Lighting device with dog-legged light guide(s)

Abstract

A lighting device (DE) comprises N light guides (GL) each comprising a first portion (P1) that receives, through an end face (FE), photons generated by an associated source (S), and a second portion (P2) that comprises a front face (FV) through which photons issuing from this first portion (P1) exit, with N ≥ 1. The first portion (P1) of each light guide (GL) has at least one curvature defining a dogleg and constraining photons that enter through its end face (FE) to end up at the front face (FV) of the second portion (P2) after at least one internal reflection in this first portion (P1).

Description

[0001] DESCRIPTION

[0002] TITLE: LIGHTING DEVICE WITH ANGLED LIGHT GUIDE(S)

[0003] Technical field of the invention

[0004] The present invention claims priority from French application 2203828 filed on 04 / 25 / 2022, the content of which (text, drawings and claims) is incorporated herein by reference. The invention relates to lighting devices which comprise N light guides associated with N photon sources, with N > 1, and which must participate in the realization of at least one photometric function.

[0005] State of the art

[0006] In the following, the term "photometric function" means a photometric signaling function, a photometric lighting function or a photometric function for a light effect, possibly decorative.

[0007] In certain fields, such as for example that of vehicles, possibly of the automobile type, lighting devices are used comprising N light guides which each comprise a first part receiving via an end face photons generated by an associated source and a second part which comprises a front face through which photons from this first part emerge, with N > 1. The N light guides and the N associated sources are generally housed in an internal housing (or cavity) which is defined by a casing and a glass located in front of the second parts of the N light guides.

[0008] It should be noted that such lighting devices may be part of (or constitute) optical units (front or rear) of vehicles responsible for providing at least one photometric function. In this case, the photometric function may, for example, be a signaling function, such as a daytime running light function (or DRL ("Daytime Running Light (or Lamp)" - light signaling automatically switched on when the vehicle is put into operation during the day)), or a direction indicator function (or flashing light), or a position light function.

[0009] When the second part of each light guide has a bent (or curvilinear) sub-part, the end face of the first part and the associated source are located substantially in the axis of this bent sub-part. Consequently, the front face of each bent sub-part of a second part constitutes a "hot spot" which appears, for a person placed in front, notably brighter than the sub-part of the second part which follows this bent sub-part, even though it is desired to obtain a relative homogeneity of the illumination on the visible front face of this second part. This results from the fact that the photons penetrating through the end face of a first part reach the bent sub-part after a reduced number of reflections at obtuse angles, which are also large, and therefore can exit at this bent sub-part, in particular by reflections or diffractions, constituting light leaks.

[0010] To avoid these unwanted exits (or light leaks), it is possible to install a mask (or cover) locally against each bent sub-section. However, this results in a significant additional cost for the lighting system.

[0011] It is also possible to use a two-colored glass (crystal / black) in which each black area is intended to mask a technical part and / or at least part of at least one bent sub-part, in order to prevent the photons released by each bent sub-part from passing through the glass and therefore creating a visible hot spot. But this has a negative impact on the style and / or perceived quality of the lighting device, because a person placed in front of it observes a large black and opaque area without understanding the reason when it is not in operation.

[0012] The invention therefore aims in particular to improve the situation.

[0013] Presentation of the invention

[0014] For this purpose, it proposes in particular a lighting device comprising N light guides, each comprising a first part receiving photons generated by an associated source via an end face and a second part comprising a front face through which photons from this first part emerge, with N > 1.

[0015] This lighting device is characterized by the fact that the first part of each light guide has at least one curvature defining an elbow and forcing the photons penetrating through its end face to reach the front face of the second part after at least one internal reflection in this first part.

[0016] Thanks to the invention, it becomes impossible for photons from a source to propagate to the front face of a second part of a light guide either directly without any reflection, or indirectly with at least one reflection at a very obtuse angle.

[0017] The lighting device according to the invention may include other characteristics which may be taken separately or in combination, and in particular:

[0018] - the first part of each light guide may have two different curvatures defining two successive bends and forcing the photons penetrating through its end face to reach the front face of the second part after at least two internal reflections in this first part;

[0019] - it may comprise a housing in which the N light guides are installed and comprising a rear part comprising a wall provided with N first through holes each located opposite the end face of a first part of a corresponding light guide and having an external face in front of which the source which is associated with this light guide is installed;

[0020] - in the presence of the last option, it may include a support part to which the N sources are coupled and installed on the external face of the wall of the rear part of the housing in front of the first N through holes;

[0021] - in the presence of the last sub-option, the support part can be installed in a liquid- and dust-tight manner on the external face of the wall of the rear part of the housing;

[0022] - in the presence of the last sub-option, the support part can provide a heat exchanger function;

[0023] - it can comprise N supports on each of which is installed a second part of a corresponding light guide;

[0024] - in the presence of the last option, each support may comprise a rear part located in front of the wall of the rear part of the housing and comprising a second through hole located opposite a corresponding first through hole and allowing the passage of photons, coming from the end face and exiting at a bend of the first part of the corresponding light guide, towards an area of ​​the housing which is invisible from the outside of the latter.

