Lighting module with dioptric interface for motor vehicle

Abstract

A motor-vehicle lighting module, including a semiconductor light source including light-emitting rods of submillimeter-sized dimensions, and one optic for shaping light rays emitted by the light source, the light source including two selectively activatable zones the luminance of one of which is higher than 80 Cd/mm.sup.2.

Claims

1. A motor-vehicle lighting module, comprising a semiconductor light source comprising light-emitting rods of submillimeter-sized dimensions, and at least one optic for shaping light rays emitted by the light source, the light source including at least two selectively activatable zones, wherein the optic for shaping the light comprises at least three dioptric interfaces, and each dioptric interface separates media of different refractive indices.

2. The lighting module as claimed in claim 1, wherein the luminance of at least one activatable zone is at least higher than 100 Cd/mm.sup.2.

3. The lighting module as claimed in claim 1, wherein the luminance of at least one activatable zone is at least higher than 80 Cd/mm.sup.2.

4. The lighting module as claimed in claim 1, wherein at least one of the at least three dioptric interfaces contains a diffracting pattern.

5. The lighting module as claimed in claim 1, wherein the shaping optic comprises at most four dioptric interfaces.

6. The lighting module as claimed in claim 5, wherein the shaping optic consists of an adhesively bonded doublet, a three-faced prism, or of three mirrors.

7. The lighting module as claimed in claim 5, wherein the shaping optic consists of an adhesively bonded triplet, a non-adhesively bonded doublet, an adhesively bonded doublet and a mirror, four mirrors, a three-faced prism and a mirror, or a rhomboid prism.

8. The lighting module as claimed in claim 2, wherein the luminance of one activatable zone is higher than 80 Cd/mm.sup.2.

9. The lighting module as claimed in claim 2, wherein at least one of the at least three dioptric interfaces contains a diffracting pattern.

10. The lighting module as claimed in claim 2, wherein the shaping optic comprises at most four dioptric interfaces.

11. A motor-vehicle lighting module, comprising a semiconductor light source comprising light-emitting rods of submillimeter-sized dimensions, and at least one optic for shaping light rays emitted by the light source, the light source including at least two selectively activatable zones, wherein the optic for shaping the light comprises at least one dioptric interface which separates media of different refractive indices, and the optic comprises a non-adhesively bonded doublet, adhesively bonded doublet, or adhesively bonded triplet.

Description

(1) Other features and advantages of the invention will become more clearly apparent on reading the following description. The latter is purely illustrative and must be read with regard to the appended drawings, in which:

(2) FIG. 1 illustrates a cross-sectional view of a lighting module according to the present invention;

(3) FIG. 2 illustrates a perspective view of a light-emitting rod of submillimeter-sized dimensions of a light source of the lighting module of FIG. 1;

(4) FIG. 3 illustrates a cross-sectional view of the light source of FIG. 2;

(5) FIG. 4 illustrates a cross-sectional view of a shaping optic of the lighting module of FIG. 1 according to one embodiment;

(6) FIG. 5 illustrates a more detailed perspective view of a shaping optic of the lighting module of FIG. 1;

(7) FIG. 6 illustrates a perspective view of a shaping optic of the lighting module of FIG. 1 according to another embodiment; and

(8) FIG. 7 illustrates a perspective view of a shaping optic of the lighting module of FIG. 1 according to another embodiment.

(9) As shown in FIG. 1, the subject of the invention is a motor-vehicle lighting module, referenced 1.

(10) The lighting module 1 comprises a semiconductor light source 2 that is able to emit light rays, and at least one optic 3 for shaping the light rays emitted by the light source.

(11) Light Source

(12) As shown in FIG. 1, the light source 2 comprises at least one light-emitting rod 4.

(13) FIG. 2 illustrates in detail a light-emitting rod 4.

(14) The light-emitting rod 4 has submillimeter-sized dimensions.

(15) As shown in FIG. 2, the light-emitting rod 4 is a diode of generally vertical columnar shape, for example of hexagonal cross section.

(16) The light-emitting rod 4 comprises an assembly 5 of at least three layers that are placed substantially orthogonal to a substrate.

(17) A first vertical layer 6 of the assembly 5 consists of a semiconductor of a first doping type, whereas a second vertical layer, 7, of the assembly 5, consists of a semiconductor of a second doping type, opposite to the first type.

(18) In other words, if the first vertical layer 6 is n-type (n for negative i.e. doped with electrons), then the second vertical layer 7 is p-type (p for positive i.e. doped to create holes), and, if the first vertical layer 6 is p-type, then the second vertical layer 7 is n-type.

(19) A zone in which the electron-hole pairs of the semiconductor layers 6 and 7 recombine forms an active layer 8 of the assembly 5.

(20) Two electrodes (not shown) are connected to the first active layer 6 and the second active layer 7, respectively, in order that an electrical current may be generated in the light-emitting rod 4.

(21) As shown in FIG. 2, the layers 6, 7 and 8 of the assembly 5 lie substantially parallel to one another.

(22) Recombination of electron-hole pairs along the length of the active layer 8 ensures that light rays are preferentially emitted in a radial direction from the light-emitting rod 4.

