FR2871550A1 - Motor vehicle lighting and signaling device e.g. headlight or side marker light, has optical light guide with output side including profile with ridges, and reflecting side with indented profile forming light rays reflecting side - Google Patents

Abstract

The device has an optical light guide (5) including an output side (FS) to output light rays propagated in the guide, where the side (FS) has a profile including ridges. The guide has a reflecting side (FR) with an indented profile forming a light rays reflecting side. The reflecting side has a series of prisms (8), where facets of consecutive prisms form a truncated base angle (D).

Description

Lighting or signaling device with optical guide for a vehicle

  BACKGROUND OF THE INVENTION The present invention relates to a lighting or signaling device equipping a motor vehicle, comprising at least one optical guide capable of producing a homogeneous distribution of light. This optical guide includes prisms that allow to deflect the light rays. The invention also relates to a vehicle comprising such a lighting or signaling device.

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

  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, headlamps for vehicles with dipped-beam headlamps, or codes, with a range on the road of approximately 110 meters, and long-range headlamps with a viewing area on the road of approximately 200 meters, lighting at the rear of the vehicle with, in particular, the reversing lamps; - signaling devices at the front of the vehicle including, but not limited to, position lights, direction indicators and DRLs; (Daytime Running Light, in English term) or daytime running lights (whether or not integrated in headlamps carrying out the lighting functions mentioned above), and - signaling devices located at the rear of the vehicle with, in particular, fog lights, taillights, direction indicators and brake lights.

  Currently, it is known to use, in lighting devices or signaling devices, one or more optical guides for propagating a light beam. An example of a vehicle headlamp is described in US-A-6 107 916. This headlight comprises a light source and an optical guide, placed near the light source and propagating the light beam emitted by this light source. This light guide may run all or part of the mirror or reflector of the projector.

  An example of a projector is shown in Figure 1. More specifically, Figure 1 shows schematically the left projector of a vehicle. This projector emits a light beam directed substantially towards the front of the vehicle, that is to say along the Y axis of the road. This projector 1 comprises a protective glass 2 forming the exit face of the projector 1. It also comprises: a light source 3, emitting a light beam whose emission direction is represented by an arrow 4, and an optical guide 5, propagating said light beam 4.

  The optical guide 5 is a cylinder of transparent material provided with prisms, which ensures the propagation of the light beam 4 from an end and close to the light source 3 to an end e2 opposite the end el. This optical guide 5 can have different geometric shapes. It can, for example, form a circle, a circular arc or be rectilinear. In the case of Figure 1, the optical guide 5 follows the shape of the protective glass 2 of the projector 1.

  An example of the optical guide 5 of this headlamp is shown in more detail in FIG. 2. This FIG. 2 shows a sectional view of the optical guide 5. This optical guide 5 comprises two faces: a first face 6 constituting a face of output of light rays propagated in the optical guide 5; this exit face 6 is smooth and continuous; and - a second face 7, opposite to the first face 6 and constituting a reflection face of the optical waveguide; this reflection face 7 has a serrated profile, that is to say a profile in the form of saw teeth. This reflection face 7 comprises a succession of identical and symmetrical prisms 8. These prisms 8, placed side by side, form the saw teeth of the reflection face 7.

  According to a sectional view of the optical guide, each prism 8 has a substantially triangular shape. More specifically, each prism 8 has a triangle shape with a base 14, a facet 9 and a facet 10, flat and non-parallel. These facets 9 and 10 form between them an angle A, called the angle of the prism. The facets 9 and 10 form, with the axis X of the optical guide 5, respectively, angles B and C. The facet 9 of a prism and the facet 10 of a consecutive prism together form a bottom angle D The bottom angle D of each prism is in contact with a curve called bottom line 11. This bottom line 11 connects the vertex of all the angles D of the reflection face 6 of the optical guide 5. In other words, if it is considered that each prism 8 is a triangle, in its section, the bottom line 11 connects the base 14 of each triangle with the base of the consecutive triangle.

  It will be understood that the shape of each prism is considered triangular in a 2-dimensional view.

