Lighting device for a motor vehicle capable of producing a moiré-like optical effect

Description

Domain technique to which the invention relates

[0001] The present invention relates to a luminous, signaling and / or lighting device for a motor vehicle. Technological background

[0002] Documents WO2016120973A1, JP2013173246 and DE102011016000A1 illustrate the knowledge of a person skilled in the art at the time of the invention.

[0003] Regulations require that every motor vehicle be equipped with signaling and lighting devices to enable the driver to see the road clearly and to indicate to other road users the position of the motor vehicle and the intentions of its driver.

[0004] To facilitate the assembly of signaling devices on motor vehicles, these are grouped into optical units. An optical unit may therefore include a high beam, a turn signal, a position light, and a brake light when the optical unit is intended to be mounted at the rear of a motor vehicle.

[0005] To protect the lights from the external environment, the headlight assembly is covered by an external lens, preferably transparent so as not to alter the properties of the light beams emitted by the lights. The lights are thus visible during the day through the external lens. However, the shape and arrangement of the lights significantly alter the appearance of the motor vehicle.

[0006] In recent years, a greater variety of headlight shapes and arrangements has been achieved through the use of LEDs and light guides. This has resulted in more discreet and aesthetically pleasing headlights. Now, the appearance and arrangement of lights within headlight assemblies are major differentiating factors between motor vehicles.

[0007] The present invention aims to provide a lighting, signaling and / or lighting device capable of creating an optical illusion known as moiré, when the lighting device is switched on. Object of the invention

[0008] To this end, the present invention proposes a lighting device for a motor vehicle comprising a transparent or translucent light guide. The light guide is defined by a first large face, parallel or substantially parallel to a second large face. The large faces are connected by an entrance face arranged opposite a light source, so as to allow the propagation of a light beam, emitted by the light source, between the large faces of the light guide. The light guide includes diffusing elements, capable of diffusing the light beam emitted by the light source illuminating its entrance face.

[0009] The invention is remarkable in that a transparent or translucent blade is positioned opposite the second large face of the light guide, and in that the blade includes diffusing elements capable of diffusing the light beams emitted by the light source.

[0010] According to the invention, the diffusing elements present in the light guide and the blade form identical or substantially identical patterns.

[0011] According to the invention, the diffusing elements present in the light guide and the blade are at least partially opposite each other.

[0012] According to the invention, the greatest distance between two adjacent diffusing elements is equal to or less than 0.8 mm, preferably between 0.18 mm and 0.2 mm.

[0013] According to the invention, the density of diffusing elements in the light guide and the blade varies between 200 diffusing elements per cm² and 2,500 diffusing elements per cm².

[0014] According to another embodiment of the invention, the diffusing elements form quincunx-shaped patterns.

[0015] According to the invention, the diffusing elements in the light guide and the blade comprise cavities opening onto the same face, each cavity defining an opening on said face whose largest dimension is equal to or less than 0.12 mm, and each cavity having a depth equal to or less than 0.1 mm. Preferably, the cavities open onto the first large face of the light guide, and the cavities open onto a first large face of the blade positioned opposite the second large face of the light guide.

[0016] According to another embodiment of the invention, the smallest distance between the light guide and the blade is equal to or greater than 6 mm.

[0017] According to another embodiment of the invention, the light source is controlled by a control unit configured to control the intensity of the emitted light beam over time.

[0018] According to another embodiment of the invention, the lighting device includes means for translating and / or pivoting the blade relative to the light guide.

[0019] According to another embodiment of the invention, the blade forms an angle with the light guide with a value between 0° and 60°, or between 0° and 45°, preferably between 15° and 25°. In a particular embodiment, the largest faces opposite the light guide and the blade form an angle with a value within the ranges of values ​​mentioned above.

[0020] According to another embodiment of the invention, the light guide and / or the blade can be curved or partially curved.

[0021] The invention also relates to a lighting and / or lighting device for a motor vehicle comprising a lighting device as described above.

[0022] The invention also relates to a motor vehicle comprising a lighting and / or illumination device as described above. Description of the figures

[0023] The following description, with reference to the attached drawings, given as non-limiting examples, will allow for a better understanding of what the invention consists of and how it can be implemented: there figure 1 represents a profile view of a lighting device according to the invention; the figure 2 represents a partial longitudinal section of a light guide of the lighting device illustrated by the figure 1 ; there figure 3 represents a partial front view of a light guide of the lighting device illustrated by the figure 2 . Detailed description of an example of implementation

[0024] As a reminder, the invention proposes a luminous, signaling and / or lighting device, capable of creating an optical illusion known as moiré, when the luminous device is lit.