[0025] The invention also proposes a vehicle, possibly of the automobile type, and comprising at least one lighting device of the type presented above.

[0026] For example, each lighting device may constitute a front or rear optical unit providing at least one photometric lighting or signaling function.

[0027] Brief description of the figures

[0028] Other characteristics and advantages of the invention will appear on examining the detailed description below, and the attached drawings (obtained in CAD / CAM (“Computer Aided Design / Computer Aided Drawing”)), in which:

[0029] [Fig. 1] schematically illustrates, in a perspective view, a part of an exemplary embodiment of a lighting device according to the invention,

[0030] [Fig. 2] schematically illustrates, in a perspective view, the lighting device of Figure 1 without its support piece,

[0031] [Fig. 3] schematically illustrates, in a perspective view from the front side, a rear part of the lighting device of Figures 1 and 2, and

[0032] [Fig. 4] schematically illustrates, in a sectional view in a longitudinal and vertical plane at the level of a light guide, a part of the lighting device of figure 1.

[0033] Detailed description of the invention

[0034] The invention aims in particular to propose a lighting device DE having at least one light guide GL comprising a first bent part P1, in particular so as to prevent the creation of a hot spot on a bent sub-part SPC of the second part P2 which extends this first part P1 and comprises a front face FV through which photons participating in a photometric function exit.

[0035] It is considered in the following, by way of non-limiting example, that the lighting device DE is intended to be part of a motor vehicle, such as for example a car. But the invention is not limited to this application. Indeed, the lighting device DE can be equipment that can be added and used in numerous systems or that can be part of other equipment that is itself part of a system. Thus, the lighting device DE can be part of any vehicle (land, sea (or river), or air), any installation, including industrial type, any device (or system), including consumer type, and any building, for example.

[0036] Furthermore, it is considered in the following, by way of non-limiting example, that the lighting device DE constitutes an optical unit of a motor vehicle providing at least one photometric function. But this is not obligatory.

[0037] Furthermore, it is considered in the following, by way of non-limiting example, that the lighting device DE constitutes a front light. But it could constitute a rear light or a front headlight (or projector) of a vehicle.

[0038] Finally, taking into account the preceding choices, it is considered in the following, by way of non-limiting example, that the lighting device DE is intended to provide at least one photometric signaling function. For example, in the case of an application to a motor vehicle, this photometric signaling function may be a daytime running light (or DRL) function. But it could be a position light function (possibly partly on the side) or even a direction indicator function (or flashing light).

[0039] It should be noted, however, that the invention is not limited to photometric signaling functions. Indeed, the lighting device DE, according to the invention, is a lighting device capable of providing at least one photometric signaling or lighting or light effect function (possibly decorative).

[0040] In the above and the following, the notion of "front" is defined in relation to the place where the photons participating in the (a) photometric function exit, and the notion of "back" is defined in relation to the place which is opposite to that where the photons participating in the (a) photometric function exit. Consequently, the front face of an element is oriented outwards, while the back face of this element is oriented inwards and opposite to the front face.

[0041] Figures 1 to 4 schematically illustrate part of an exemplary embodiment of a lighting device DE according to the invention, here constituting a front optical unit of a vehicle.

[0042] As illustrated at least partially in Figures 1 to 4, a lighting device DE, according to the invention, comprises N light guides GL and N photon sources S associated respectively with these N light guides GL, with N > 1. It will be noted that in the example illustrated non-limitingly in Figures 1 to 3 the lighting device DE comprises three light guides GL and therefore also three photon sources S (i.e. N = 3). But a lighting device DE according to the invention can comprise any number N of light guides GL and photon sources S, provided that this number N is greater than or equal to one (1).

[0043] Each source S is arranged to generate photons when supplied with electric current.

[0044] For example, each photon source S may comprise at least one light-emitting diode (or LED) or at least one laser diode or gas laser or at least one bulb (possibly xenon). The choice of the type of each photon source S may depend on the (each) photometric function in which it participates. Also for example, and as illustrated non-limitingly in Figure 4, each photon source S may be installed on an electronic card CE which may be a printed circuit board of the PCB type.

[0045] Each light guide GL comprises a first part P1 and a second part P2 which extend each other. The first part P1 comprises an end face FE which receives the photons which are generated by the associated source S. The second part P2 comprises a front face FV through which photons emerge which come from the first part P1, and which have been reflected one or more times in the latter (P1).

