FR3097935A1 - Lighting and / or signaling device - Google Patents

Abstract

Lighting and / or signaling device The invention relates to a device (1) for lighting and / or signaling a vehicle comprising a linear light guide (2) which has a main longitudinal direction of elongation and a light source (3), the light guide (2) comprising an input face (7) and an output face (8) of the light rays emitted by the light source (3), the output face s' extending along the direction of elongation of the light guide, characterized in that the inlet face (7) is disposed opposite to the outlet face (8) and the light source (3) comprises a printed circuit board (4) on which is arranged a plurality of microLEDs (5) forming a linear series (6) in a direction parallel to the main longitudinal direction of elongation of the light guide, within which the microLEDs ( 5) neighbors are spaced apart by a distance (D) of between 200 microns and 1 millimeter. Figure for the abstract: Figure 1

Description

Lighting and/or signaling device

The present invention relates to a lighting and/or signaling device for a vehicle. The invention relates to the field of optical devices intended to illuminate the interior of a vehicle passenger compartment, or to visually warn other users on the road.

The technology of lighting and/or signaling devices has developed enormously in recent years, and it is now known to use linear light guides, that is to say having a large longitudinal dimension with respect to to the passage section of the guide, associated with light sources, so as to provide lighting with a linear appearance.

It is for example known to place a light-emitting diode facing an input face of a light guide, placed at a longitudinal end of the guide, and the light beam is propagated along this same light guide by successive total reflections. Decoupling means, such as prisms, are formed in the thickness of the guide to reflect the light rays of the beam so that these rays impact the wall of the guide arranged opposite the prisms with an angle such that the rays can exit of the guide to achieve the desired lighting function. These technologies have certain shortcomings, in particular the fact of having to use a light guide of a substantial diameter to allow guidance by successive total reflections towards the decoupling means, or the fact of having an inhomogeneous light output due to the spacing of the decoupling means.

It is also known to implement laser technology, in particular accompanied by the use of glass light guides, in order to improve optical performance. The glass light guide can be very thin but must be surrounded by a sheath for the protection of the glass tube and it is necessary to provide an associated phosphor to perform the wavelength conversion of the blue laser source. Provision should also be made for the formation of decoupling means of more complex shapes than those of the prisms produced in a guide associated with a light-emitting diode. If this implementation makes it possible to obtain a very flexible and very luminous device, with a good ratio between the luminance of the start and the end of the guide in particular, it generates other problems, in particular the fact that a laser beam presents a risk of safety and that a laser diode requires a management of the cooling of the diode whose costs turn out to be significant.

The present invention falls within this context and it aims to propose a lighting and/or signaling device with optimal optical performance, in particular ensuring uniform lighting, regardless of the length or shape of the zone in which the device is implanted, at reduced cost and without presenting security risks.

The invention consists of a lighting and/or signaling device for a vehicle comprising a linear light guide which has a main longitudinal direction of elongation and a light source, the light guide comprising an entry face and an output face for the light rays emitted by the light source, the output face extending along the direction of elongation of the light guide, characterized in that the input face is disposed opposite from the exit face and that the light source comprises a printed circuit board on which is arranged a plurality of microLEDs forming a linear series in a direction parallel to the main longitudinal direction of elongation of the light guide, within which the neighboring microLEDs are spaced apart by a distance of between 200 microns and 1 millimeter.

According to a feature of the invention, the neighboring microLEDs are spaced apart by a distance of between 300 microns and 500 microns.

It should be noted that according to the invention, the light beam is not generated by the presence of a diode arranged at the end of a light guide and whose light radiation propagates in a longitudinal direction within this guide. of light which must include means for decoupling the light, but that this beam is generated by several diodes whose light radiation passes through the light guide in a transverse direction, that is to say substantially perpendicular to the light guide .

The term microLED will be used throughout the description of the invention to designate a light-emitting diode whose dimension of the emitting zone is of the order of ten microns. Typically microLEDs have a size between 20 and 150 microns. It is these microLEDs that light the lighting and/or signaling device.

The light guide is advantageously of substantially cylindrical shape, and extends over a main longitudinal dimension. The light guide is made of substantially transparent material. The material can for example be a polymer such as silicone, polycarbonate or polymethyl acrylate.

