LIGHT MODULE COMPRISING AN ELEMENT WITH VARIABLE LIGHT TRANSMISSION RATE

Abstract

The invention relates to a luminous module for automotive vehicle including a light source and a projection optic designed to project a light field onto the ground. The luminous module also includes an element with a variable light transmission rate positioned between the light source and the projection optic, the element with a variable light transmission rate includes at least one first portion and at least one second portion. Each of these portions has a different light transmission rate so that the image sectors respectively formed by the first portion and the second portion have the same luminous intensity.

Claims

1. A luminous module for automotive vehicle comprising: a light source; a projection optic designed to project a light field onto the ground; with the luminous module including an element with a variable light transmission rate positioned between the light source and the projection optic, the element with a variable light transmission rate including: a first portion receiving light rays suitable for forming a first sector of the light field; a second portion receiving light rays suitable for forming a second sector of the light field, the second sector being situated further away from the light source than the first sector; and the first portion having a light transmission rate, referred to as the first light transmission rate, that is lower than the light transmission rate of the second portion, referred to as the second light transmission rate; and the first light transmission rate and the second light transmission rate being defined so that the luminous intensity of the first sector is substantially equal to the luminous intensity of the second sector.

2. The luminous module as claimed in claim 1, further comprising a slide placed between the light source and the projection optic that bears a pattern to be projected, and in that the element with a variable light transmission rate is positioned on the slide.

3. The luminous module as claimed in claim 2, wherein the slide includes a first face oriented toward the projection optic and a second face oriented toward the light source, the first face being placed in a focal plane of the projection optic and including the pattern to be projected, the projection of which is contained in the light field or forms the light field.

4. The luminous module as claimed in claim 3, wherein the element with a variable light transmission rate is positioned on the first face of the slide.

5. The luminous module as claimed in claim 3, wherein the element with a variable light transmission rate is positioned on the second face of the slide.

6. The luminous module as claimed in claim 1, wherein the light field consists of the projected image of the light source.

7. The luminous module as claimed in claim 1, wherein the element with a variable light transmission rate has a variable thickness.

8. The luminous module as claimed in claim 1, wherein the element with a variable light transmission rate is formed by a layer including a plurality of elementary units, known as the layer with a variable light transmission rate, the elementary units being distributed so that the first portion has a higher density of elementary units than the density of elementary units of the second portion.

9. The luminous module as claimed in claim 8, wherein the elementary units are completely opaque.

10. The luminous module as claimed in claim 8, wherein the elementary units are made from metal.

11. The luminous module as claimed in claim 8, wherein the layer with a variable light transmission rate is obtained by a photolithography process.

12. The luminous module as claimed in claim 1, wherein the element with a variable light transmission rate includes a transparent third portion, the third portion receiving light rays suitable for forming a third sector of the light field that is situated furthest away from the light source.

13. The luminous module as claimed in claim 12, wherein the second portion is positioned between the first portion and the third portion.

14. The luminous module as claimed in claim 1, wherein the projection optic includes a plurality of lenses, the lenses being stacked on top of each other.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0049] Further innovative features and advantages will become apparent from the following description, which is given by way of non-limiting indication, with reference to the appended drawings, in which:

[0050] FIG. 1 shows a side view of an automotive vehicle comprising a luminous module according to one exemplary embodiment of the invention;

[0051] FIG. 2 shows a cross-sectional view of the luminous module in FIG. 1;

[0052] FIG. 3 shows a schematic perspective view of a first face of the slide forming part of the luminous module in FIG. 1;

[0053] FIG. 4 shows a schematic perspective view of a second face of the slide forming part of the luminous module in FIG. 1;

[0054] FIG. 5 shows a rear view of the device in FIG. 3, accompanied by detailed views A, B, and C; and

[0055] FIG. 6 shows a transverse cross-sectional view of the slide along a plane passing through the line VI-VI illustrated in FIG. 3 and FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

[0056] With reference to these figures, in particular FIG. 1, an automotive vehicle 10 comprises, on the left-hand side illustrated, a front door 11 and a rear door 13. A luminous device comprising a luminous module 1 (not visible in FIG. 1) is installed in a door sill 12 situated under the front door 11 and rear door 13. In the example illustrated, the luminous device is situated at the front end of the door sill 12 and is arranged to project onto the ground a light field S that extends parallel to the main axis P of the vehicle 10. The projection axis forms an angle ? with a horizontal axis.

[0057] The luminous device acts as a lateral means for lighting the space situated next to the front and rear entrance doors.

[0058] Here, the light field S extends to the rear of the vehicle 10. In the prior art, the light field has a variable luminous intensity, which sometimes makes the difference in luminous intensity between the different sectors of this light field visible, that is, sectors that are darker than others can be distinguished.

