FR2872256A1 - Lighting and/or signaling device e.g. taillight, for motor vehicle, has optical waveguide diffracting light beam by lateral reflection of light beam and comprising groove and non traversing orifices - Google Patents

Abstract

The device has an optical waveguide (G) comprising an end (e1) illuminated by an LED (3) and non traversing orifices. The orifices are situated opposite to a light engine (2) and have thickness same as that of the waveguide. The waveguide diffracts the light beam by lateral reflection of the beam and has a groove (9). The waveguide assures a dispersion of axial and lateral light rays, or only lateral ray. An independent claim is also included for a motor vehicle equipped with a lighting and/or signaling device.

Description

Illuminating and / or signaling device with optical guide for

vehicle

  FIELD OF THE INVENTION The invention relates to a lighting and / or signaling device equipping a motor vehicle and comprising at least one light engine and an optical guide capable of propagating the light axially and laterally. The invention also relates to a vehicle comprising such a lighting or signaling device.

  The invention has applications in the field of vehicles on the road and, in particular, motor vehicles. It finds, in particular, applications in the field of lighting and signaling of these vehicles on the road.

  STATE OF THE ART In the field of lighting and signaling of motor vehicles, various types of devices are known among which we find essentially: lighting devices located at the front of the vehicle with, in particular, projectors vehicles equipped with position lamps of low light intensity and range, low beam, or codes, having a higher luminous intensity and a range on the road of approximately 110 meters, and high beam with a long light range and producing an area of vision on the road of approximately 200 meters, - lighting devices at the rear of the vehicle including, in particular, the reversing lights, - signaling devices at the front of the vehicle with, in particular , direction indicators and daytime running lights also known as DRL, (which is the abbreviation of Daytime Running Light), and - signaling devices s at the back of the vehicle, including, fog lights, rear lights, direction indicators and brake lights.

  Currently, it is known to use, in lighting devices and / or signaling devices, one or more optical guides for propagating a light beam. An example of such a lighting device is described in EP-A-0515921. This device is intended to provide illumination inside a vehicle by being incorporated in a door handle. The luminous intensity in a direction orthogonal to the length of the optical guide has no preferred zone and remains relatively low.

  Now, it is desirable that a signaling or lighting device, generally oriented towards the outside of a vehicle, makes it possible to attract the attention of other drivers and pedestrians.

  In addition, it is interesting for a car manufacturer to use a particular signage or lighting to give, by its visual appearance, a particular style to its vehicles.

  DISCLOSURE OF THE INVENTION The purpose of the invention is precisely to remedy the disadvantages of the techniques mentioned above. To this end, the invention proposes a lighting or signaling device in which the light emitted by the light source can be propagated by the optical waveguide, on the one hand, axially to create an area of high light intensity and, d on the other hand, laterally to create a zone of less luminous intensity over a greater length. For this, the device of the invention comprises at least one optical guide and at least one light source, placed near the optical guide. The optical guide comprises, in its thickness, at least one orifice located opposite the light source and ensuring a distribution of light rays axially and laterally.

  More specifically, the invention relates to a lighting and / or signaling device, for a motor vehicle, comprising - at least one light engine, comprising at least one light-emitting diode emitting a light beam in the direction of the engine, in particular according to the axis of said motor and - at least one optical guide, one end of which is illuminated by the or at least one of the electroluminescent diode (s), this optical guide being able to emit light, in particular on all or part of its length, - the optical guide comprising at least one orifice formed in the thickness of said optical guide and located opposite the light engine, and deviating the light beam, in particular by a lateral reflection thereof.

  The optical guide therefore has an end which receives the light beam emitted by the or at least one of the light-emitting diodes. Such an optical guide ensures a distribution of the light rays axially or laterally.

  The invention may include one or more of the following features: - the orifice is a through hole.

  - The optical guide has two non-through holes.

  - The optical guide has a groove made in the thickness of said guide, along the length of the optical guide. Such a throat ensures a diffusion of light rays to the exit face of the guide.

  - The groove has a diffusing zone located at the bottom of the groove of the optical guide. This diffusing zone makes it possible to accentuate the diffusion effect of the throat.

  the diffusing zone is close to the center of the section of the optical guide.

  the diffusing zone is provided with micro-diffusions whose dimension is of the order of one tenth of a millimeter.

  the micro-diffusions may be micro-prisms, roughness, micro-fresnel or depolis, etc. - The throat of the optical guide has a progressive form.

  - The light engine is placed in a central position, between at least two parts of the optical guide. In this way, the light rays can be emitted in both parts of the optical guide.

  The invention also relates to a motor vehicle equipped with at least one such lighting device and / or signaling.

