Patent Description:
It is well known to use a light guide for achieving a lighting and/or signaling function of an automobile. The light guide is a transparent or translucent part within which light rays propagate in a controlled manner from one end of the guide, called entry face, to the other end, called exit face. Near the entry face, there are one or more light sources, for example, Light Emitting Diodes (LEDs) are provided. The rays of the light emitted by the light source travel by several total internal reflections along the length of the light guide toward the exit face. <CIT> and <CIT> are disclosing such light guides, which furthermore present sections that can be of pentagonal shape.

Some light guides are designed in such a way that their light coupling portion is highly bended compared to an adjacent main portion. In such a case, notably in the case of a circular section light guide, the lighting surface of the guide will not appear as homogeneous, as the light will be not out coupled uniformly along the light guide, especially in the coupling zone.

One objective of the present invention is to provide a light guide with a better homogeneity of its illuminating surface, notably when the light guide is more curved near its light input surface.

The present invention provides a light guide configured to be mounted in a vehicle with the features of claim <NUM>.

In other words the input face has a pentagonal or pentagonal-like shape. In this application the terms "pentagonal-like shape" encompass shapes that are globally a pentagon but that would differ with small differences, for example a Reuleaux polygon with five sides.

The applicant discovered that surprisingly with a light guide light input face having the features of claim <NUM>, the homogeneity and the luminance in a curved coupling portion of a light guide was highly improved, more particularly where the curved coupling portion joins the less curved portion of this light guide, compared to an input face with a circular shape.

A light guide of this shape is better to increase the rebound of the light inside of the guide and to mix better the light, the result is a smaller dark area in comparison with the initial dark area, and therefore a better homogeneity.

More particularly, this will enable to arrange the light source(s) near the wall of a housing of a lighting or signaling device of a vehicle, which would include this light guide. For example, it would be possible to have a stripe of light running closer to this wall, while keeping homogeneity. For example, the light guide would be particularly useful in a signaling device arranged in a vehicle trunk and adjacent with the tail lamp of the fender of this vehicle, especially with this tail lamp including also a signaling device generating a stripe of light in continuity with the stripe of light generated in this case by the light guide.

In this text the words "front" and "behind" are to be understood in respect of the direction the light is going out of the light guide.

Also the term "vehicle" designates any kind of vehicle such as a car or a motorized bike but also other motorized vehicle, having a human driver, being remotely controlled or being autonomous. It also designates such vehicles with no motor, for example but not imitatively bikes with no motors.

The light guide of the present invention can also comprise one or any combination of several of the following features:.

The invention also relates to a luminous device designed to be mounted on a vehicle and comprising a light guide according to the invention and at least one light source emitting light toward the input face in such a way that this light propagates along the light guide and goes out of the output face.

The luminous device can be, but is not limited to, a headlamp or a rear lamp, notably a rear lamp mounted in a trunk or in a fender of a car.

The luminous device of the present invention can also comprise one or any combination of several of the following features:.

said coupling portion first extending along said side wall and then being curved such that it extends away from this side wall and up to the front exit face, said main portion running along said front exit face.

The invention also relates to a system of two luminous devices, at least one being according to the invention, wherein the side walls of the two luminous devices being adjacent or in contact together, in such a way that the front exiting face of the two luminous devices are adjacent or in contact and that their corresponding light guides form a single lit line together, when the light source(s) is(are) lit on.

The invention also relates to a vehicle comprising a luminous device according to the invention or a system according to the invention.

To complete the description and to provide a better understanding of the invention, a set of drawings is provided. Said drawings form an integral part of the description and illustrate an embodiment of the invention, which should not be construed as restricting the scope of the invention, but only as an example of how the invention can be carried out. The drawings comprise the following characteristics.

The following description of examples of embodiments with reference to the drawings is intended to explain the general inventive concept of the present application, instead of limiting to the present invention.

<FIG> show light guide <NUM> according to an embodiment of the present invention. For example, the light guide <NUM> may be used in a vehicle lamp of an automotive vehicle. In particular, the light guide <NUM> may be used in a rear lamp of an automotive vehicle.

Referring to <FIG>, the light guide <NUM> comprises:.

The light guide <NUM> is here made of transparent material such as polycarbonate. Other materials may be used for example polymethyl methacralate (PMMA) or other suitable transparent polymers.

According to the invention and as in this example, the light guide <NUM> can comprise decoupling elements <NUM>, <NUM> along its length, in order to decouple light from the light guide <NUM> out of its output surface <NUM>. Here the decoupling elements are provided along both the coupling portion <NUM> and the main portion <NUM>. Therefore here, the output face extends along the coupling portion <NUM> and the main portion <NUM>.

Here first decoupling elements <NUM> are arranged on the front of the light guide <NUM> and decouples light via refraction, and second decoupling elements <NUM> are arranged at the rear of the light guide <NUM> and decouples light via reflection towards the output face <NUM>.

[<FIG>] shows two light sources <NUM>, here LEDs, arranged such that they face and lit the input face <NUM>.

