Light generator comprising a phosphor layer and a dichroic filter

Abstract

A light generator (1) comprising: - an optoelectronic device (11) configured to produce a first monochromatic beam (R1) so as to generate light (L1) at a first wavelength (λ1), - a phosphor layer (12) offset from said optoelectronic device (11) and configured to convert all or part of the first monochromatic beam (R1) into a second beam (R2) so as to obtain converted light (L2) at one or more second, higher wavelengths (λ2) and to diffuse it, characterized in that it comprises: - a first dichroic filter (13) configured to transmit the light (L1) emanating from the first monochromatic beam (R1) towards the phosphor layer (12) and to reflect the converted light (L2) by the phosphor layer (12), - a protective layer (15) disposed opposite the phosphor layer (12) on the side opposite the first filter Dichroic (13). Figure for the abstract: figure 1

Description

Title of the invention: Light generator comprising a phosphor layer and a dichroic filter

[0001] The present invention relates to a light generator. It also relates to a lighting device comprising such a light generator. It finds particular, but not limiting, application in vehicles or in domestic or industrial applications.

[0002] A light generator, known to those skilled in the art, comprises: - a reflective cavity, - an opto-electronic device composed of semiconductor materials configured to produce a first monochromatic radiation so as to generate light at a first wavelength and disposed at the bottom of the reflective cavity, - a phosphor layer offset from the opto-electronic device and disposed opposite it or glued to the opto-electronic device, comprising a first diopter and a second diopter and configured to convert the first incident monochromatic radiation into a second radiation so as to generate light at one or more second wavelengths greater than that of the light emanating from the first monochromatic radiation.

[0003] One disadvantage of this prior art is that the luminous efficiency is not optimum because there is a loss of light due to the light being backscattered towards the opto-electronic device.

[0004] In this context, the present invention aims to provide a light generator that makes it possible to resolve the aforementioned drawback.

[0005] To this end, the invention proposes a light generator comprising: - at least one optoelectronic device composed of semiconductor materials and configured to produce a first monochromatic radiation so as to generate light at a first wavelength, - a phosphor layer offset from said at least one optoelectronic device and comprising a first diopter and a second diopter and configured to convert all or part of the first incident monochromatic radiation into a second radiation so as to obtain converted light at one or more second wavelengths higher than that of the light emanating from the first monochromatic radiation and to diffuse this converted light, characterized in that the light generator further comprises: - a first dichroic filter positioned on the side of the first interface of the phosphor layer and configured to transmit the light emanating from the first radiation monochromatic in the direction of the phosphor layer and to reflect the light converted by the phosphor layer, - a protective layer positioned opposite the phosphor layer on the side of the second diopter.

[0006] Thus, as will be seen in detail later, the dichroic filter, which is positioned between the optoelectronic device and the phosphor layer, allows the light converted by the phosphor layer and backscattered towards the dichroic filter to be recovered and reflected outwards from the light generator. Light losses are thus reduced, which in turn improves the luminous efficiency of the light generator.

[0007] According to non-limiting embodiments, said light generator may further comprise one or more additional features taken alone or in all technically possible combinations, among the following.

[0008] According to a non-limiting embodiment, said at least one optoelectronic device is disposed opposite the first dichroic filter and the phosphor layer and the first dichroic filter is disposed between the phosphor layer and said at least one optoelectronic device, and the light generator further comprises at least one reflective cavity at the bottom of which said at least one optoelectronic device is disposed.

[0009] According to a non-limiting embodiment, the light generator comprises a plurality of reflective cavities and a plurality of opto-electronic devices.

[0010] According to a non-limiting embodiment, the light generator further comprises a light guide disposed opposite the first dichroic filter on the side opposite the phosphor layer, and configured to refract and reflect the light emanating from the first monochromatic radiation towards the phosphor layer, and said at least one opto-electronic device is disposed at one of the two ends of the light guide.

[0011] According to a non-limiting embodiment, when the light generator includes a light guide, it includes one or two opto-electronic devices.

[0012] According to a non-limiting embodiment, the phosphorus layer is offset by a distance of between approximately 4 millimeters and 10 millimeters.

[0013] According to a non-limiting embodiment, said at least one optoelectronic device (11) is a native light-emitting diode or a laser diode.

[0014] According to a non-limiting embodiment, the first wavelength is between 400 and 500 nanometers.

[0015] According to a non-limiting embodiment, the light generator further comprises a second dichroic filter complementary to the first dichroic filter, disposed between the phosphor layer and the protective layer, and configured to transmit the light converted and diffused by the phosphor layer towards the outside of the light generator and to reflect the light emanating from the first monochromatic radiation towards the phosphor layer.

[0016] According to a non-limiting embodiment, the phosphorus layer is mixed with resin.

[0017] According to a non-limiting embodiment, the first dichroic filter is laminated onto the phosphorus layer and placed on a substrate, the whole being glued or overmolded onto the protective layer.

[0018] According to a non-limiting embodiment, the light generator comprises a plurality of opto-electronic devices.