Brief description of the drawings

  Figure 1 shows a partially sectional view of a first embodiment of the device according to the invention.

  FIG. 2 represents a partially sectional view of a second embodiment of the device according to the invention.

  Figure 3 shows a view of a section of the optical guide according to the invention.

  Figure 4 shows a perspective view of an example of an evolutive groove.

  FIG. 5 represents an example of evolution of the light in the optical waveguide of FIGS. 1 and 2.

  FIG. 6 represents an exemplary signaling device with hot spots and linear zones.

  DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION The invention relates to a lighting or signaling device for a motor vehicle for axial and / or lateral diffusion of light. This device comprises at least one light engine emitting a light beam and at least one optical guide for propagating and emitting along its length this light beam.

  A first embodiment of the lighting or signaling device of the invention is shown in Figure 1. This Figure 1 shows a partially sectional view of an optical guide and a light engine according to the invention.

  The optical guide is an elongate solid element, for example having a cylindrical section, of transparent material which ensures the propagation of the light beam emitted by the light source from an end close to the light source to an opposite end. The section of the guide may be different, for example oval or polygonal of the square type, or cylindrical base but with prisms or local reliefs. This optical guide can have different geometric shapes. It may, for example, have the shape of a circle, an arc or be rectilinear or have curved areas and rectilinear areas. In the embodiment shown in FIG. 1, the optical guide is of rectilinear type with a cylindrical section. Such a rectilinear optical guide can be used, for example, in the production of a raised brake light, that is to say the third brake light situated opposite the rear window of a vehicle and designated by CHMLS (Central High Mounted Lamp Stop, in Anglo-Saxon terms).

  In the embodiment of Figure 1, the optical guide G has a first guide portion G1 and a second guide portion G2. Each guide portion G1 and G2 has a first end el, common to both parts, and a second end e2, opposite the end el. The optical guide G receives the light beam emitted by the light engine 2, in the vicinity of the end e1. In other words, the light engine 2 which emits the light beam is placed close to the central zone of the optical guide G, that is to say near the end el.

  The light engine 2 emits a treated beam of light. For this, the light engine 2 comprises a high-power LED 3 or LED, and an optical system for processing light. Preferably, the light emitting diode 3 is a hemispherical diode, lambertian type, that is to say it comprises a cone-shaped emitting zone, for example 120. Such a diode has the advantage of emitting a light beam in several directions. This light beam is then transformed by the optical system into parallel sessions.

  The optical system may comprise a reflector whose role is to modify the distribution of the light flux of the light-emitting diode. It may include a Fresnel lens that deflects light to produce a uniform distribution of light. The light engine 2 thus ensures the emission of light and its transformation into parallel beams, ready to be redistributed in the optical guide G. Thus, the light beam is emitted by the light engine 2, in the optical guide G, in a main direction of emission, or axial direction, that is to say along the X axis of the light engine 2. In other words, the rays emitted by the LED 3 are transformed by the optical system into parallel light rays. The light rays thus enter, through the end el, in the optical guide G, parallel or substantially parallel to the axis X. Some of the rays of this light beam pass axially through the guide: these are the axial light rays 4. These rays axial luminous 4 provide a first signaling function, that is to say that they form, on the output face 7 of the optical guide G, a bright spot of high intensity, called hot spot.

  Other rays of the light beam are totally reflected towards the ends e2 of the guide G: they are the lateral rays 5. The principle of the total reflection is an optical phenomenon which allows the transmission of light in an optical guide. When a light ray passes from one medium to another medium with a different refractive index, its direction is changed; it is the effect of refraction. For a certain angle of incidence, and if the index of the initial medium is greater than that of the final medium, the light ray is no longer refracted, it is totally reflected: it is called total reflection.

  More precisely, certain rays are reflected in the portion G1 of the optical guide, other rays are reflected in the portion G2 of said guide. It is understood that the light engine 2 can also be placed at the end of a single portion of the optical guide. In this case, the light beam has radii propagated axially and rays reflected to one side of the optical guide.

  In Figure 1, there is shown in detail, in a sectional view, the light rays in the portion G1 of the guide. Part G2 of the optical guide is shown in a perspective view.

  The optical guide G has two faces: a smooth first face 7, forming the exit face of the optical guide; a second face 8, opposite to the exit face 7, forming the diffusion face of the optical guide. This face 8 diffuses the light rays towards the exit face 7.

  This diffusion face 8 has a groove 9. This groove 9 is a transverse recess, or groove, forming a channel in the thickness of the optical guide G. This groove 9 serves to return the light to the outlet face 7, in particular in a diffuse manner, that is to say in the form of a light cone. Indeed, the light rays coming into contact with the bottom of the groove 9 are diffusely reflected, as a function of their angle of incidence, towards the exit face 7.

