Abstract:
A carrier of one or more light sources for a lighting and/or signaling module especially for an automotive vehicle, comprising: a substrate having at least one aperture and electrical tracks on at least one side; and at least one light-emitting diode having a body and electrical connection leads lateral to the body. The LED or at least one of the LEDs is placed through a respective aperture of the substrate, and the connection leads make contact with respective electrical tracks. The substrate is a rigid molded part having a three-dimensional shape possibly providing an optical function such as that of a reflector. In this case, the LEDs are directly supported by the optical part.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to the French application 1457415 filed on Jul. 31, 2014, which application is incorporated herein by reference and made a part hereof. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The invention relates to the field of lighting and luminous signaling, especially for automotive vehicles. More precisely, the invention relates to the field of lighting and luminous signaling by means of light-emitting diodes (LEDs), and more particularly to the mounting of the LEDs in a signaling module. 
         [0004]    2. Description of the Related Art 
         [0005]    U.S. Pat. No. 5,331,512 discloses mounting an LED on a printed circuit board. The LED is reverse mounted (i.e. it is a “reverse mount” LED), namely the LED emits its light rays on that side of the board which is opposite the side on which the LED is mounted. For this purpose, the board comprises an orifice through which the optical part of the LED is inserted. The latter comprises a base with two extensions extending laterally in opposite directions, these extensions comprising contact zones intended to be soldered to corresponding contact zones of the board. The board and the base of the LED are made of a conventional circuit-board material, namely of glass-fiber reinforced epoxy resin. Such a material is designed to withstand the high temperatures induced locally by conventional soldering operations. The LED carrier disclosed in this teaching .is advantageous for planar mounting. It is however less so for signaling modules of complex shape. 
         [0006]    U.S. Pat. No. 7,924,371 discloses a screen for a night-vision imaging system. The screen comprises a printed circuit board on which a series of LEDs are arranged in a matrix, the series of LEDs being intended to backlight a liquid-crystal display. Certain of the LEDs are placed on the front side of the board, i.e. on the face directed toward the liquid-crystal display. Other LEDs are reverse mounted, i.e. they are placed on the back side of the board, through corresponding orifices, so as to provide forward illumination through the orifices. The LEDs are fixed in place and connected to the electrical tracks of the board by conventional solder joints. Similarly to the preceding teaching, the LED carrier disclosed in this teaching is advantageous for planar mounting. It is however less so for signaling modules of complex shape. 
         [0007]    U.S. Patent Publication No. 2005/0243558, which issued as U.S. Pat. No. 7,213,029, discloses an LED carrier for a rear automotive vehicle light type signaling module. It consists of a printed circuit board comprising a series of orifices through which reverse mount LEDs are inserted. These LEDs comprise optical portions taking the form of domes, these domes being visible from the front side. The LEDs comprise fastening and electrical connection leads soldered to the electrical tracks on the back side of the board. This mounting schema provides a carrier that is attractive when it is observed by an observer located on the front-side side, the electrical connections being exclusively on the back side. In addition, it allows a radiator to be placed on the back side of the base of the LED. Similarly to the two preceding teachings, the LED carrier disclosed in this teaching is advantageous for planar mounting. It is however less so for signaling modules of complex shape. 
       SUMMARY OF THE INVENTION 
       [0008]    The objective of the invention is to provide an LED carrier mitigating at least one of the drawbacks of the prior art. More precisely, the objective of the invention is to provide an LED carrier solution that is compatible with a module of non-planar shape and more particularly of complex shape. Another objective of the invention is to provide an LED carrier allowing the construction of a signaling module to be simplified and, therefore, its production cost to be decreased. 
         [0009]    One subject of the invention is a carrier of one or more light sources for a luminous module especially for an automotive vehicle, comprising: a substrate having at least one aperture and electrical tracks on at least one side; and at least one light-emitting diode, light-emitting diode being abbreviated LED below, having a body and electrical connection leads lateral to the body, the or each of the LEDs being placed through a respective aperture of the substrate, the connection leads making contact with respective electrical tracks; noteworthy in that the substrate is a rigid molded part having a three-dimensional shape. 
         [0010]    The expression “luminous module” is understood to mean a lighting module for lighting the road in front of the vehicle, or a signaling module for signaling the position of the vehicle to other road users, or even an interior lighting module for lighting the interior of a passenger compartment of the vehicle. 
         [0011]    The aperture or each of the apertures is a through-aperture passing right through the thickness of the substrate. 