[0025] There figure 1This illustrates a non-limiting embodiment of a lighting device 2 according to the invention. In this example, the lighting device comprises a slightly curved light guide 4. The radius of curvature of the light guide is between 40 mm and 1000 mm. The light guide is delimited by a first large face 6 parallel or substantially parallel to a second large face 8. The smallest distance separating the first large face 6 from the second large face 8 is between 1 mm and 8 mm, preferably between 2 mm and 5 mm. The light guide 4 extends between a proximal end 10, delimited by an entrance face 12, and an opposite distal end 14, delimited by an exit face 16. The smallest distance separating the entrance face 12 from the exit face 16 is between 10 mm and 550 mm, preferably between 30 mm and 200 mm. The entrance face 12 is normal or substantially normal to the large faces of the light guide.The exit face 16 is inclined relative to the large faces of the light guide, so as to form a bevel at the distal end 14. The light guide 4 is made of polycarbonate or polymethyl methacrylate. The light guide 4 is translucent, preferably transparent to daylight.

[0026] Light guide 4 includes diffusing elements designed to diffuse daylight. The diffusing elements are visible on the figures 2 And 3Figures 18 and 18 respectively represent a longitudinal section and a front view of the first large face 6 of the light guide 4. The diffusing elements comprise cavities 18 formed through the first large face 6. The depth of the cavities 18, defined along a direction normal to the first large face 6, is equal to or less than 1.2 mm, preferably between 0.05 mm and 0.7 mm. Each cavity 18 defines an opening 20 in the first large face 6 of the light guides. The openings 20 are identical in shape. The largest dimension d of an opening 20 is equal to or less than 0.7 mm, preferably between 0.03 mm and 0.5 mm. The smallest distance D separating two adjacent openings is equal to or greater than 0.12 mm, preferably between 0.2 mm and 0.8 mm.The total surface area enclosed by the openings 20 is equal to or less than 21% of the total surface area of ​​the first large face 6 of the light guide, preferably between 3% and 21%. In other words, the density of the diffusing elements on the first large face 6 of a light guide is between 10 cavities per cm² and 2,500 cavities per cm², preferably between 50 and 500 cavities per cm². The cavities 18 are arranged to form a staggered pattern. The density can be adjusted according to the length and the desired homogeneity.

[0027] The lighting device 2 also includes a slightly curved blade 22. The radius of curvature of the blade is between 40 mm and 1000 mm. Preferably, the radius of curvature of the blade is the same as that of the light guide. The blade is delimited by a first large face 24 parallel or substantially parallel to a second large face 26. The smallest distance between the first large face 24 and the second large face 26 of the blade is between 1 mm and 8 mm, preferably between 2 mm and 5 mm, so as to facilitate airflow and limit condensation between the blade and the light guide. The blade 22 extends from a proximal end 28 to an opposite distal end 30. The smallest distance between the proximal and distal ends is between 10 mm and 550 mm, preferably between 30 mm and 200 mm. The 20 blade is made from polycarbonate or polymethyl methacrylate.Blade 20 is translucent, preferably transparent in daylight.

[0028] According to the invention, the blade 22 also includes diffusing elements capable of diffusing daylight. The diffusing elements are visible on the figure 2The diffusing elements comprise cavities 18 formed through the first large face 24 of the plate. The depth of the cavities 18, defined along a direction normal to the first large face 24, is equal to or less than 1.2 mm, preferably between 0.05 and 0.7 mm. Each cavity 18 defines an opening in the first large face 24 of identical shape. The largest dimension of an opening is equal to or less than 0.7 mm, preferably between 0.03 mm and 0.5 mm. The smallest distance separating two adjacent openings is equal to or greater than 0.12 mm, preferably between 0.2 mm and 0.8 mm. The total surface area defined by the openings is equal to or less than 21% of the total surface area of ​​the first large face 24 of the plate, preferably between 3% and 21%.In other words, the density of the diffusing elements at the first large face 24 of the plate is between 10 cavities per cm 2< and 2,500 cavities per cm 2<, preferably between 50 and 500. The cavities 18 are arranged so as to form patterns identical to that formed by the cavities 18 present in the light guide 4. The density can vary according to the length and the desired homogeneity.

[0029] The light guide 4 and the blade 22 are held at their proximal end by means of a frame 32 visible on the figure 1The frame holds the light guide 4 and the blade 22 so that they are parallel or nearly parallel to each other, or form an angle of 60° or less. The light guide and the blade are centered on the same observation axis 34, perpendicular or nearly perpendicular to the first large faces. In other words, the blade 22 is positioned in front of the light guide. The smallest distance between the blade and the light guide is 2 mm or more, preferably between 4 mm and 50 mm.

