FR3134166A1 - LIGHTING DEVICE WITH LIGHT GUIDE WITH MULTIPLE REFLECTION SIDES TO DISTRIBUTE PHOTONS - Google Patents

Abstract

A lighting device (DE) comprises N sources (S1-S3) generating photons and a light guide (GL) comprising N first parts (P11-P13) each receiving the photons generated by the associated source (S1-S3). and N first zones (Z11-Z13) receiving the photons from the first parts (P11-P13) and each comprising a first reflection face (A1-A3), having a first parabolic shape reflecting the photons received to transfer them according to a first general direction in a second part (P2), and a second reflection face (B11-B13) having a second parabolic shape reflecting the photons received to transfer them in a second general direction. The light guide (GL) also comprises N second zones (Z21-Z22) each reflecting the photons transferred in the second general direction to transfer them in a third general direction in the second part (P2) next to the photons having the first direction general. Figure to be published with the abstract: Fig. 1

Description

LIGHTING DEVICE WITH LIGHT GUIDE WITH MULTIPLE REFLECTION SIDES TO DISTRIBUTE PHOTONS Technical field of the invention

The invention relates to lighting devices which comprise N sources of photons, with N ≥ 1, and a light guide which must participate in the realization of at least one photometric function.

State of the art

In what follows, the term “photometric function” means both a photometric signaling function, a photometric lighting function or a photometric light effect function, possibly decorative.

In certain fields, such as for example that of vehicles, possibly of the automobile type, lighting devices are used comprising N sources generating photons, with N ≥ 1, and a light guide receiving in N first parts the photons generated by the sources respectively associated so that they are transferred into a second part, by means of at least one reflection face of parabolic shape, so that they participate in at least one chosen photometric function.

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

Thanks to the parabolic shape of each reflection face, the photons received by the latter can be reflected and transferred in a general direction in the second part which has a front face through which the transferred photons exit. Note that in a vehicle the general direction is usually parallel to the longitudinal direction.

When we want to obtain a visual effect of a flat and thin bar, the light guide is generally flat. Due to the very strong directivity of each flow of photons (propagating substantially in the general direction after reflection by one of the N reflection faces), the greater the extension of the front face of the light guide in the direction transversal (for example of a vehicle), the smaller the distance (or the step) separating two neighboring sources must be if we want this front face to appear completely and substantially uniformly illuminated. In this case, the larger the front face of the light guide, the greater the number N of photon sources and associated reflection faces must be, and therefore the greater the manufacturing cost and the electrical energy consumption of the device. lighting are important.

In order to improve the distribution of photons over the entire front face of the light guide, it has been proposed, in particular in patent document US-B2 10,436,406, to define in this light guide numerous optical structures defining prisms and lenses. . This makes it possible to slightly reduce the number N of sources and therefore the electrical energy consumption of the lighting device. But this significantly complicates the production of the light guide and therefore leads to a notable increase in its cost.

The invention therefore aims in particular to improve the situation.

Presentation of the invention

It proposes in particular for this purpose a lighting device comprising N sources generating photons, with N ≥ 1, and a light guide comprising N first parts each receiving the photons generated by an associated source and N first zones respectively receiving the photons from of the first parts and each comprising a first reflection face having a first parabolic shape capable of reflecting the photons received in order to transfer them in a first general direction into a second part comprising a front face through which the transferred photons exit.

This lighting device is characterized by the fact:

- that each first zone also comprises at least a second reflection face having a second parabolic shape capable of reflecting the photons received in order to transfer them in a second general direction, and

- that its light guide comprises N second zones each capable of reflecting the photons transferred in the second general direction in order to transfer them in a third general direction in the second part next to the photons having the first general direction.

Thanks to the invention, the photons can be distributed over the entire front face of the light guide, which makes it possible to obtain total and substantially uniform illumination of this front face, even though the complexity of the light guide is relatively low. .

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

- each first zone may comprise two second reflection faces having different main orientations relative to a main orientation of the first reflection face in order to reflect the photons received towards different sub-parts of the second associated zone so that they are transferred along the third general direction in the second part on either side of the photons having the first general direction;

- in the presence of the first option, each second reflection face can have a main orientation relative to a main orientation of the first reflection face which makes an angle whose absolute value is between 90° and 150°;

- each second zone can comprise, on the one hand, a third reflection face having a third parabolic shape capable of reflecting the photons transferred in the second general direction in order to transfer them in a fourth general direction, and, on the other hand, a fourth reflection face having a fourth parabolic shape capable of reflecting the photons transferred along the fourth general direction in order to transfer them into the second part following the third general direction;

- in the presence of the last option, the third and fourth reflection faces can have main orientations which form an angle between them between 80° and 100°;

- the first and third general directions can be parallel to each other;

- the photons transferred in the second part can participate in a single chosen photometric function;

- as a variant, the photons transferred in the second part following the first general direction can participate in a first chosen photometric function, and the photons transferred in the second part following the third general direction can participate in a second chosen photometric function different from this first chosen photometric function;

- the first chosen photometric function and/or the second chosen photometric function may be a signaling function(s).