         [0012]    In one example embodiment, the body of the LED comprises a top wall comprising at least one light emission area and a side wall extending around the top wall. The lateral electrical connection leads advantageously extend from the side wall substantially parallel to the top wall. Advantageously, the LED has two electrical connection leads, placed on either side of the body. 
         [0013]    The one or more LEDs are configured to light that side of the substrate which corresponds to the side opposite that comprising the electrical tracks. 
         [0014]    According to one advantageous embodiment of the invention, the substrate forms a wall having over its extent variations in height of more than 10% and preferably 20% of its extent. The variations in height are in a direction generally perpendicular to a reference plane. The latter may correspond to a portion of the wall, or even to its midplane. The thickness of the wall may be generally constant. It may be comprised between 0.5 and 3 mm. 
         [0015]    According to one advantageous embodiment of the invention, the substrate has one or more cavity- and/or step-shaped portions. 
         [0016]    According to one advantageous embodiment of the invention, the leads of the one or more LEDs are connected to respective electrical tracks by an adhesive filled with metal particles, said adhesive preferably being a polymer adhesive that it is possible to polymerize after application. The use of the adhesive is advantageous in that it makes it possible to avoid subjecting the substrate to thermal stresses. 
         [0017]    According to one advantageous embodiment of the invention, the leads of the one or more LEDs are connected to respective electrical tracks by a metal, for example copper, this metal being deposited by a chemical metalization process. The metalization process for connecting the leads to the tracks may especially be carried out at the same time as the process allowing these tracks of the substrate to be metalized. 
         [0018]    According to one advantageous embodiment of the invention, the carrier comprises a connector integrally formed with the substrate. 
         [0019]    According to one advantageous embodiment of the invention, the material of the substrate is a thermoplastic doped with metal particles so as to allow electrical tracks to adhere. 
         [0020]    According to one advantageous embodiment of the invention, the substrate comprises at least one electronic component connected electrically to the diode or to at least one of the LEDs by the electrical tracks. The one or more components may be electrically and mechanically connected by an adhesive filled with metal particles such as described above. 
         [0021]    According to one advantageous embodiment of the invention, the substrate has at least one surface interacting with the light rays emitted by the one or more LEDs so as to provide an optical function. The substrate may play both the role of a carrier of the one or more LEDs and the role of a reflector. 
         [0022]    According to one advantageous embodiment of the invention, the surface or at least one of the surfaces of the substrate, interacting with the light rays, is reflective, absorbent or scattering. 
         [0023]    According to one advantageous embodiment of the invention, the substrate comprises a reflective, absorbent or scattering coating on its side opposite that of the electrical tracks. This reflective coating may advantageously be deposited via the same metalization process allowing these tracks to be produced. 
         [0024]    Another subject of the invention is a signaling module comprising: a carrier of one or more light sources; and an optical part, such as a reflector, interacting with the light rays emitted by the one or more light sources; noteworthy in that the carrier is according to the invention. 
         [0025]    According to one advantageous embodiment of the invention, the carrier comprises the optical part and preferably the carrier forms the optical part. 
         [0026]    Another subject of the invention is a lighting and/or signaling device, comprising: a housing; a luminous module disposed in the housing; and an outer lens placed on the housing; noteworthy in that the module is according to the invention. 
         [0027]    The measures of the invention are advantageous in that they simplify the production of the LED carrier, in particular for signaling devices or modules of complex shape. Specifically, in the case of a module comprising many LEDs distributed over a reflector of complex shape, such as for example a generally curved shape matching the curvature at one of the rear corners of a vehicle, and having a series of reflective surface portions directed toward the rear of the vehicle. Such a reflector may thus have a tiered shape compatible with production by molding. In the absence of the invention, it would be necessary to produce a series of small planar carriers or even to provide a flexible elongate substrate (a “flex PCB” or “flex circuit”), and to fasten it or them with precision to the back side of the reflector. By virtue of the invention, the carrier may closely follow the back side of the reflector or even also provide the reflector function. 
