Brevet FR3129457A1 — publié le 20230526

The present invention pertains to a luminous device comprising an optical element and a light source arranged facing the optical element. The light source comprises a plurality of light emitting elements extending from a substrate and disposed in an array of at least one column and/or at least one row. Further, the light source and the optical element are eccentrically arranged in such a way that the optical axis of the optical element and the central axis of the light source are offset along the vertical axis to create vertical asymmetrical distribution of light emitting elements about the optical axis.. FIG. 3 LUMINOUS DEVICE FOR VEHICLE The present invention relates to a luminous device for an automotive vehicle, and more particularly to a luminous device for an automotive vehicle having light sources capable of projecting high-resolution light beam. Automotive vehicles and the like use various luminous devices for lighting the path ahead. These luminous devices generally include at least one light source and an optical element (such as a lens or lens assembly) that is associated with said light sources. Modern luminous devices are known to use semiconductor light sources, particularly LED light sources (for light emitting diode), that are mounted on a light source support and are predominantly arranged in an array of multiple rows and columns. These LED light sources produces brighter and better light beam pattern as compared to traditional light sources such as halogen bulbs. Further, these LED light sources can be controlled individually to enable the luminous device to produce various light distributions adapted to external factors, such as vehicles located in a region ahead of the self-vehicle, while keeping a sufficient illumination for the driver of the vehicle. Further, these arrays of light sources can be used for road writing functions that projects specific images and/or words on the road surface to convey message to the driver and to any receiver outside of vehicle such as pedestrians and/or other vehicles. For achieving said lighting functions modern automotive vehicle are provided with luminous devices having monolithic light source with light-emitting elements arranged in an array that are capable of projecting a pixelated light beam. In the monolithic light source array, the light source elements are grown from a common substrate and are electrically connected so that they can be activated either individually or as a subset. Conventionally, the light-emitting elements in said array are generally arranged centered on an optical axis of an optical element such that the light-emitting elements are arranged symmetrically about said optical axis, this invariably improves the optical quality. Conventionally, the light source support is arranged vertically in the luminous device such that the light-emitting elements are arranged facing the optical element. In some luminous system having road projection system for projecting an image, the luminous devices may be arranged such that they form a tilt angle with the horizontal plane P (or specifically the plane of vehicle travel) specifically, they be arranged tilted upwards as shown in . Such luminous device includes an optical element 180 presenting an optical axis LP1-LP1’ and further a central axis CP1-CP1’. Said optical axis and the central axis coincide with each other such that the light emitting elements 160 are symmetrically arranged along the optical axis LP1-LP1’ of the optical element 180. In addition, the light emitting elements 160 arranged above the optical axis LP1-LP1’ are configured to project light beam towards the ground surface and the light emitting elements 160 arranged below the optical axis LP1-LP1’ are configured to project light beam away from the ground surface. It can be understood that the light sources 160 arranged above the optical axis L1-L1’ can be used to enhance the lighting of a low beam distribution and/or to perform a road writing function. The light sources 160 arranged below can be used to enhance the lighting of a high beam distribution while contribute to enhance the beam area. Further, in the conventional embodiment illustrated in , the light source 140 and the optical element 180 are arranged at an angle with respect to the horizontal axis of the vehicle. Due to said arrangement, the resolution of the light beam produced by such luminous device may not be optimal and it may be difficult to produce sharper road projection images due to the tilt angle. The upward tilted luminous devices are aesthetically unappealing and may not match the overall styling of the vehicle. Further, as the left and right luminous devices are arranged as divergent modules. It is difficult to form a merged beam pattern with good accuracy. Further, above said luminous device may need to have individual pattern adjustment means and may not be synchronized. In addition, they may be complex to design, assemble and control inside the vehicle. The prior art and the conventional methods have various disadvantages as described earlier and there is a need for an luminous device that can provide a better road resolution providing sharper images on the road surface. In addition, the luminous device needs have a smaller tilt angle to the horizontal plane, thus, providing an aesthetically appealing luminous device. An object of the present invention is to solve the disadvantages described above of known luminous devices. In particular, it is the object of the present invention to provide a luminous device that is capable of producing a light beam having a sharper light beam projection