[0019] According to a non-limiting embodiment, the converted light is visible light.

[0020] A lighting device is further proposed, according to which said lighting device comprises at least one light generator according to any one of the preceding characteristics.

[0021] According to a non-limiting embodiment, said lighting device is a vehicle lighting device, or a domestic or industrial lighting device.

[0022] According to a non-limiting embodiment, said vehicle lighting device is a lighting and / or signaling device, or a welcome scenario device, or an extended signaling device, or a front or rear lighting device, or an interior lighting device.

[0023] The invention and its various applications will be better understood upon reading the following description and examining the accompanying figures:

[0024] [Fig.1] is a schematic representation of a light generator according to the invention, said light generator comprising at least one optoelectronic device, a phosphor layer, a first dichroic filter, and a protective layer,

[0025] [Fig.2] illustrates the phosphor layer of the light generator of [Fig.1], said a layer of phosphorus being mixed with resin,

[0026] [Fig.3] is a diagram of the light generator of [Fig.1], said generator of light including, in addition, a second dichroic filter

[0027] [Fig.4] is a diagram of a first non-limiting embodiment of the generator of light from [Fig. 1], said light generator further comprising a reflective cavity,

[0028] [Fig. 5] illustrates the light generator of the preceding figure, said generator of light including, in addition, a second dichroic filter

[0029] [Fig.6] illustrates a non-limiting variant embodiment of the light generator [Fig. 4], the light generator comprising a plurality of reflective cavities and a plurality of optoelectronic devices,

[0030] [Fig.7] is a diagram of a second, non-limiting embodiment of the generator of light from [Fig. 1], said light generator further comprising a light guide and in which said opto-electronic device is disposed at one end of said light guide,

[0031] [Fig.8] illustrates the light generator of the preceding figure, said generator of light including, in addition, a second dichroic filter

[0032] [Fig.9a] is a diagram of a lighting device comprising the generator of light of [Fig.1], said light device being a lighting and / or signaling device for vehicle.

[0033] [Fig.9b] is a diagram of a lighting device comprising the light generator of the [Fig.1], said light device being a welcome scenario device or an extended vehicle signaling device.

[0034] [Fig.9c] is a diagram of a lighting device comprising the light generator of the [Fig.1], said lighting device being a front-facing lighting device for a vehicle.

[0035] [Fig.9d] is a diagram of a lighting device comprising the light generator of [Fig.l], said lighting device being an interior lighting device for a vehicle.

[0036] [Fig. 10] is a diagram of a lighting device comprising the light generator of the [Fig.1], the said light device being a domestic lighting device.

[0037] [Fig. 11] is a diagram of a lighting device comprising the light generator of the [Fig.1], said luminous device being an industrial lighting device.

[0038] Identical elements, by structure or by function, appearing on different figures retain, unless otherwise specified, the same references.

[0039] The light generator 1 according to the invention is described with reference to figures 1 to 11.

[0040] As illustrated in figures 1, 4 and 7, the light generator 1 comprises: - at least one opto-electronic device 11, - a phosphor layer 12, - a first dichroic filter 13, and - a protective layer 15.

[0041] The light generator 1 has a first direction D (also called the observation direction) and a second direction D' opposite to the first direction D and parallel to the first direction D as illustrated in Figures 1 to 8. The first direction D is transverse (in other words perpendicular) to all the layers of the light generator 1. The first direction D corresponds to the direction in which an external observer can, in particular, observe the light generated by the light generator 1.

[0042] The light generator 1 comprises a face turned towards the first direction D and a face turned towards the second direction D'. It has a direction of light emission which corresponds to the first direction D. We will speak of forward direction or backward direction respectively for the first direction D and the second direction D'.

[0043] In a non-limiting embodiment, the light generator 1 comprises a single opto-electronic device 11. In another non-limiting embodiment, the light generator 1 comprises a plurality of opto-electronic devices 11. The non-limiting embodiment of a single opto-electronic device 11 is taken as a non-limiting example in the following description.

[0044] The optoelectronic device 11 is composed of semiconductor materials. It is configured to produce a first monochromatic radiation RI so as to generate light L1 at a first wavelength XL. The optoelectronic device 11 emits unpolarized light L1. This light L1 is otherwise called the first light wave LL

[0045] In a non-limiting embodiment, the opto-electronic device 11 is a native light-emitting diode or a laser diode.

[0046] By light-emitting diode, we mean any type of light-emitting diode, whether in non-limiting examples LEDs (“Light Emitting Diode” in English), OLEDs (“Organic LED” in English), AMOLEDs (“Active-Matrix-Organic LED” in English), or FOLEDs (“Flexible OLED” in English).

[0047] By native light-emitting diode, it is understood that the color of the light-emitting diode is generated by opto-electronic conversion (before the generated light passes through the phosphor layer 12).

