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 exit dioptric surface having a first lower portion of a first curvature and a first upper portion of a second curvature, and a second lens (4b) comprising a second entrance dioptric surface, the second incident refractive surface comprises a second lower portion having a third curvature and a second upper portion having a fourth curvature, characterized in that the first curvature is different from the second curvature and is configured to produce a greater light diffusion than the light diffusion produced by the second curvature, and / or the third curvature is different from the fourth curvature and is configured to produce a greater light diffusion than the light diffusion produced by the fourth curvature.

Description

Field of the Invention

[0001] The present invention relates to the field of lighting and / or signaling, and to the components involved, in particular optical components. The present invention is particularly advantageously applicable to the field of motor vehicles. In particular, the present invention relates to a lighting device. Background Art

[0002] In the automotive industry, devices capable of emitting light beams (also known as lighting and / or signaling functions) are known.

[0003] These devices must comply with applicable regulations by emitting light to the desired positions while limiting the brightness of certain areas. One of the limitations that manufacturers also face is to reduce the size of the device in order to obtain the most user-friendly device.

[0004] To achieve these different objectives, a solution has been proposed in document CN211040826U. This solution is based on the development of a device for increasing the illumination area in front of the vehicle. More specifically, it relates to increasing the lighting distance and the lighting width.

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

[0006] Therefore, one subject of the present invention is to propose a device that overcomes the above drawbacks.

[0007] Other subjects, features, and advantages of the present invention will become apparent by studying the following description and the drawings. It should be understood that other advantages can be combined. Summary of the Invention

[0008] To achieve this objective, according to one embodiment, there is provided a lighting device, comprising:

[0009] · A first row of light sources, the first row of light sources comprising light sources aligned in a first direction,

[0010] · 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,

[0011] · A first lens, the first lens comprising a first incident refractive surface and a first exit refractive surface, the first exit refractive surface comprising a first lower portion having a first curvature in the second plane and a first upper portion having a second curvature in the second plane, the first upper portion and the first lower portion being on opposite sides of a third plane, the third plane being parallel to the first plane, the first upper portion being above the first lower portion, and

[0012] · A second lens, the second lens including a second exit refractive surface and a second entrance refractive surface, the second entrance refractive surface including a second lower portion having a third curvature in a second plane and a second upper portion having a fourth curvature in the second plane, the second upper portion and the second lower portion being on opposite sides of a third plane, the second upper portion being above the second lower portion, and

[0013] wherein the first lens, the second lens, and the first row of light sources are positioned along an optical axis such that light rays from the first row of light sources propagate through the first lens and then through the second lens

[0014] characterized in that the first curvature is different from the second curvature and is configured to produce a greater light divergence in the second plane than the light divergence produced by the second curvature, and / or the third curvature is different from the fourth curvature and is configured to produce a greater light divergence in the second plane than the light divergence produced by the fourth curvature.

[0015] Thus, since the first curvature is different from the second curvature and / or the third curvature is different from the fourth curvature, the lighting device can optimize the light distribution and more precisely distribute it in a plane orthogonal to the plane containing the optical axis and the first row of light sources. This light distribution allows the contour (in particular the lower limit) of the area illuminated by each light-emitting element of the light source to be precisely defined. This ensures good sharpness of the images projected by the various pixels and satisfactory vertical divergence thereof.

[0016] According to another aspect, the invention relates to a lighting device, wherein the first exit refractive surface includes a third upper portion positioned above a first upper portion, the third upper portion having a fifth curvature that is more convex than the second curvature.

[0017] Thus, the fact that the fifth curvature is more convex than the second curvature provides greater illumination in the upper portion of the illuminated area, thereby also enhancing safety.

[0018] The invention also relates to a vehicle equipped with at least one such device. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The objects, subject matter, features, and advantages of the invention will become more apparent from a detailed description of an embodiment of the invention, which is illustrated by the following drawings, in which:

[0020] Figure 1 is a cross-sectional view of the lighting device in the second plane, showing the first row of light sources, the first lens, and the second lens.

[0021] Figure 2 is a cross-sectional view of the first lens in the second plane, showing the configuration of the first curvature according to the invention.

[0022] ​​​Figure 3 is a cross-sectional view of the second lens in the second plane, showing the configuration of the third curvature according to the present invention.

[0023] The drawings are provided by way of example and do not limit the present invention. The drawings are schematic representations intended to facilitate understanding of the present invention and are not necessarily drawn to scale of actual applications. Detailed Description

[0024] Before beginning a detailed discussion of embodiments of the present invention, optional features that may be used in combination or alternatively will be set forth below.