  FIG. 2 shows, by arrows 12 and 13, an example of a trajectory of a light ray propagating in an optical waveguide of the type described in US Pat. No. 6,107,916. light ray may be one of the light rays contained in the light beam 4 emitted by the light source 3. In this example, the light ray propagates in the optical guide 5 in a straight initial trajectory 12 until it meets a facet of a prism. This trajectory 12 forms, with the axis X of the optical guide 5, an angle of incidence E. When a light ray encounters a facet of a prism, for example the facet 10 of a prism 8, in the case of 2, the path 12 of the light beam is deflected by an angle F with respect to the initial trajectory 12. The deflected trajectory of the light beam is referenced 13. The deflection angle F between the trajectory 12 and the trajectory 13 is variable because linked in particular to the angles of the prisms. Thus, the light ray is redirected, by the prisms 8 of the reflection face 7, towards the exit face 6 of the optical guide 5.

  In the example of Figure 2, and for simplification of this figure, the path of a single light beam has been shown. It is understood that other light rays with other trajectories may propagate in the optical guide, these rays may have been reflected one or more times, by one or more prisms or the other face of the optical guide, before to reach a prism that redirects it to the exit face 6.

  In the example of FIG. 2, the deflection 13 of the light beam responds to the principle of total reflection in an optical guide. The principle of total reflection is an optical phenomenon that allows the transmission of light in an optical guide 5. When a light ray passes from one medium to another medium having 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 12 is no longer refracted, it is totally reflected: it is called total reflection.

  Thus, if we consider again Figure 1, it is understood that the light beam 4 must be distributed over the entire length of the optical guide, that is to say between the end el and the end e2. However, part of the light beam 4 is lost, with constant prisms, because the flow that passes through the section decreases as it spreads. It is therefore understood that at the end e2 of the optical guide 5, the quantity of light lost is greater than at the end e1, close to the light source 3. In other words, the light output is less than the end e2 that at the end el of the optical guide, which has the consequence that there is a natural decrease in the flow of light emitted along the optical guide. This decay is visible to anyone outside the vehicle.

  Also, for visual reasons, it is sought to improve / better control the emission of light by lighting and / or signaling devices using light guides, in particular to improve the homogenization of the light distributed / emitted by these guides.

  DESCRIPTION OF THE INVENTION The purpose of the invention is precisely to remedy the problems of the techniques mentioned above. It proposes a lighting device and / or signaling optical guide, in which the light is distributed uniformly and homogeneously along the optical guide. For this, the invention proposes an optical guide having a reflection face provided with a succession of prisms, the angles between two consecutive prisms of the reflection face being, at least for some, truncated.

  More specifically, the invention relates to a lighting or signaling device for a motor vehicle comprising at least one light source emitting a light beam and at least one optical guide in which the light beam propagates, said optical guide comprising a first face forming an exit face of the light beam, and a second face, opposite to the exit face, having a serrated profile forming a reflection face of the light beam and comprising a succession of prisms, each prism forming, with the following prism, a bottom angle, characterized in that at least one bottom angle of the reflection face is truncated.

  The invention may comprise one or more of the following features: at least some of the bottom angles of the reflection face comprise a truncated zone, the size of the truncated zone being variable from one angle to another. Such a truncated zone makes it possible to modulate and control the efficiency of each prism, that is to say the flux exiting locally from a prism with respect to the total flux passing through the section of the guide at this prism, and of optimize the homogeneous appearance of the light emitted by the light guide along its length.

  - The size of the truncated areas decreases as the distance of the light source; the second face comprises both truncated bottom-angle prisms and non-truncated bottom-angle prisms; in a first variant, the prisms have variable pitch and a constant height, which makes it possible to modulate the output of each prism while modulating the visual effect; according to a second variant (which can be associated with the previous one), the prisms have a constant pitch and variable heights, which also makes it possible to modulate the output of each prism, with a simple embodiment to be implemented; the pitch of the prisms has a dimension of the order of 0.2 to 2 mm; The height of the prisms is of the order of 0.2 to 2 mm; the prisms (or at least one of them) of the reflection face are symmetrical. This embodiment is preferable when the device comprises several light sources (in particular one at each end of the guide) - the prisms (or at least one of these) of the reflection face are asymmetrical, which allows a better performance of the light sources. prisms, and is also preferable when a single light source is used to power the guide, the device comprises at least two light sources each placed at one end of the optical guide; the device comprises several optical guides having a common intersection, at least one light source being located at this point of intersection; then there is a branched light guide, preferably with a source at the branches and possibly at least one of the ends of the branches of such a guide, - the first face has ridges, which allows to have radii luminous having a negative value exit angle with respect to the normal of the optical waveguide (the negative sign being understood with respect to the mean direction of propagation of the light in the guide) -the light sources may be standard of halogen type or be The invention also relates to a motor vehicle equipped with at least one lighting or signaling device according to the invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1, already described, represents an example of a vehicle headlamp equipped with an optical guide.