[0046] As shown in Figures 3 and 4, the first part P1 of each light guide GL has at least one curvature which defines a bend and forces the photons entering through its end face FE to reach the front face FV of the second part P2 after at least one internal reflection in this first part P1.

[0047] In Figure 4, photon “paths” are shown by dashed lines.

[0048] It will be understood that due to the bent shape of each first part P1, it becomes impossible for the photons from the associated source S to propagate from the end face FE to the front face FV of the second part P2 either directly without any reflection, or indirectly with at least one reflection at a very obtuse angle. As a result, the photons reach the front face FV of the second part P2 with angles of incidence which favor either their reflection towards sub-parts located downstream from where they will emerge in a predefined general direction dg (adapted to the photometric function to be ensured), or their exit in this predefined general direction dg.In particular, if each second part P2 comprises a bent sub-part SPC, as illustrated in Figures 3 and 4, there is no longer any risk of creating a hot spot at this bent sub-part SPC since the photons can no longer propagate substantially in the axis of the latter (SPC), and therefore the front face FV of each second part P2, visible from the outside, appears to be subject to homogeneous illumination. It will be noted that this particular arrangement advantageously makes it possible to dispense with the local installation of a mask (or cover) against each bent sub-part SPC or the definition (or extension) of black zones intended to mask at least part of the bent sub-parts SPC.

[0049] It will be noted, as appears non-limitingly in Figure 3, that the first part P1 of each light guide GL can have two different curvatures which define two successive bends and force the photons penetrating through its end face FE to reach the front face FV of the second part P2 after at least two internal reflections in this first part P1. This makes it possible to further reduce the probability of a photon exiting at a bent sub-part SPC of a second part P2.

[0050] In the example illustrated in Figure 3, each first part P1 comprises a first bent sub-part comprising the end face FE and extending from top to bottom and from left to right, and a second bent sub-part extending the first bent sub-part extending from bottom to top to the start of the second part P2. This results from the fact that the sources S are placed above the end faces FE which are oriented upwards. But other arrangements corresponding to other orientations of the sources S and the end faces FE, and therefore also of the bends of the first parts P1, can be envisaged.For example, the FE end faces could be oriented downwards and in this case the S sources are placed below the FE end faces, or to the left and in this case the S sources are placed to the left of the FE end faces, or to the right and in this case the S sources are placed to the right of the FE end faces.

[0051] It will also be noted, as illustrated non-limitingly in Figures 1 to 4, that the lighting device DE may comprise a housing BB in which the N light guides GL are installed. It will be noted that in the example illustrated non-limitingly in Figure 4, the N light guides GL are housed in an internal housing L1 which is defined by the housing BB and a glass GD placed in front of the second parts P2 of the N light guides GL and forming part of the lighting device DE. But in an alternative embodiment in which the lighting device DE is part of an optical unit, the housing BB is part of the latter.

[0052] As illustrated in Figures 2 to 4, the housing BB comprises a rear part PRB comprising a wall PP which is provided with N first through holes T1 each located opposite the end face FE of a first part P1 of a corresponding light guide GL. In addition, and as illustrated in Figure 4, this housing BB has an external face opposite the internal housing L1 and in front of which is installed each source S associated with one of the N light guides GL. In other words, the N sources S are installed outside the housing BB (and therefore the internal housing L1), which makes them invisible to a person placed in front of the mirror GD and avoids having to define a mask in the internal housing L1 to mask them, and therefore makes it possible to reduce the space requirement in the latter (L1). In addition, this makes it possible to avoid the accumulation in the internal housing L1 of calories generated during operation by the N sources (and the associated electronics).

[0053] For example, and as illustrated non-limitingly in Figures 1 and 4, the lighting device DE may comprise a support piece PS to which the N sources S are coupled. This support piece PS is installed on the external face of the wall PP of the rear part PRB of the housing BB, in front of the first N through holes T1. This installation can be done by clipping and / or screwing, for example. When the N sources are installed on an electronic card CE, the latter (CE) is fixedly secured to the internal face of the support piece PS which is oriented towards the wall PP of the rear part PRB (and therefore towards the first N through holes T1), as illustrated non-limitingly in Figure 4.

[0054] It should be noted that this support part PS can be installed in a liquid- and dust-tight manner on the external face of the PP wall of the rear part PRB of the BB housing. This makes it possible to protect the N sources (and the associated electronics on the possible CE electronic card), but also to prevent the entry of liquid and dust into the internal housing L1, via the first N through holes T1. For example, this sealing can be obtained by means of small first PE1 and second PE2 closed peripheral walls (or ribs) defined respectively on the internal face of the support part PS and the external face of the PP wall of the rear part PRB of the BB housing, one surrounding the other, possibly with the interposition of a seal.