[0025] 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.

[0026] This means that, compared to the case where the first curvature 8 has the same concavity as the second curvature 10, the light rays from the first row of light sources 2 are directed in a direction more toward the top of the second lens 4b after passing through the first lower portion 7. These light rays irradiate the area located above the optical axis 3 by diffusing in height in a plane transverse to the plane formed by the optical axis and the first row of light sources 2 after passing through the second lens 4b. Similarly, the light rays are directed in a more upward direction (compared to the position of the optical axis) after passing through the second lower portion 13 than in the case where the third curvature 14 has the same concavity as the fourth curvature 16.

[0027] According to one example, the third plane p3 of the lighting device 1 includes the optical axis 3.

[0028] In this configuration, the third plane p3 is thus the mid-plane of the lenses 4a and 4b. This means that the light rays passing through the first lens 4a and the second lens 4b, above and near the optical axis 3, are deviated by the second curvature 10 and the third curvature 14, while the light rays would not be deviated 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.

[0029] According to one example, the first row of light sources 2 of the lighting device 1 includes at least one electroluminescent light source having a maximized emission portion.

[0030] Thus, in this way, in the case of using a plurality of electroluminescent light sources, the spatial resolution between these different light sources is minimized. In fact, there is a minimum space between the different light sources.

[0031] According to one example, at least one second row of light sources 19 including 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 such that the light rays from the second row of light sources 19 propagate through the first lens 4a.

[0032] Implementing a number of second row light sources 20 increases the spatial density of the emitted light. The number of light rays will be greater in the area of interest and more precisely greater in the area significantly close to the optical axis, which will result in a greater brightness in this area.

[0033] According to an 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 from the first lens 4a.

[0034] This distance can be measured on the optical axis of the first lens 4a.

[0035] This distance is chosen in particular taking into account the thermal resistance of the material of the first lens 4a, which is chosen to minimize as much as possible the distance between these rows of light sources and the first lens 4a in order to collect the maximum amount of light and thus maximize the efficiency.

[0036] According to an example, the lighting device is configured to produce a light beam, preferably participating in a high beam function, and 70% to 90% of the light rays of the light beam are diffused above the first plane.

[0037] According to an example, the light sources of the first row of light sources and the second row of light sources of the lighting device can be individually activated, and the lighting device includes control means for selectively activating the light sources of the first row of light sources and the second row of light sources.

[0038] The selective activation of the light sources provides different beam configurations that can be adapted to various situations.

[0039] According to an embodiment, as Figure 1 shown, the lighting device 1 includes a first row of light sources 2, an optical axis 3, a first lens 4a and a second lens 4b. The first lens may form a field lens. The second lens 4b preferably forms a projection lens. However, other lenses may be used especially downstream of the second lens 4b.

[0040] The light sources in the first row of light sources 2 are arranged in a straight line in the first direction d1. The optical axis 3 and the first direction d1 form a first plane p1. A second plane p2 is defined as being orthogonal to the first plane p1 and containing the optical axis 3.

[0041] The light sources can be individually turned on, thus producing a pixelated light source.

[0042] The first lens 4a includes a first incident refractive surface 5 and a first exit refractive surface 6. The first exit refractive surface 6 includes a first lower part 7 and a first upper part 9. Preferably, the first incident refractive surface 5 and the first exit refractive surface 6 are convex.

[0043] The intersection line between the first lower part 7 and the second plane p2 forms a curve called the "first curvature 8". The intersection line between the first upper part 9 and the second plane p2 forms a curve called the "second curvature 10". Advantageously, the first curvature 8 and the second curvature 10 define circular arcs.

[0044] 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 meet at the third plane p3.

[0045] The second lens 4b includes a second exit refractive surface 11 and a second entrance refractive surface 12. The second entrance refractive surface 12 includes a second lower part 13 and a second upper part 15. The intersection line between the second lower part 13 and the second plane p2 forms a curve called the "third curvature 14". The intersection line between the second upper part 15 and the second plane p2 forms a curve called the "fourth curvature 16". Advantageously, the second exit refractive surface 11 and the second entrance refractive surface 12 are convex. Preferably, the first curvature 8 and the second curvature 10 define circular arcs. The second upper part 15 is positioned above the third plane p3, while the second lower part 13 is positioned below the third plane p3. The second upper part 15 and the second lower part 13 meet at the third plane p3.

[0046] The first lens 4a, the second lens 4b and the first row of light sources 2 are distributed on the optical axis 3 such that the light rays from the first row of light sources 2 first pass through the first lens 4a and then through the second lens 4b. This means that the first row of light sources 2, the first lens 4a and the second lens 4b are successively positioned on the optical axis 3.

