WO2017098107A1

WO2017098107A1 - Lighting device with light guide comprising polygonal holes to reflect photons

Info

Publication number: WO2017098107A1
Application number: PCT/FR2016/053111
Authority: WO
Inventors: Rodolphe Peron; Gilles Moynier
Original assignee: Peugeot Citroen Automobiles Sa
Priority date: 2015-12-08
Filing date: 2016-11-28
Publication date: 2017-06-15
Also published as: FR3044744A1; FR3044744B1; EP3387320A1; CN108368982A

Abstract

The invention relates to a lighting device (DE) including light sources (SL) that generate photons and a light guide (GL) for transferring the photons supplying an input surface (FS) from a rear area (ZR) to a front surface (FV) in order to transfer same outward in order to provide a photometric function. This light guide (GL) includes, at predefined locations between the rear area (ZR) and the front surface (FV) and according to the respective positions of the light sources (SL) relative to the input surface (FS), at least two holes (TR) each having a generally polygonal shape defined by walls (PT) capable of reflecting toward the front surface (FV) or toward a wall (PT) of another hole (TR) some photons in the process of being transferred, in order to provide, by means of other photons transferred but not reflected by a hole (TR), substantially homogeneous lighting contributing to the photometric function.

Description

LIGHT GUIDE LIGHTING DEVICE COMPRISING POLYGONAL HOLES FOR REFLECTING PHOTONS

The invention relates to lighting devices, and more specifically those which comprise at least two light sources and a light guide.

The term "lighting device" is understood here to mean a light device capable of providing at least one photometric function of lighting or signaling or of a luminous effect, possibly decorative.

In certain fields, such as for example vehicles, possibly of the automotive type, lighting devices comprising at least two light sources capable of generating photons, and a light guide capable of transferring photons supplying a photon face, are used. input from a rear area to a front face for transfer to the outside to provide a photometric function. The light guide is for example made of polycarbonate (or PC) or polymethyl methacrylate (or PMMA).

In the non-limiting case of a vehicle, a photometric lighting function may be, for example, a low beam function (or code), a fog lamp function, or a high beam function, and a function photometric signaling may be, for example, a direction change indicator function (or flashing), a stop light function, a reversing light function, a position light function (or night light or lantern) , a daylight running function (or DRL (for "Daytime running Light (or Lamp)" - light signaling automatically when the vehicle is put into operation during the day), or a welcome function (or courtesy) .

Lighting devices of the type presented above can be realized in at least two different ways.

In a first embodiment, the rear zone of the light guide comprises reflecting structures which are associated with each at least one light source, each of which is adapted to reflect the generated photons received by the input face towards the front face. The photons thus enter the light guide from above or below the reflective structures. These reflective structures are generally joined to each other, they have junction areas that induce on the front face shaded areas that interfere with the homogeneity of the photometric function in which their lighting device participates.

In a second embodiment, the entrance face of the light guide is the rear face which is located opposite the front face and opposite which are installed the light sources. The photons thus enter the light guide by its back side (or "slice"). The main disadvantage of this second embodiment lies in the fact that it creates at the level of the front face what the man of the art calls "hot spots", that is to say zones where the light intensity is higher than elsewhere, which affects the homogeneity of the photometric function concerned.

The invention is therefore particularly intended to improve the situation.

It proposes for this purpose a lighting device comprising at least two light sources adapted to generate photons, and a light guide adapted to transfer photons, which penetrate through an entrance face in a rear area that it comprises, towards a front face for their transfer to the outside to ensure a photometric function.

This lighting device is characterized in that its light guide comprises, at predefined locations located between the rear zone and front face and function of the respective positions of the light sources with respect to the input face, at least two holes each having a general polygonal shape defined by walls that are adapted to reflect towards the front face or to a wall of another hole some of the photons being transferred, to ensure with other photons transferred but not reflected by a hole a substantially homogeneous illumination participating in the photometric function.