[0059] Given that the luminous device comprises the luminous module 1 produced according to the principle of the invention, the light field S has a uniform luminous intensity over its entire extent. In other words, the light field S is not divided into several sectors with different luminous intensity, but consists here of a single sector with the same luminous intensity everywhere.

[0060] The quality of the light field is thus improved. To achieve this, the luminous device comprises the luminous module 1 as illustrated schematically in FIGS. 2 to 6.

[0061] In FIG. 2, the luminous module 1 comprises a light source 2, a projection optic 3 and a slide 5 positioned between the light source 2 and the projection optic 3.

[0062] Here, the light source 2 is an LED (light-emitting diode). Other types of light source can be envisaged. The light source 2 can comprise one or more LEDs. Here, a collimator 20 is placed in front of the light source 2 in order to produce a beam resulting from parallel rays oriented in the direction of the slide 5 and the projection optic 3.

[0063] In the example illustrated, the projection optic 3 has a focal plane F and is made up of a plurality of lenses 30 that are stacked on top of each other. There are four lenses here.

[0064] Each of the lenses 30 comprises a central part 301 with dioptric surfaces and an outer ring 302 surrounding the central part 301. The dioptric surfaces are configured to project the rays coming from the light source 2 while limiting, or even eliminating, optical aberrations such as distortion.

[0065] The outer ring 302 is provided with engagement means suitable for interacting with complementary engagement means of the outer ring of the adjacent lens. By way of example, engagement means can comprise a groove or a rib.

[0066] In order to guarantee that all of the lenses 30 are held satisfactorily, they are placed in a lens holder (not illustrated in FIG. 2) that grips the two opposite ends of the assembly. To this end, the lens holder comprises edges that press on the outer ring of the first lens and the last lens in the assembly.

[0067] Here, the slide 5 is a transparent plate 53 having, by way of illustration, a rectangular cross-section. The slide 5 can be made from glass or plastic, for example polyethylene terephthalate (PET). The slide 3 has a first face 51 and a second face 52. The slide is placed in the luminous module 1 so that the first face 51 is oriented toward the projection optic 3 and so that the second face 52 is oriented toward the light source 2. The first face 51 is also known as the downstream face and the second face 52 is also known as the upstream face. The terms upstream and downstream are defined in the direction of propagation of light in the luminous module 1.

[0068] As illustrated on FIG. 3, a pattern 510 is produced on the first face 51 of the slide 5. The pattern 510 will be projected onto the ground and thus forms the light field S. In this example, the pattern 510 is the letter V.

[0069] The pattern 510 is obtained by a process for treating the surface of the first face 51. This is for example a photolithography process that creates a transparent zone 510 and an opaque zone 511 on the first face 51. The opaque zone 511 is covered with an opaque layer 513 (visible in FIG. 6) that does not let the light through, in particular a layer of chromium oxide. The opaque layer 513 can be made from other materials, such as aluminum or silver. In the transparent zone 510, the first face 51 remains uncovered, that is, the first face 51 is not covered with material. The light rays can therefore pass through the transparent zone 510 to reach the projection optic 3. The transparent zone therefore forms the pattern 510 to be projected. The first face 51 is placed in the focal plane F of the projection optic 3 so that the image of the pattern is projected infinitely, and is therefore sharp on the projection surface.

[0070] In another example, the transparent zone can be covered by a transparent layer that lets through all of the light rays that reach it.

[0071] FIGS. 4 and 5 show the second face 52 of the slide 5. According to the invention and as in this example, an element with a variable light transmission rate 4 is positioned on the second face 52. Here, the element with a variable light transmission rate 4 extends in a zone 520 delimited by a circle P illustrated in FIG. 4. The zone 520 is also known as the active zone 520, as it is placed facing the pattern 510 on the first face 51. In other words, the active zone 520 receives the light rays, which then reach the pattern 510.

[0072] The rest of the second face 52, which is not placed facing the pattern 510, is known as the inactive zone 525. An opaque coating layer is deposited on this inactive zone 521 to prevent any stray rays that might reach the projection optic 3 and would thus be imaged in the light field S. This opaque coating layer can be of the same type as the opaque layer 513 deposited on the first face 51.

[0073] Here, the element with a variable light transmission rate is formed by a layer of material 4 comprising a plurality of elementary units 400 spaced apart from each other.

[0074] The distance between one elementary unit 400 and neighboring units can be varied within the layer of material 4.

[0075] As illustrated in FIG. 5, the layer of material 4 comprises a density of elementary units that decreases from top to bottom in FIG. 5, represented by the arrow F. For example, the density of elementary units decreases continuously from top to bottom. This decrease can be linear or non-linear. Described otherwise, the layer of material 4 can be divided into a plurality of portions that follow on from each other in the direction of extension of the layer of material, here shown by the arrow F. Each portion can have a very small dimension and can comprise a defined density of elementary units. Any given portion has a density of elementary units greater than the portion situated immediately below.

