Lighting device

Abstract

The invention relates to a lighting device (1) comprising a first row of light sources (2), an optical axis (3), a first lens (4a) comprising a first output dioptre comprising a first lower portion having a first curvature and a first upper portion having a second curvature, and a second lens (4b) comprising a second input dioptre comprising a second lower portion having a third curvature and a second upper portion having a fourth curvature, characterised in that the first curvature is different from the second curvature and is configured to produce a greater spread of the light rays than the spread produced by the second curvature, and / or the third curvature is different from the fourth curvature and is configured to produce a greater spread of the light rays than the spread produced by the fourth curvature.

Description

Lighting device

[0001] The present invention relates to the field of lighting and / or signaling and the components, particularly optical components, which participate therein. It finds particularly advantageous application in the field of motor vehicles. In particular, it relates to a lighting device. STATE OF THE ART

[0002] In the automotive sector, we know of devices capable of emitting light beams, also called lighting and / or signaling functions.

[0003] These devices must comply with current regulations by emitting light in the desired locations while limiting brightness in certain areas. One of the constraints that manufacturers also face is reducing the size of the device, in order to achieve a device that is as easy to use as possible.

[0004] In order to achieve these different objectives, a solution was proposed in document CN211040826U. This solution is based on the development of a device to increase the illuminated surface at the front of the vehicle. More precisely, the aim is to obtain a greater lighting distance as well as a greater lighting width.

[0005] However, this type of solution has drawbacks, notably the fact that it is limited in terms of areas that can be properly lit.

[0006] An object of the present invention is therefore to propose a device making it possible to overcome the aforementioned drawback.

[0007] Other objects, features, and advantages of the present invention will become apparent from the following description and accompanying drawings. It is understood that other advantages may be incorporated. SUMMARY

[0008] To achieve this objective, according to one embodiment, a lighting device is provided comprising:a first row of light sources comprising light sources aligned in a first direction,an optical axis, the optical axis and the first direction defining a first plane, a second plane being perpendicular to the first plane and comprising the optical axis,a first lens comprising a first input diopter and a first output diopter comprising a first lower part having a first curvature along the second plane and a first upper part having a second curvature along the second plane, the first upper part and the first lower part being located on either side of a third plane, the third plane being parallel to the first plane,the first upper part being located above the first lower part anda second lens comprising a second exit diopter and a second entrance diopter comprising a second lower part having, along the second plane, a third curvature and a second upper part having, along the second plane, a fourth curvature, the second upper part and the second lower part being located on either side of the third plane, the second upper part being located above the second lower part andin which the first lens,the second lens and the first row of light sources are positioned along the optical axis so that light rays from the first row of light sources propagate through the first lens and then through the second lens, characterized in that the first curvature is different from the second curvature and is configured to produce, according to the second plane, a spreading of the light rays greater than the spreading produced by the second curvature and / or the third curvature is different from the fourth curvature and is configured to produce, according to the second plane, a spreading of the light rays greater than the spreading produced by the fourth curvature.,

[0009] Thus, given that the first curvature is different from the second curvature and / or that the third curvature is different from the fourth curvature, the lighting device allows an optimized light distribution and more precisely according to planes orthogonal to the plane containing the optical axis and the first row of light sources. This light distribution makes it possible to precisely define the contour (in particular the lower limit) of the zones illuminated by each luminous element of the source; there is thus a good definition of the images projected by the different pixels and their vertical spread is satisfactory.

[0010] According to another aspect, the invention relates to an illumination device in which the first output diopter comprises a third upper portion positioned above the first upper portion, the third upper portion having a fifth curvature being more convex than the second curvature.

[0011] Thus, due to the fact that the fifth curvature is more convex than the second curvature, greater illumination will be obtained in the upper part of the illuminated area, this also allowing increased safety.

[0012] The invention also relates to a vehicle equipped with at least one device. BRIEF DESCRIPTION OF THE FIGURES

[0013] The aims, objects, as well as the characteristics and advantages of the invention will emerge more clearly from the detailed description of an embodiment thereof which is illustrated by the following accompanying drawings in which:

[0014] represents a sectional view of the lighting device according to the second plane where the first row of light sources, the first lens and the second lens are represented.

