Lighting module in particular for a high-mounted stop light of smooth appearance

Abstract

A lighting module intended to be placed behind a translucent or transparent outer lens or window, the module including: a place for at least one light source that is able to emit light rays; and an optical system that is able to deviate the light rays emitted by the one or more light sources so as to form a light beam along an optical axis of the module, the optical system extending in a main direction that is transverse to the optical axis and including an exit face for rays. The exit face of the optical system has in sagittal cross section a concave or convex curved general profile.

Claims

1. A lighting module intended to be placed behind a translucent or transparent outer lens or window, said module comprising: a place for at least one light source that is configured to emit light rays; and an optical system that is configured to deviate the light rays emitted by the one or more light sources to form a light beam along an optical axis of the module, said optical system extending in a main direction that is transverse to the optical axis and comprising a first optical element and a second optical element; wherein: the first optical element includes a first entrance face to deviate the light rays that are emitted by the light source along the optical axis and a first exit face having Fresnel echelons to control spreading of the light rays along the main direction, and the second optical element includes a second entrance face having Fresnel echelons to receive and deviate the light rays originating from the first optical element, and a second exit face with a curved profile to distribute the light rays away from the optical system, the light rays being distributed away in one of a dispersing way and a converging way.

2. The module as claimed in claim 1, wherein the first optical element comprises a translucent or transparent material, at least one of said faces of the first optical element comprising Fresnel echelons.

3. The module as claimed in claim 1 wherein the second exit face of the second optical element forms an exit face of the optical system.

4. The module as claimed in claim 3, wherein the exit face of the optical system is free of optical patterns.

5. The module as claimed in claim 4, wherein the exit face of the optical system is smooth.

6. The module as claimed in claim 4, wherein the exit face of the optical system is grained and preferably has a roughness R.sub.a, lower than 20 micrometers.

7. The module as claimed in claim 4, wherein the exit face of the optical system includes smooth zones and grained zones.

8. The module as claimed in claim 1, wherein the first entrance face of the first optical element comprises Fresnel echelons.

9. The module as claimed in claim 8, wherein the Fresnel echelons on the first entrance face of the first optical element have annular and/or curved profiles, said first optical element comprising the first exit face with rectilinear Fresnel echelons.

10. The module as claimed in claim 9, wherein the Fresnel echelons on the first exit face of the first optical element are perpendicular to the main direction of the optical system.

11. The module as claimed in claim 1, wherein the second optical element comprises a translucent or transparent material.

12. The module as claimed in claim 1, wherein the second entrance face of the second optical element comprises rectilinear Fresnel echelons.

13. The module as claimed in claim 12, wherein the Fresnel echelons on the second entrance face of the second optical element are perpendicular to the main direction of the optical system.

14. The module as claimed in claim 3, wherein the second optical element comprises two sub-elements that are separated by an air-filled cavity, the first sub-element bearing the second entrance face and the second sub-element bearing the second exit face forming the exit face of the optical system.

15. A lighting device for a motor vehicle, said device comprising: a housing and a lighting module, wherein the housing is configured to contain the light module; and the lighting module includes at least one light source that is configured to emit light rays, and an optical system that is configured to deviate the light rays emitted by the one or more light sources to form a light beam along an optical axis of the module, said optical system extending in a main direction that is transverse to the optical axis and comprising a first optical element, a shield and a second optical element, wherein: the first optical element includes a first entrance face to deviate the light rays that are emitted by the light source along the optical axis and a first exit face to control spreading of the light rays along the main direction; the second optical element includes a second entrance face to receive and deviate the light rays transmitted by the first optical element, and a second exit face with a curved profile to transmit the light rays away from the optical system; and the shield is connected to the first optical element and positioned to cover the second optical element.

16. The module as claimed in claim 3, wherein the exit face of the optical system has one of a concave profile and a convex profile.

17. The module as claimed in claim 1, wherein the first entrance face of the first optical element is smooth.

18. The module as claimed in claim 1, wherein the first optical element is curved over a sector comprised between 90 and 180.