Thanks to the polygonal holes the photons can be distributed on the front light of the light guide, which allows the latter to offer a good homogeneity of light on its entire front.

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

each hole may have a general polygonal shape chosen from (at least) a triangle and a rhombus;

each hole may have an angle oriented towards the rear zone and shifted transversely with respect to a transverse position of the light source which is the least distant from it;

each wall of a hole may have dimensions and an orientation relative to the rear zone which are a function of the arrangement of the latter and of a distance separating the front face of a rear face from the rear zone, situated opposite of the front face;

in a first embodiment, the rear zone of the light guide may comprise reflecting structures each associated with at least one light source, and each adapted to reflect the photons generated received by the input face towards at least one hole and the front face;

in a second embodiment, the entrance face of the light guide may be a rear face located opposite the front face and facing which the light sources are installed;

its light guide can be flat type;

each light source may be a light diode, for example an LED, a laser diode or an OLED structure.

The invention also proposes a vehicle optical unit, possibly of automotive type, comprising at least one lighting device of the type of that presented above.

The invention also proposes a vehicle, possibly of automobile type, and comprising at least one lighting device of the type of the one presented above or at least one optical block of the type of that presented above.

Other features and advantages of the invention will appear in review of the detailed description below, and accompanying drawings (CAD / CAD (Computer Aided Design / Computer Aided Drafting)), hence the seemingly discontinuous nature of some lines and gray levels ), on which ones :

FIG. 1 schematically illustrates, in a perspective view, a first exemplary embodiment of a lighting device according to the invention,

FIG. 2 schematically illustrates, in a perspective view, a part of the lighting device of FIG. 1,

FIG. 3 schematically illustrates, in a perspective view, a second exemplary embodiment of a lighting device according to the invention,

FIG. 4 schematically illustrates, in a view from above, a part of the lighting device of FIG. 1, with the materialization of certain photon paths generated by the light sources, and

FIG. 5 schematically illustrates, in a view from above, an example of a triangular hole that may be part of a lighting device according to the invention.

The object of the invention is notably to propose a lighting device DE intended to allow a homogeneity of the photometric function in which it participates or which it ensures integrally.

In what follows, it is considered, by way of non-limiting example, that the lighting device DE is intended to equip an optical block of a vehicle of the automotive type, such as a car. But the invention is not limited to this application. Indeed, a lighting device DE may be an equipment in itself (possibly including its own housing), or may be part of another equipment that a vehicle optical unit. Thus, a lighting device DE can be part of any vehicle (land, sea (or fluvial), or air), any installation, including industrial type, any device ( or system), and any building.

Furthermore, it will be considered in what follows, by way of nonlimiting example, that the optical unit (comprising at least one lighting device DE) is a rear lamp providing at least one photometric function of signaling, such as a change of direction indicator function (or flashing) or a stop light function or a reversing light function. But the invention is not limited to this application. Indeed, the lighting device DE, according to the invention, is a light device that can provide at least a photometric function of lighting or signaling or light effect, possibly decorative. Thus, in the non-limiting case of a vehicle, it can participate in a photometric lighting function, such as a low beam function (or code), a fog lamp function, or a high beam function. , or to a photometric signaling function, such as a change of direction indicator function, a stop light function, a reversing light function, a position light function (or pilot light or lantern), a daylight running function (or DRL (for "Daytime running Light (or Lamp)" - automatic illuminated warning when the vehicle is put into operation during the day), or a welcome function (or courtesy), or a photometric function of light effect, possibly decorative.

FIGS. 1 and 3 show schematically two nonlimiting exemplary embodiments of a lighting device DE according to the invention.

As illustrated in FIGS. 1 and 3, a lighting device DE according to the invention comprises at least two light sources SL and a light guide GL.

Each light source SL is arranged to generate photons.

For example, each light source SL may be a light diode. In this case, each light diode may be a light-emitting diode (or LED) or a laser diode or an OLED (Organic Light-Emitting Diode) type structure.