[0047] The first curvature 8 is different from the second curvature 10 and is configured to produce an interleaving of light rays in the second plane p2 such 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 is different from the fourth curvature 16. The third curvature 14 is configured to produce an interleaving of light rays in the second plane p2 such 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.

[0048] 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 circular arcs, the radius of the first curvature 8 is at least 33% smaller than the radius of the second curvature 10.

[0049] Additionally or alternatively, the third curvature 14 is more concave than the fourth curvature 16. According to a preferred embodiment, in the case where the third curvature 14 and the fourth curvature 16 define circular arcs, the radius of the third curvature 14 is at least 30% smaller than the radius of the fourth curvature 16.

[0050] According to a preferred embodiment, the third plane p3 passes through the optical axis 3.

[0051] Advantageously, the first exit refractive surface 6 includes a third upper portion 17 positioned above the first upper portion 9. The third upper portion 17 has a fifth curvature 18 that is more divergent than the second curvature 10. According to a preferred embodiment, in the case where the fifth curvature 18 and the second curvature 10 define circular arcs, the radius of the fifth curvature 18 is at least 30% smaller than the radius of the second curvature 10.

[0052] This means that, compared to the case where the fifth curvature 18 is the same as the second curvature 10, the light rays passing through the fifth curvature 18 are more directed towards the top of the second lens 4b. After passing through the second lens 4b, the light rays continue their path while maintaining substantially the same upward orientation, which results in a higher density of light rays in the target area and thus a higher luminous intensity.

[0053] Preferably, the second lens 4b is made of PMMA121. The system including the first lens 4a and the second lens 4b can have a focal length of 45.7 mm. Advantageously, the second lens 4b has dimensions of 40 mm × 70 mm. The geometric aperture of the system including the first lens 4a and the second lens 4b is 0.55. Preferably, the first lens 4a has a thickness between 2 mm and 30 mm. The thickness of the second lens 4b is between 2 mm and 30 mm. In a preferred option, the first row of light sources 2 includes at least one electroluminescent source having a maximized emission portion. The maximized emission portion can be the emission portion exposed on the surface of the light source, in the sense that it is not coated with any optically active portion (especially no lens or filter) or photonically active portion (especially no light-emitting re-emission layer, such as by luminescence, especially by luminescent particles).

[0054] These light sources can in particular include at least one semiconductor chip capable of emitting light. Moreover, a "light source" is understood here to mean a set of at least one elementary light source that is capable of generating the flux that causes at least one light beam to exit the device of the present invention.

[0055] Thus, using this type of light source allows these light sources to be arranged very close to each other (typically with a gap of less than 50 microns, or even less than 25 microns). An image can be formed directly from these light sources. However, the efficiency of the optical device is maintained, and the pixels are shaped by the main optical element, especially vertically shaped, which is a common element of the light sources.

[0056] The light source can be laterally bounded by a number of circumferential walls and end faces extending along the growth axis of the diode. In this case, the end face includes the emission portion through which light is emitted when the diode is biased.

[0057] The emission part can be a layer, which can be referred to as the active layer, where photon generation occurs through electron-hole recombination, or more commonly, especially for white light, a conversion layer with charges (such as phosphor particles) allows the photons generated in the active layer to be re-emitted within a wavelength band suitable for the application.

[0058] The light source according to the present invention can be provided with a maximized emission part. In fact, the emission part is exposed at the end face of the light source and occupies at least 90%, preferably 98%, and even more preferably 100% of the surface of the end face. In the latter case, the emission part then forms the exit surface of the light from the light source.

[0059] In an advantageous embodiment, the end face of the light source has a rectangular cross-section, which is typical for an LED chip. Thus, the emission part also has a rectangular cross-section, which is slightly smaller than the rectangular cross-section of the exit surface. In particular, the length of one of the sides of the emission part is smaller than the length of one of the sides of the end face of the light source by a value between 10 microns and 40 microns. In other words, the distance between the edge of the end face and the edge of the emission part can be between 5 microns and 20 microns.

[0060] In the case of a separately encapsulated light source (also called an LED chip), maximizing the size of the emission part reduces the size of the housing surrounding the light-emitting diode. In fact, the housing can include an edge covering the circumferential wall of the diode. By making the emission part occupy almost all or all of the end face of the diode, these edges can be configured to have a very small thickness, for example, on the order of a few microns. Thus, the housing surrounding the light-emitting diode is almost the same size as the diode. The housing is only a few microns larger than the end face of the diode.