[0048] In a non-limiting embodiment, the first wavelength XI is between 400 and 500 nanometers (nm). This yields, for example, blue light L1 at 400 nm or cyan light at 490 nm. In a non-limiting variant, Xl = 450 nm. In another non-limiting embodiment, XI = 530 nm. This yields green light L1. It should be noted that the advantage of having, for example, a native blue LED (or a blue laser diode) is that it consumes less energy than a native green or red LED in terms of optical Amperes / Watts.Furthermore, as described later in the description, since the phosphor layer 12 only converts the first monochromatic radiation RI to second wavelengths X2 greater than its first wavelength XI, using a blue light L1 makes it possible to obtain a yellow or red light L2, for example, which is not possible with a red or green light L1 which has a first wavelength XI greater than that XI of the blue color.

[0049] The phosphor layer 12 is offset from the opto-electronic device 11. In other words, it is not in contact with it. By "remote," we mean that it is located at a certain distance from it. It is therefore not directly encapsulated on the optoelectronic device 11. This avoids thermal heating that would reduce the light conversion efficiency (described later) of the phosphor layer 12. In a non-limiting embodiment, the phosphor layer 12 is offset by a distance dl (illustrated in Figures 1 to 5 and 6 and 7) of between approximately 4 and 10 millimeters (mm) from the optoelectronic device 11. This distance dl is understood to be along a transverse axis Axl (illustrated in Figures 1 to 8) of the light generator 1 parallel to the first direction D and the second direction D'. This distance dl is sufficient to prevent a temperature increase in the phosphor layer 12.

[0050] In a first, non-limiting embodiment illustrated in Figures 1 to 6, the phosphor layer 12 is offset from the optoelectronic device 11 along the transverse axis Axl of the light generator 1. Thus, in this case, the optoelectronic device 11 is positioned opposite the first dichroic filter 13 and the phosphor layer 12, and, where applicable, the second dichroic filter 18. In other words, the phosphor layer 12 is positioned opposite the optoelectronic device 11 with the first dichroic filter 13 between the two. In this case, in a non-limiting example, dl = 10 mm.

[0051] In a second, non-limiting embodiment illustrated in Figures 7 and 8, the phosphor layer 12 is offset from the optoelectronic device 11 along a longitudinal axis Ax2 (illustrated in Figures 7 and 8) perpendicular to the transverse axis Axl. Thus, in this case, the phosphor layer 12 and the first dichroic filter 13, and where applicable the second dichroic filter 18, are not positioned opposite the optoelectronic device 11. In this case, in a non-limiting example, dl = 4 mm.

[0052] The phosphor layer 12 comprises a first diopter 120 and a second diopter 121. The first diopter 120 is turned towards the first dichroic filter 13 and the second diopter 121 is turned towards the protective layer 15, namely towards the outside of the light generator 1.

[0053] The phosphor layer 12 is configured to convert all or part of the first incident monochromatic radiation RI into a second radiation R2 so as to obtain a converted light L2 at one or more second wavelengths L2 greater than the first wavelength XI emanating from the first monochromatic radiation RI, and to scatter it. In the following description, the converted light L2 is otherwise referred to as L2 light or the second light wave L2.

[0054] Thus, the converted light L2 is notably diffused by the phosphor layer 12 outwards from the light generator 1. It should be noted that the fact of having light The conversion of L2 to a single second wavelength or to multiple second wavelengths is intrinsically linked to the composition of the phosphorus in the phosphorus layer 12 and its conversion properties, which are known to those skilled in the art. The converted light L2 is visible light. Thus, the second wavelength(s) X2 are greater than the first wavelength XI and less than or equal to 700 nanometers. The resulting second wavelength(s) X2 are defined by the composition of the phosphorus layer 12.

[0055] Thus, in a non-limiting example of blue light L1 Xl=450nm, converted light L2 is obtained at one or more second wavelengths X2 greater than Xl=450 nm, namely in the range of values ​​between 451 nanometers and 700 nanometers. Thus, in another non-limiting example of blue light L1 at Xl=490nm, converted light L2 is obtained at one or more second wavelengths X2 greater than Xl=490 nm, namely in the range of values ​​between 491 nanometers and 700 nanometers.

[0056] In non-limiting examples: - with XI = 530nm (green color), we can use a so-called red phosphor which generates a converted light L2 of red color (X2=650nm), - with XI = 450nm (blue color), we can use a so-called red phosphor which generates a converted light L2 of red color (X2=650nm), - with XI = 450nm (blue color), we can use a so-called yellow phosphor (550nm) which generates a converted light L2 of white color at the second wavelengths (X2= 500nm to 700nm) and at the first wavelength Xl=450nm corresponding to a part of the unconverted blue light, - with XI = 490nm (cyan color), we can use a red phosphor (600nm) which generates a converted light L2 of white color at the second wavelengths (X2= 500nm to 700nm) and at the first wavelength Xl=490nm corresponding to a part of the cyan light not converted. - with XI = 450nm (blue color) we can use a so-called green phosphor which generates a converted light L2 of green color (X2=535nm).

[0057] It should be noted that the phosphor layer 12, due to its composition, converts the monochromatic radiation RI into a second monochromatic radiation R2 to obtain light L2. However, there comes a point where the phosphor layer 12 becomes saturated and can no longer convert the remaining monochromatic radiation RI to obtain light L2, which implies that the color of light L1 emanating from this first monochromatic radiation RI mixes with the color of light L2. Thus, when the phosphor layer 12 is saturated, it converts only a portion of the first monochromatic radiation RL

[0058] Thus, to obtain white light L2, an additive color mixing process is used. For example, in the non-limiting case of blue light L1, the blue color mixes with the yellow color to produce white. Similarly, in the non-limiting case of cyan light L1, the cyan color mixes with the red color to produce white.

[0059] To choose the colour of the phosphorus layer 12, different materials are used.

[0060] Thus, to obtain yellow phosphorus, in a non-limiting embodiment, the YAG material, which is yttrium and aluminum garnet-based phosphorus powder, is used. To obtain red phosphorus, in a non-limiting embodiment, the Y2O3 material, which is yttrium(III) oxide, is used. To obtain green phosphorus, in a non-limiting embodiment, the orthosilicate ((Ba,Sr)2SiO4:Eu) powder material is used.

[0061] Thus, the phosphor layer 12 is excited by the first wavelength XI and generates light L2 with a longer wavelength X2. It therefore allows the so-called shorter wavelengths to pass through and generates the longer wavelengths. This is the phenomenon known as phosphorescence. It should be noted that the phosphor layer 12 scatters the light L2 thus generated in all directions. It thus scatters light L2, in particular, outwards from the light generator 1. Thus, in the non-limiting example of blue light L1, the phosphor layer 12 converts the first monochromatic radiation RI, of which light L1 is blue, and scatters it in all directions.

[0062] It should be noted that the scattering encompasses the backscattering which occurs towards its original direction and the generation of light which occurs in the opposite direction. Thus, when the phosphor layer 12 receives the light L1 from the opto-electronic device 11, the scattering encompasses the backscattering which occurs towards the rear (namely in the second direction D') of the phosphor layer 12 and the generation of light which occurs towards the front of the phosphor layer 12 (namely in the first direction D), and consequently towards the outside of the light generator 1.

[0063] As illustrated in [Fig.2], in a non-limiting embodiment, the phosphor layer 12 is mixed with resin 122. This makes it possible to give a reflective appearance for the aesthetics of the light generator 1, which is seen by an external observer.

[0064] It should also be noted that the phosphor layer intrinsically has a Lambertian light distribution profile which makes it possible to obtain a homogeneous appearance of the light from the point of view of an external observer.

[0065] Furthermore, it should be noted that part of the converted light L2 is backscattered by the phosphor layer 12 and potentially by Fresnel reflections on the interface phosphor layer 12-protective layer 15, namely on the second diopter 121, the back scattering is towards its original direction, here towards the rear of the phosphor layer 12 (namely in the second direction D'), namely towards the opto-electronic device 11 in the case of figures 1 to 7, or towards the light guide 17 described later in the case of figures 7 and 8.

[0066] As we will see below, thanks to the first dichroic filter 13, this converted L2 backscattered light is not lost.

[0067] The first dichroic filter 13 is arranged on the side of the first diopter 120 of the phosphor layer 12. It is positioned opposite and in contact with the phosphor layer. It is thus adjacent to the phosphor layer 12.

[0068] In the case of Figures 1 to 6, it is positioned between the phosphor layer 12 and the optoelectronic device 11. It is positioned opposite the optoelectronic device 11. In the case of Figures 7 and 8, it is positioned between the phosphor layer 12 and the light guide 17. It is positioned opposite and in contact with the latter. It is thus adjacent to the light guide 17.

[0069] The first dichroic filter 13 is configured to transmit only the light L1 emanating from the first monochromatic radiation RI towards the phosphor layer 12 and to reflect the converted light L2 by the phosphor layer 12, namely that which has been backscattered towards the rear of the phosphor layer 12. This is referred to as a dichroic mirror. Thus, the first dichroic filter 13 makes it possible to reflect all the light L2 backscattered by the phosphor layer 12, in the first direction D, towards the outside of the light generator 1. This drastically reduces the converted light L2 backscattered towards the optoelectronic device 11 or towards the light guide 17.

[0070] Thus, in the non-limiting example of blue L1 light, the first dichroic filter 13 lets the blue light pass through and reflects the second wavelengths X2.

[0071] Thus, the transmission properties (at the first wavelength XI) and reflection properties (at all wavelengths X2 above) depend on a given wavelength, here the first wavelength XL

[0072] It should be noted that the first dichroic filter 13 reflects the converted light L2 arriving at an angle of incidence on the dichroic filter 13 between 0° and approximately 40°, the remainder being less reflected. It should be noted that the reference for this angle of incidence is the normal to the interface between the dichroic filter 13 and the phosphor layer 12, namely the first interface 120.

[0073] The first dichroic filter 13 is composed of several thin dielectric layers. In a non-limiting embodiment, these thin dielectric layers are vaporized onto a substrate or directly onto the phosphorus layer 12, the whole being bonded or overmolded onto the protective layer 15. Vaporization is carried out by a physical vapor deposition process. In another, non-limiting embodiment, these thin dielectric layers are laminated onto the phosphorus layer 12 and placed on a substrate, the whole assembly being bonded or overmolded onto the protective layer 15.

[0074] In a non-limiting embodiment, the first dichroic filter 13 is between 100 nm and 2000 nm. It can be made on a substrate that is between 50 µm (micrometers) and 300 µm thick. In a non-limiting embodiment, the protective layer 15 is between 5 µm and 5000 µm thick. In a non-limiting variant, when made in PUR material, it is between 200 µm and 5 mm thick. In a non-limiting variant, when made in resin, it is between 5 µm and 500 µm thick. In a non-limiting embodiment of this variant, it is between 5 µm and 100 µm thick.

[0075] The assembly of the phosphorus layer 12-first dichroic filter 13-protective layer 15 forms an overall film. This overall film is very thin.

[0076] In non-limiting examples, the substrate is PC (Polycarbonate) or PMMA (Polymethyl methacrylate).

[0077] These two processes allow for cost reduction, are simple to carry out and allow the dichroic filter to be cut into a desired shape so that it can adapt to the protective layer 15.

[0078] Thus, the first dichroic filter 13 and the phosphor layer 12 play an effective light-diffusing role, the phosphor layer 12 diffusing the light and the first dichroic filter 13 not diffusing it, but maximizing the light efficiency.

[0079] The protective layer 15 is positioned opposite the phosphor layer 12 on the side of the second diopter 121. It forms a protective screen that shields the optoelectronic device 11, the phosphor layer 12, and the first dichroic filter 13 from external elements such as dust or water. It thus provides the light generator 1 with a good seal. Furthermore, it enables the device to pass the pedestrian impact crash test.

[0080] In a non-limiting embodiment, the protective layer 15 is rigid. In non-limiting examples, it is made of PC for its face facing outwards from the light generator 1 and of PMMA for its face facing inwards from the light generator 1, i.e., facing the other elements 12, 13, and where applicable 17 and / or 18. In another non-limiting example, the protective layer 15 is made of resin. In yet another non-limiting embodiment, the protective layer 15 is semi-rigid. In this case, in a non-limiting example, the deformable polyurethane material PUR may be considered.

[0081] The protective layer 15 comprises a first face 15.1 and a second face 15.2 opposite the first face 15.1 (illustrated in [Fig. 1]). The first face 15.1 is turned outwards from the light generator 1 while the second face 15.2 is turned inwards from the light generator 1. It should be noted that the bonding or overmolding of the first dichroic filter 13 and phosphor layer 12 assembly is carried out on the face of the protective layer 15 turned inwards from the light generator 1, i.e. the second face 15.2.

[0082] Thus, thanks to the phosphor layer 12 and first dichroic filter 13 assembly, a transmission and conversion of light of approximately 80% is obtained, i.e. a gain in luminous efficiency of more than 30 points of efficiency compared to the light generator of the prior art.

[0083] As previously seen, there may be residuals of the first monochromatic radiation RI (also called residual light Ll) that are not converted by the phosphor layer 12 and are also scattered by the phosphor layer 12 in all directions, including backwards (i.e., in the second direction D') and forwards (i.e., in the first direction D). As illustrated in Figures 1, 4, 6, 7, and 9a to 11, the forward-scattered residual light Ll is shown in front of the protective layer 15. Thus, the phosphor layer 12 also scatters some of the light Ll if the first monochromatic radiation RI is not completely converted.This unconverted part of the light L1 is backscattered by the phosphor layer 12 and potentially by Fresnel reflections on the interface phosphor layer 12-protective layer 15, namely on the second diopter 121, the backscattering being towards its original direction, here towards the back of the phosphor layer 12 (namely in the second direction D'), namely towards the opto-electronic device 11 in the case of figures 1 to 6, or towards the light guide 17 described later in the case of figures 7 and 8.

[0084] As we will see below, thanks to the second dichroic filter 18, these unconverted and scattered light residues Ll are not lost.

[0085] In order to be able to further increase the conversion efficiency of the phosphor layer 12, in a non-limiting embodiment illustrated in [Fig.3], the light generator 1 further includes a second dichroic filter 18 complementary to the first dichroic filter 13.

[0086] The second dichroic filter 18 is arranged between the phosphor layer 12 on the side of its second diopter 121 and the protective layer 15 on the side of its second face 15.2. It is therefore arranged opposite these two layers 12 and 15. There is therefore the first dichroic filter 13 positioned on the side of the first diopter 120 of the phosphor layer 12 and the second dichroic filter 18 positioned on the side of the second diopter 121 of the phosphor layer 12.

[0087] The second dichroic filter 18 is configured to: - to transmit the light L2 converted and scattered by the phosphor layer 12 to the outside of the light generator 1, namely in the first direction D, and - reflect the light L1 emanating from the first monochromatic radiation RI towards the phosphor layer 12, namely in the second direction D', which was not converted the first time when the first light radiation RI passed through the phosphor layer 12.

[0088] The second dichroic filter 18 thus allows the light L2 converted and diffused by the phosphor layer 12 to pass out of the light generator 1. Thus, in the non-limiting example of the first monochromatic radiation RI which generates blue light L1 and which is converted into red light L2, it allows the red light to pass through.

[0089] We speak of complementarity with respect to the first dichroic filter 13 because, unlike the first dichroic filter 13 which transmits the light L1 emanating from the first monochromatic radiation RI, it does not transmit this light L1, but reflects it. And, unlike the first dichroic filter 13 which reflects the light converted L2 by the phosphor layer 12, it does not reflect this converted light L2, but transmits it, that is to say, it lets it pass through.

[0090] Thus, the residual light L1 emanating from the first monochromatic radiation RI is reflected by the second dichroic filter 18 towards the phosphor layer 12. This light L1 then passes back through the phosphor layer 12, which converts it into light L2 at one or more second wavelengths L2 above the first wavelength XL. The second dichroic filter 18 thus allows the conversion of the residuals of the first monochromatic radiation RI that were not converted by the phosphor layer 12 the first time the first monochromatic radiation RI passed through it. In [Fig. 3], the absence of this residual light L1 in front of the protective layer 15 will be noted.

[0091] In the non-limiting example of the first monochromatic radiation RI which generates blue L1 light, the second dichroic filter 18 allows the residual blue L1 light to be converted into red L2 light in a non-limiting example. Thus, in the end, the external observer will be able to observe a deeper red than if there had only been the first dichroic filter 13.

[0092] In a non-limiting embodiment, the second dichroic filter 18 is between 100 nm and 2000 nm. It can be made on a substrate which is between 50 µm (micrometers) and 300 µm.

[0093] Thus, thanks to the assembly of phosphorus layer 12, first dichroic filter 13 and second dichroic filter 18, transmission and conversion of the light of approximately 80%, but in addition, a purer color is obtained at the second wavelength(s) / .2. In the example of the native blue color, since no blue residue remains, a brighter red color is obtained at the output of light generator 1.

[0094] We can observe a measurement with a video luminescence meter which measures the luminance of the light generator 1 which is 1554 candela (cd) / square meter (m2 ) compared to 1200 cd / m2 for that of the prior art.

[0095] In a first, non-limiting embodiment illustrated in [Fig. 4], the light generator 1 further comprises at least one reflective cavity 16, and said at least one optoelectronic device 11 is disposed at the bottom of the reflective cavity 16. In a non-limiting embodiment, the reflective cavity 16 has a depth of between 3 mm and 2 cm (centimeters). This allows for an overall compact light generator 1.

[0096] The reflective cavity 16 is configured to confine the first monochromatic radiation RI emitted by the optoelectronic device 11, particularly if the light L1 emanating from L1 has a large angle of incidence upon arrival at the first dichroic filter 13. This prevents light loss. It allows for resonant coupling, namely obtaining multiple reflections of light within the reflective cavity 16, which increases the luminous efficiency of the light generator 1.

[0097] In non-limiting embodiments, the reflective cavity 16 is made of silicone or plastic. In one non-limiting embodiment, it is painted white to obtain the reflective effect. In another non-limiting embodiment, it is composed of TiO2-type elements known to those skilled in the art to be highly reflective.

[0098] Thanks to the reflective cavity 16, the loss of light L2 backscattered towards the optoelectronic device 10 that was not reflected by the first dichroic filter 13 is compensated, namely that at high angles of incidence, i.e., beyond 40°. Indeed, by the multiple reflections of light inside the reflective cavity 16, more light arrives at low angles of incidence on the dichroic filter 13.

[0099] Thanks to the reflective cavity 16, light losses due to the dispersion of the phosphor layer 12, which radiates in all directions, are also reduced. Indeed, this reflective cavity 16 will, by reflection, redirect the light in the first direction D. This maximizes luminous efficiency and limits light losses.

[0100] The assembly of phosphor layer 12 - first dichroic filter 13 - protective layer 15 and where applicable second dichroic filter 18, forms a light-diffusing film which thus covers the reflective cavity 16. It should be noted that the reflective cavity 16 has for this purpose a closed transparent end disposed on the opposite side of its bottom in order to place this light-diffusing film on it.

[0101] It should be noted that in the case where there is no reflective cavity 16 (as in Figures 1 and 3), in order to keep the phosphor layer 12 away from the optoelectronic device(s) 11, in a non-limiting embodiment, pads (not shown) arranged on either side of the optoelectronic device(s) 11 may be used. Thus, the light-diffusing film, composed of the phosphor layer 12, first dichroic filter 13, protective layer 15, and, where applicable, a second dichroic filter 18, may rest on these pads.

[0102] In a non-limiting embodiment illustrated in [Fig.5], the light generator 1 of [Fig.4] further comprises a second dichroic filter 18 as described above.

[0103] In a non-limiting embodiment illustrated in [Fig. 6], the light generator 1 comprises a plurality of reflective cavities 16 and a plurality of optoelectronic devices 11. In a non-limiting example illustrated in [Fig. 5], it comprises three optoelectronic devices 111, 112, and 113 arranged respectively in three corresponding cavities 161, 162, and 163. It should be noted that the protective layer 15 - phosphor layer 12 - first dichroic filter 13 and, where applicable, second dichroic filter 18, covers all the reflective cavities 161, 162, and 163.

[0104] In a non-limiting example, to achieve pixelated lighting, one can use from 2 to more than 3000 optoelectronic diodes 11 and corresponding reflective cavities 16. In a non-limiting example, such a light generator 1 comprises 1700 optoelectronic diodes 11 and corresponding reflective cavities 16. This makes it possible, in particular, to implement a projection and / or signaling function for a lighting device 2 described later in the description, which incorporates the light generator 1.

[0105] In a second, non-limiting embodiment illustrated in [Fig. 7], the light generator 1 further comprises a light guide 17. The light guide 17 is arranged opposite the first dichroic filter 13 on the side opposite the phosphor layer 12 on the side of its first diopter 120. Thus, the first dichroic filter 13 is located between the phosphor layer 12 and the light guide 17. The light guide 17 comprises a first end 17.1 and a second end 17.2 opposite the first end 17.1.

[0106] It should be noted that the light guide 17 does not heat up. Therefore, there is no heat transfer from the optoelectronic device 11 to the phosphor layer 12 via the light guide 17.

[0107] The light guide 17 is configured to refract and reflect the light L1 emanating from the first monochromatic radiation RI towards the phosphor layer 12.

[0108] The light L1 at the first wavelength XI is thus coupled to the light guide 17. The light guide 17 is composed of a prismatic or diffusing structure which thus directs the first monochromatic radiation RI towards the phosphor layer 12 and the first dichroic filter 13.

[0109] It should be noted that in this second non-limiting embodiment, the optoelectronic device 11 is disposed at one of the two ends of the light guide 17, here at the end referenced 17.1 in [Fig. 7]. In a non-limiting variant of the embodiment, there are two optoelectronic devices 11 disposed respectively at each end 17.1 and 17.2 of the light guide 17.

[0110] In a non-limiting embodiment, the light generator 1 includes a mechanical fastener (not shown) for maintaining the light guide 17 at a distance from the phosphor layer 12-first dichroic filter 13-protective layer 15 assembly and, where applicable, the second dichroic filter 18. In a non-limiting embodiment, the distance is between 3 mm and 10 mm. In another non-limiting embodiment, after overmolding the phosphor layer 12-first dichroic filter 13-protective layer 15 assembly and, where applicable, the second dichroic filter 18, which forms an overall film, the latter is overmolded onto the light guide 17 or bonded to the light guide 17. In this case, the distance is 0 mm.

[0111] The use of a light guide 17 makes it possible, with a single optoelectronic device 11 (or a maximum of two), to perform the entirety of a desired lighting function, such as, in a non-limiting example, the function of lighting and / or signaling. It is not necessary to use a multitude of optoelectronic devices 11.

[0112] Thanks to the light guide 17, the energy performance of the light generator 1 is optimized, resulting in lower energy consumption. Indeed, there is an overall gain in luminous efficiency when considering the number of optoelectronic devices 11 used, in terms of lumens, which corresponds to the luminous flux output of the light generator 1 per electrical watt.

[0113] The assembly of phosphor layer 12 - first dichroic filter 13 - protective layer 15 and where applicable second dichroic filter 18, forms a light-diffusing film which thus covers the light guide 17.

[0114] In a non-limiting embodiment illustrated in [Fig.8], the light generator 1 of [Fig.7] further comprises a second dichroic filter 18 as described above.

[0115] In a non-limiting embodiment, the light generator 1 is part of a lighting device 2 which includes at least one light generator 1.

[0116] When the light generator 1 is integrated into the light device 2, the protective layer 15 is turned outwards from the light device 2, namely in the first direction D.

[0117] In non-limiting embodiments, the lighting device 2 is a lighting device for a vehicle 3 as illustrated in Figures 9a to 9d or a domestic or industrial lighting device as illustrated in Figures 10 and 11. In non-limiting embodiments, the vehicle 3 is a vehicle with an internal combustion engine, a hybrid engine, or an electric motor. Figure 10 illustrates a house including the lighting device 2, and Figure 11 illustrates an industrial building including the lighting device 2. In Figures 9a to 11, the light generator 1 of Figure 1 has been taken as a non-limiting example. Obviously, this Figure 1 can also be replaced in Figures 9a to 11 by the other examples of the light generator 1 in Figures 3 to 8.

[0118] In non-limiting embodiments, the vehicle 3 lighting device 2 is: - a lighting and / or signaling device as illustrated in [Fig. 9a] where the lighting device 2 is a spotlight in a non-limiting example; it may be a rear light in another non-limiting example, - a welcome scenario device or an extended signaling device, as illustrated in [Fig. 9b], where the light device 2 is located on the lower body of the vehicle 3 in a non-limiting example; - a front or rear lighting device, as illustrated in [Fig. 9c], where the light device 2 is located on the front of the vehicle 3 in a non-limiting example. - an interior lighting device as illustrated in [Fig.9d] where the light device 2 is located in the passenger compartment of the vehicle 3, here on the ceiling in a non-limiting example.

[0119] In a non-limiting embodiment, the front or rear lighting device makes it possible to create an illuminated logo or an illuminated metal grid.

[0120] In non-limiting embodiments, the signaling device enables the stop function or the rear light function (also called in English "TAIL") to be performed.

[0121] In non-limiting embodiments, the lighting device enables the function of a projector or the daytime running lamp (called in English "Daytime Running Lamp" whose acronym is DRL).

[0122] Of course, the description of the invention is not limited to the embodiments and the field described above. Thus, the invention can be applied to any lighting product in any application that complies with regulations. Thus, in another non-limiting embodiment, in the non-limiting example of a lighting and / or signaling device, the light device 2 can be arranged in a rear light or in a third brake light.

[0123] Thus, the described invention has the following advantages in particular: - it increases the luminous efficiency of the light generator 1, - it prevents the phosphor layer 12 from heating up, which would limit its light conversion efficiency, - it allows the converted and backscattered L2 light to be recycled through reflection on the first dichroic filter 13, which increases the light conversion efficiency, - it allows the conversion of the residues of the first monochromatic RI radiation thanks to the second dichroic filter 18, - it allows, from a monochromatic opto-electronic device 11, to obtain different monochromatic colors or a white color, - It helps reduce light loss due to light being scattered within the phosphor and radiating in all directions. - thanks to the fact that the phosphor layer 12 is offset, there is better light conversion compared to a solution which would stick the phosphor layer 12 to the opto-electronic device 11, because there is less thermal heating.

Claims

Demands

1. Light generator (1) comprising: - at least one optoelectronic device (11) composed of semiconductor materials and configured to produce a first monochromatic radiation (RI) so as to generate light (L1) at a first wavelength (X1), - a phosphor layer (12) offset from said at least one optoelectronic device (11) and comprising a first diopter (120) and a second diopter (121) and configured to convert all or part of the first incident monochromatic radiation (RI) into a second radiation (R2) so as to obtain converted light (L2) at one or more second wavelengths (X2) greater than that (X1) of the light (L1) emanating from the first monochromatic radiation (RI) and to diffuse this converted light (L2),characterized in that the light generator (1) further comprises: - a first dichroic filter (13) disposed on the side of the first diopter (120) of the phosphor layer (12) and configured to transmit the light (L1) emanating from the first monochromatic radiation (RI) towards the phosphor layer (12) and to reflect the converted light (L2) by the phosphor layer (12), - a protective layer (15) disposed opposite the phosphor layer (12) on the side of the second diopter (121).

2. Light generator (1) according to claim 1, wherein said at least one opto-electronic device (11) is disposed opposite the first dichroic filter (13) and the phosphor layer (12) and the first dichroic filter (13) is disposed between the phosphor layer (12) and said at least one opto-electronic device (11), and wherein the light generator (1) further comprises at least one reflective cavity (16) at the bottom of which said at least one opto-electronic device (11) is disposed.

3. Light generator (1) according to the preceding claim, wherein the light generator (1) comprises a plurality of reflective cavities (16) and a plurality of opto-electronic devices (H).

4. Light generator (1) according to claim 1, wherein the light generator (1) further comprises a light guide (17) disposed opposite the first dichroic filter (13) on the side opposite the phosphor layer (12), and configured to refract and reflect the light (L1) emanating from the first monochromatic radiation (RI) towards the phosphor layer (12), and wherein said at least one opto-electronic device (11) is disposed at one of the two ends (17.1, 17.2) of the light guide (17).

5. Light generator (1) according to any one of the preceding claims, wherein said at least one optoelectronic device (11) is a native light-emitting diode or a laser diode.

6. Light generator (1) according to any one of the preceding claims, wherein the first wavelength (XI) is between 400 and 500 nanometers.

7. Light generator (1) according to any one of the preceding claims, wherein the light generator (1) further comprises a second dichroic filter (18) complementary to the first dichroic filter (13), disposed between the phosphor layer (12) and the protective layer (15), and configured to transmit the converted light (L2) and scattered by the phosphor layer (12) outwards from the light generator (1) and to reflect the light (L1) emanating from the first monochromatic radiation (RI) back to the phosphor layer (12).

8. Light generator (1) according to any one of the preceding claims, wherein the phosphor layer (12) is mixed with resin.

9. Lighting device (2), wherein said lighting device (2) comprises at least one light generator (1) according to any one of the preceding claims.

10. Lighting device (2) according to the preceding claim, wherein said lighting device (2) is a lighting device for a vehicle (3), or a domestic or industrial lighting device.

11. Light device (2) according to the preceding claim, wherein said light device (2) for vehicle (3) is a lighting and / or signaling device, or a welcome scenario device, or an extended signaling device, or a front or rear lighting device, or an interior lighting device.

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