[0030] The lighting device 2 comprises a light source 36 arranged opposite the entrance face 12 of the light guide, so as to allow the propagation of a light beam within the light guide. When the light source is activated, the light guide illuminates and diffuses a portion of the light beams along the observation axis 34. The light guide thus forms a luminous screen capable of illuminating a scene and / or being visible to an observer. The light source 36 consists of one or more light-emitting diodes (LEDs) positioned along the entrance face 12 of the light guide 4. The light source 36 is controlled by a control unit 38 so as to allow the light source to operate alternately. In this example, the light source 36 is capable of emitting a light beam with an intensity between 0.1 lm and 500 lm, preferably between 2 lm and 150 lm.Optionally, the light source is capable of emitting beams of light of different colors over time.

[0031] The invention thus proposes a lighting device 2 comprising a light guide 4 capable of emitting light signals towards an observer. The light guide is positioned behind a blade 22. Both the blade and the light guide comprise diffusing elements 18 forming identical, opposite patterns. Advantageously, the diffusing elements are shaped so as not to be visible to an observer with 20 / 20 vision positioned at a distance of 50 cm or more from the second large face 26 of the blade when the light source 36 is switched off. In other words, for an observer at a sufficient distance from the lighting device 2, the diffusing elements are not visually perceptible and therefore do not produce any particular visual effect when the light source is switched off.Conversely, when the light source is activated, the diffusing elements 18 scatter the light beams emitted by the light source at the first large faces of the light guide and the blade. The observer then perceives the presence of the diffusing elements through the light beams scattered by them. This results in a visual effect, or optical illusion, known as moiré. Depending on the viewing angle, the observer perceives a pattern with a changing shape. Advantageously, this visual effect is perceptible to an observer only when the light source is activated. In other words, the lighting system appears discreet when the light source is off.

[0032] According to one embodiment, the lighting device includes means for translating and / or pivoting the blade, relative to the light guide, so as to amplify and / or modify the optical illusion when the light source is switched on.

Claims

1. Light device (2) for a motor vehicle capable of creating an optical effect known as Moiré when the device is lighted, comprising a transparent or translucent light guide (4), the light guide (4) being delimited by a first major face (6) parallel or essentially parallel to a second major face (8), the major faces being connected by an inlet face (12) situated in front of a light source (36) so as to allow the propagation of a light beam emitted by the light source (36) between the major faces of the light guide, the light guide comprising diffusing elements (18) lighting its inlet face (12), characterized in that a transparent or translucent blade (22) is positioned opposite the second major face (8) of the light guide and in that the blade (22) comprises diffusing elements (18) able to diffuse the light beams emitted by the light source (36), and in that the diffusing elements (18) present in the light guide (4) and in the blade (22) are at least partially opposite one another, and in that the greatest distance (D) between two adjacent diffusing elements (18) is equal to or less than 0.8 mm, and in that the density of diffusing elements (18) in the light guide and in the blade (22) varies between 200 diffusing elements per cm2 and 2500 diffusing elements per cm2, and in that the diffusing elements in the light guide and in the blade (22) comprise cavities (18) open at the level of a same face, and in that each cavity (18) delimits an opening (20) on said face the greatest dimension (d) of which is equal to or less than 0.12 mm, and in that each cavity (18) has a depth equal to or less than 0.1 mm.

2. Light device (2) according to claim 1, characterized in that the diffusing elements (18) form patterns in quincunx.

3. Light device (2) according to claim 1 or 2, characterized in that the cavities (18) are open on the first major face (6) of the light guide (4), and in that the cavities are open on a first major face (24) of the blade (22) positioned opposite the second major face (8) of the light guide (4).

4. Light device (2) according to anyone of claims 1 to 3, characterized in that the shortest distance between the light guide (4) and the blade (22) is equal to or more than 6 mm.

5. Light device (2) according to anyone of claims 1 to 4, characterized in that the light source (36) is controlled by a control unit (38) configured for controlling the intensity of the light beam emitted over time.

6. Light device (2) according to anyone of claims 1 to 5, characterized in that it comprises means for traveling and / or pivoting the blade (22) in relation to the light guide.

7. Light device (2) according to anyone of claims 1 to 6, characterized in that the blade (22) forms an angle with the light guide (36) the amount of which is between 0° and 45°.

8. Signaling and / or lighting device or a motor vehicle comprising a light device (2) according to anyone of claims 1 to 7.

9. Motor vehicle comprising a signaling and / or lighting device according to claim 8.