[0055] It should also be noted that the PS support part can possibly provide a heat exchanger (or radiator) function, in order to evacuate through its external face (opposite its internal face) the calories generated during operation by the N sources (and the associated electronics on the possible CE electronic card).

[0056] It will also be noted, as illustrated non-limitingly in Figures 1 to 4, that the lighting device DE may comprise N supports SG on each of which is installed a second part P2 of a corresponding light guide GL. This makes it possible to precisely position each light guide GL in the internal housing L1.

[0057] Each SG support can be a part which is attached to the internal face of the rear part PRB of the BB housing, for example by gluing, clipping or screwing, or can be an integral part of the rear part PRB of the BB housing, in particular when the latter (PRB) is produced by molding.

[0058] Furthermore, each support SG may, optionally and as illustrated non-limitingly, comprise a support face on which is placed the rear face FR of the second part P2 of the corresponding light guide GL and having a shape homologous to that of this second part P2. This makes it possible to position the second part P2 of each light guide GL even more precisely in the internal housing L1, but also to return by reflection inside the second part P2 concerned the photons which exit via its rear face FR.

[0059] It will also be noted, as illustrated non-limitingly in Figure 4, that each support SG may comprise a rear part located in front of the wall PP of the rear part PRB of the housing BB and comprising a second through hole T2 which is located opposite a corresponding first through hole T1. Each second through hole T2 advantageously allows the passage of photons, coming from the end face FE and exiting at a bend of the first part P1 of the corresponding light guide GL, towards a zone Z of the housing BB which is invisible from the outside of the latter (BB), in order to trap them. This avoids parasitic reflections of these photons, prematurely exiting from a first part P1, on at least one wall of the rear part PRB of the housing BB, and which could bring them back towards the glass GD by giving them an exit direction different from the predefined general direction dg.It should also be noted that in the illustrated example the N GL light guides are elongated with a circular section. But they could have sections with other geometric shapes (for example elliptical).

[0060] It should also be noted that the N GL light guides can be made in a molding phase with a plastic or synthetic material. For example, polycarbonate (or PC) or polymethyl methacrylate (or PMMA) can be used.

Claims

DEMANDS 1. Lighting device (ED) comprising N light guides (GL) each having a first part (P1) receiving by an end face (FE) photons generated by an associated source (S) and a second part (P2) having a front face (FV) through which exit photons from said first part (P1), with N > 1, characterized in that said first part (P1) of each light guide (GL) has at least one curvature defining a bend and forcing the photons entering by its end face (FE) to join said front face (FV) of the second part (P2) after at least one internal reflection in this first part (P1).

2. Lighting device according to claim 1, characterized in that said first part (P1) of each light guide (GL) has two different curvatures defining two successive bends and forcing the photons entering through its end face (FE) to join said front face (FV) of the second part (P2) after at least two internal reflections in this first part (P1).

3. Lighting device according to claim 1 or 2, characterized in that it comprises a housing (BB) in which said N light guides (GL) are installed and comprising a rear part (PRB) having a wall (PP) provided with N first through holes (T1) each located opposite said end face FE of a first part (P1) of a corresponding light guide (GL) and having an external face in front of which is installed the source (S) associated with this light guide (GL).

4. Lighting device according to claim 3, characterized in that it comprises a support piece (PS) to which said N sources (S) are coupled and installed on said external face of said wall (PP) of the rear part (PRB) of said housing (BB) in front of said first N through holes (T1).

5. Lighting device according to claim 4, characterized in that said support piece (PS) is installed in a liquid- and dust-tight manner on said external face of said wall (PP) of the rear part (PRB) of said housing (BB).

6. Lighting device according to claim 4 or 5, characterized in that said support piece (PS) provides a heat exchanger function.

7. Lighting device according to any one of claims 1 to 6, characterized in that it comprises N supports (SG) on each of which is installed a second part (P2) of a corresponding light guide (GL).

8. Lighting device according to claim 7 taken in combination with any one of claims 3 to 6, characterized in that each support (SG) comprises a rear part located in front of said wall (PP) of the rear part (PRB) of said housing (BB) and comprising a second through hole (T2) located opposite a corresponding first through hole (T1) and allowing the passage of photons, originating from said end face (FE) and exiting at the level of a bend in said first part (P1) of the corresponding light guide (GL), to an area of ​​said housing (BB) invisible from outside the latter (BB).

9. Vehicle, characterized in that it comprises at least one lighting device (ED) according to any one of claims 1 to 8.

10. Vehicle according to claim 9, characterized in that each lighting device (ED) constitutes a front or rear optical unit providing at least one photometric function of lighting or signaling.

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