EP2504619B1 - Lighting unit having light guide(s) inserted between a reflector and a screen - Google Patents

Description

The invention relates to lighting devices comprising light guides, and in particular those used in vehicles, possibly of the automotive type.

In certain fields, such as for example vehicle light units, light guides are used to form light bar species. These light guides are supplied with light, at at least one of their opposite ends, by light sources such as light-emitting diodes (or LEDs). The light propagates inside the light guide and is transferred to the outside by its external (lateral) face.

The use of a planar light guide makes it possible to produce lighting devices of relatively large dimensions, but prohibits the effects of style and / or three-dimensional effects (such as for example a volume or depth effect).

The use of a tubular light guide makes it possible to obtain some style effects, but prohibits the production of medium or large size lighting devices (the diameter is typically limited to about 1 cm for a question of luminous homogeneity ). Moreover, when a light guide is used in an optical block, it is essentially the light that it transfers at the level of the front part of its external face (oriented towards the optical block interface glass) which actually serves the lighting, which does not offer a good performance. To remedy this drawback, it has been proposed, in particular in patent documents FR 2850731 , EP 1036979 and US 2006/0193144 placing a reflector facing the rear part of the outer face of the light guide to reflect the light towards the inner part of this light guide, and as far as possible towards its front part. This solution noticeably improves light output, but it does not provide for various style effects, really three-dimensional effects.

The invention therefore aims to propose an alternative solution that improves the situation.

It is also known from the document DE102007010023 , a lighting device according to the preamble of claim 1. However, this document does not achieve the desired three-dimensional effect or to obtain a larger width of light guide effect with a limited number of LEDs.

It proposes for this purpose a lighting device according to the characterizing part of claim 1.

• la partie arrière de chaque guide de lumière peut être logée dans un logement que comprend son réflecteur dans une zone de section concave ;
• chaque partie centrale de l'écran peut être rainurée ou grainée ou sablée ou polie;
• son écran peut présenter une section concave qui est définie par une partie centrale et deux parties latérales, situées de part et d'autre de cette partie centrale, de manière à renforcer l'effet tridimensionnel et/ou l'effet de style ;
  • ➢ les parties latérales peuvent être transparentes et rainurées, ou transparentes et grainées, ou transparentes et sablées, ou transparentes et polies, ou encore métallisées ;
• son écran peut présenter une section de forme variable entre ses deux extrémités opposées ;
  • ➢ la section de l'écran peut présenter un évasement croissant ;
• la partie arrière de chaque guide de lumière peut comprendre une portion sensiblement plane ;
  • ➢ la portion sensiblement plane peut être munie d'un relief agencé de manière à favoriser la réflexion de lumière vers la partie avant de son guide de lumière ;
    • le relief peut être constitué de rainures sensiblement parallèles entre elles et sensiblement perpendiculaires à la direction générale du guide de lumière ;
      • o les rainures peuvent présenter une section de forme triangulaire ;
• chaque source de lumière peut comprendre au moins une diode électroluminescente ;
• son réflecteur peut comprendre au moins deux sections concaves qui sont destinées à être placées respectivement en regard des parties arrière de guides de lumière correspondants, et son écran peut comprendre au moins deux parties centrales qui sont destinées à être placées respectivement en regard des parties avant de ces guides de lumière correspondants ;
• chaque guide de lumière et/ou son réflecteur et/ou son écran peu(ven)t être réalisé(s) en polycarbonate (ou PC) ;
• son réflecteur peut comprendre une face interne métallisée.

The lighting device according to the invention may comprise other characteristics that can be taken separately or in combination, and in particular:

• the rear part of each light guide can be housed in a housing that comprises its reflector in a concave sectional area;
• each central part of the screen may be grooved or grained or sanded or polished;
• its screen may have a concave section which is defined by a central portion and two side portions, located on either side of this central portion, so as to enhance the three-dimensional effect and / or the style effect;
  • ➢ the lateral parts can be transparent and grooved, or transparent and grained, or transparent and sanded, or transparent and polished, or metallized;
• its screen may have a section of variable shape between its two opposite ends;
  • ➢ the section of the screen may have a widening flare;
• the rear portion of each light guide may comprise a substantially flat portion;
  • The substantially planar portion may be provided with a relief arranged so as to promote the reflection of light towards the front part of its light guide;
    • the relief may consist of substantially parallel grooves between they are substantially perpendicular to the general direction of the light guide;
      • the grooves may have a section of triangular shape;
• each light source may comprise at least one light emitting diode;
• its reflector may comprise at least two concave sections which are intended to be placed respectively opposite the rear parts of corresponding light guides, and its screen may comprise at least two central parts which are intended to be placed respectively facing the front parts of these corresponding light guides;
• each light guide and / or its reflector and / or its screen may be made of polycarbonate (or PC);
• its reflector may comprise a metallized inner face.