[0015] La represents a sectional view of the first lens according to the second plane where the configuration of the first curvature according to the invention is represented.

[0016] The figure represents a sectional view of the second lens along the second plane where the configuration of the third curvature according to the invention is represented.

[0017] The drawings are given by way of example and are not limiting of the invention. They constitute schematic representations of principle intended to facilitate the understanding of the invention and are not necessarily to the scale of practical applications. DETAILED DESCRIPTION

[0018] Before commencing a detailed review of embodiments of the invention, optional features which may optionally be used in combination or alternatively are set out below.

[0019] According to one example, the first curvature 8 of the lighting device 1 is more convex than the second curvature 10 and / or the third curvature 14 of the lighting device 1 is more convex than the fourth curvature 16.

[0020] Thus, in this way, the light rays coming from the first row of light sources 2 after having crossed the first lower part 7 are directed in a direction more oriented towards the top of the second lens 4b in comparison with the case where the first curvature 8 would have the same concavity as the second curvature 10. These light rays after having crossed the second lens 4b illuminate an area located above the optical axis 3 by spreading in height according to planes transverse to the plane formed by the optical axis and the first row of light sources 2. In the same way, the light rays after having crossed the second lower part 13 are directed in a direction more oriented towards the top (as opposed to the position of the optical axis) than in the case where the third curvature 14 would have the same concavity as the fourth curvature 16.

[0021] According to one example, the third plane p3 of the lighting device 1 comprises the optical axis 3.

[0022] Thus, by this configuration the third plane p3 consists of a median plane for the lenses 4a and 4b. In this way, the light rays passing through the first lens 4a and the second lens 4b while being above the optical axis 3 and close to the optical axis 3 are deflected thanks to the second curvature 10 and thanks to the third curvature 14 whereas they would not be deflected if the first curvature 8 had the same concavity as the second curvature 10 and if the third curvature 14 had the same concavity as the fourth curvature 16.

[0023] According to one example, the first row of light sources 2 of the lighting device 1 comprises at least one electroluminescent source with maximized emissive part.

[0024] Thus, in this way, in the case where several electroluminescent sources are implemented, the spatial resolution between these different sources is minimal. Indeed, there is a minimal space between the different light sources.

[0025] According to one example, at least a second row of light sources 19 comprising light sources is positioned in contact with the first row of light sources 2 in a second direction d2 parallel to the first direction d1 so that light rays from the second row of light sources 19 propagate through the first lens 4a.

[0026] Implementing several second rows of light sources 20 makes it possible to increase the spatial density of the emitted light rays. The number of light rays will be greater in the area of ​​interest and more precisely in an area substantially close to the optical axis, which will result in greater brightness in this area.

[0027] According to one example, the first row of light sources 2 of the lighting device 1 is positioned at a distance between 0.25 mm and 10 mm relative to the first lens 4a.

[0028] This distance can be taken at the level of the optical axis of the first lens 4a.

[0029] This distance is notably chosen as a function of the thermal resistance of the material of the first lens 4a which is selected so as to minimize as much as possible the distance between the rows of light sources and the first lens 4a, in order to collect the maximum amount of light and therefore maximize efficiency.

[0030] In one example, the lighting device is configured to produce a beam, preferably to participate in a high beam function, with 70% to 90% of the light rays of the beam extending above the foreground.

[0031] According to one example, the light sources of the first row of light sources and the second row of light sources of the lighting device are individually activatable and the lighting device comprises control means for selective activation of the light sources of the first row of light sources and the second row of light sources.

[0032] Selective activation of light sources allows for varied light beam configurations to be obtained to adapt to various situations.

[0033] According to one embodiment, as illustrated in, the lighting device 1 comprises a first row of light sources 2, an optical axis 3, a first lens 4a and a second lens 4b. The first lens can form a field lens. The second lens 4b preferably forms a projection lens. Other lenses, in particular downstream of the second lens 4b are however possible.