[0076] Here, the layer of material 4 extends partially in the active zone 520 of the second face 52 of the slide 5. Here, the elementary units are positioned on part of the active zone 520 with a decreasing density from top to bottom in this part. The remaining part of the active zone 520 is not provided with elementary units. This remaining part is also known as the zone not covered by the layer of material 4 and is denoted 523 in FIGS. 4 and 5.

[0077] By way of example, the distribution of the elementary units in an upper portion 41 of the layer of material 4 is illustrated in the enlarged view denoted A in FIG. 5. The distribution of the elementary units in a middle portion 42 of the layer of material 4 is illustrated in the enlarged view denoted B in FIG. 5. It will be noted that the density of the elementary units is higher in the upper zone 41 than in the middle zone 42. Another enlarged view denoted C in FIG. 5 illustrates the distribution of the elementary units in a lower portion 43 with a density that decreases gradually up to the zone 523 not covered by the layer of material 4.

[0078] In another exemplary embodiment, the elementary units can be positioned with a variable density over the entire surface of the active zone 520 of the second face 52. In this case, the zone 523 will be covered by a lower density of elementary units.

[0079] According to another exemplary embodiment, the elementary units can be distributed in several groups with constant density, and the density is different from one group to another. In this case, the arrangement of these groups with respect to each other depends on how the luminous module is installed in the vehicle, for example for projection that is non-raking or perpendicular to the ground. In addition, the distribution by group of elementary units with constant density can be suitable for patterns with surfaces with particularly contrasting luminance.

[0080] Returning to the example illustrated, it will be observed in FIG. 6 that the elementary units 400 are the same size, which makes it possible for the layer of material 4 to have a constant thickness. In addition, the layer of material 4 with identical elementary units is simple to produce.

[0081] The elementary units 400 are produced from an opaque material. Here, the elementary units 400 are made from metal, for example, chromium or aluminum. Optionally, the elementary units 400 can be made from the same material as the layer covering the inactive zone 525.

[0082] With their opaque body, each elementary unit prevents the light rays that reach it from passing through it. In addition to the above, the elementary units 400 can be a dark color, or even black.

[0083] The presence of the elementary units 400 on the second face 52 of the slide reduces the quantity of light rays that can reach the second face 52 and pass through the body 53 to arrive at the first face 51. In other words, the elementary units 400 have an impact on the transparency of the slide. The more elementary units 400 there are, the more opaque the part of the slide concerned becomes. The degree of opacity of this part is linked to the density of the elementary units 400 that are present thereon.

[0084] The layer 4 containing the elementary units 400 described above is known as the layer with a variable light transmission rate, as it modifies the degree of opacity of the slide, in a manner that changes on the second face 52. The part of the second face 52 that is covered by the layer 4 has an opacity that varies in proportion to the density of elementary units of this layer 4. The upper part 521 of the active zone 520 is more opaque than the middle part 522 of the same zone. Finally, the zone 523 that is not provided with elementary units 400 retains its initial transparency.

[0085] Bearing the layer with a variable transmission rate 4 as described, the slide 5 is arranged in the luminous module 1 so that the light rays reaching the upper part 521 and the middle part are the rays suitable for forming the sectors of the light field S that are near the light source. These sectors are denoted S1 and S2 in FIG. 1. In parallel, the light rays that reach the zone 523 contribute to forming the sector of the light field that is furthest away from the light source. This sector is denoted S3 in FIG. 1.

[0086] As a result, the luminous intensity is the same throughout the light field S, as the quantity of light forming the first and second sectors S1 and S2 is reduced to the same level as the quantity of light forming the third sector S3. This reduction originates from the presence of the elementary units 400 on the parts 521 and 522 of the second face 52, which prevents some of the light from passing through the slide 5.

[0087] The layer with a variable light transmission rate therefore makes it possible to remedy the uneven light distribution of the light field in the prior art. In the prior art, the sector that is situated nearest to the luminous module, and therefore to the light source, has greater luminous intensity than the sector that is situated a little further away from the source. Due to the layer with a variable light transmission rate, the luminous intensity of the first sector, which is more illuminated, is reduced so as to reach the same luminous intensity as the second sector, which is situated further away from the light source and is therefore less illuminated.

[0088] Of course, the present invention is not limited to the example described above. Various modifications can be made to the example described without departing from the scope of the invention.

[0089] For example, the pattern produced on the first face of the slide can be different. The number of portions of the layer with a variable light transmission rate and therefore the number of parts into which the second face is divided can be different. Other materials and other processes can be envisaged for producing the layer with a variable light transmission rate.