The invention also proposes an optical unit comprising at least one lighting device of the type of that presented above.

The invention may for example be used in the field of vehicles, possibly of the automotive type.

• la figure 1 illustre schématiquement, dans une vue en perspective, un premier exemple de réalisation d'un dispositif d'éclairage selon l'invention, avant assemblage,
• la figure 2 illustre schématiquement, dans une vue en perspective (du dessus), le dispositif d'éclairage de la figure 1 après assemblage,
• la figure 3 illustre schématiquement, dans une vue en perspective, l'une des deux extrémités du dispositif d'éclairage de la figure 1, avant assemblage, et
• la figure 4 illustre schématiquement, dans une vue en coupe transversale, un second exemple de réalisation d'un dispositif d'éclairage selon l'invention.

Other characteristics and advantages of the invention will appear on examining the detailed description below, and the attached drawings (obtained for the most part in CAD / DAO), in which:

• the figure 1 illustrates schematically, in a perspective view, a first embodiment of a lighting device according to the invention, before assembly,
• the figure 2 schematically illustrates, in a perspective view (from above), the lighting device of the figure 1 after assembly,
• the figure 3 schematically illustrates, in a perspective view, one of the two ends of the lighting device of the figure 1 , before assembly, and
• the figure 4 illustrates schematically, in a cross-sectional view, a second embodiment of a lighting device according to the invention.

The accompanying drawings may not only serve to supplement the invention, but also contribute to its definition, if necessary.

It is an object of the invention to provide a light guide (D) lighting device (D), which allows for many light style effects and / or three-dimensional (or 3D) effects.

In the following, it is considered, by way of non-limiting example, that the lighting device (D) is intended to be part of an optical unit (not shown) of a vehicle, possibly of automotive type. But, the invention is not limited to this application. A lighting device (D), according to the invention, can indeed equip any type of system, equipment or device, including interior or exterior building walls (possibly by providing additional sealing means to protect the electronic).

Note that the optical block can be a headlight (or front projector), a fire (rear).

We first refer to Figures 1 to 3 to present a first embodiment of a lighting device D according to the invention.

As illustrated, a lighting device D according to the invention comprises at least one light guide GL, at least one light source SL, a reflector RL and an EC screen.

In the non-limiting example illustrated on the Figures 1 to 3 , the (lighting) device D has only one light guide GL. But, it could include several, at least two, as is the case of the second example of realization illustrated on the figure 4 (which has three).

Each light guide GL has two ends E1 and E2 which are opposed to one another and at least one of which is coupled to a light source SL.

In the non-limiting example illustrated on the Figures 1 and 2 only the first E1 of the two ends of the light guide GL is coupled to a light source SL. But, it is conceivable that the two ends E1 and E2 are each coupled to a light source SL so as to enhance the homogeneity and / or the intensity of the illumination, and / or to create a style effect.

It will be understood that the light, which is generated by a light source SL, enters through an end face of the light guide GL, which is here at its first end E1, and propagates internally (that is, to say in its mass).

Each light source SL may comprise at least one light-emitting diode (or LED) whose light-emitting end is placed substantially against an end face of the first end E1 of the light guide GL, which has been chosen for the injection from light.

When using light-emitting diodes SL, it is advantageous that they be mounted on a support plate intended to allow at least their control and their power supply. This support plate may for example be a printed circuit board, of the PCB type ("Printed Circuit Board"), rigid or flexible ("type" Flex ").

Each light-emitting diode SL may be coupled to the light guide GL either directly, for example by gluing or by embedding in a hole defined in its injection end face, or indirectly, for example via the support plate.

Each light-emitting diode SL may be arranged to emit white light or a colored light. Moreover, in the presence of at least two light-emitting diodes SL, the latter can be arranged to emit lights of different or identical colors.

In the non-limiting examples illustrated on the Figures 1 to 4 each GL light guide has a generally circular cross section. But this is not obligatory. This section could indeed be rectangular or square or pentagonal or hexagonal, for example.