  Figure 2, already described, shows a sectional view of an optical guide of the prior art.

  Figure 3 shows a sectional view of an exemplary truncation optical guide according to the invention.

  FIG. 4 represents a sectional view of a first embodiment of a variable truncation optical guide according to the invention.

  FIG. 5 represents a sectional view of a second embodiment of a variable truncation optical guide according to the invention.

  Figure 6 shows a sectional view of an optical guide according to the invention in the case where the face of the guide sotie is striated.

  DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION The invention relates to an illumination or signaling device with an optical guide allowing a homogeneous and uniform diffusion of light. The device of the invention can be a projector like that of Figure 1 or a signaling device. Whether it is a projector or a signaling device, the optical guide has characteristics ensuring a homogeneous and uniform appearance to the light output of the optical guide. In the remainder of the description, a projector will be described, it being understood that it may also be a signaling device.

  An example of an optical guide according to the invention, which can be mounted in a projector of Figure 1, is shown in Figure 3. In the example to be described, the lighting device considered is a position light located in a projector at the front of a vehicle. Also, the optical guide, in this example, is curved and forms a circle or an arc.

  It is understood that the optical guide according to the invention may have other shapes such as, for example, rectilinear curve with one or more curvatures. FIG. 3 shows a sectional view of an optical guide intended to propagate a light beam emitted by the light source 3. In this embodiment, the optical guide 5 has a circular section; it is understood that it can also, in other embodiments, have an elliptical section, square, oval, square or even. This optical guide 5 has two faces: a first face 6 constituting an exit face of the light rays propagated in the optical guide 5; this exit face 6 may be smooth and continuous, as in FIGS. 3 to 5 or may comprise ridges, as shown later in FIG. 6; a second face 7, opposite the first face 6, constituting a reflection face of the optical guide 5; this reflection face 7 comprises a succession of prisms 8. These prisms 8 are placed side by side and provide a reflection of the light rays having a non-zero angle of incidence with the axis X of the optical guide 5.

  According to a sectional view of the optical guide 5, each prism 8 has a substantially triangular shape; each prism comprises a base 14, a facet 9 and a facet 10, flat and non-parallel. The facet 9 and the facet 10 of a prism 8 may be symmetrical with respect to an axis T perpendicular to the axis X of the optical guide, that is to say that they have dimensions and angles B and C identical, on both sides of the bisector T. It is said that the optical guide is symmetrical prisms. The facet 9 and the facet 10 may also be asymmetrical, that is, they have different dimensions and / or angles B and C. It is said that the optical guide is asymmetrical prisms.

  The facet 10 of a prism 8 and the facet 9 of a consecutive prism together form a bottom angle D. According to the invention, the bottom angle D of a prism 8 is truncated. In other words, at least some of the bottom angles D have a truncated area. This truncated area of the bottom angle D forms a flat surface 16. A flat 16 is therefore a flat part of the bottom line curve 11 shown in dashed lines in FIG. 3. In the example of FIG. 3, the line 11 is merged with the X axis of the optical guide 5.

  Everything happens as if the space between two prisms 8 formed an air prism 15: we then have, in the invention, the air primer 15 clipped type. In this case, the clipping of the air prisms 15 is made according to a section of the vertices of said air prisms. This section is made along the curve of the bottom line 11.

  As will be seen more precisely below, the flats 16 of the bottom angles D are preferably of geometric shape of the rectangle type. They can have different dimensions. These dimensions of the flats can vary from one optical guide to another. They can also be variable within the same optical guide. In this case, the flats 16 may have different dimensions for each bottom angle D associated with each prism. Some bottom angles D may also have no flat surface 16. In this case, the optical guide 5 comprises both bottom angles D with flats 16 and bottom corners D without flat, for example alternately.

  According to the invention, the bottom angle D between two prisms 8 is truncated, which allows a light ray to propagate in the optical guide 5 without touching one of the facets 9 or 10 of the prism. As a result, the light beam is reflected by the flat towards the exit face 6 so as to be totally reflected thereon. It then continues its propagation in the optical guide.

  For example, near the el end of the optical guide, a large portion of the light rays, emitted by the light source 3, are not reflected, because they do not meet facets 9 or 10 prism.