         [0028]    These and other objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS 
         [0029]    Other features and advantages of the present invention will be better understood from the description and drawings, in which: 
           [0030]      FIG. 1  is a schematic illustration of a carrier according to a first embodiment of the invention; 
           [0031]      FIG. 2  is an illustration of the LED present in  FIG. 1 ; 
           [0032]      FIG. 3  is a cross-sectional view of a signaling device according to the first embodiment; 
           [0033]      FIG. 4  is a schematic illustration of a carrier according to a second embodiment of the invention; 
           [0034]      FIG. 5  is a cross-sectional view of a signaling device according to the second embodiment; and 
           [0035]      FIG. 6  is a perspective view of a carrier according to a third embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0036]      FIG. 1  is a schematic illustration of a first embodiment of the invention. This illustration corresponds to a cross-sectional or profile view of a carrier  2  comprising a substrate  4  having at least one orifice  16  through which a reverse mount light-emitting diode (LED)  6  is placed. The LED  6  comprises a body  18  having an optical portion  20  and fastening and electrical connection leads  8 . The substrate  4  comprises electrical tracks  10  on its back side, this side corresponding to the bottom side in the figure. The LED  6  is placed on the back side, so that its body  18  and more particularly its optical portion  20  penetrates at least partially the orifice  16 . The leads  8  make mechanical and electrical contact with corresponding electrical tracks  10  via a polymer adhesive doped with metal particles or via copper deposited by a chemical process. 
         [0037]    The back side of the substrate  4  may comprise one or more electrical or electronic components  12 . 
         [0038]    An optical element or reflector  14  is placed on the front side of the substrate  4  in such a way as to interact with the light rays emitted by the LED  6 . This optical element or reflector  14  may be reflective, absorbent or even scattering, or even a combination of the latter. 
         [0039]    In contrast to what  FIG. 1  may have led the reader to believe, the substrate  4  is not planar, i.e. it has a three-dimensional shape. It essentially consists of a wall extending with variations in height so as to form a three-dimensional shape. The substrate  4  is produced by molding one or more plastic materials. The one or more materials is/are preferably thermoplastic. The molding may thus be carried out by injecting the material into a mold. The latter, installed on a press, most often consists of two halves corresponding to a stationary portion and a movable portion that are firmly pressed one against the other at the moment of the molding then separated in order to allow the molded part to be ejected. The mold may also comprise one or more cores intended to form hollow portions of the part and punches allowing apertures to be produced in its walls. It is also possible to place in the mold inserts made of another material or at least of another color, which are subsequently included in the part. 
         [0040]    The plastic material of the substrate  4  may be doped with metal particles able to ensure the adhesion of metal tracks to its exterior surface. This technology is commonly designated by the acronym MID (for Molded Interconnect Device). 
         [0041]    The electrical tracks  10  may be produced using the technology designated by the acronym LDS (for Laser Direct Structuring). It is a question of tracing a laser beam over the corresponding surface of the substrate  4 , according to the configuration of the electrical tracks  10  to be produced. The laser beam has the effect of forming a roughness able to promote adhesion. This step is followed by a metalization operation in which the substrate  4  is dipped into one or more successive metal baths. 
         [0042]    Alternatively or additionally, the electrical tracks  10  may be produced by inkjet printing of an ink containing metal particles. 
         [0043]    The electrical tracks  10  may also be produced by two-shot molding. It is a question of an injection molding process using two different resins only one of which is metalizable. Typically, the metalizable resin is ABS and the non-metalizable resin is polycarbonate. The substrate  4  is then subjected to an electroless deposition process in which butadiene is used to make the surface rough chemically and allow a copper primer layer to adhere. 
         [0044]    Because of the thermoplastic nature of the substrate  4 , it is not appropriate to use conventional soldering processes for the electrical contacts  10 . The fastening and connection leads  8  of the LED  6  are thus electrically and mechanically fastened by applying a polymer-based adhesive filled with metal elements. It is thus a question of what is referred to as a “cold” application process that does not damage the substrate  4 . After polymerization of the adhesive, the latter ensures the LED  6  is electrically and mechanically fastened. 
         [0045]      FIG. 2  illustrates the LED  6  in  FIG. 1 . The left-hand side view is a schematic plan view corresponding to that in  FIG. 1 , whereas the right-hand side view is a perspective representation of a corresponding commercially available LED  6 . In the two views, the reverse nature of the LED  6 , its body  18 , its optical portion  20  and its fastening leads  8  may be clearly seen. More particularly, in the right-hand view the circular shape of the optical portion  20  and the stepped cross section of the leads  8  may be seen. 
         [0046]      FIG. 3  is a cross-sectional view of a signaling device  22  according to the first embodiment, implementing the principle illustrated in  FIG. 1 . The device  22  comprises a housing  26  with an outer lens  24  and a reflector  14 . The latter has a stepped shape with a series of orifices through which LEDs  6  are placed. The latter are fastened to a substrate  4  that closely follows at least partially the stepped shape of the reflector  14 . The molded substrate  4  may closely follow the shape of the reflector  14  or at least have a complex shape able to match or conform to a reflector  14  or at least an optical element of nonplanar shape. 