to increase the beam resolution and to definition of projected images on the ground. Another object of the invention is to reduce the upward tilt angle of the light sources in in the luminous device for better styling. According to an embodiment of the present invention, there is provided a luminous device for a vehicle. The luminous device comprises an optical element presenting an optical axis. The luminous device further comprises at least one light source comprising a substrate extending at least along a vertical axis. Further the luminous device comprises a plurality of light emitting elements extending from the substrate and disposed in an array of at least one column and/or at least one row, otherwise called a light-emitting elements array, in such a way that the plurality of light-emitting elements are disposed symmetrically about a central axis perpendicular to the substrate. Further, the at least one light source is arranged on a focal zone of the optical element and disposed such that the central axis is orientated substantially parallel to the optical axis. Further, the at least one light source and the optical element are eccentrically arranged in such a way that the optical axis and the central axis are offset along the vertical axis to create vertical asymmetrical distribution of light emitting elements of the at least one light source about the optical axis. The arrangement allows a light beam that is projected towards the road surface by light sources to be subjected to less optical aberration thus resulting in an increase of the optical resolution of said light beam. In addition, the arrangement enables increasing the optical blur of the light beam projected away from the road surface, thus increasing the overall field of the light beam. Further, the eccentric arrangement of the light sources with respect to the optical axis help reduce the tilt angle of the luminous device that is preferable from a stylistic point of view. The terms "horizontal", "vertical" or "transverse", "lower", "upper", "top", "bottom", "side" are defined with respect to the orientation of the light module or a part forming part of the light module according to the invention in which it is intended to be mounted in the vehicle. In particular, in this application, the term "vertical" refers to an orientation perpendicular to the horizon while the term "horizontal" refers to an orientation parallel to the horizon. Similarly, the term central axis refers to an axis that passes through the center of the light source array and is generally perpendicular to the vertical axis. Here, the center of the light source array designates a point around which the light emitting elements are disposed symmetrically. In other words, each light emitting elements has its counterpart the same distance from said center. Further, the lighting elements may be arranged with respect to the central axis to define a proper beam pattern. Further, the symmetric arrangement of the light sources signifies that the individual light emitting elements as such LEDs of the matrix array arranged surrounding the central axis such that the light emitting elements on either side of the central axis in the longitudinal direction of the substrate and/or the transverse direction of the substrate are same. This arrangement may allow providing an equal number of rows and columns of the matrix array to be arranged around the central axis. According to an embodiment of the present invention, the number of light emitting elements arranged above the optical axis is unequal to the number of the light emitting elements arrange below the same optical axis. The arrangement allows the luminous device to produce a light beam that has different characteristics and/or pattern pertaining to the light sources arranged above and below the optical axis. In addition, the arrangement allows enhances driver visualization and comfort. According to an embodiment of the present invention, the number of light emitting elements arranged below the optical axis are greater than the number of rows above the optical axis. The greater number of rows at the bottom increase the distance travelled by the light beam from said light sources towards the optical element, thus increasing the optical blur of the light beam for enhancing the overall field of the beam. Further, the less number of light sources above the optical axis are relatively less distant from the optical axis; this allows increasing their optical resolution of the light beam, thus enabling the luminous device to produce a sharper projection of image and/or low beam function. According to an embodiment of the present invention, the optical element is designed such that the optical axis extends along a projection axis of the luminous device, and specifically such that the optical axis of the optical element and the projection axis of the luminous device are merged. In the present document, the projection axis of the luminous device refers to the axis about which the whole beam is distributed. The projection axis of the luminous device is usually extends along the length of the vehicle and is generally aligned with the direction of movement of the vehicle. According to an embodiment of the present invention, the light emitting elements arranged above the optical axis are configured to project light beam towards a ground surface. This allows producing a sharper image of light being projected towards the ground surface to produce low beam function or projection of images. Further, as said light beam is projected closer to the vehicle it eases driver comfort as well. According to an embodiment of the present