The light guide includes a light entry face and a light exit face. The entry face and the exit face each correspond to a portion of a wall of the light guide. The output face and the input face are globally opposite to each other, thus separated by the internal volume defined by the wall of the light guide. More particularly, when the light guide has a cylindrical shape with a substantially circular section, the output face and the input face of the light guide are diametrically opposed. Thus, the light rays enter the light guide through the entry face, and the light guide distributes the emitted light according to the desired photometry to the exit face. The distribution of the light created by the light guide guarantees to obtain a good homogeneity of the light at the exit of the light guide, and this whatever the angle of observation. The configuration of the output face and of the input face make it possible to arrange the diodes forming the light source in such a way that a direct imaging system is generated in which the light beam resulting from the emission of the light rays is easy to make homogeneous over the entire light guide. Homogeneity is to be understood in terms of intensity and/or colorimetry of the light emitted.

The use of microLEDs makes it possible to reduce the spacing between each diode and thus makes it possible, combined with this system in direct imaging, not to generate a chopped beam as can be the case with a prismatic light guide.

The light source comprises a printed circuit board which, like the light guide, extends over a major longitudinal dimension. The printed circuit board can be rigid or flexible. A flexible printed circuit board is for example able to be arranged on a non-planar area of the vehicle, being able to be subjected to a torsion so as to create a curvature if this is desired. The printed circuit board is fixed to a wall of the vehicle or to a support supported by the vehicle, for example by gluing.

A plurality of microLEDs is installed on the printed circuit board, for example by welding or soldering. The microLEDs are arranged next to each other so as to form a linear series, extending along the main longitudinal elongation direction of the guide and the printed circuit board. The microLEDs are supplied with energy by a generator to emit light radiation. The lighting of the microLEDs can be constant, or can be activated following a command specifically provided for this purpose, or for signaling purposes, for example by means of the brake pedal or the vehicle's indicator lever. The microLEDs can emit a specific color depending on their composition, as will be described in more detail later.

According to the invention, each microLED is spaced from one another by a pitch of between 100 microns and 300 microns. This maximum distance of 300 microns between each microLED makes it possible to maintain a homogeneous, uninterrupted appearance of the light emitted by the device. Indeed, the inventors have established that an observer located approximately one meter from the device is not able to distinguish the pixels formed by each microLED from each other if the distance separating each microLED is less than or equal to 300 microns. It is understood that according to the invention, it is possible to bring the microLEDs closer to each other on the printed circuit board, provided that appropriate means for installing the diodes on the printed circuit board are implemented, and that this bringing together of the diodes makes it possible to generate a regular beam without demarcation of the pixels. And that such precision in the projected beam cannot be obtained in a conventional light guide comprising means for decoupling the light rays such as prisms, the manufacturing constraints preventing a very tight realization of the prisms one after the other.

Thus, it is the combination between the arrangement of the light guide, with an entry face and an exit face facing each other, and the use of microLEDs, with a specific pitch between each microLED, which guarantees excellent homogeneity of the light coming out of the light guide, which in addition to obtaining a better aesthetic rendering, also makes it possible to improve the quality of the warning signals against other road users. road in the case where the device has a signaling function.

According to a characteristic of the invention, the printed circuit board is arranged directly in contact with the light guide. The light guide is therefore placed directly opposite the emission zone of the microLEDs. This arrangement by direct contact guarantees that all the light rays pass through the light guide and limits parasitic reflections or diffusions. The light guide can therefore be fixed directly to the printed circuit board, or else to the support supporting the printed circuit board.

According to a characteristic of the invention, the light guide comprises a flat configured to form a flat receiving surface for the printed circuit board. The light guide has a cylindrical shape, relatively regular, with the exception of the portion of the wall corresponding to the entrance face which consists of a flat. This flat makes it possible to ensure that the wall portion of the light guide in contact with the printed circuit board is parallel to the latter. Thus, the light radiation emitted by the microLEDs is almost perpendicular to the input face, which greatly guarantees to limit the appearance of parasitic optical phenomena of diffraction or refraction caused by a non-perpendicular incidence of the light rays emitted by the microLEDs .