Moreover, in the nonlimiting example illustrated on the Figures 1 to 3 each GL light guide has at least one curvature. But, each GL light guide could have several curvatures (at least two), possibly in different planes, or none (purely rectilinear case). Note that in the presence of several light guides GL, the latter (GL) may have different shapes (and therefore curvatures).

It will also be noted, as illustrated without limitation, on the Figures 3 and 4 that the rear portion PR of each light guide GL may comprise a substantially planar portion PP for promoting the reflection of light towards the front portion PV. Moreover, as illustrated in no way on the figure 3 this substantially planar portion PP may advantageously be provided with an RF relief arranged so as to further promote the reflection of light towards the front portion PV.

Here, the term "rear part PR" is the part of a light guide GL whose outer face (perpendicular to an end face) is substantially oriented towards the reflector RL, and "front part PV" the part of a light guide GL whose outer face is substantially oriented towards the EC screen.

The RF relief is intended to optimize the transfer towards the front part PV of a light guide GL, on the one hand, of the light which has been reflected by the reflector RL, and on the other hand, of the light which is propagates inside this GL light guide.

Here, the term "light transfer" is understood to mean a deflection caused by a reflection or a refraction, or even a diffraction, at a material-air or air-material interface, and therefore at the level of the possible RF relief (side internal or external).

The RF relief may for example consist of grooves (or ribs, which amounts to the same) which are, on the one hand, substantially parallel to each other (and therefore here substantially perpendicular to the general direction of a light guide GL. It is important to note that because of the possible curvatures that a light guide GL presents, the grooves (or ribs) RF may no longer be locally parallel to one another (in particular in the curvature zones). understood as a general trend.

For example, the grooves (or ribs) RF may have a section of substantially triangular shape (possibly isosceles), or more generally in the form of sawtooth.

Note that the RF relief is not necessarily made of lines (grooves or ribs or streaks). It may indeed consist of three-dimensional (3D) patterns, possibly diffracting, or be arranged in the form of a diffraction grating.

Each GL light guide can for example be made by molding in a synthetic material, for example PC (polycarbonate) or PMMA. Moreover, each GL light guide may be optionally colored in the mass.

The reflector RL has at least one concave section and is intended to be placed facing a rear portion PR of each light guide GL in order to reflect towards a front portion PV of the latter GL of the guided light which is derived from each SL light source to which it is coupled.

It will be noted, as illustrated without limitation on the Figures 1 to 4 , that the rear part PR of each light guide GL can be housed inside a housing LR which comprises the reflector RL in a concave sectional area. This housing does not necessarily imply that the outer face of the rear portion PR of each light guide GL is partially or completely in contact with the inner face which defines a housing LR of the reflector RL. Indeed, it is conceivable that a light guide GL is slightly spaced from the inner face which defines a housing LR of the reflector RL.

In the non-limiting example illustrated on the figure 4 , the device comprises three GL light guides (here slightly different shapes). Therefore, its reflector RL comprises three housings LR respectively adapted to these three light guides GL.

It will be understood that each housing LR has a shape similar to that of the light guide GL which it must partially accommodate.

The reflective nature of the inner face of the reflector RL can come from a metallization (at least each LR housing it comprises).

Such a reflector RL can for example be made by molding in a synthetic material, for example PC (polycarbonate) or PMMA or PPTD40.

The EC screen has at least one central part PC which is transparent and which is intended to be placed facing at least part of the front portion PV of a light guide GL in order to be illuminated by the light it transfers to the outside and thus induce an effect of style and / or a three-dimensional effect.

Here, the term "three-dimensional (or 3D) effect" means a volume effect giving an observer an impression of mass and / or thickness (or depth) and / or fleshiness at least when the device D functions.

In the non-limiting examples illustrated on the Figures 1 to 4 the EC screen has as many concave sections as there are GL light guides. Thus, in the non-limiting example of Figures 1 to 3 , the EC screen has only one concave section, while in the non-limiting example of the figure 4 he understands three of them. It will be understood that each concave section defines a housing which has a shape similar to that of the light guide GL which it must partially accommodate, considered in the general direction of extension of this light guide GL.

Each screen portion EC concave section is defined by a central portion PC and two side portions PL which are located on either side of this central portion PC. It will be understood that each housing of the screen EC is intended to at least partially accommodate the front portion PV of the corresponding light guide GL.

This housing does not necessarily imply that the outer face of the front portion PV of each light guide GL is partially or completely in contact with the inner face which defines a housing of the EC screen. Indeed, it is conceivable that a light guide GL is slightly spaced from the inner face which delimits a housing of the EC screen.