Although it does not appear in FIGS. 1 to 4, the SL light sources may, for example, be installed on a support plate. This support plate may, for example, be a printed circuit board, PCB type ("Printed Circuit Board"), rigid or flexible ("type" Flex ").

The light guide GL comprises a rear zone ZR having an input face FS or FR and a front face FV, located opposite its rear zone ZR. It is able to transfer photons, generated by the light sources SL and which enter its rear zone ZR by the input face FR or FS, towards its front face FV, with a view to their transfer to the outside to ensure a photometric function.

In the first example shown in non-limiting manner in FIGS. 1, 2 and 4, the input face of the rear zone ZR is the upper face FS. In this case, the rear zone ZR comprises reflecting structures SR which are each associated with at least one light source SL, and which are each adapted to reflect the generated photons received by the input face FS (here the upper face) towards the FV front panel. The photons thus enter the light guide GL from above the reflective structures SR. As a variant, the input face of the rear zone ZR could be the lower face which is opposite to the upper face FS. In this variant, the photons penetrate into the light guide GL from below the reflecting structures SR.

In the second example shown in non-limiting manner in FIG. 3, the input face of the rear zone ZR is the rear face FR which is situated opposite the front face FV. In this case, the light sources SL are installed opposite the rear face FR, and therefore the photons penetrate into the light guide GL by its rear face FR (or "slice").

It will be noted that in the first and second examples illustrated in non-limiting manner in FIGS. 1 to 4, the light guide GL is of flat type (in English "flat guide"). It is therefore intended to provide "direct" lighting. But it could have at least one curvature (and in this case the SL light sources are preferentially installed on a flexible printed circuit board (or "Flex")).

For example, the light guide GL may be made of polycarbonate (or PC) or polymethyl methacrylate (or PMMA).

According to the invention, and as illustrated in FIGS. 1 to 4, the light guide GL comprises at least two holes TR in predefined places which are located between its rear zone ZR and its front face FV and which are a function of the respective positions of the light sources SL with respect to its input face FR or FS. Each TR hole has a general polygonal shape which is defined by PT walls suitable to reflect towards the front face FV or to a wall PT of another hole TR some of the photons that are being transferred, to ensure with other photons, transferred but not reflected by a hole TR, a substantially homogeneous illumination participating in the photometric function of the lighting device DE.

FIG. 4 schematically shows a few paths of the photons generated by the light sources SL inside the light guide GL. As can be seen, some photons are transferred directly from the rear zone ZR to the front face FV (without being reflected by a hole TR), other photons are transferred indirectly from the rear zone ZR to the front face FV after having have been reflected either by a wall PT of a hole TR, or by two walls PT of two neighboring holes TR.

It will be understood that the objective of the reflections on the walls PT holes TR is to allow a transfer of photons on areas of the front face FV that would be unreachable in the absence of holes TR (and therefore where would occur shadows ), while avoiding the formation of hot spots, so as to offer a homogeneity of the photometric function of the lighting device DE. The TR holes therefore act as "distributors" of photons.

To do this, each wall PT of a hole TR can advantageously have dimensions and an orientation relative to the rear zone ZR which are a function of the arrangement of the latter (ZR) and the distance that separates the front face FV of the rear face FR. In the presence of reflective structures SR, the shape of the latter SR and the position of each light source SL with respect to the associated SR reflective structure influence the choice of dimensions and orientation of each hole PT wall TR. The shapes and dimensions of the holes TR and the positions of the latter (TR) within the light guide GL can therefore be determined by the calculation, thanks to the laws of linear optics. It will be understood that the calculation makes it possible to optimize the distribution of the photons on the front face FV, and therefore the homogeneity of the illumination participating in the photometric function of the lighting device DE.

In the examples illustrated in FIGS. 1 to 5, each hole TR has a general polygonal shape of triangle type. But in an alternative embodiment not illustrated, the general polygonal shape could be a rhombus, for example.