[0034] The light sources of the first row of light sources 2 are arranged in a straight line along a first direction d1. The optical axis 3 and the first direction d1 form a first plane p1. A second plane p2 is defined so that it is orthogonal to the first plane p1 and contains the optical axis 3.

[0035] The light sources can be switched on individually, creating a pixelated light source.

[0036] The first lens 4a comprises a first entrance diopter 5 and a first exit diopter 6. The first exit diopter 6 comprises a first lower part 7 and a first upper part 9. Preferably, the first entrance diopter 5 and the first exit diopter 6 are convex.

[0037] The intersection between the first lower part 7 and the second plane p2 forms a curved line called “first curvature 8”. The intersection between the first upper part 9 and the second plane p2 forms a curved line called “second curvature 10”. Advantageously, the first curvature 8 and the second curvature 10 define an arc of a circle.

[0038] The first upper part 9 is positioned above the third plane p3 while the first lower part 7 is positioned below the third plane p3. The first upper part 9 and the first lower part 7 are joined at the third plane p3.

[0039] The second lens 4b comprises a second exit diopter 11 and a second entrance diopter 12. The second entrance diopter 12 comprises a second lower portion 13 and a second upper portion 15. The intersection between the second lower portion 13 and the second plane p2 forms a curved line called the “third curvature 14”. The intersection between the second upper portion 15 and the second plane p2 forms a curved line called the “fourth curvature 16”. Advantageously, the second exit diopter 11 and the second entrance diopter 12 are convex. Preferably, the first curvature 8 and the second curvature 10 define an arc of a circle. The second upper portion 15 is positioned above the third plane p3 while the second lower portion 13 is positioned below the third plane p3. The second upper portion 15 and the second lower portion 13 are joined at the third plane p3.

[0040] The first lens 4a, the second lens 4b and the first row of light sources 2 are distributed on the optical axis 3 in such a way that light rays from the first row of light sources 2 pass first through the first lens 4a and second through the second lens 4b. In this way, the first row of light sources 2, the first lens 4a and the second lens 4b are positioned successively on the optical axis 3.

[0041] The first curvature 8 differs from the second curvature 10 and is configured to produce, according to the second plane p2, a staggering of the light rays in such a way that the average distance between any two light rays is greater than the average distance between any two light rays produced by the second curvature 10. Additionally or alternatively, the third curvature 14 differs from the fourth curvature 16. The third curvature 14 is configured to produce, according to the second plane p2, a staggering of the light rays in such a way that the average distance between any two light rays is greater than the average distance between any two light rays produced by the fourth curvature 16.

[0042] Preferably, the first curvature 8 is more convex than the second curvature 10. Advantageously, in the case where the first curvature 8 and the second curvature 10 define an arc of a circle, the first curvature 8 has a radius at least 33% smaller than the radius of the second curvature 10.

[0043] Additionally or alternatively, the third curvature 14 is more re-entrant than the fourth curvature 16. According to a preferred embodiment, in the case where the third curvature 14 and the fourth curvature 16 define an arc of a circle, the third curvature 14 has a radius at least 30% smaller than the radius of the fourth curvature 16.

[0044] According to a preferred embodiment, the third plane p3 passes through the optical axis 3.

[0045] Advantageously, the first exit diopter 6 comprises a third upper part 17 positioned above the first upper part 9. The third upper part 17 has a fifth curvature 18 being more re-entrant than the second curvature 10. According to a preferred embodiment, in the case where the fifth curvature 18 and the second curvature 10 define an arc of a circle, the fifth curvature 18 has a radius at least 30% smaller than the radius of the second curvature 10.

[0046] In this way, the light rays passing through the fifth curvature 18 are more oriented towards the top of the second lens 4b than if the fifth curvature 18 were identical to the second curvature 10. After passing through the second lens 4b, the light rays continue their path while maintaining substantially the same upward orientation, which leads to a greater density of light rays in the targeted area, thus resulting in a greater light intensity.