[0061] In particular, it is possible to use the light sources sold by the company under the brand name Luxeon NEO

[0062] Another example of a light source with a maximized emission part is a light source including at least two rows of light sources on a common substrate. Such an arrangement of elements can result from growth on a substrate (from which the elements grow separately), or from any other production method, such as using transfer techniques to transfer these elements. Various arrangements of electroluminescent elements can meet this definition of a monolithic array, provided that one of the main extension dimensions of the electroluminescent elements is substantially perpendicular to the common substrate, and the lateral spacing between the pixels formed by one or more electroluminescent elements grouped together electrically is smaller compared to the spacing used in the known arrangement of a typically flat square chip soldered to a printed circuit board.

[0063] ​In other words, in the present invention, it may be an integral electroluminescent light source divided into several separate segments. Each segment is separated by a thin wall made of, for example, silicone resin. The thickness of the thin wall is between 10 micrometers and 25 micrometers. In particular, a light source sold under the trademark name may be used.

[0064] Preferably, at least one 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 relative to the first row of light sources 2 such that the light rays from the second row of light sources 19 propagate through the first lens 4a.

[0065] If the LED has an emission surface area of 1 mm 2 , the first row of light sources 2 may be spaced apart from the second row of light sources 19 by a distance equal to 1.025 mm.

[0066] Preferably, the first row of light sources 2 and the second row of light sources 19 are composed of 24 light sources.

[0067] Advantageously, the LED has an emission surface area of 1 mm 2 .

[0068] According to one option, 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.

[0069] These rows of light sources may be positioned perpendicular to the optical axis of the first lens 4a. These rows of light sources may be positioned symmetrically with respect to the optical axis such that an equal number of light sources are present on both sides of the optical axis.

[0070] The lighting device 1 of the present invention may be assembled onto a vehicle, and preferably, the vehicle is also equipped with at least one other device for projecting at least one other light beam. This means that several lighting devices 1 may be arranged in a housing enclosed by an outer lens in order to obtain one or more lighting and / or signaling light beams at the output of the headlight. The headlight may also be complex and combine multiple devices, which may also optionally share components.

[0071] Advantageously, the lighting device 1 of the present invention may be assembled onto the headlight of a vehicle, particularly onto the headlight of a vehicle or onto the two headlights of a vehicle, where one headlight is positioned on the right side and the other headlight is positioned on the left side.

[0072] Preferably, the lighting device 1 is configured to form a light beam, preferably to participate in forming the high beam. Between 70% and 90% of the light rays of the light beam thus formed are located above a first plane p1. The first plane p1 may correspond to the projection along the horizon. ​

[0073] The present invention can contribute to a high beam function that provides illumination over a wide area in front of the vehicle and also over a relatively long distance (typically about two hundred meters). This light beam is mainly above the horizon due to its illumination function. It can have, for example, a slightly upwardly inclined illumination optical axis. In particular, it can be used to generate a "complementary" illumination function that forms part of a high beam that is complementary to the part generated by a near-field light beam, with the complementary high beam part illuminating entirely or at least mainly above the horizon, while the near-field light beam (which may have specific characteristics of a low beam) is intended to illuminate entirely or at least mainly below the horizon. Thus, the complementary high beam part can be the main part of the overall "high beam" and is associated with another light beam involved in the low beam.

[0074] By means of the functions described above for the adaptive light beam or otherwise, the device can also be used for other illumination functions. This makes it possible to generate an illumination matrix to selectively illuminate parts of the space in front of the vehicle.

[0075] 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 can be individually switched on. The lighting device 1 includes control means that make it possible to individually select which of the light sources in the first row of light sources 2 and the second row of light sources 19 are switched on.

[0076] It should be noted that each row of light sources can be controlled so as to selectively activate them. This means that not all of the emitting elements need be active, i.e., emitting light simultaneously. This function allows modulation of the shape of the generated light beam. If a light source is not activated, its image (such as projected by an optical device) will not be present. Thus, an illumination void is formed in the overall generated light beam. This void is only interrupted by the effects of light source coupling and stray light from the optical device.

[0077] These light sources are preferably part of a light generation system that preferably includes a support member, one face of which carries selectively activatable light sources based on semiconductor emitting elements (including light-emitting diodes (LEDs)) as detailed below.

[0078] The system according to the invention can include a unit for driving the activation of each of the light sources, the unit being configured to generate at least one dark zone that forms a tunnel in the projected light beam by deactivating a group of adjacent light sources, the driving unit being configured to determine the number of light sources in the group corresponding to the dark zone based on the width of the light sources.