19. The module as claimed in claim 16, wherein the exit face of the optical system has the concave profile with a radius between 10 mm and 50 mm so that the light rays are distributed away in the dispersing way.

20. The module as claimed in claim 16, wherein the exit face of the optical system has the convex profile with a radius between 10 mm and 50 mm so that the light rays are distributed away in the converging way.

Description

(1) Other features and advantages of the present invention will be better understood from the description and drawings, in which:

(2) FIG. 1 is a rear view of a motor vehicle equipped with a high-mounted stop lamp according to the invention;

(3) FIG. 2 is a view in cross section along II-II of the lamp of FIG. 1, according to the invention;

(4) FIG. 3 is a view in cross section along III-III of the lamp of FIG. 1, according to the invention.

(5) In the following description, the notions of verticality and horizontality are expressed when the lighting device is oriented in a mounting position on the vehicle. The orientation of the lighting device is moreover clearly defined in the various figures.

(6) FIG. 1 is a view of the rear of a motor vehicle 2. In a conventional and known way, the vehicle comprises a rear windshield 4, the latter possibly being fastened to the body or being on a rear opening such as a tailgate. The vehicle 2 comprises a signaling lamp 6, which is placed at the top of the rear windshield 4, and more precisely behind said windshield. It is in the present case a question of what is commonly called a third stop lamp, or a high-mounted stop lamp, with reference to the two conventional stop lamps placed lower down to the left and to the right. This high-mounted stop lamp or third stop lamp is also designated a CHMSL (acronym for the expression Center High-Mounted Stop Lamp. Such a high-mounted stop lamp may also be installed at the bottom of the rear windshield, on the parcel shelf, or be mounted in the body, above the rear windshield or even at the top of the trunk lid. When it is intended to be placed behind the rear windshield, the high-mounted stop lamp includes a housing the aperture of which is closed by the rear windshield, whereas in the case where it is integrated into the body, it includes a housing closed by a translucent or transparent outer lens, which may, where appropriate, be red in color. According to the invention, this outer lens is devoid of an opaque partition.

(7) FIG. 2 is a partial view of a transverse, i.e. longitudinal (with respect to the vehicle) and horizontal, cross section along II-II of the lighting device or lamp 6 of FIG. 1.

(8) FIG. 3 is a view of a sagittal, i.e. longitudinal (with respect to the vehicle) and vertical, cross section along III-III of the lamp 6 of FIG. 1.

(9) The signaling lamp 6 extends in a main direction 13 that corresponds to the horizontal when the lamp is in its position mounted on the vehicle. This main direction 13 also corresponds to the horizontal in FIG. 2. The lamp comprises a holder 8 of one or more light sources 10. It may be a question of light-emitting diodes (LEDs) or even of incandescent bulbs. In the case where the light sources are LEDs, the holder 8 may be a printed circuit board (PCB). In the case where a plurality of light sources are present, the latter may be placed side-by-side or even distributed in the main direction of the lamp. The one or more light sources are configured to illuminate in a main direction parallel to the optical axis 13 of the signaling lamp 6.

(10) The signaling lamp 6 also comprises an optical system that essentially consists of a first optical element 14 and of a second optical element 18. The first optical element consists of a translucent or transparent material, similarly to a lens, with an entrance face 14.sup.1 and an exit face 14.sup.2. In the present case, the first optical element 14 is generally curved over a sector comprised between 90 and 180, so as to collect most of the light emitted by the light source 10. The entrance face 14.sup.1 may be generally smooth or, as is shown in FIG. 3, comprise what are called Fresnel echelons that are configured to deviate the rays originating from the one or more light sources essentially vertically. The exit face 14.sup.2 advantageously comprises what are called Fresnel echelons or striations, as is shown in FIG. 2, so as to control horizontal spreading of the light rays. A shield 16 may be provided about the first optical element 14.

(11) The second optical element 18 is placed so as to receive the light rays deviated by the first optical element 14. Just like the first optical element, the second optical element 18 consists of a translucent or transparent material, similarly to a lens, with an entrance face 18.sup.1 and an exit face 18.sup.2. The second optical element is advantageously generally planar, and extends in the main direction of the lamp 6. The entrance face 18.sup.1 comprises what are called Fresnel echelons or striations so as to be able to deviate the rays originating from the first optical element 14 essentially horizontally. These striations or echelons therefore extend essentially vertically. They may however have a certain curvature centered on the optical axis 12.