[0047] Preferably, the second lens 4b is made of PMMA 121. The system comprising the first lens 4a and the second lens 4b may have a focal length of 45.7 mm. Advantageously, the second lens 4b has a size of 40 by 70 mm. The geometric aperture of the system comprising the first lens 4a and the second lens 4b is 0.55. Preferably, the first lens 4a has a thickness of between 2 mm and 30 mm. The second lens 4b has a thickness of between 2 mm and 30 mm. According to a preferred possibility, the first row of light sources 2 comprises at least one electroluminescent source with maximized emissive part.A maximized emissive part may be an emissive part exposed to the surface of the source, in the sense that it is not coated with any optically active portion (in particular absence of lenses or filters) or photonically active portion (in particular absence of light re-emission layers, for example by luminescence in particular by luminescent particles).

[0048] In particular, these sources may be equipped with at least one chip using semiconductor technology and capable of emitting light. Furthermore, the term light source here means a set of at least one elementary source capable of producing a flux leading to the generation of at least one light beam at the output of the device of the invention.

[0049] Thus, we take advantage of this type of light source so as to arrange these sources very close to each other (typically with a space of less than 50 microns, or even less than 25 microns). It is possible to image directly at the level of these sources; however, the efficiency of the optical device is maintained and we operate a shaping, in particular vertical, of the pixels, by means of the primary optical element which is an element common to the sources.

[0050] The source may be laterally delimited by several circumferential walls extending along the diode's growth axis and by an end face. The end face, in this case, includes an emissive portion through which light is emitted when the diode is biased.

[0051] The emissive part can be either a layer, which can be called an active layer, in which photons are generated by electron-hole recombinations, or, which is more common especially for white light, a conversion layer with charges, such as phosphorus particles, allowing photons produced in the active layer to be re-emitted in a wavelength band adapted to the application.

[0052] The light source according to the invention may be provided with a maximized emissive part. Indeed, the emissive part is exposed to the terminal face of the source and occupies at least 90% of the surface of said terminal face, preferably 98% and even more preferably 100% of the surface. In the latter case, the emissive part then forms the light exit face of the source.

[0053] In an advantageous embodiment, the end face of the source has a rectangular cross-section, which is typical for LED chips. Thus, the emissive part also has a rectangular cross-section whose size is slightly smaller than that of the output face. In particular, the length of one of the sides of the emissive part is less than the length of one of the sides of the source end face by a value between 10 micrometers and 40 micrometers. In other words, the distance between an edge of the end face and an edge of the emissive part can be between 5 micrometers and 20 micrometers.

[0054] In the case of individually packaged light-emitting sources, also called LED chips, the maximized size of the emissive portion results in a reduction in the size of the package surrounding the light-emitting diode. Indeed, the package may include edges that cover the circumferential walls of the diode. By having the emissive portion occupying almost all, or even the entire, end face of the diode, these edges can be configured so that they have a very small thickness, for example of the order of a few micrometers. Thus, the package surrounding the light-emitting diode is almost the same size as this diode. The size of the package protrudes only a few micrometers from the end face of the diode.

[0055] In particular, such sources marketed under the Luxeon NEO Exact® brand by the Lumileds® company can be used.

[0056] Another example of light sources with maximized emissive part: the light sources comprise at least two rows of sources on a common substrate. This arrangement of elements may be the result of growth on the substrate from which they were respectively grown, or of any other method of realization, for example by transferring the elements by transfer techniques. Different arrangements of electroluminescent elements may meet this definition of monolithic matrix, as long as the electroluminescent elements have one of their main dimensions of elongation substantially perpendicular to a common substrate and the transverse spacing between the pixels, formed by one or more electroluminescent elements grouped together electrically, is small in comparison with the spacings imposed in known arrangements of generally flat square chips soldered on a printed circuit board.

[0057] In other words, the invention may be a monolithic electroluminescent source that is divided into several individual segments. The individual segments are separated by a thin wall, made for example of silicone. The thickness of this thin wall is between 10 micrometers and 25 micrometers. Such sources marketed under the brand name PixCell® by the company Samsung® may be used in particular.

[0058] Preferably, at least a second row of light sources 19 is aligned with the first row of light sources 2 in a second direction d2. The second direction d2 is parallel to the first direction d1. The second row of light sources 19 is positioned opposite the first row of light sources 2 so that light rays from the second row of light sources 19 propagate through the first lens 4a.

[0059] The first row of light sources 2 may be spaced from the second row of light sources 19 by a distance equal to 1.025 mm if the LEDs have an emissive surface of 1 mm. 2 .

[0060] Preferably, 24 light sources make up the first row of light sources 2 and the second row of light sources 19.

[0061] Advantageously, LEDs have an emissive surface of 1 mm 2 .

[0062] According to one possibility, the first row of light sources 2 is located at a distance between 0.25 mm and 10 mm from the first lens 4a. The distance between the first row of light sources 2 and the first lens 4a may be 2.2 mm.

[0063] The rows of light sources may be positioned perpendicular to the optical axis of the first lens 4a. The rows of light sources may be positioned symmetrically with respect to the optical axis so that there are as many light sources on each side of the optical axis.

[0064] A lighting device 1 of the invention may equip a vehicle, and, preferably, the latter is also equipped with at least one other device for projecting at least one other beam. In this way, several lighting devices 1 may be arranged in a housing closed by a glass so as to obtain one or more lighting and / or signaling beams at the output of the projector. A projector may also be complex and combine several devices which may, in addition, possibly share components.

[0065] Advantageously, a lighting device 1 of the invention can equip headlights of a vehicle and in particular a front headlight of a vehicle or two front headlights of a vehicle in the case where one headlight is positioned on the right and another is positioned on the left.

[0066] Preferably, the lighting device 1 is configured to form a beam, preferably to participate in forming a high beam beam. 70% to 90% of the light rays of the beam thus formed are located above the first plane p1. The first plane p1 may correspond to a projection along a horizon line.

[0067] The invention can participate in a high beam function which aims to illuminate the scene in front of the vehicle over a wide area, but also over a significant distance, typically around two hundred meters. This light beam, due to its lighting function, is located mainly above the horizon line. It can have a slightly ascending optical axis of illumination for example. In particular, it can be used to generate a lighting function of the "complementary" type which forms a portion of a high beam complementary to that produced by a near-field beam, the high beam complement seeking entirely or at least mainly to illuminate above the horizon line while the near-field beam (which can have the specificities of a dipped beam) seeks to illuminate entirely or at least mainly below the horizon line.The route complement can therefore be a main part of the overall “route” beam and be associated with another beam participating in the code.

[0068] The device can also be used to form other lighting functions via or outside those described above, in relation to the adaptive beams. It is thus possible to produce a lighting matrix to selectively illuminate parts of the space in front of the vehicle.

[0069] Preferably, the light sources of the first row of light sources 2 and the second row of light sources 19 of the lighting device 1 are individually switchable. The lighting device 1 comprises control means for the individual selection of the light sources of the first row of light sources 2 and the second row of light sources 19 to be switched on.

[0070] It should be noted that each row of sources can be controlled so as to activate them selectively. This means that not all emissive elements are necessarily simultaneously active, i.e. emitting light. This function makes it possible to modulate the shape of the rendered beam. In the case where a light source is not activated, its image, as projected by the optical device, will be zero. It then forms a lighting void in the resulting overall beam. This void is understood to include coupling phenomena at the source and the effects of stray light from the optics.

[0071] The sources are preferably part of a light generation system which preferably comprises a support, one face of which carries selectively activatable sources, based on semiconductor emissive element technology, including LED light-emitting diodes, as detailed below.

[0072] The system according to the invention may comprise a unit for controlling the activation of each of the sources, configured to produce at least one dark zone forming a tunnel in a projected beam by deactivating a group of adjacent sources, the control unit being configured to determine the number of sources in the group corresponding to the dark zone as a function of the width dimension of the sources.

[0073] The control unit may comprise a computer program product, preferably stored in a non-transitory memory, in which the computer program product comprises instructions which, when executed by a processor, make it possible to determine the sources to be activated, in particular to obtain at least one dark zone (in which the sources are not activated) of a determined surface taking into account the variable surface of the images of the elements.