[0079] The drive unit may include a computer program product (preferably stored in a non-transitory memory), the computer program product including instructions which, when executed by a processor, determine the light sources to be activated, in particular to obtain at least one dark zone of a defined area (in which the element is not activated) taking into account the variable surface area of the image of the element.

[0080] Conventional light sources currently used in the automotive field are light-emitting diodes individually encapsulated in a housing, commonly also referred to as LEDs. The light-emitting part of the diode is covered by at least one light-transmitting layer made of, for example, a transparent polymer material. Depending on the shape of the transmission layer, once light is generated in the diode, the transmission layer can be used as a primary optical device. Thus, such an LED forms a complex component combining an emission part and an optical part. Moreover, when these LEDs are arranged next to each other, the emission parts of adjacent LEDs are relatively far apart from each other, which requires an optical projection that is designed to form an image that does not include such an interval between the LEDs.

[0081] List of reference numerals

[0082] Illumination device (1)

[0083] First row of light sources (2)

[0084] First direction (d1)

[0085] Optical axis (3)

[0086] First plane (p1)

[0087] Second plane (p2)

[0088] First lens (4a)

[0089] Second lens (4b)

[0090] First incident refractive surface (5)

[0091] First exit refractive surface (6)

[0092] First lower part (7)

[0093] First curvature (8)

[0094] First upper part (9)

[0095] Second curvature (10)

[0096] Second exit refractive surface (11)

[0097] Second incident refractive surface (12)

[0098] Second lower part (13)

[0099] Third curvature (14)

[0100] Second upper part (15)

[0101] Fourth curvature (16)

[0102] Third upper part (17)

[0103] Fifth curvature (18)

[0104] Second row of light sources (19)

[0105] Second direction (d2)

Claims

1. A lighting device (1), comprising: · A first row of light sources (2), the first row of light sources comprising light sources aligned in 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), the first lens comprising a first incident refractive surface (5) and a first exit refractive surface (6), the first exit refractive surface comprising a first lower portion (7) having a first curvature (8) in the second plane (p2) and a first upper portion (9) having a second curvature (10) in the second plane (p2), the first upper portion (9) and the first lower portion (7) being on opposite sides of a third plane (p3) parallel to the first plane (p1), the first upper portion (9) being above the first lower portion (7), and · - A second lens (4b), the second lens comprising a second exit refractive surface (11) and a second incident refractive surface (12), the second incident refractive surface comprising a second lower portion (13) having a third curvature (14) in the second plane (p2) and a second upper portion (15) having a fourth curvature (16) in the second plane (p2), the second upper portion (15) and the second lower portion (13) being on opposite sides of the third plane (p3), the second upper portion (15) being above the second lower portion (13), and wherein the first lens (4a), the second lens (4b) and the first row of light sources (2) are positioned along the optical axis (3) such 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 a greater light diffusion in the second plane (p2) than the light diffusion produced by the second curvature (10), and / or the third curvature (14) is different from the fourth curvature (16) and is configured to produce a greater light diffusion in the second plane (p2) than the light diffusion produced by the fourth curvature (16).

2. The 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).

3. The lighting device (1) according to any one of the preceding claims, wherein, the third plane (p3) comprises the optical axis (3).

4. The lighting device (1) according to any one of the preceding claims, wherein, the first exit refractive surface (6) comprises a third upper portion (17) positioned above the first upper portion (9), the third upper portion (17) having a fifth curvature (18) that is more convex than the second curvature (10).

5. The lighting device (1) according to any one of the preceding claims, wherein, the first row of light sources (2) comprises at least one electroluminescent light source having a maximized emission portion.

6. The lighting device (1) according to any one of the preceding claims, wherein, at least one second row of light sources (19) comprises light sources positioned to be in contact with the first row of light sources (2) in a second direction (d2) parallel to the first direction (d1), such that light rays from the second row of light sources (19) propagate through the first lens (4a).

7. The lighting device (1) according to the preceding claim, wherein, the light sources in the first row of light sources (2) and the second row of light sources (19) can be individually activated, and comprises control means for selectively activating the light sources in the first row of light sources (2) and the second row of light sources (19).

8. The lighting device (1) according to any one of the preceding claims, wherein, the first row of light sources (2) is positioned at a distance between 0.25 mm and 10 mm from the first lens (4a).

9. The lighting device (1) according to any one of the preceding claims, the lighting device being configured to produce a light beam, preferably participating in a high beam function, 70% to 90% of the light rays of the light beam being diffused above the first plane (p1).

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