  These light rays continue their propagation in the optical guide 5 as if there were no prism. These light rays are thus directed towards the end e2 of the optical guide 5. The properties of the reflection face 7 are thus modified by the presence of these flats. In this way, between the ends e1 and e2 of the optical guide 5, the luminous flux coming out of the optical guide can be uniformly distributed over the entire length of the optical waveguide by this flattening phenomenon.

  The invention also makes it possible to obtain, at the output of the optical waveguide, a luminous flux distributed, voluntarily, in a non-uniform manner. In this case, the non-uniform distribution is controlled to obtain a particular visual effect, for example an alternation of illuminated areas and unlit areas.

  Thus, the bottom angles D make it possible to adjust the light input of the prisms 8 in the optical guide 5. It is then understood that an optical guide 5 according to the invention makes it possible to compensate for the decrease in the luminous flux passing through the optical guide between the end el and the end e2.

  The uniform or non-uniform but controlled distribution of the luminous flux is preferably obtained by means of variable flats and, more specifically, the width of the flats along the variable X axis. In a preferred embodiment, the size of the flats 16 is decreasing from the end e1 to the end e2 of the optical guide 5. This reduction in the size of the flats 16 makes it possible to optimize the guiding of the light rays propagating in the 5. Near the end el, the dimension of the flats 16 is large, thus allowing a large portion of the light rays not to encounter a facet 9 or 10 of prism and, thus, to continue their propagation toward the light. end e2. Near the end e2, the size of the flats 16 is smaller and smaller until it is zero. There is then a large amount of light rays that meet one of the facets 9 or 10 of a prism. These light rays are then reflected towards the exit face 6 of the optical guide 5.

  This reduction in the size of the flats 16 makes it possible to compensate for the natural luminous decay and, consequently, to uniformly regulate the luminance (that is to say the luminous intensity emitted by m) at any point of the optical guide. 5. As a result, the optical guide 5, as a whole, has a homogeneous appearance.

  In other embodiments, the size of the flats may be increasing from the end e1 to the end e2, or flat bottom angles may alternate with flat bottom angles, etc. FIG. 4 shows a first embodiment of a variable truncation optical guide, that is to say the size of the flats of which is variable. In the example of Figure 4, the flats 16 have decreasing dimensions between the end el and the end e2 of the optical guide 5, as explained above. As seen in the sectional view of the optical guide 5 of Figure 4, the flats 16a, 16b, ... 16n have different dimensions from each other and, more specifically, decreasing dimensions. This decrease is obtained by modulating the height of the prisms. More precisely, in the example of FIG. 4: the pitch 17 between two prisms is constant. Step 17 is the length connecting the apex of a prism with the apex of the consecutive prism. Step 17 is represented by a double arrow in FIG. 4. In other words, pitch 17 corresponds to the base of air prism 15. Step 17 between two prisms is preferably of the order of 0 , 2 to 2 millimeters the height 18 of the prisms 8 is variable. Height 18 is the distance between a point of a curve Z and a point of the bottom line 11 of the optical guide 5. The curve Z, shown in dotted lines in FIG. 4, is a curve connecting the apex of the angles A of each prism. The height 18 is represented by a double arrow in FIG. 4. Preferably, the height 18 is of the order of 0.2 to 2 millimeters.

  In the embodiment of FIG. 4, the height 18 of a prism 8 increases proportionally with the decrease in the size of the flat 16 corresponding to it. The reflection face 7 is contained between two curves, along the optical guide. One of the curves is the bottom line 11 and the other curve is the curve Z. FIG. 5 shows a second embodiment of an optical guide 5 with variable truncation. As in the case of FIG. 4, the flats 16 have decreasing dimensions between the end e1 and the end e2 of the optical guide 5. As can be seen in the sectional view of the optical guide 5 of FIG. flats 16a, 16b, ... 16n have decreasing dimensions. In this embodiment, the decay is obtained by modulating the pitch of the prisms. More precisely, in the example of FIG. 5: the pitch 17 between two prisms is variable. Step 17 is represented by a double arrow in FIG. 5. The pitch 17 between two prisms is preferably less than or equal to 2.5 mm, in particular of the order of 0.2 to 2 millimeters; the height 18 of the prisms 8 is constant. The height 18 is represented by a double arrow in FIG. 5. The height 18 is less than or equal to 2.5 mm, in particular of the order of 0.2 to 2 millimeters. In this embodiment, the pitch 17 of a prism 8 decreases in proportion to the decrease in the size of the flat 16 corresponding. Since the height 18 is constant, the curve Z is parallel to the axis X of the optical guide 5.