(12) According to one variant (not shown), the second optical element 18 comprises two sub-elements that are separated by an air-filled cavity, the first sub-element bearing the entrance face 18.sup.1 and the second sub-element bearing the exit face 18.sup.2 forming the exit face of the optical system 14, 18. This advantageously allows the esthetics of the module when it is turned off to be improved, in that the Fresnel patterns borne by the entrance face 18.sup.1 are less easily visible through the exit face 18.sup.2 and through the transparent outer lens or window.

(13) The exit face 18.sup.2 of the second optical element 18 is generally concave. More precisely, the profile of its cross section along a vertical longitudinal or sagittal plane (FIG. 3) is generally curved and concave. The vertical profile in question has a single concavity. It may correspond to a circular arc or to a more complex function. Its average radius may be comprised between 10 and 50 mm. The shape of this profile advantageously extends over more than 50%, and preferably over more than 80% of the length of the exit face 18.sup.2 in question. It will however be understood that the profile in question may vary along the main axis of the lamp. The cross section of the exit face 18.sup.2 in a horizontal longitudinal or transverse plane (i.e. along the section line II-II in FIG. 1) may also have a concave and curved profile. In this case, this horizontal profile also then has a single concavity with an average radius of curvature higher than that of the vertical profile. This radius may be comprised between 7 and 12 meters.

(14) As may be seen in FIG. 3, the rays exiting from the first optical element 14 and entering into the second optical element 18 are essentially in horizontal planes. They thus propagate essentially in horizontal planes through the thickness of the translucent or transparent material of the second optical element 18. The concave exit face 18.sup.2 disperses the rays vertically and thus ensures a distribution of the light rays. This effect is particularly advantageous when the lamp has a small height (along the vertical direction).

(15) With reference to the above discussion in which the horizontal profile of the exit face may also be concave, such a concave profile has a similar effect to that of the vertical profile, namely that of spreading the light rays horizontally.

(16) Alternatively to what was just described above, the vertical or sagittal profile of the exit face of the second optical element may be convex. In this case, the effect will be to make the rays converge toward a zone in front of and close to the signaling lamp. The rays will then diverge vertically, similarly to the signaling lamp of concave profile. The convex profile may correspond to a circular arc or to a more complex function. Its average radius may be comprised between 10 and 50 mm. The convex shape of the vertical profile advantageously extends over more than 50%, and preferably over more than 80% of the length of the exit face in question. It will however be understood that the profile in question may vary along the main axis of the lamp. The cross section of the exit face in a horizontal longitudinal or transverse plane (i.e. along the section line II-II of FIG. 1) may also have a convex and curved profile. In this case, this horizontal profile then also has a single convexity with an average radius of curvature higher than that of the vertical profile. This radius may be comprised between 7 and 12 meters.

(17) Generally, the entire area or only certain zones of the exit face 18.sup.2 of the second optical element 18 may be grained, for example with a roughness R.sub.a lower than 20 micrometers, preferably lower than 10 micrometers and higher than 3 micrometers. This fine graining scatters the rays, making it possible to avoid or decrease the impact of any moir patterns or nonuniform ities.

(18) According to one essential feature of the invention, the optical system is a single part made of man-made polymer: the first optical element and the second optical element, and where appropriate both sub-elements of the second optical element, are integrally formed and made of the same material. They are joined by a base. The optical system is produced by injecting molding man-made polymer. Preferably, the polymer is polycarbonate (PC) or polymethyl methacrylate (PMMA).

(19) Although one particularly preferred application of the invention is to the production of a high-mounted stop lamp for a motor-vehicle, whether it be of the type placed in a housing behind the rear windscreen shield of the vehicle or of the type with a housing closed by a translucent or transparent outer lens and integrated into the body on the exterior of the vehicle, the lighting module may also be used to produce interior lighting devices including a housing closed by a translucent or transparent outer lens.