The invention also proposes an optical unit suitable for equipping a vehicle and comprising at least one lighting device of the type presented above.

For example, this optical unit can be a front or rear light or a front projector.

The invention also proposes a vehicle, possibly of the automobile type, and comprising at least one optical unit of the type presented above.

Brief description of the figures

Other characteristics and advantages of the invention will appear on examination of the detailed description below, and the appended drawings (obtained in CAD/CAD (“Computer Aided Design/Computer Aided Drawing”)), on which :

schematically illustrates, in a perspective view from the side of the rear face, an exemplary embodiment of a lighting device according to the invention,

illustrates schematically, in a sectional view along line II-II of the , the lighting device of this same , And

illustrates schematically, in a sectional view along line III-III of the , the lighting device of this same .

Detailed description of the invention

The invention aims in particular to propose a lighting device DE having a light guide GL with multiple reflection faces to distribute the photons over the entirety of its front face FV.

We consider in the following, by way of non-limiting example, that the lighting device DE is intended to be part of an automobile type vehicle, such as for example a car. But the invention is not limited to this application. Indeed, the DE lighting device can be equipment that can be attached and used in numerous systems or that can be part of other equipment that is itself part of a system. Thus, the DE lighting device can be part of any vehicle (land, sea (or river), or air), of any installation, including industrial type, of any device ( or system), including the general public type, and any building, for example.

Furthermore, we consider in the following, by way of non-limiting example, that the lighting device DE is intended to form part of an optical unit constituting a front light of a motor vehicle and ensuring at least one function photometric. But the optical unit could constitute a rear light or a headlight (or headlight) of a vehicle, for example.

Furthermore, taking into account the preceding choices, we consider in what follows, by way of non-limiting example, that the DE lighting device is intended to provide at least one photometric signaling function. It should be noted, however, that the invention is not limited to photometric signaling functions. Indeed, the DE lighting device, according to the invention, is a luminous device capable of providing at least one photometric function of signaling or lighting or luminous effect (possibly decorative).

In what precedes and what follows the notion of “before” 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. Therefore, the front side of an element faces outward, while the back side of that element faces inward and opposite the front side.

We have schematically illustrated in Figures 1 to 3, an exemplary embodiment of a DE lighting device according to the invention, intended to be part of a vehicle optical unit (here a front light). It will be noted that such an optical unit generally and in particular comprises a housing delimiting, possibly with a protective glass, a cavity housing in particular a DE lighting device according to the invention, as well as possibly at least one mask intended to mask technical parts (such as for example the N photon sources Sn (n = 1 to N, with N ≥ 1) and the CE electronic card).

As illustrated in Figures 1 to 3, a lighting device DE, according to the invention, comprises at least N photon sources Sn (n = 1 to N, with N ≥ 1) and a light guide GL. It will be noted that in the example illustrated non-limitingly on the the lighting device DE comprises three sources of photons S1 to S3 (n = 1 to 3, i.e. N = 3). But a lighting device DE according to the invention can comprise any number N of photon sources Sn, as long as this number N is greater than or equal to one (1).

Each Sn source is arranged so as to generate photons when supplied with electric current.

For example, each photon source Sn may comprise at least one light emitting diode (or LED (“Light Emitting Diode”)) or at least one laser diode or a gas laser or even at least one bulb (possibly xenon). The choice of the type of each Sn photon source may depend on the (each) photometric function in which it participates.

Also for example, and as illustrated non-limitingly on the , each photon source Sn can be installed on a CE electronic card which can be a printed circuit board of the PCB type (“Printed Circuit Board”).

The light guide GL comprises N first parts P1n and a second part P2 which here extend mutually, N first zones Z1n respectively receiving the photons from the associated first parts P1n, and N second zones Z2n.

In the figures, photon “paths” are shown by dashed lines.

Note that in the example illustrated the light guide GL is of the flat type (or “flat guide”), because its thickness is small in its first(s) P1n and second P2 parts, compared to the other characteristic dimensions (length and width).

Each first part P1n receives at an input face FE the photons which are generated by the associated source Sn and which must be transferred into the second part P2 of the light guide GL. For example, and as illustrated without limitation in Figures 2 and 3, each input face FE can be located opposite the associated source Sn. But this is not obligatory, because a return or routing system can be considered if necessary.

As illustrated in Figures 1 to 3, the second part P2 of the light guide GL comprises a front face FV through which the photons transferred to it (P2) exit in order to be illuminated.