  To improve the refraction by the groove 9, it comprises, according to a preferred embodiment of the invention, a diffusing zone located on the bottom 6 of the groove 9. As explained in more detail later, this diffusing zone comprises micro diffusions which, depending on their shape, make it possible to diffuse the light beam with different patterns at the output of the optical guide G. As explained above, the light rays emitted by the light engine 2 can pass axially through the optical guide for forming a hot spot on the outlet face 7 or be reflected laterally in the optical guide G. This lateral reflection is obtained, according to the invention, by means of at least one orifice.

  In the embodiment of FIG. 1, the axial and / or lateral distribution is obtained by means of a single orifice 10. This orifice 10 is made in the central zone of the guide G, that is to say at the joining portions G1 and G2 of the optical guide G. This orifice 10 is described only for the portion G1 of the guide, it being understood that it is symmetrical, with respect to the axis X, in the part G2.

  This orifice 10 is a through opening made in the width of the optical guide. It is preferably produced in the central zone 11 of the guide, facing the light engine 2. This orifice 10, of asymmetric shape, creates flat areas and inclined zones, in the central zone 11. This difference in levels in the central zone 11 distributes the light beam according to the main direction of emission X and in lateral directions. The so-called lateral directions are non-axial directions, that is to say directions forming a non-zero angle with the axis X. A lateral direction may be, for example, the direction along the Y axis of the guide G, perpendicular to the X axis. It should be noted that the fact that the X and Y axes are perpendicular according to this example is not a necessity of the invention: the light engine can also be associated with the light guide so that their respective axes are not exactly perpendicular. It is understood by axis, (particularly with regard to the light guide which can be curved along its length), optionally the longitudinal axis passing through the tangent to the element when it is not substantially straight.

  Thus, when the light engine 2 emits a light beam, it propagates in the optical guide G. Some of the rays of this light beam (the radii referenced 4) are propagated in an axial direction X by the optical guide G. These axial radii 4 are propagated directly by the planar zones 10a of the orifice 10, towards the outlet face 7, without undergoing any deflection and / or reflection. In other words, part of the light rays 4 is directly distributed towards the output face 7 of the optical guide.

  Another part of the light rays 5 is deflected by the inclined zones 10b of the orifice 10. As a function of the angle of incidence of the light rays with the inclined zones 10b, the lateral rays 5, reflected by the inclined zones, can to have different trajectories in the optical guide: - these rays 5 can be sent, by total reflection, to the diffusion face 8 and then diffused, by this face 8, to the output face 7 of the optical guide. This diffusion is provided by the groove 9 itself and by the diffusing zone of said groove; these light rays 5 may undergo one or more internal reflections (refractions by the exit face 7 and the groove 9) before being returned, towards the outlet face 7, by diffusion through the groove bottom.

  The trajectory of these lateral rays 5 depends in particular on the shape and dimensions of the orifice 10. By modifying this shape and / or these dimensions, it is possible to modify the distribution of the light towards the main direction of emission X and towards the lateral directions.

  The lateral light rays 5 provide, in the device of the invention, a second signaling function, that is to say a linear signaling function. This second function consists of a lighting of less intensity than the first function but on a greater length. This signaling function of great length allows a highlighting effect or light junction of two hot spots.

  FIG. 2 represents a second embodiment of the device of the invention. As in FIG. 1, there is shown in this FIG. 2 the first portion G1 of the optical guide G in a sectional view and the second portion G2 of the guide in a perspective view.

  In this embodiment, the axial and / or lateral distribution of the light rays 4 and 5 is obtained by means of two orifices 12 and 13 made in the width of the optical guide. These two orifices 12 and 13 are non-emerging, that is to say they each form a cavity, or hollow, non-through. They are preferably made in the central zone 11 of the optical guide G, that is to say at the junction of the portions G1 and G2 of said guide. These orifices 12 and 13 are located facing the light engine 2. They create in the guides G1 and G2 different levels of cavities, with flat areas and inclined zones, which allows to distribute the light beam according to the main direction X and in lateral directions.

  As in the embodiment of FIG. 1, when the light engine 2 emits a light beam, this beam propagates in the optical guide G. Some of the rays of this light beam (the radii referenced 4) are propagated according to a axial direction X by the optical guide G. These axial radii 4 are propagated directly by the non-hollow zones, towards the outlet face 7, without undergoing deviation and / or reflection. In other words, a portion of the light rays 4 is directly distributed to the output face 7 of the optical guide thus providing a high intensity illumination forming a hot spot.