By way of purely illustrative example, and as illustrated schematically in FIG. 5, a triangular TR hole intended to form part of a light guide GL of the type illustrated in FIGS. 1, 2 and 4 and having its zone rear ZR separated from its front face FV of about 55 mm, may have a first angle A1 of 22 °, a second angle A2 of 27 °, a third angle A3 of 131 °, and be defined by a first wall PTi 15 mm long, a second wall PT ₂ 8 mm long and a third wall PT ₃ 10 mm long.

It will be noted, as shown in non-limiting manner in FIG. 2, that the holes TR may be non-through. But alternatively they could be through. For example, when the thickness of the light guide GL is about 5 mm, the depth (or height) of each hole TR may be about 4 mm.

It will also be noted that it is the material / air interfaces of the TR holes that induce the reflections.

It will also be noted, as illustrated without limitation in FIGS. 1 to 4, that each hole TR may have a first angle A1 which is oriented towards the rear zone ZR and which is shifted transversely with respect to the transverse position of the light source SL who is the least distant from him (A1).

The positions of the TR holes depend on the shape of the SR reflective structures.

It will also be noted, as shown in non-limiting manner in FIGS. 1, 3 and 4, that the front face FV of the light guide GL may optionally comprise three-dimensional (or 3D) patterns capable of transferring the photons outwards according to preferred directions. chosen, adapted to the photometric function. As illustrated, these patterns For example, three-dimensional structures may be stepped with transverse recesses.

Thanks to the distribution of the photons induced by the polygonal holes, the hot spots and the shadows are avoided on the front face of illumination of the light guide, which allows the latter to offer a (very) good homogeneity lighting on its entire front.

Claims

1. A lighting device (DE) comprising at least two light sources (SL) capable of generating photons and a light guide (GL) capable of transferring photons, which penetrate through an input face (FR, FS) in a rear zone (ZR) which it comprises, towards a front face (FV) with a view to their outward transfer to ensure a photometric function, characterized in that said light guide (GL) comprises, at predefined locations located between said rear zone (ZR) and front face (FV) and function of the respective positions of said light sources (SL) with respect to said input face (FR, FS), at least two holes (TR) each having a general polygonal shape defined by walls (PT) adapted to reflect towards said front face (FV) or to a wall (PT) of another hole (TR) some of said photons being transferred, to ensure with other photons transferred but not reflected by a hole (TR) sensitive lighting homogeneously participating in said photometric function.

2. Device according to claim 1, characterized in that each hole (TR) has a generally polygonal shape selected from a group comprising a triangle and a rhombus.

3. Device according to one of claims 1 and 2, characterized in that each hole (TR) has an angle (A1) oriented towards said rear zone (ZR) and shifted transversely relative to a transverse position of the light source (SL) who is the least distant from him (A1).

4. Device according to one of claims 1 to 3, characterized in that each wall (PT) of a hole (TR) has dimensions and an orientation relative to said rear zone (ZR) according to the arrangement of the latter (ZR) and a distance separating said front face (FV) from a rear face (FR) of said rear zone (ZR) situated opposite said front face (FV).

5. Device according to one of claims 1 to 4, characterized in that said rear zone (ZR) comprises reflecting structures (SR) each associated with at least one light source (SL), and clean each to reflect the generated photons received by said input face (FS) to at least one hole (TR) and said front face (FV).

6. Device according to one of claims 1 to 4, characterized in that said input face (FR) is a rear face located opposite said face.

5 front (FV) and opposite which are installed said light sources (SL).

7. Device according to one of claims 1 to 6, characterized in that said light guide (GL) is flat type.

8. Device according to one of claims 1 to 7, characterized in that î o each light source (SL) is a light diode.

9. Vehicle optical unit, characterized in that it comprises at least one lighting device (DE) according to one of the preceding claims.

10. Vehicle, characterized in that it comprises at least one optical unit according to claim 9.