Each first zone Z1n comprises a first reflection face An and at least a second reflection face Bnj. For example, and as illustrated without limitation in Figures 1 to 3, each first zone Z1n can be part of the first associated part P1n of the light guide GL. But this is not obligatory. Indeed, each first zone Z1n could be part of an intermediate part of the light guide GL, located between the first P1n and second P2 parts.

It will be understood, as illustrated in Figures 1 to 3, that each first zone Z1n is defined hollowly in the thickness of the light guide GL.

Each first reflection face An has a first parabolic shape which is suitable for reflecting the photons received in order to transfer them along a first general direction d1 in the second part P2, as illustrated in the . It will be noted that in a vehicle the first general direction d1 is generally substantially parallel to the longitudinal direction.

Each second reflection face Bnj has a second parabolic shape which is suitable for reflecting the photons received in order to transfer them in a second general direction d2.

Each second zone Z2n is capable of reflecting the photons which have been transferred along the second general direction d2 in order to transfer them along a third general direction d3 in the second part P2 so that they exit through its front face FV next to the photons which have the first general direction d1.

It will be understood that if the first flow of photons having the first general direction d1 arrives in a first sub-part of the front face FV, then a second flow of photons having the third general direction d3 arrives in a second sub-part of the face before FV which is located next to this first sub-part. The notion of “next door” is not exclusive of a small overlap between neighboring sub-parts. In the example illustrated non-limitingly on the , a second sub-part of the front face FV is located to the right or to the left of the first sub-part of the front face FV.

Thus, it is now possible to distribute the photons over the entire front face FV and therefore to obtain total and substantially uniform illumination of the latter (FV), despite the very strong directivity of each flow of photons, which allows the device DE lighting to participate in the impression of quality or appearance of the system (here a vehicle) that it equips. This is particularly advantageous when the lighting device DE comprises at least two Sn sources (as illustrated), because this makes it possible to increase the distance (or the pitch) between neighboring Sn sources, and therefore also to reduce the number N of Sn sources, and thus reduce the manufacturing cost and the electrical energy consumption of the DE lighting device. It will be understood that this double advantage makes it possible to use light guides GL having a front face FV having a significant extension (for example in the transverse direction (when the second flow is placed to the right or left of the first flow as illustrated) or vertical (when the second flow is placed above or below the first flow)). In addition, the complexity of the GL light guide remains relatively low, particularly compared to that of the light guide described in the aforementioned patent document US-B2 10,436,406.

For example, and as illustrated without limitation on the , each first zone Z1n can comprise two second reflection faces Bn1 and Bn2 (j = 1 or 2) having different main orientations relative to the first reflection face An. Here we mean “main orientation” the normal to the center d 'a face of reflection.

This makes it possible to reflect the photons received towards different sub-parts of the second associated zone Z2n so that they are transferred along the third general direction d3 in the second part P2 on either side of the photons having the first general direction d1 . It will be understood that in this case, illustrated on the , if the first flow of photons having the first general direction d1 arrives in a first sub-part of the front face FV, then a first second flow of photons having the third general direction d3 arrives in a first second sub-part of the face front FV which is located on a first side of this first sub-part, and a second second flow of photons having the third general direction d3 arrives in a second second sub-part of the front face FV which is located on a second side of this first sub-part (opposite to the first side). The notion of “next door” is not exclusive of a small overlap between neighboring sub-parts.

In the example illustrated non-limitingly on the , a first second sub-part of the front face FV is located to the right of the first sub-part of the front face FV and a second second sub-part of the front face FV is located to the left of the first sub-part of the front face FV. But in a variant embodiment the first and second second flows could be placed respectively above and below the first flow.

For example, each second reflection face Bnj can have a main orientation relative to the main orientation of the first reflection face An which makes an angle whose absolute value is between 90° and 150°. This means, for example, that the main orientation of the first second reflection face Bn1 (j = 1) makes an angle relative to the main orientation of the first reflection face An which is between +90° and + 150°, and that the main orientation of the second second reflection face Bn2 (j = 2) makes an angle with respect to the main orientation of the first reflection face An which is between -150° and -90° . Preferably, the absolute value of each angle is between 100° and 140°.

It will be noted that the absolute values of the angles made respectively by the main orientations of the first Bn1 and second Bn2 second reflection faces with respect to the main orientation of the first reflection face An are identical here. But we could envisage a variant of realization in which the absolute values of the angles which respectively make the main orientations of the first Bn1 and second Bn2 second reflection faces with respect to the main orientation of the first reflection face An are different.