  Another part of the lateral light rays 5 is deflected by orifices 12 and 13. In fact, the orifices 12 and 13 make it possible to retain the light rays emitted by the light engine 2. These rays thus retained are sent by refraction into the optical guide G. Depending on the depth of the orifices 12 and 13, the lateral rays 5 may have different trajectories in the optical guide: a part of these lateral rays 5 is sent by reflection towards the diffusion face 8 and, more precisely, by the groove 9 of the face 8 which then ensures the diffusion of these rays to the exit face 7. This diffusion can be further improved by the presence of a diffusing zone located on the bottom 6 of the groove 9.

  another part of the lateral rays 5 undergoes internal multi-reflections in the guide, that is to say that these rays are reflected at least once towards the exit face 7 and then towards the diffusion face 8 before finally be broadcast to the output face 7 of the optical guide. In this embodiment, the reflection coefficient is close to 1, which has the effect that there is no or almost no loss of light energy during these multi-reflections.

  The trajectory of these lateral rays 5 depends in particular on the shape and the depth of the orifices 12 and 13. By modifying this shape and / or these depths, it is possible to modify the distribution of the light towards the main direction of emission X and towards the lateral directions.

  Thus, whatever the embodiment (that of Figure 1 or that of Figure 2), the light is distributed in the optical guide axially and laterally. It is distributed laterally in the portion G1 of the optical guide and in the portion G2 of said optical guide. In addition, multiple internal reflections propagate the light to the ends e2 of the optical guide G. The optical guide can thus be relatively long, for example of the order of 1300 mm.

  FIG. 3 represents a section of the optical waveguide G of FIGS. 1 and 2. Indeed, whatever the embodiment chosen (a through orifice or two non-through holes), the section of the optical waveguide is the same. It can thus be seen in FIG. 3 that the optical guide G has a generally circular section. It should be noted however that this section may have a different form of circular, for example rectangular. In the embodiments described, the section is generally circular with a diameter of the order of 8 to 12 mm.

  This FIG. 3 shows the exit face 7 of the optical guide G as well as the diffusion face 8 with its groove 9. This groove 9 has a hollow shape, for example a U shape, the base of the U being the bottom 6 of the 9. The bottom 6 of said groove is preferably close to the center of the optical guide, that is to say located near the axis of symmetry of the optical guide.

  This groove 9 has the main effect of diffusing light towards the opposite face, that is to say the exit face 7 of the optical guide. To improve the diffusion effect of the groove, the latter may include a diffusing zone 14. This diffusing zone 14 comprises diffusion means which make it possible to efficiently diffuse the light towards the exit face 7 of the optical guide G. These means diffusions can be micro-diffusions whose diameter is of the order of one-tenth of a millimeter.

  These micro-diffusions may have different patterns, for example: rectilinear or curved striations - micro-prisms triangular section - microfresnels, - optical micro-patterns, that is to say, holes of specific shape, made in the material to improve the homogeneous appearance of the optical guide.

- roughness or frosting.

  These different diffusion patterns give the optical guide a different visual appearance.

  The diffusing zone 14 forms a diffusing band on the bottom 6 of the groove 9. This diffusing band 14 has a width h which, preferably, is identical to the width of the bottom of the groove 9. The width h of the diffusing band 14 can be constant. It can also be scalable so as to widen the apparent luminance field for an observer.

  In Figure 4, there is shown, in a perspective view, an example of scalable groove. In this example, the shape of the groove 9 evolves between an end el and an end e2 of the portion G2 of the optical guide G. It is said that the throat undergoes a morphing, that is to say a progressive deformation of its shape . In this example, the end el, close to the light engine, has a shape of groove 9 different from that of the end e2. The evolution of the shape of the groove is a slow transformation of a groove with a small cylindrical section into a U-shaped groove. This is of course only an example. All kinds of evolutions can be envisaged, with enlargement of the section of the groove or reduction of this section or alternation of enlargement and decrease, all with change of shape of the section.

  The fact of choosing a cylindrical optical guide with a circular cross-section makes it possible to obtain, visually, an enlargement of the diffusing zone 14 by a conventional magnifying glass effect. Thus, the external visual appearance of the diffusion pattern is amplified by this magnifying effect.