(23) The layers 6 and 7 are for example made of GaN.

(24) The substrate for example comprises Si.

(25) Preferably, each layer 6, 7 and 8 extends a length of about a few microns, for example of about 2 m, for a cross section of about 1.6 m diameter.

(26) As shown in FIG. 3, the light source 2 preferably comprises a plurality of light-emitting rods 4 that are advantageously identical to one another.

(27) The light-emitting rods 4 lie substantially parallel to one another.

(28) The light-emitting rods 4 are spaced apart from one another by a distance for example of about 10 m.

(29) The light source 2 includes at least two selectively activatable zones, the luminance of at least one activatable zone being at least higher than 80 Cd/mm.sup.2.

(30) Advantageously, the luminance of at least one activatable zone is at least higher than 100 Cd/mm.sup.2, or even at least higher than 120 Cd/mm.sup.2.

(31) Shaping Optic

(32) The expressions shaping optic and optic for shaping are understood to mean an optical device comprising at least one dioptric interface and configured to deviate at least some of the light rays emitted by the source.

(33) The optic 3 for shaping the light rays emitted by the light source 2 ensures a controlled projection of the rays emitted by the light source 2.

(34) Advantageously, the optic for shaping the light comprises at least two dioptric interfaces.

(35) By dioptric interface, what is meant is an interface separating two media of different refractive indices.

(36) Preferably, the shaping optic comprises at most four dioptric interfaces, or even, advantageously, at most three dioptric interfaces.

(37) Specifically, because of the high luminance of the source 2 of the light, the shaping optic may be simplified with respect to the prior art; in particular, a small aperture is sufficient to obtain the intensity desired for the image projected by the lighting module 1.

(38) Thus, three dioptric interfaces are enough to obtain a clear projected image, without unacceptable aberration (and in particular unacceptable chromatic aberration) and of an intensity compliant with the legislation in force.

(39) In the two-dioptric-interface configuration, the shaping optic 3 for example comprises a lens or even two mirrors arranged with respect to each other so as to form a telescope.

(40) The telescope has the advantage of being achromatic.

(41) It is also possible for each dioptric interface, or at least one of the dioptric interfaces, to contain diffracting patterns.

(42) Diffracting patterns allow chromatic aberration (hybrid doublet) to be corrected.

(43) In the three-dioptric-interface configuration, according to a first variant illustrated in FIGS. 4 and 5, the shaping optic consists of an adhesively bonded doublet, also called an achromatic doublet.

(44) In FIG. 4, the adhesively bonded doublet comprises a plano-concave lens 9 and a biconvex lens 10.

(45) The concave dioptric interface of the lens 9 makes contact with one of the convex dioptric interfaces of the biconvex lens 10, their concavities being identical in absolute value.

(46) The diameter of each lens is about 30 mm.

(47) The focal length of the adhesively bonded doublet is about 50 mm.

(48) In FIG. 5, the adhesively bonded doublet comprises two biconcave lenses 11 and 12

(49) One of the concave dioptric interfaces of the lens 11 makes contact with one of the concave dioptric interfaces of the lens 12, their concavities being identical. To obtain this form, one of the lenses is for example made of silicone.

(50) According to another variant, illustrated in FIG. 6, the three-dioptric-interface shaping optic 3 consists of a lens 13 and a mirror 14.

(51) The mirror 14 is a nonplanar fold mirror designed in collaboration with the lens in order to minimize the geometric aberrations of the shaping optic 3.

(52) As shown in FIG. 6, the shaping optic 3 also comprises a heat sink 18.

(53) According to another variant (not illustrated), the shaping optic consists of a three-faced prism at least one of the faces of which is preferably not planar.

(54) According to this variant, a light ray of the light source 2 penetrates into the prism by refraction at a first face of the prism, before being reflected by a second face of the prism.

(55) Next, the light ray exits from the prism by refraction at a third face.

(56) According to another variant (not illustrated), the shaping optic consists of three mirrors.

(57) In the four-dioptric-interface configuration, according to variants none of which are illustrated, the shaping optic consists of an adhesively bonded triplet, or a non-adhesively bonded doublet, or even an adhesively bonded doublet and a mirror, or four mirrors, or a three-faced prism and a mirror, or a rhomboid prism.

(58) The non-adhesively bonded doublet is for example a Galilean telescope or a single Gauss lens.

(59) The rhomboid prism allows a light ray emitted by the source 2 to enter via refraction at a first face of the rhomboid, then to be reflected a first and a second time from two other faces of the rhomboid.

(60) Next, the light ray exits from the prism via refraction at a fourth face.

(61) According to another embodiment illustrated in FIG. 7, the shaping optic consists of a mirror 15, an entrance lens 16 and an exit lens 17.

(62) A light ray emitted by the light source 2 is reflected by the mirror 15, then passes in succession through the lenses 16 and 17.

(63) As already indicated, because of the high luminance of the light source 2, a small aperture is sufficient to obtain the intensity desired for the image projected by the lighting module 1, thereby allowing the shaping optic to be simplified and the number of dioptric interfaces therein to be decreased.