As can be better seen on <FIG>, the input face is a pentagonal-like shape as its five angles α have the same value of <NUM> degrees and the five edges <NUM> to <NUM> are approximatively of the same length. Also, three of the edges <NUM>, <NUM>, <NUM>, here the lower edges, are straight edges. However, the two upper edges <NUM>, <NUM>, are here presenting a convex curvature which is an arc of circle. On [<FIG>] a straight dotted line has been represented to show the curvature of the edge <NUM> located above this dotted line.

On [<FIG>] is also represented a doted circle which represents the joining section <NUM> delimiting the main portion <NUM> from the coupling portion <NUM>.

The joining section <NUM> is here circular. The main portion <NUM> extends from the joining section <NUM>, such that it is arranged as a rod having a circular section, here constant, i.e. equal to the joining section <NUM> diameter.

As can be seen on [<FIG>], the coupling portion <NUM> has a continuous evolution from the five sided shape of the input face <NUM> to the joining section <NUM>. In other words, the shape of the coupling portion has a continuous transition from a pentagonal-like section to a circular section.

Each of the five angles α formed by the five edges <NUM> to <NUM> presents a vertices <NUM>. As in a pure pentagon, the five corresponding vertices <NUM> are positioned on a circumscribed circle C1, which has the same diameter as the joining section <NUM>.

Here the coupling portion also comprises a mounting portion <NUM>, which comprises mounting organs <NUM>, <NUM> to mount the light guide <NUM> on a support. These mounting organs <NUM>, <NUM> can be made integrally in one part with the mounting portion.

These mounting organs <NUM>, <NUM>, can be but are not limited to position means, clipping means, or holes for receiving clipping means.

Here, said mounting portion <NUM> extends from the top and from the bottom of the coupling portion <NUM> at a coupling position and is integrally formed with it.

The mounting portion <NUM> can for example be mounted on a bezel, a bracket, and/or a housing (not shown in the Figures) of a luminous device of a vehicle.

According to the invention and as in this example, the mounting position can be distant from the input face <NUM> and from the joining section <NUM>, this mounting position being arranged closer to the input face <NUM>, so that, as it can be seen on <FIG>, the coupling section presents a shape with five distinct faces from the input face <NUM> to the mounting portion <NUM>. Notably, the coupling portion <NUM> has globally a pentagonal-like shape section all along its length from the input face <NUM> to the mounting portion <NUM>.

The five distinct faces can present a demolding angle inferior or equal to <NUM> degrees to eject the part from the mold.

As can be seen on [<FIG>], the coupling portion <NUM> presents a curvature with a radius equal to four times or more than four times the diameter of the main portion <NUM>.

In [<FIG>], schematically represents the LEDs light emission axis, which is forming an incident angle β with the normal to the input face <NUM>. On [<FIG>], for each angle β represented, the said normal is the right dotted line and the light emission axis is the left dotted line. This incident angle β is inferior or equal to <NUM> degrees.

[<FIG>] is a schematic diagram of a system of two luminous devices <NUM>, <NUM>, according to embodiments of the invention. These devices <NUM>, <NUM> are arranged at a rear end portion of an automotive vehicle, each with a light guide <NUM>, <NUM> of the present invention.

The first luminous device <NUM> is here a signaling device arranged in a vehicle trunk and adjacent with the second luminous device <NUM>, here a tail lamp of a rear fender of the vehicle.

Each of these luminous devices <NUM>, <NUM>, comprises a housing <NUM>, which comprises:.

Here, in each cases the coupling portion <NUM> first extends along said side wall <NUM> and then is curved such that it extends away from this side wall <NUM> and up to the front exit face, said main portion <NUM> running along said front exit face.

The respective light guides <NUM>, <NUM> of the first and second luminous devices <NUM>, <NUM> are here particularly useful, as the light guide <NUM> is generating a stripe of light in continuity with the stripe of light generated by the light guide <NUM> of the second luminous device <NUM>. As can be seen from the [<FIG>], the second luminous device <NUM> can emit a continuous strip of light through the output surface <NUM> of the light guide <NUM> of the first luminous device <NUM> and the output face of the light guide <NUM> of the second luminous device <NUM>.

The light guide <NUM> of the present invention will enable to arrange the LEDs <NUM> near the side wall <NUM> of the housing <NUM>. It would be possible to have a stripe of light running closer to this side wall <NUM>, which will enhance the stripe continuous effect above mentioned, while keeping homogeneity.

Claim 1:
A light guide (<NUM>) configured to be mounted in a vehicle, said light guide comprising:
- a coupling portion (<NUM>) presenting an input face (<NUM>),
- a main portion (<NUM>) extending from said coupling portion,
- an output surface (<NUM>) extending at least along the main portion,
the light guide (<NUM>) being arranged in such a way that light rays that enter into the light guide through the input face (<NUM>) are propagated by total internal reflection along the coupling portion (<NUM>) and then along the main portion (<NUM>), before reaching out of the light guide trough the output surface (<NUM>),
wherein the said input face is flat,
characterized in that said input face has a periphery that is formed by only five edges (<NUM> to <NUM>) of substantially the same size, these edges joining together such that they form five angles (α) with substantially the same value, wherein at least one of the edges (<NUM>, <NUM>) is a convex edge.