  Figure 5 shows an example of a light evolution in an optical guide. This FIG. 5 shows an example of the visual appearance of an optical guide when the groove has a progressive shape. In this example, the evolution corresponds to an enlargement from a pseudo-circular section 15, from the end e2 to a central zone 16, to a totally flat zone 17. In other words, by a gentle evolution, the pseudo-circular section 15 is transformed into a surface section 17. For this, the U-shaped groove 9 has been stretched to form a large diffusing surface. This surface section 17 comprises the diffusing zone 14 of the groove 9. The diffusing zone 14 being relatively narrow, it spreads over the entire back of the surface section 17. Thus, the diffusing surface appears much larger for an outside observer , by a trompe l'oeil effect. This trompe l'oeil effect is obtained when the diffusing zone 14 is close to the center of the groove 9.

  An example of a signaling device according to the invention is illustrated in FIG. 6. In this example, several light engines 2 are placed along the same optical guide G to form a light line. By thus bringing together several light engines along the same optical guide, or several optical guides together, it is possible to realize optical zones of high luminous intensity alternating with less luminous zones and of great lengths.

  It will be understood from the previous description that the device of FIG. 6 comprises several hot spots, more precisely as many hot spots as there are light engines. Figure 6 shows three light engines 2 corresponding to three hot spots a, b, c. These hot spots a, b, c provide the first signaling function. The hot spots are interconnected by one or more optical guides providing the signaling function of great length.

  This long signal function can generate styling effects, for example by highlighting the shapes of a vehicle. The device of the invention allows, for example, to follow the rotation of the rear window or part of the body. It can also be used to illuminate interior door edges or raised stop lights.

  In addition to the advantages previously given (in particular axial and lateral diffusion), the device of the invention has advantages from the point of view of manufacture. The manufacture of this device, and in particular of the optical guide used in this device, can be achieved by injecting a transparent material into a mold. It can be monobloc, that is to say that the optical guide is made of a single piece, a housing being provided in the center of said guide for the light engine. The optical guide can also be made in several parts joined by connection zones containing the housing for the light engine. These bonding zones are polished in order to minimize the loss of luminous flux.

  Whatever the method of manufacture of the optical guide, the groove is formed in the thickness of said guide, during the injection of the material into the mold. The presence of this groove significantly reduces the amount of material and therefore the cooling time required. The groove, like the orifices, behaves like a source of cooling in the mold, thus allowing to evacuate the heat.

  The orifices may also be made during the injection of the material into the mold through the presence of parts whose shape corresponds to the desired shape of the orifices. These parts can be adjustable, which allows to change the depth of the orifices (in the second embodiment) which can thus be asymmetrical.

  The groove is made by means of a blade mounted in the mold.

  This blade is polished on each side allowing easy demolding the guide, after cooling. This blade may also have, on its inner edge, roughnesses which will form on the bottom of the groove patterns of micro-diffusions. These roughnesses may have dimensions of the order of 2 to 3 tenths of a millimeter. These roughnesses have complementary shapes of the desired micro-diffusion patterns.

  In the case where the micro-diffusions are optical micro-patterns, these can also be obtained, after cooling of the optical guide, by laser attack of the bottom of the groove.

Claims (1)

  1 - Lighting and / or signaling device, for a motor vehicle, comprising - at least one light engine (2), comprising at least one light-emitting diode (3) emitting a light beam towards the engine, in particular according to the axis (X) of said motor and - at least one optical guide (G), one end (el) of which is illuminated by the or at least one of the electroluminescent diode (s), said optical guide being able to emit light, especially over all or part of its length, characterized in that the optical guide comprises at least one orifice (10) formed in the thickness of said optical guide and located opposite the light engine (2), and deviating the beam bright, in particular by a lateral reflection of it.   2 - Device according to claim 1, characterized in that the orifice (10) is a through hole.   3 - Device according to claim 1, characterized in that the optical guide has two non-through holes (12,13).   4 - Device according to any one of the preceding claims, characterized in that the optical guide comprises a groove (9) formed in the thickness of said optical guide, along the length of the guide.   - Device according to claim 4, characterized in that the groove (9) comprises a diffusing zone (14) located on a bottom (6) of the groove.   6 - Device according to claim 5, characterized in that the diffusing zone (14) is close to the center of the section of the optical guide.   7 - Device according to one of claims 5 and 6, characterized in that the diffusing area is provided with micro-diffusions, the dimensions of which are preferably of the order of one tenth of a millimeter.   8 - Device according to claim 7, characterized in that the microdiffusions comprise micro-prisms, roughness, micro-fresnel, frosted.   9 - Device according to any one of claims 4 to 8, characterized in that the groove (9) has a progressive form.   - Device according to any one of the preceding claims, characterized in that the light engine is placed in a central position between at least two parts (G1, G2) of the optical guide.   11 - Motor vehicle, characterized in that it is equipped with at least one lighting and / or signaling device according to any one of the preceding claims.