  The two embodiments that have just been described allow one and the other to achieve a decrease in the size of the flats. In addition, they offer the same light output and the same homogeneity of the light emitted by the optical guide 5 over its entire length. The choice of one or other of these embodiments depends on the visual appearance, or aesthetic, wanted.

  In an embodiment shown in Figure 6, the output face 6 of the optical guide is not smooth. She has a striated profile. In other words, the exit face 6 has ridges which make it possible to straighten the light rays at the exit of the optical waveguide, that is to say to make them leave the optical waveguide with a negative angle relative to the normal N to the light. X axis of the guide.

  These streaks can be of different shapes, for example, in the form of prisms or domes or a combination of prisms and domes.

  In the example of Figure 6, the grooves 24 have a dome-shaped profile, that is to say a curved profile. More specifically, according to a sectional view, each groove 24 has an arcuate shape. In other words, each stripe 24 forms a kind of dome forming, with the consecutive streak, a bottom angle H. Each stripe 24 of the outlet face 6 is located opposite a prism 8 of the reflection face. The streaks 24 therefore have a pitch identical to the pitch of the prisms 8 of the reflection face 7. In other words, the ridges 24 of the exit face 16 are located facing the active areas of the prisms 8 of the reflection face. This embodiment has the advantage of allowing a controlled distribution of light, which makes it possible to homogenize the appearance of the optical guide for an outside observer.

  In one embodiment, not shown in the figures, for the sake of simplification, the lighting or signaling device of the invention comprises at least two light sources each placed at one end of the optical guide. The optical guide can thus propagate light rays from both ends of the optical guide, which increases the length of the optical guide.

  In another embodiment of the invention, the lighting or signaling device comprises a plurality of optical guides placed so as to have at least one common intersection. A light source is placed at this point of intersection so as to emit light beams in each of the optical guides.

Claims (2)

13 Claims   1 - Lighting and / or signaling device for a motor vehicle comprising at least one light source (3) emitting a light beam (4) and at least one optical guide in which the light beam (4) propagates, said light bar having - a first face (6) forming an exit face of the light beam, and - a second face (7), opposite to the exit face, having a serrated profile forming a reflection face of the light beam and comprising a succession of prisms (8), each prism (8) forming, with the following prism (8), a bottom angle (D), characterized in that at least one bottom angle (D) of the reflection face is truncated.   2 - Lighting and / or signaling device according to claim 1, characterized in that at least some of the bottom angles (D) of the reflection face comprise a truncated area (16), the size of the truncated area being variable from one angle to another.   3 - A lighting and / or signaling device according to claim 2, characterized in that the size of the truncated areas (16) decreases as the distance away from the light source (3).   4 - A lighting and / or signaling device according to any one of claims 1 to 3, characterized in that the second face (7) comprises both truncated bottom angle prisms and background angle prisms. not truncated.     Lighting and / or signaling device according to any one of claims 1 to 4, characterized in that the prisms have variable steps (17) and a constant height (18).   6 - A lighting and / or signaling device according to any one of claims 1 to 4, characterized in that the prisms have a constant pitch (17) and variable heights (18).   7 - Lighting and / or signaling device according to claim 5 or 6, characterized in that the pitch (17) prisms has a dimension less than or equal to 2.5 millimeters, in particular of the order of 0.2 to 2 millimeters.   8 - A lighting and / or signaling device according to any one of claims 5 to 7, characterized in that the height (18) of the prisms is less than or equal to 2.5 millimeters, in particular of the order of 0.2 to 2 millimeters.   9 - A lighting and / or signaling device according to any one of claims 1 to 8, characterized in that the prisms of the reflection face are symmetrical.   - Lighting and / or signaling device according to any one of claims 1 to 8, characterized in that the prisms of the reflection face are asymmetrical.   11 - A lighting and / or signaling device according to any one of claims 1 to 10, characterized in that it comprises at least two light sources each placed at one end of the optical guide.   12 - A lighting and / or signaling device according to any one of claims 1 to 11, characterized in that it comprises a plurality of optical guides having a common intersection, at least one light source being located at this point of intersection .   13 Lighting and / or signaling device according to any one of claims 1 to 12, characterized in that the first face (6) comprises streaks.   14 - Motor vehicle, characterized in that it is equipped with at least one lighting and / or signaling device according to any one of claims 1 to 13.