invention, the light beam projected towards the ground surface is for low beam lighting and/or road projection function. The projected beam allows the driver to clearly view the vicinity of the vehicle, thus providing the driver a relatively safe driving environment. Further, in case of road projection function a clear and sharper image is projected thus allowing the driver (or a receiver) to easily read said image. According to an embodiment of the present invention, the light emitting elements arranged below the optical axis are configured to project the light beam away from the ground surface. These light sources may be configured to produce a light beam to be projected relatively farther from the vehicle, thus enabling a motorway beam function having a wide field of view. According to an embodiment of the present invention, the at least one light source offset vertically such that the central axis and the optical axis are separated by at a predetermined distance. The vertical offset having the predetermined distance enables to design a luminous device with a specified beam output in terms of the light resolution of the beam projected towards the ground surface and further allows controlling the blur of the beam projected away from ground surface to control the beam width. By controlling said parameters a wide field of the beam can be achieved, in addition the beam can include a sharper image projected on the road surface. According to an embodiment of the present invention, the light emitting elements are arranged in an array having plurality of rows and columns. The light elements arranged in array allows to control the light beam pattern by controlling the light sources in the array either individually or in subset, thus producing a controlled light beam projection based on the requirements. In a preferred embodiment the determined distance for offsetting the at least one light source ranges preferably between 2 and 30 rows. However, the light sources can be offset to n number of rows depending on the design of the luminous device and/or the design requirements. According to an embodiment of the present invention, the light emitting elements are arranged in a strip configuration having plurality of rows. Strip configuration may allow designing a compact luminous device and may be designed to increase the styling of the luminous device. The strip configuration may be used in narrow light sources where the light sources may be arranged in a single row along the vertical axis. The above-disclosed luminous device may work similar to the luminous device having a pixalised matrix array. Further, if needed the light sources may be arranged in a zigzag manner within the scope of the invention and achieve similar results. According to an embodiment of the present invention, the at least one of light sources is a solid-state light source. The solid-state light sources allows designing a luminous device that is having a small size and allows ease of control. Further, said light sources provide high performance output whilst consuming lower energy. According to an embodiment of the present invention, the at least one light source is a pixelised solid-state light source. The pixelised light source allows to project images and messages on the ground by controlling and illuminating only the needed pixels. A first example of the pixelized light sources comprises a monolithic source. This monolithic source comprises a matrix of monolithic electroluminescent elements arranged in several columns by several rows. In a monolithic matrix, the electroluminescent elements can be grown from a common substrate and are electrically connected to be selectively activatable either individually or by a subset of electroluminescent elements. The substrate may be predominantly made of a semiconductor material. The substrate may comprise one or more other materials, for example non-semiconductors (metals and insulators). Thus, each electroluminescent element/group can form a light pixel and can therefore emit light when its/their material is supplied with electricity. The configuration of such a monolithic matrix allows the arrangement of selectively activatable pixels very close to each other, compared to conventional light-emitting diodes intended to be soldered to printed circuit boards. The monolithic matrix may comprise electroluminescent elements whose main dimension of height, measured perpendicularly to the common substrate, is equal to one micrometer. The electroluminescent elements may each be semiconductor elements, in other words they each comprise at least one semiconductor material. The electroluminescent elements may for the most part be made of semiconductor material. This semiconductor material may be the same as or different from the semiconductor material of the substrate. The electroluminescent elements may more generally all be made of the same material or materials. The electroluminescent elements may be of the same nature, for example identical or similar. All the electroluminescent elements may be positioned to form a regular pattern, for example a grid. Another aspect of the disclosed subject matter can include a lighting system comprising a right-hand luminous device and a left-hand luminous device, at least one of the right-hand luminous assembly and the left-hand luminous assembly including a luminous device according to the present invention. In an exemplary light assembly, each of the right-hand luminous device and the left-hand luminous device include a luminous device according to the invention. This may allow producing an overall light beam that is sharper and has a wider range. Further, said