         [0047]    The carrier  2  formed by the substrate  4  and the LEDs  6 , which are assembled therewith, may thus be placed directly on the other elements of the signaling device  22 . 
         [0048]      FIGS. 4 and 5  schematically illustrates a carrier  102  of one or more light sources according to a second embodiment. The reference numbers of the first embodiment are used for identical or corresponding elements of the second embodiment, these numbers being however increased by  100  in order to make it easy to tell the two embodiments apart. 
         [0049]    The carrier  102  comprises a substrate  104  of nonplanar shape and providing an optical function. This substrate  104  comprises electrical tracks  110  on its back side. It may also comprise one or more electrical or electronic components  112  on its back side, electrically connected to the electrical tracks  110 . The substrate  104  comprises an orifice  116  through which is inserted, at least partially, an LED  106 . The latter is of similar construction to that of the first embodiment. It is a question of a reverse mount LED model, i.e. of an LED intended to be placed on that side of the substrate  104  which is opposite the side on which the light rays will be emitted. The body  118  of the LED  106  is thus inserted through the orifice  116  from the back side of the substrate  104 , so that its optical portion  120  faces forward, i.e. on the same side as the front side of the substrate  104 . During the insertion of the LED  106 , its leads  108  make contact with the back side of the substrate  104  and more precisely with corresponding electrical tracks  110 . The contact is ensured by metal-doped adhesive. This adhesive is preferably a synthetic polymer adhesive that can be polymerized after application in the pasty state. The reader is referred to the description of the adhesive fastening operation of the first embodiment. 
         [0050]    As may be seen in  FIGS. 4 and 5 , the substrate  104  is not planar, i.e. it has a three-dimensional shape. Similarly to the substrate  4  of the first embodiment, it essentially consists of a wall extending with variations in height so as to form a three-dimensional shape. The substrate  104  is produced by molding one or more plastic materials. The reader is referred to the description of the first embodiment as regards the substrate molding process. 
         [0051]    In order to provide an optical function the substrate  104  may be covered, especially on its front side or at least on portions of its front side, with a reflective, absorbent or scattering coating. This coating may be applied by various processes well known per se to those skilled in the art, such as metalization for a reflective coating, or application of a coat of absorbent or scattering paint. 
         [0052]      FIG. 5  is a cross-sectional view of a signaling device  122  according to the second embodiment, implementing the principle illustrated in  FIG. 4 . The signaling device  122  comprises a housing  126  with an outer lens  124  and a reflector  114 . The latter has a stepped shape and forms a substrate  104  with a series of orifices through which and on which LEDs  106  are placed directly. The front side of the substrate  104  is reflective. The LEDs  106  are fastened to the back side of the substrate  104  by means of their leads  108 . The molded substrate  104  may thus take the form of an optical element of complex shape. The mounting of the signaling device  122  is thus made particularly simple. Specifically, in the example in  FIG. 5 , the signaling device  122  essentially consists of only three elements to be assembled, namely the carrier  102  equipped with the LEDs  106 , the housing  126  and the outer lens  124 . The housing  126  and the outer lens  124  may form a single part. 
         [0053]      FIG. 6  illustrates an LED carrier  202  according to a third embodiment of the invention. The reference numbers of the second embodiment are used for identical or corresponding elements of this third embodiment, these numbers being however increased by  100  in order to make it easy to tell the two embodiments apart. 
         [0054]    This third embodiment is similar to the second embodiment shown in  FIGS. 4 and 5 . The carrier  202  comprises a substrate  204  of complex shape with a series of stepped profiles. The front side (corresponding to the side on the left in the figure) is reflective. The LEDs  206  are placed on and fastened to the back side (corresponding to the side on the right in the figure). Only three LEDs  206  have been shown in the figure, it being understood that more LEDs  206  may be present. The conductive tracks  210  are formed on the back side of the substrate  204 , so as to extend continuously from surface portion to surface portion and to connect the leads  208  to one another.  FIG. 6  thus shows an optical part of complex shape able to be formed by molding of a plastic material and able to serve as a carrier  202  of LEDs  206  and electrical tracks  210 . 
         [0055]    Generally, the substrate  4  may provide other functions such as especially that of a connector. Specifically, a connector may be molded directly with the material of the substrate  4 . It may also comprise an insert around which the material of the substrate  4  is injection molded. Other elements may also be provided on the substrate  4  providing other functions, such as especially fastening elements. 
         [0056]    While the system, apparatus, process and method herein described constitute preferred embodiments of this invention, it is to be understood that the invention is not limited to this precise system, apparatus, process and method, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims. 
         [0057]    What is claimed is: