un trou de lampe du réflecteur ;
• les moyens de maintien du filtre sont prévus pour autoriser un déplacement de ce dernier jusqu'à une position où il s'étend par sa surface le long d'une bordure du flux de lumière ;
• les moyens de maintien sont constitués par des moyens de rotation du filtre ;
• les moyens de rotation comprennent un pivot dont l'axe est situé en aval de la position active du filtre par rapport à la direction de propagation de la lumière ;
• le filtre présente, dans sa position active, un emplacement et une étendue choisis pour laisser passer un rayonnement allant du réflecteur à la lentille sans traverser le filtre ;
• la lentille est munie de zones prévues pour désorganiser un flux de lumière, ces zones étant placées sur le trajet des rayons circulant du réflecteur à la lentille sans traverser le filtre ;
• les zones prévues pour désorganiser les rayons forment des régions annulaires sur la lentille.

According to advantageous, but not limiting, provisions:

• it includes a filter holding piece adapted to deform under the effect of thermal expansion of the filter;
• the source is placed in the internal focal region of the reflector and the filter is placed downstream of the reflected light spot;
• the filter holding means are provided to allow a displacement of the filter to a position where it is substantially in a shadow zone corresponding to the optical image of a lamp hole of the reflector;
• the filter holding means are provided to allow a displacement of the latter to a position where it extends by its surface along a border of the light flow;
• the holding means are constituted by filter rotation means;
• the rotation means comprise a pivot whose axis is located downstream of the active position of the filter relative to the direction of propagation of the light;
• the filter has, in its active position, a location and an extent chosen to allow radiation passing from the reflector to the lens without passing through the filter;
• the lens is provided with zones intended to disorganize a light flux, these zones being placed in the path of the rays flowing from the reflector to the lens without passing through the filter;
• the zones provided for disorganizing the rays form annular regions on the lens.

• la figure 1 est une coupe verticale d'un projecteur selon l'invention où le filtre est en position active ;
• la figure 2 est une coupe verticale du même projecteur où le filtre est en position escamotée ;
• la figure 3 est une coupe verticale d'un projecteur selon l'invention dans lequel le filtre est monté à translation horizontale transversale au rayonnement ;
• la figure 4 est une coupe verticale d'un projecteur selon l'invention dans lequel le filtre est monté à translation horizontale parallèle au rayonnement ;
• la figure 5 est une coupe verticale d'un projecteur selon l'invention dans lequel le filtre est monté à rotation autour d'un axe horizontal parallèle à la direction du rayonnement ;
• a figure 6 est une coupe verticale d'un projecteur selon l'invention dans lequel le filtre est monté à rotation autour d'un axe vertical transversal à la direction du rayonnement ;
• la figure 7 est une coupe verticale d'un projecteur selon l'invention dans lequel l'axe est placé de telle façon que le filtre borde le trajet interne de la lumière lorsqu'il est escamoté ;
• la figure 8 est une coupe verticale d'un projecteur selon l'invention dans lequel le filtre est monté à rotation autour d'un axe horizontal transversal à la direction du rayonnement ;
• la figure 9 est une coupe verticale d'un projecteur selon l'invention comportant une lentille apte à diffuser des rayons ayant circulé du réflecteur à la lentille sans traverser le filtre activé.

Other characteristics, objects and advantages of the invention will appear on reading the detailed description which follows, made with reference to the appended figures in which:

• Figure 1 is a vertical section of a projector according to the invention wherein the filter is in the active position;
• Figure 2 is a vertical section of the same projector where the filter is in the retracted position;
• Figure 3 is a vertical section of a projector according to the invention wherein the filter is mounted in horizontal translation transverse radiation;
• Figure 4 is a vertical section of a projector according to the invention wherein the filter is mounted in horizontal translation parallel to the radiation;
• Figure 5 is a vertical section of a projector according to the invention wherein the filter is rotatably mounted about a horizontal axis parallel to the direction of the radiation;
• Figure 6 is a vertical section of a projector according to the invention in which the filter is rotatably mounted about a vertical axis transverse to the direction of the radiation;
• Figure 7 is a vertical section of a projector according to the invention wherein the axis is placed so that the filter borders the inner path of the light when it is retracted;
• Figure 8 is a vertical section of a projector according to the invention wherein the filter is rotatably mounted about a horizontal axis transverse to the direction of the radiation;
• Figure 9 is a vertical section of a projector according to the invention comprising a lens capable of diffusing rays having circulated from the reflector to the lens without passing through the activated filter.

The general structure of the projectors shown in FIGS. 1 to 9 comprises a reflector 100 of ellipsoidal type, internal focus 110 and external focus 120, a lens 200 whose focus coincides with the external focus 120 of the reflector 100, and a source of light 105 placed on the internal focus 110 of the reflector 100.

The surfaces of ellipsoidal genus are usually surfaces defined mathematically respectively from two focal zones, which are here called the foci 110 and 120, but which in practice have a slight extent. This range encompasses the filament of the source in the case of the internal focal zone 105, and forms a light spot in the case of the external focal zone 120. The mathematically defined surface is therefore substantially close to an ellipsoid.

The rays emitted by the source, after reflection on the ellipsoidal reflector 100 cross in the vicinity of the external focus 120. The light rays arriving on the lens 200 therefore appear emitted by a small source placed on the focus 120. The rays are then projected in front of the vehicle forming an appropriate light distribution beam suitable for the "road" function.

As seen in Figures 1 to 9, a small movable filter 300 is in the active position, positioned in the vicinity of the external focus 120 of the reflector 100, so that it intercepts the radiation almost luminous as a whole, due to the concentration of the rays at this location.

The filter 300, here placed downstream of the external focus 120, may be arranged upstream or exactly on the external focus 120 relative to the path of the light rays.

The filter 300 thus placed intercepts almost all the light that propagates from the reflector 100 to the lens 200, while being placed in a zone of large volume relative to the size of the filter. It is thus possible to easily place improved holding and moving means in this area.

Taking into account the general geometry of the headlamp, the positioning of the filter in the vicinity of the external hearth 120 further allows positions of the filter 300 which are close to the active position and which do not interfere with any radiation, which can therefore be adopted as inactive position of filter 300.

The filter 300 is here formed by a small square-shaped plate. It is placed perpendicular to the main axis of projection.

A first embodiment of this device is illustrated in Figures 1 and 2, wherein the filter 300 is movable in a vertical translation y direction. In this embodiment, the filter 300 can be guided on a rail 400 symbolized in the figure by a broken line axis and can be driven for example by an electric motor or an electromagnet.

The filter 300 is preferably housed in a frame made of a flexible material, for example sheet metal, this frame being deformed under the effect of the expansions of the filter, without breaking the filter. According to one variant, the filter 300 is maintained by means of elastic return means that extend or fold under the effect of the expansions of the filter 300.

According to a variant indicated in FIG. 3, the translation of the filter can be done in a horizontal Z direction, also transverse to the main direction of propagation.

In FIG. 4, the filter 300 is mounted in translation on a rail parallel to the main direction of propagation.

In the erased position, the filter 300 is sufficiently distant in front of the external focus 120, to interfere with very little light.

Indeed, elliptical projectors typically have a shadow cone 150 corresponding to the bottom hole of the reflector in which the lamp is held. This hole, occupied by the base of the lamp, non-reflective assembly, is the cause of a virtual absence of light ray in this cone which typically surrounds the main axis of propagation.

This cone 150 generally has a small angular aperture. However, since the dimensions of the filter 300 thus disposed are particularly small, the filter 300 is housed almost completely within this cone 150 by simply moving the filter towards the opening direction of the cone 150.

In another embodiment illustrated in Figures 5 and 6, the filter 100 is rotatable about a horizontal axis.

In Figure 5, the axis of rotation is parallel to the main direction of propagation of light.

In Figure 6, the y1 axis is transverse to the direction of propagation of the light above the light flux.

The axis of rotation y1 simply follows a border of the filter so that it disappears on the side of the radiation, particularly concentrated in the vicinity of the focus 120.

In Figure 7, the axis of rotation y2 is placed horizontally and in front of the active position of the filter.

In FIG. 7, the path of light between the second focus 120 and the lens 200 is shown. The light here describes a cone 250 whose tip is on the second focus 120, and the base on the periphery of the 200. The y2 axis is placed sufficiently in front of the active position of the filter 300 so that a rotation of about 60 ° is enough to cause the filter 300 to come out of the light cone 250.

More precisely, the axis y2 is however sufficiently close to the filter 300 for the filter 300 to come close to the cone 250, parallel to its conical envelope.

More generally, such a retraction movement bringing the filter in direct border of the internal light flux proves both very effective in terms of optics, and particularly satisfactory in terms of size because the direct border of the cone of light proves to be a very advantageous storage area for the filter 300, because of extent and thickness very well adapted.

In Figure 8, the axis of rotation y3 is placed vertically and offset towards the front of the active position of the filter. The displacement means of the filter cause a 180 ° rotation of the latter, so that the filter, when retracted, undergoes not only a rotation, but also a forward shift, until it is placed in the cone of the filter. shadow 150 previously cited.

The axis y3 and for example placed transversely to the center of the radiation, at the intersection with the main beam of the projector. Thus, between the active and inactive positions, the filter just seems to have been translated.

Of course, the invention extends to any type of movement of the filter, that is to say using any degree of freedom, for example a rotation along any one of three main axes of rotation and / or a translation according to the invention. any of these three axes.

In FIG. 9, there is shown a filter 300 placed slightly downstream of the external focal zone 120.

In this arrangement, the filter 300 has a range and a positioning such that it does not intercept all of the light. A portion of the rays reaches the lens 200 passing outside the edges of the filter 300. These rays join the lens 200 at the periphery thereof.

These rays are used to produce light in the front of the vehicle in visible light (ordinary light) which drowns a possible red parasitic glow due to the presence of the filter 300.

In order to accentuate the visibility of the white glow thus formed in the peripheral zone of the lens, without dazzling the opposite conductors, a lens 300 is adopted in this annular peripheral zone of the lens 300. clean layout to accentuate the diffusion of light, that is to say to disorganize the rays (lantern effect).

The lens has for example in this area a frosted glass or a light graining. Thus the diffusion of white leakage at the periphery of the lens produces a lateral photometry of the "lantern" type which provides a white appearance to projectors, with, however, preferentially a high intensity in the axis to allow a sustained signaling close to the maximum authorized for a lantern (60 candela) or "Day Running Light" type.

More generally, preference is given to such arrangements in which an organized leakage of white light is maintained outside the filter, and these leaks are preferably diffused at the output of the projector.

This avoids the use of a white lantern constituted by a second source.

Claims (10)

1. Motor vehicle headlamp comprising a light source (105), a reflector (100) with two focal regions (110, 120), and a lens (200), the source (105) being placed in one of the two focal regions (110, 120) so as to produce a reflected light spot (120) in the other focal region (120), the lens (200) being intended to convert the reflected light spot (120) into a beam projected onto the road, a screen (300) placed between the reflector (100) and the lens (200) being mobile between a position away from the light reflected by the reflector (100) and a second position, the screen (300) being a filter (3) opaque to visible radiation and transparent to infrared radiation which, in the second position, intercepts a substantial part of the light reflected by the reflector (100) to the lens (200).
2. Headlamp according to Claim 1, characterised in that it includes a piece for holding the filter (300), which is designed to deform under the effect of thermal expansions of the filter (300).
3. Headlamp according to Claim 1 or 2, characterised in that the source (105) is placed in the inner focal region (110) of the reflector (100), and in that the filter (300) is placed downstream of the reflected light spot (120).
4. Headlamp according to any one of Claims 1 to 3, characterised in that the means for holding the filter (300) are intended to allow displacement of the latter to a position where it lies substantially in a shadow zone, corresponding to the optical image of a lamp hole of the reflector (100).
5. Headlamp according to any one of Claims 1 to 3, characterised in that the means for holding the filter (300) are intended to allow displacement of the latter to a position where it extends with its surface along an edge of the light flux (250).
6. Headlamp according to Claim 4 or Claim 5, characterised in that the means for holding the filter consist of means (y2, y3) for rotating the filter (300).
7. Headlamp according to Claim 6, characterised in that the rotation means comprise a pivot whose axis (y2, y3) lies downstream of the active position of the filter (300) with respect to the propagation direction of the light.
8. Headlamp according to any one of the preceding claims, characterised in that in its active position, the filter (300) has a position and an extent which are selected in order to transmit radiation travelling from the reflector (100) to the lens (200) without crossing the filter (300).
9. Headlamp according to the preceding claim, characterised in that the lens (200) is provided with zones intended to disorganise a light flux, these zones being placed on the path of the rays going from the reflector (100) to the lens (200) without crossing the filter (300).
10. Headlamp according to the preceding claim, characterised in that the zones intended to disorganise the rays form annular regions on the lens (200).

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