[0074] Conventional sources currently used in the automotive field are light-emitting diodes, also commonly called LEDs, individually encapsulated in a housing; the light-emitting portion of the diode is covered by at least one light-transmitting layer, for example made of transparent polymer material. Depending on the shape given to the transmissive layer, it can serve as primary optics as soon as light is generated in the diode. Thus, such an LED forms a complex assembly combining an emissive part and an optical part. Furthermore, when these LEDs are arranged next to each other, the emissive parts of adjacent LEDs are relatively far from each other, which requires an optical projection designed not to image this spacing between the LEDs.

[0075] Reference listsIllumination device (1)First row of light sources (2)First direction (d1)Optical axis (3)First plane (p1)Second plane (p2)First lens (4a)Second lens (4b)First entrance diopter (5)First exit diopter (6)First lower part (7)First curvature (8)First upper part (9)Second curvature (10)Second exit diopter (11)Second entrance diopter (12)Second lower part (13)Third curvature (14)Second upper part (15)Fourth curvature (16)Third upper part (17)Fifth curvature (18)Second row of light sources (19)Second direction (d2)

Claims

Lighting device (1) comprising:a first row of light sources (2) comprising light sources aligned along a first direction (d1),an optical axis (3), the optical axis (3) and the first direction (d1) defining a first plane (p1), a second plane (p2) being perpendicular to the first plane (p1) and comprising the optical axis (3),- a first lens (4a) comprising a first input diopter (5) and a first output diopter (6) comprising a first lower part (7) having, along the second plane (p2), a first curvature (8) and a first upper part (9) having, along the second plane (p2), a second curvature (10), the first upper part (9) and the first lower part (7) being located on either side of a third plane (p3), the third plane (p3) being parallel to the first plane (p1),the first upper part (9) being located above the first lower part (7) and- a second lens (4b) comprising a second exit diopter (11) and a second entrance diopter (12) comprising a second lower part (13) having, along the second plane (p2), a third curvature (14) and a second upper part (15) having, along the second plane (p2), a fourth curvature (16), the second upper part (15) and the second lower part (13) being located on either side of the third plane (p3), the second upper part (15) being located above the second lower part (13) andin which the first lens (4a),the second lens (4b) and the first row of light sources (2) are positioned along the optical axis (3) so that light rays from the first row of light sources (2) propagate through the first lens (4a) and then through the second lens (4b) wherein the first curvature (8) is different from the second curvature (10) and is configured to produce, according to the second plane (p2), a spreading of the light rays greater than the spreading produced by the second curvature (10) and / or the third curvature (14) is different from the fourth curvature (16) and is configured to produce, according to the second plane (p2), a spreading of the light rays greater than the spreading produced by the fourth curvature (16)., Lighting device (1) according to the preceding claim wherein the first curvature (8) is more convex than the second curvature (10) and / or the third curvature (14) is more convex than the fourth curvature (16). Lighting device (1) according to any one of the preceding claims wherein the third plane (p3) comprises the optical axis (3). A lighting device (1) according to any preceding claim wherein the first output diopter (6) comprises a third upper portion (17) positioned above the first upper portion (9), the third upper portion (17) has a fifth curvature (18) being more convex than the second curvature (10). Lighting device (1) according to any one of the preceding claims in which the first row of light sources (2) comprises at least one electroluminescent source with maximized emissive part. Lighting device (1) according to any one of the preceding claims wherein at least a second row of light sources (19) comprising light sources is positioned in contact with the first row of light sources (2) in a second direction (d2) parallel to the first direction (d1) so that light rays from the second row of light sources (19) propagate through the first lens (4a). Lighting device (1) according to the preceding claim wherein the light sources of the first row of light sources (2) and of the second row of light sources (19) are individually activatable and comprising control means for selective activation of the light sources of the first row of light sources (2) and of the second row of light sources (19). A lighting device (1) according to any preceding claim wherein the first row of light sources (2) is positioned at a distance of between 0.25 mm and 10 mm from the first lens (4a). Lighting device (1) according to any one of the preceding claims configured to produce a beam, preferably to participate in a high beam function, 70% to 90% of the light rays of the beam extending above the first plane (p1).

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