According to one characteristic of the invention, the dimension of the light guide perpendicular to its longitudinal dimension is between 1 and 5 mm. This dimension corresponds to the longest distance between the entry face and the exit face of the light guide. In particular, when the light guide has a cylindrical shape with a substantially circular section, the diameter of the light guide can be between 1 and 5 mm. This dimension is generally lower than that of the light guides of the prior art, which is of the order of 5 to 8 mm for the light guides comprising decoupling means, and around 8 mm for the light guides of the laser diodes implementing a thin glass tube and a protective sheath around. Thus the section formed is very small which limits the mechanical size.

According to one characteristic of the invention, the microLEDs are associated with at least one phosphor. The phosphor is an element placed on the microLED which makes it possible to modify the emission color of the latter, the semiconductor equipping the microLED being configured to emit blue light converted by the phosphor. The phosphors used for this type of optical device can in particular be white, red, yellow or amber in color, that is to say be configured to convert the light rays emitted by the semiconductor into a color such as additive synthesis rays passing through the phosphor gives a beam of white, red, yellow or amber color, it being understood that these colors advantageously correspond to vehicle lighting and/or signaling standards. The phosphors used can for example be phosphors.

According to one characteristic of the invention, the phosphor can be arranged at the output of the microLED on the path of the light rays emitted by this microLED, or it can be integrated into the volume of the microLED, this is then referred to as packaged microLED.

According to a characteristic of the invention, the microLEDs can be associated with several phosphors. Such a microLED can emit two different colors through two different phosphors, distributed over the emission surface of the microLED in at least two distinct emitting zones and separated by an optical barrier.

According to one characteristic of the invention, the light source can comprise two types of microLEDs, each type being powered independently of one another and being arranged linearly in a single series on the printed circuit board so as to create a alternation of colors, the distance between two microLEDs of the same type being of the order of 500 microns. By two types of microLEDs, we mean two microLEDs each comprising a distinct phosphor and emitting a different color from each other. It is possible to install the microLEDs on the printed circuit board by alternating two different types of microLEDs, in order to create a signaling device capable of providing two different types of lighting or signaling for the same output surface. The two colors used can for example be red and amber for the rear of the vehicle or amber and white for the front of the vehicle. Thus, the microLEDs are powered or not depending on the commands made by the driver of the vehicle, displaying the color corresponding to the action performed, for example the lighting of the red microLEDs when the driver activates the brake pedal.

As previously specified, neighboring microLEDs can be spaced apart by a distance of between 200 microns and 1 millimeter. In the context of two types of microLEDS which has just been described, in order to maintain a continuous linear appearance without hatching for each of the lighting and/or signaling functions, the pitch between two microLEDs of the same type, that is to say between two microLEDs allowing the implementation of a given lighting and/or signaling function, i.e. as small as possible. Indeed, in this embodiment, it happens that when one of the types of microLED is on, the other is off. It is therefore essential to maintain the linear aspect to reduce the pitch between each microLED. Given that the microLEDs are arranged so as to form an alternation of colors, for this embodiment, two microLEDs of the same type are distanced from each other by a distance at least equal to twice the minimum value of the initial step between each microLEDs. Preferably, in this context, two microLEDs of the same type are distanced from each other by a distance of the order of 500 microns.

According to a characteristic of the invention, at least two types of microLEDs can be arranged in several linear series, each type of microLED forming a linear series. Just like the previous embodiment, this embodiment involves types of microLEDs of different colors lighting up independently of each other, for example for signaling purposes. Contrary to what has just been described previously, the different types of microLEDs are here not arranged on the printed circuit board alternately in one and the same linear series, but each type of microLED is arranged in its own linear series of microLEDs. In other words, there are as many linear series of microLEDs as there are types of microLEDs, thus making it possible to maintain the same spacing of a maximum of 300 microns between each microLED, just as in the case where the device only comprises one type of microLED. The gap between two linear series of microLEDs is between 150 microns and 1 mm, typically 300 microns.

The presence of several linear series of microLEDs implies modifying the dimensions of certain elements of the device accordingly. Several linear series of microLEDs are placed on the circuit board. The latter must therefore be wider than when it accommodates a single linear series of microLEDs in order to avoid any mechanical clutter. This change in size also leads to an increase in the width of the light guide flat which must cover each of the linear series of microLEDs. The general shape of the light guide is therefore more oblong than in the previous embodiments. This embodiment will be illustrated below.

According to one characteristic of the invention, at least one phosphor can be arranged on the printed circuit board and/or on the input face of the light guide. The embodiment with a phosphor arranged on the printed circuit board is suitable when a linear series of microLEDs comprises only one type of microLED. Thus, rather than adapting an individual phosphor to each of the microLEDs, it is simpler to use a single phosphor in the form, for example, of a strip of phosphor extending continuously along the printed circuit board. , and covering all the microLEDs of the linear series. This strip of phosphor is fixed to the printed circuit board, for example by gluing. Just like the phosphors associated respectively with each of the microLEDs previously described, the strips of phosphors make it possible to obtain the desired color according to the need. The microLEDs covered by this strip of phosphor therefore logically have no phosphor on their structure.

Similar to the arrangement of the phosphor on the printed circuit board, the phosphor, instead of being arranged individually on a microLED, can be arranged on the light guide. This alternative can have advantages when the optical index of the material which constitutes the light guide is close to the optical index of the phosphor material, which ensures the avoidance of parasitic radiation that can harm the homogeneity of the light radiation induced by the device.

For this alternative, the phosphor can for example be a structure directly integrated into the flat of the light guide, extending longitudinally along the light guide and covering the linear series of microLEDs when the printed circuit board is placed facing of the light guide flat. It is understood that the phosphor covers the input face of the light guide, which does not present any problems given that, as previously presented, the optical indices of the light guide and of the phosphor material are similar.

According to one characteristic of the invention, the light guide comprises at least one notch on the entry face, configured to allow the phosphor to be deposited. The realization of such a notch makes it possible to ensure the adequate position of the strip of phosphor brought to be deposited against the entry face of the light guide, and therefore of the adequate position of the strip of phosphor so that it is arranged facing the alignment of the linear series of microLEDs when the light guide is fixed on the printed circuit board.

According to one characteristic of the invention, the printed circuit board or the light guide comprises at least one wall between two separate phosphors or strips of phosphors. It is understood that a wall is arranged between two luminophores embedded on the same microLED, or between two luminophores arranged in a strip on the printed circuit board or on the entry face of the light guide, in order to prevent the light rays emitted by a microLED passes successively through the two phosphors and alters the desired color of the beam at the output of the light guide.

The wall may in particular consist of an air gap in the thickness of the light guide or of a wall made of a screening material and molded onto the light guide or the printed circuit board.

Other characteristics, details and advantages of the invention will emerge more clearly on reading the detailed description given below, and several embodiments given by way of indication and not limitation with reference to the schematic drawings appended on the other hand. , on which ones :

figure 1 is a perspective view of a first embodiment of the device according to the invention, the microLEDS implemented in this device being represented in dotted lines,

figure 2 is a sectional view along a transverse plane of the device according to the first embodiment of Figure 1,

figure 3 is a perspective view of the device of FIG. 1, in an exploded representation showing a printed circuit board and an area of a light guide against which the printed circuit board is intended to be placed,

figure 4 is a perspective view, similar to that of FIG. 1, illustrating a second embodiment of the device according to the invention,

figure 5 is a perspective view, similar to that of FIG. 1, illustrating a third embodiment of the device according to the invention,

figure 6 is a front view of a first variant embodiment relating to an arrangement of phosphors associated with the microLEDS, here in the case of the first embodiment,

figure 7 is a view similar to FIG. 6 of the first variant embodiment relating to an arrangement of phosphors associated with the microLEDS, here in the case of the third embodiment,

figure 8 is a sectional view along a transverse plane of a second variant embodiment relating to an arrangement of phosphors, here in the case of the third embodiment.

For conditions of clarity of the detailed description, the LVT trihedron will represent the orientation of the device according to the invention. The longitudinal direction L corresponds to the main direction of elongation of, for example, the light guide or the printed circuit board, and the transverse T and vertical V directions correspond to axes perpendicular to the longitudinal direction L.

Figures 1 to 3 show a lighting and/or signaling device 1 according to a first embodiment of the invention. The device 1 can be used for lighting, interior or exterior, or for signaling, for example for any means of visual signaling located at the front or at the rear of the vehicle.

The device 1 comprises a light guide 2 and a light source 3. The function of the light source 3 is to emit light rays through the light guide, the latter being configured to form an appropriate light beam at the output.

The light guide 2 is made of a material making it possible to diffuse the light rays emitted by the light source 3. The material can for example be a rigid or flexible polymer depending on the need. By way of non-limiting example, the material may be a transparent thermoplastic polymer, of the polymethyl methacrylate (PMMA) type. The light guide 2 has a substantially cylindrical shape, of circular or oblong section and it extends mainly along a longitudinal direction of elongation L. Depending on the need, the longitudinal dimension of the light guide 2 can extend for example from several tens of centimeters or even more than a meter. The light guide 2 on the other hand has a section of very small size with regard to its length, the section being between one and five millimeters. This section corresponds to the transverse T and vertical V dimensions defining the internal volume of the light guide 2. As illustrated in FIGS. 2 and 3, the light guide 2 has a specific shape at the level of a wall which will be described in more detail later.

The light source 3 comprises a printed circuit board 4 and a plurality of microLEDs 5. The printed circuit board 4 extends along a plane defined by the longitudinal L and vertical V directions, and may for example have a substantially rectangular shape. , whose longitudinal dimension is greater than the vertical dimension. The printed circuit board 4 extends along the longitudinal direction L over a length similar to that of the light guide 2. The printed circuit board 4 comprises a first face 41 capable of facing the light guide 2 when the device is assembled and a second face 42 facing away from the guide. Several components, and in particular the microLEDs, are arranged on the first face 41 of the printed circuit board.

The plurality of microLEDs 5 here form one and only one linear series 6 extending longitudinally, parallel to the direction of longitudinal elongation of the light guide 2 and of the printed circuit board 4. The distance D between each microLEDs 5 is between 300 and 500 microns. It is thus understood that the number of microLEDs 5 forming the linear series 6 depends on the length of the light guide 2 and of the printed circuit board 4.

The microLEDs 5 are placed on the printed circuit board 4 by suitable process solutions specific to the implementation of a large number of microLEDs on the printed circuit board. By way of example, with a device and a light guide approximately 1 m long, for a spacing of 400 microns between two neighboring microLEDs, it is then understood that there are approximately 2500 microLEDs to be fixed on the circuit board. printed and that mass transfer and fixation solutions should be provided.

More precisely, a tool is configured and controlled to capture on a substrate a large number, for example of the order of a hundred, of microLEDs to transfer them to the printed circuit board in order to keep a reasonable number of transfers to optimize the module production time and therefore its cost.

The microLEDs 5 are light-emitting diodes with a dimension of the order of ten microns, typically between 20 and 150 microns. The microLEDs that make up the linear series 6 are configured to emit a light beam of regulatory color when the device is an outdoor lighting device or a signaling device, and of any ambient color when the device is a device. interior lighting.

By way of non-limiting example, the desired colors are obtained by combining an emission of blue light and by wavelength conversion via a suitable phosphor. The phosphor can for example be a phosphor. The phosphor, and consequently the color, is chosen according to the need to which the device 1 must respond. If the device 1 must emit several colors, the microLEDs 5 can be organized to respond to this function as will be described below. These phosphors can in particular be arranged on the path of the rays emitted in microLEDs 5 of the packaged type, in which a box houses the various semiconductor layers and the phosphor layer.

Furthermore, whether the microLEDs are of the packaged type or not, each of these microLEDs 5 can be associated with several phosphors so as to be able to emit several different wavelengths. As will be described below, in this context of multiple wavelength emissions, the microLEDs 5 may also contain only a single phosphor with several types of microLEDs 5 emitting in a different wavelength which are arranged in a single device 1.

According to the invention, the light guide 2 is defined with an input face 7 through which the rays emitted by the light source enter the light guide and with an output face 8, arranged opposite the entry face, through which the rays leave the device to form an illuminating or signaling beam. These two faces are formed by a portion of the peripheral wall delimiting the internal volume of the light guide.

The printed circuit board 4 being directly in contact with the light guide 2, the light rays 9 emitted when the microLEDs 5 are lit propagate directly through the light guide 2 around the optical axis, or main direction of emission , microLEDs, that is to say a transverse direction T perpendicular to the plane of extension of the printed circuit board. As can be seen in particular in FIGS. 1 and 2, the light rays 9 emitted closest to the optical axis pass directly through the cylindrical section of the light guide 2 in the direction of the exit face 8, while the light rays exploded at the entry face 7 of the guide are reflected on the wall delimiting the guide in the direction of this exit face 8. The serial arrangement of the microLEDs, with a gap between two neighboring microLEDs of the order of 300 microns , opposite an input face opposite the output face, makes it possible to generate a device in which the output of the light rays 9 by the output face 8 of the light guide 2 forms a homogeneous light over the entire length of light guide 2 when all microLEDs are on.

FIG. 2 makes the shape of the entry face 7 more particularly visible. The light guide 2 has a substantially circular section with the exception of a flat 14, which forms the entry face 7 located opposite the printed circuit board 4 and microLEDs when the device is assembled, that is to say when the printed circuit board 4 is pressed against the flat 14, in accordance with the arrows present in the illustration of figure 3.

The flat 14 allows the fixing of the light guide 2 to the printed circuit board 4, for example by gluing. The flat surface of the flat 14 makes it possible to have a parallelism of the surfaces of the input face and the printed circuit board 4. Thus, the light rays 9 emitted by the microLEDs 5 undergo a minimum of parasitic optical phenomena when they penetrate in the light guide by crossing the flat 14. The light source 3 is electrically connected to a control module, not shown in Figure 1. The control module controls the lighting or not of the microLEDs 5 of the device 1, by function of the actions carried out by the driver of the vehicle or by the passengers, for example the switching on of lighting, inside or outside the vehicle, or else the performance of a particular action by the user of the vehicle requiring the signaling of this action, such as operating the brake pedal or the lever controlling the indicators. Depending on the lighting or signaling function to be performed, the control module determines which microLEDs 5 to activate and, if necessary, in which configuration the microLEDs must be activated when they are likely to emit beams of several colors. .

FIG. 4 represents device 1 according to a second embodiment. In this embodiment, the microLEDs 5 are still aligned in a single linear series, but are divided into two types of microLEDs, a first type of microLED 51 and a second type of microLED 52. The first type of microLED 51 and the second type of microLED 52 are differentiated by the emission wavelength of their semiconductor, and therefore by the type of associated phosphor. The difference in wavelength resulting from the arrangement of these two types of microLEDs is illustrated in the figure by hatching of different orientation and thickness.

In this second embodiment, the microLEDs are arranged so that the two types of microLEDs are arranged alternately along the linear series and the control module is configured to simultaneously light only the microLEDs of one of the types. The two colors are chosen according to the need to be met by the device 1 within the vehicle and also according to the standards of the vehicles, for example red and amber if the device 1 is located at the rear of the vehicle, or white and amber if the device 1 is located at the front of the vehicle. It is understood from this second embodiment that two microLEDs of the same type of microLED are not directly juxtaposed. It is therefore important to reduce the distance between each microLEDs in order to maintain a linear aspect of one or the other color of the beam emitted when only a first or a second type of microLEDs is lit. The inventors have determined a maximum distance D1 to be respected, in order to maintain the perception by a user one meter from the vehicle of a linear aspect of one or other of the beams emitted, of the order of 500 microns between two microLEDs of the same type, and therefore the distance D must here be less than 250 microns for two juxtaposed microLEDs on the same linear series 6.

FIG. 5 represents a third embodiment of the device 1. This embodiment comprises, in accordance with what has just been described for the second embodiment, two different types of microLEDs symbolized by hatching of orientation and of different thickness to be able to distinguish them. However, contrary to what has just been described with reference to the previous figure, the two types of microLEDs are here not arranged alternately on one and the same linear series. In this third embodiment, each type of microLEDs is arranged on its own linear series. There are therefore as many linear series as there are types of microLEDs. FIG. 4 represents an embodiment comprising two types of microLEDs, such that the light source comprises a first linear series 61 and a second linear series 62, each comprising only one type of microLED. Thus, it is not necessary to reduce the distance D between each microLED of the same type as has been specified for the second embodiment and the distance value D can be maintained between 300 microns and 500 microns such that mentioned with reference to the first embodiment. The spacing E between the two linear series can be between 150 microns and one millimeter.