Note that the two side portions PL of each concave section EC screen portion are intended to enhance the three-dimensional effect and / or the style effect offered by the device D (at least when it works). They make it possible to give the impression that the corresponding GL light guide is wider than it actually is, without the need to use more LEDs (which is of real interest economic).

It is important to note that each central part PC is a part to which the light is directed in a preferred manner by the arrangement of the reflector RL and the corresponding light guide GL. It therefore has a strong illumination compared to that of the associated side portions PL.

In order to further enhance the three-dimensional effect and / or the styling effect, the side portions PL may be either transparent and grooved, either transparent and grained, or transparent and sanded, or transparent and polished, or metallized. Sandblasting more particularly allows to induce a volume effect (strengthening of the width and thickness) when the device D works. The metallization makes it possible in particular to impart a volume effect when the device D does not work.

Alternatively or additionally, each central portion PC may be optionally grooved, or grained, or sanded, or polished. Sandblasting more particularly makes it possible to mask a light guide GL and to induce a volume effect (strengthening of the width and the thickness) when the device D operates.

Each zone separating two adjacent concave section EC screen portions may optionally be metallized.

It will be noted, as illustrated without limitation on the figure 2 , that the EC screen may have a section whose shape varies between its two opposite ends (respectively close to the ends E1 and E2 of the light guides GL). For example, and as illustrated without limitation, this section of the screen EC may have a flare that increases from the end which is located in the vicinity of the first end E1 of a light guide GL. But, increasing flaring and flaring flare sections can coexist.

The screen EC can for example be made by molding in a synthetic material, for example PC (polycarbonate) or PMMA or APEC (especially when it is located in a zone that can be thermally hot). Moreover, the screen EC can be optionally colored in the mass.

When the device D is part of an optical block, its screen EC is intended to be placed upstream of the lens of this optical block (that is to say on the inside).

The invention is not limited to the embodiments of lighting device and optical block described above, only by way of example, but it encompasses all the variants that can be considered by those skilled in the art in the the scope of the claims below.

Claims (13)

1. Lighting device (D) comprising at least two light guides (GL), each light guide comprising two opposite ends, at least one of which is coupled to a light source (SL), said lighting device further comprising a reflector (RL) having a concave cross section and intended to be placed opposite a rear part (PR) of each light guide (GL) in order to reflect guided light issuing from their respective light source (SL) towards a front part (PV) of each light guide (GL), and a screen (EC), characterised in that the screen (EC) comprises as many parts with a concave cross section as there are light guides (GL), each concave cross section being defined by a transparent central part (PC) and two lateral parts (PL) situated on either side of said central part (PC), so as to cause a three-dimensional and/or style effect, said concave cross section being intended to at least partially house the front part (PV) of the light guide (GL).
2. Device according to claim 1, characterised in that said rear part (PR) of each light guide (GL) is housed in a housing (LR) that said reflector (RL) comprises in a zone with a concave cross section.
3. Device according to one of claims 1 and 2, characterised in that each central part (PC) of the screen (EC) is grooved or embossed or shot blasted or polished.
4. Device according to one of claims 1 to 3, characterised in that said lateral parts (PL) are transparent and grooved, or transparent and embossed, or transparent and shot blasted, or transparent and polished, or metallised.
5. Device according to one of claims 1 to 4, characterised in that said screen (EC) has a cross section of variable form between its two opposite ends.
6. Device according to claim 5, characterised in that said cross section of the screen (EC) has an increasing splay.
7. Device according to one of claims 1 to 6, characterised in that the rear part (PR) of each light guide (GL) comprises a substantially planar portion (PP).
8. Device according to claim 7, characterised in that said substantially planar portion (PP) is provided with a relief (RF) arranged so as to assist the reflection of light towards said front part (PV) of its light guide (GL).
9. Device according to claim 8, characterised in that said relief (RF) consists of grooves substantially parallel to each other and substantially parallel to the overall direction of said light guide (GL).
10. Device according to claim 9, characterised in that said grooves (RF) have a triangular-shaped cross section.
11. Device according to one of claims 1 to 10, characterised in that each light source (SL) comprises at least one light emitting diode.
12. Optical unit, characterised in that it comprises at least one light device (D) according to one of the preceding claims.
13. Use of the lighting device (D) according to one of claims 1 to 11 and of the optical unit according to claim 12 in the vehicle field.

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