It will also be noted, as illustrated without limitation in Figures 1 to 3, that each second zone Z2n can comprise third Cn and fourth Dn reflection faces. As illustrated on the , the third reflection face Cn has a third parabolic shape which is suitable for reflecting the photons which have been transferred along the second general direction d2, in order to transfer them along a fourth general direction d4. Also as shown in , the fourth reflection face Dn has a fourth parabolic shape which is suitable for reflecting the photons which have been transferred along the fourth general direction d1, in order to transfer them into the second part P2 following the third general direction d3. We thus have a 180° return system, which makes it possible to return towards the front face FV with the third general direction d3 the photons which have been reflected along the second general direction d2 towards a second zone Z2n (or rear side).

For example, the third Cn and fourth Dn reflection faces can have main orientations which form an angle between them between 80° and 100°. As an illustrative example, and as illustrated in Figures 1 to 3, this angle can be equal to 90°.

It will also be noted that in the example illustrated non-limitingly in the figures the first d1 and third d3 general directions are parallel to each other. But this is not an obligation.

In a first embodiment, the photons transferred in the second part P2 can participate in a single chosen photometric function, whether they have a first d1 or third d3 general direction of propagation. For example, in the case of an application to a motor vehicle this single photometric function can be a signaling function, such as for example a daytime running light (or DRL (“Daytime Running Light (or Lamp)”) function or a position light function (possibly in the side part) or even a change of direction indicator function (or flashing light).

In a second embodiment, the photons transferred in the second part P2 following the first general direction d1 can participate

to a first chosen photometric function, and the photons transferred in the second part P2 following the third general direction d3 can participate in a second chosen photometric function which is different from the first chosen photometric function. For example, in the case of an application to a motor vehicle, the first photometric function can be a signaling function, such as for example a direction change indicator (or flashing) function, and the second photometric function can be a other signaling function, such as a daytime running light (or DRL) or position light function.

Note also, as illustrated non-limitatively in the , that each first reflection face F1j and/or each second reflection face Bnj can be subdivided into at least two sub-parts (or facets) which together contribute to its definition.

It should also be noted that the GL light guide can be produced at least in a molding phase with a plastic or synthetic material. For example, polycarbonate (or PC) or poly-methyl methacrylate (or PMMA) can be used. When the molding does not define the first reflection faces An and/or the second reflection faces Bnj and/or the third reflection faces Cn and/or the fourth reflection faces Dn, a machining phase can be implemented , for example by laser, to produce after molding those which have not been defined.

Claims (10)

Lighting device (DE) comprising N sources (Sn) generating photons, with N ≥ 1, and a light guide (GL) comprising N first parts (P1n) each receiving the photons generated by an associated source (Sn) and N first zones (Z1n) respectively receiving said photons from said first parts (P1n) and each comprising a first reflection face (An) having a first parabolic shape capable of reflecting said photons received in order to transfer them along a first general direction in a second part (P2) comprising a front face (FV) through which said transferred photons exit, characterized in that each first zone (Z1n) further comprises at least one second reflection face (Bnj) having a second parabolic shape suitable for reflecting said photons received in order to transfer them in a second general direction, and in that said light guide (GL) comprises N second zones (Z2n) each capable of reflecting said photons transferred in said second general direction in order to transfer them in a third general direction in said second part (P2) next to the photons having said first general direction. Device according to claim 1, characterized in that each first zone (Z1n) comprises two second reflection faces (Bnj) having different main orientations relative to a main orientation of said first reflection face (An) in order to reflect said photons received towards different sub-parts of the second associated zone (Z2n) so that they are transferred along said third general direction in said second part (P2) on either side of the photons having said first general direction. Device according to claim 2, characterized in that each second reflection face (Bnj) has a main orientation relative to said main orientation of said first reflection face (An) making an angle whose absolute value is between 90° and 150°. Device according to one of claims 1 to 3, characterized in that each second zone (Z2n) comprises i) a third reflection face (Cn) having a third parabolic shape capable of reflecting said photons transferred in said second general direction in order to transfer them in a fourth general direction, and ii) a fourth reflection face (Dn) having a fourth parabolic shape capable of reflecting said photons transferred in said fourth general direction in order to transfer them into said second part (P2) in said third direction general. Device according to claim 4, characterized in that said third (Cn) and fourth (Dn) reflection faces have main orientations which form an angle between them between 80° and 100°. Device according to one of claims 1 to 5, characterized in that said first and third general directions are parallel to each other. Device according to one of claims 1 to 6, characterized in that said photons transferred in said second part (P2) participate in a single chosen photometric function. Device according to one of claims 1 to 6, characterized in that said photons transferred into said second part (P2) along said first general direction participate in a first chosen photometric function, and said photons transferred into said second part (P2) along said third general direction participates in a second chosen photometric function different from said first chosen photometric function. Optical unit suitable for equipping a vehicle, characterized in that it comprises at least one lighting device (DE) according to one of claims 1 to 8. Vehicle, characterized in that it comprises at least one optical unit according to claim 9.