This third embodiment involves a modification of the dimensions of certain elements, the printed circuit board accommodating several linear series of microLEDs. Thus, the vertical dimension of the printed circuit board 4 is increased so that several linear series can be arranged thereon. This modification of the dimension of the printed circuit board 4 therefore leads to a modification of the dimension of the flat of the light guide 2, the flat having to cover all of the linear series of microLEDs. This modification justifies the shape of the light guide 2 which is more oblong than for the previous embodiments.

FIGS. 6 and 7 are views according to a longitudinal plane of a first variant embodiment, in which the phosphor is arranged in the form of a continuous strip, unlike the examples previously described where the phosphor was individually associated with a microLED. It is understood that what has been previously described on the arrangement of the microLEDs relative to each other and the arrangement of the light guide and the printed circuit board are repeated here, the light guide not being not shown here for clarity. Indeed, rather than arranging a fraction of phosphor individually on each microLED 5, it may be judicious, when a plurality of microLEDs 5 of the same type are arranged so as to form a linear series 6 to fix a single phosphor on the set of linear series 6.

The arrangement can thus be applied when a single linear series is formed from a single type of microLEDs, as presented in the first embodiment. Figure 6 illustrates such an arrangement with a phosphor in the form of a strip 10, fixed to the printed circuit board 4, for example by gluing. Thus, the microLEDs 5 are devoid of individual phosphor and it is the strip 10 of phosphor which converts the emission wavelength of the entire linear series 6 of microLEDs 5. The operation of depositing the strip of phosphor requires only one pass and the time required to produce the device as a whole is thereby reduced.

This arrangement can also apply to the third embodiment, as shown in Figure 7 where again, the light guide is not shown for reasons of clarity. FIG. 7 represents a first strip 101 of phosphor and a second strip 102 of phosphor, each being placed respectively on the first linear series 61 and on the second linear series 62. Each of the strips of phosphor is represented in the form of hatchings of different orientation and thickness to be distinguishable. Thus, the first strip 101 and the second strip 102 are different phosphors with respect to each other. Each of the microLEDs 5 can be identical to the other microLEDs and it is the type of phosphor of each strip which gives a different color between the beam emitted by the activation of the microLEDs 5 of the first linear series 61 and the beam emitted by the activation of 5 microLEDs of the second linear series 62.

Such an arrangement can lead to a more intense diffusion of light than when each microLED 5 comprises its own phosphor and therefore the risk that light rays emitted by a microLED having crossed the strip of phosphor which is associated with this microLED come to cross subsequently the other strip of phosphor and therefore ultimately alter the color desired for the light beam. To overcome this problem, a wall 11 is placed between the linear series of microLEDs and phosphor strip. This wall 11 is fixed to the printed circuit board 4, for example by gluing or welding, or even is made in one piece with the board. The wall 11 extends in a longitudinal direction L over the entire length of the printed circuit board 4 so as to form an optical barrier between the two linear series of microLEDs 5.

FIG. 7 is a view along a transverse plane of a second phosphor arrangement variant applied here to the third embodiment described above, this second variant differing from the above in that the phosphor strips are arranged on the guide light guide 2. As mentioned above, this arrangement has advantages when the optical index of the material which constitutes the light guide 2 is close to the optical index of the phosphor material.

The light guide is configured in this variant so as to have at least one notch, arranged respectively opposite a linear series of microLEDs, and the bottom of this notch is covered by a phosphor layer. The phosphor is placed directly on the light guide 2 so as to cover the microLEDs 5 when the device is assembled. The third embodiment comprising two linear series, the arrangement illustrated here comprises a first notch 12 and a second notch 13. It is of course understood that this variant can be applied to the first embodiment, with a single notch facing the unique linear array of microLEDs.

In accordance with the above, each of the phosphor layers deposited in a notch is represented in the form of hatches of different orientation and thickness to be able to be distinguished. Thus, the first layer 201 and the second layer 202 are different phosphors with respect to each other. In other words, each phosphor deposited in the bottom of a notch ensures the transmission of the light rays of each of the linear series that it covers by modifying the wavelength differently depending on the type of phosphor. The microLEDs 5 according to this arrangement therefore all have no individual phosphor. The notches have a longitudinal dimension similar to the longitudinal dimension of the printed circuit board 4 so that the phosphor layers can cover the entire linear array of microLEDs of their own. The notches are arranged on the light guide 2 so that when the light guide 2 is placed on the printed circuit board 4, each notch faces a linear series of microLEDs 5.

As illustrated, a wall 11 can be provided in the thickness of the light guide to prevent the rays emitted by one type of microLED from passing through the two different types of phosphors. This wall 11 can in particular be produced by the presence of an opaque portion in the material of the light guide, or else by an air void zone formed in this material of the light guide. As before, the wall 11 extends in a longitudinal direction L over the entire length of the printed circuit board 4.

The preceding description clearly explains how the invention guarantees homogeneous light, devoid of pixels, over the entire length of a light guide which can extend over several tens of centimeters, thanks to the combination of the alignment transverse of the entry and exit faces of the guide and the configuration of the light source with a serial arrangement of the microLEDs and a minimal distance between each microLEDs 5.

The invention cannot however be limited to the means and configurations described and illustrated here, and it also extends to all equivalent means or configurations and to any technically effective combination of such means. In particular, the number of microLEDs, the number of linear series or the number of phosphors can be modified without harming the invention, insofar as they fulfill the functions described in this document.

The embodiments described above are thus in no way limiting; it is possible in particular to imagine variants of the invention comprising only a selection of characteristics described below isolated from the other characteristics mentioned in this document, if this selection of characteristics is sufficient to confer a technical advantage or to differentiate the invention by compared to the prior art.

Claims (10)

Vehicle lighting and/or signaling device (1) comprising a linear light guide (2) which has a main longitudinal direction of elongation and a light source (3), the light guide (2) comprising an entry face (7) and an exit face (8) for the light rays emitted by the light source (3), the exit face extending along the direction of elongation of the light guide, characterized in that the input face (7) is disposed opposite the output face (8) and that the light source (3) comprises a printed circuit board (4) on which is disposed a plurality microLEDs (5) forming a linear series (6) in a direction parallel to the main longitudinal direction of elongation of the light guide, within which neighboring microLEDs (5) are spaced apart by a distance (D) between 200 microns and 1 millimeter. Lighting and/or signaling device (1) according to claim 1, in which the adjacent microLEDs (5) are spaced apart by a distance (D) of between 300 microns and 500 microns. Lighting and/or signaling device (1) according to Claim 1 or 2, in which the printed circuit board (4) is arranged directly in contact with the light guide (2). Lighting and/or signaling device (1) according to any one of the preceding claims, in which the light guide (2) comprises a flat (14) configured to form a flat receiving surface for the circuit board printed (4). Lighting and/or signaling device (1) according to any one of the preceding claims, in which the dimension of the light guide (2) perpendicular to its longitudinal dimension is between 1 and 5 mm. Lighting and/or signaling device (1) according to any one of the preceding claims, in which the microLEDs (5) are associated with at least one phosphor. Lighting and/or signaling device (1) according to Claim 6, in which the light source (3) comprises two types of microLEDs (51, 52), each type being powered independently of one another and being arranged linearly in a single series on the printed circuit board (4) so as to create an alternation of colors, the distance between two microLEDs of the same type being of the order of 500 microns. Lighting and/or signaling device (1) according to claim 6, in which at least two types of microLEDs (51, 52) are arranged in several linear series (61, 62), each type of microLED forming a linear series . Lighting and/or signaling device (1) according to any one of Claims 1 to 6 or according to Claim 8, in which at least one phosphor is arranged on the printed circuit board (4) and/or on the entrance face of the light guide (2). Lighting and/or signaling device (1) according to the preceding claim, in which the printed circuit board (4) or the light guide (2) comprises at least one wall (11) between two separate phosphors.