arrangement produce a merged beam that has high accuracy. In addition, the arrangement may allow simultaneous beam adjustment in both the modules, thus providing ease of operation. Another aspect of the disclosed subject matter is related to a vehicle including a lighting system as described above, the vehicle presenting a longitudinal axis. Said at least one of the right-hand luminous assembly and the left-hand luminous assembly is arranged such that the projection axis of the luminous device is misaligned with the vehicle longitudinal axis to orientate the luminous device outwardly. This arrangement helps to achieve a wide projected beam ahead of the vehicle. Exemplarily, both the right-hand luminous assembly and the left-hand luminous assembly are tilted outwardly. According to an embodiment of the invention, the projection axis of the luminous device and the longitudinal axis of the vehicle are in the same horizontal plane. This arrangement helps in enhancing the beam projection and further provides an aesthetically appealing luminous device that provides a visual appeal to the overall vehicle design. To complete the description and to provide a better understanding of the invention, a set of drawings is provided. Said drawings form an integral part of the description and illustrate an embodiment of the invention, which should not be construed as restricting the scope of the invention, but only as an example of how the invention can be carried out. The drawings comprise the following characteristics. shows a top view of a lighting system mounted in a vehicle to project a light beam in front of the vehicle, the lighting system including a luminous device according to an embodiment of the present invention. shows a top view of the light beam projected by the luminous device of , according to an embodiment of present invention. shows an isometric view of the luminous device of showing a light source and an optical. shows a light source having a plurality of light emitting elements of the luminous device of . shows a cross sectional view of a vehicle luminous device from prior art showing a light source arranged with respect to an optical element. Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The present application is directed towards addressing an issue of producing a sharper beam patter and specifically towards providing a luminous device that can produce a light beam having a sharper light beam projection to increase road resolution and to increase the definition of projected images on the ground. illustrates a cross-section in a horizontal plane X-Y substantially parallel to a main direction of propagation of light beam from the luminous devices 10, 12, when mounted in a motor vehicle. Further, the X-axis corresponds substantially towards the main direction of propagation of the light beam and defines a front-rear longitudinal axis, the light beam being projected forward. Specifically, shows a luminous device 10, 12 arranged in a lighting system 100 for producing a light beam 300 that is intended to illuminate the path in front of the vehicle 400. The light beam 300 projected by the luminous device 10, 12 is illustrated in said . Further, shows the light beam 300 projected by the luminous device 10, 12 being spread uniformly in front of the vehicle. The light beam 300 is adapted such that it does not dazzle or disturb the preceding vehicle 200’ and/or an oncoming vehicle 200, as is required by regulations. As shown in , the luminous device 10, 12 comprises a light source 14 and an optical element 18 that projects the light emitted by the light source 14 towards the front of the vehicle 400 to produce the desired light beam 300. In the described embodiment and as shown in and 4, the light source 14 comprises a substrate 15 and a plurality of light emitting elements 16 extending from a face of the substrate and arranged in an array having plurality of rows and columns. The array may be configured as a pixelized matrix array comprising a monolithic source. The source 14 may be a solid-state lighting source, which comprises at least one electroluminescent element. The electroluminescent element may be, but is not limited to, a light-emitting diode (LED), an organic light-emitting diode (OLED), a polymeric light-emitting diode (PLED). As seen in and 4, the substrate 15 extends along a vertical axis A1-A1’, and specifically in a vertical plane Z-Y. On the substrate 15, the light emitting elements 16 are disposed symmetrically about a central axis C1-C1’. More precisely, the light emitting elements 16 are distributed symmetrically around a center O of the array, the central axis C1-C1’ passing through the center O while extending perpendicularly to the substrate 15. Further, the light emitting elements 16 are arranged facing the optical element 18 having an optical axis L1-L1’. In this exemplary embodiment, the optical element is designed such that the optical axis L1-L1’ is merged with the projection axis the luminous device 10, 12 (not shown in figures). The light source 14 is arranged such that the central axis C1-C1’ is orientated substantially parallel to the optical axis L1-L1’. In addition, the light source 14 is arranged on a focal zone of the optical element 18. In a general way, this focal zone can be a focal point, also called focus, a focal line, or can be a focal plane. According to the invention and as seen in , the light source 14 and the optical element 18 are eccentrically arranged such that the optical axis L1-L1’ and the central axis C1-C1’ are offset along the vertical axis A1-A1’. As discussed earlier the light emitting elements 16 of the light source 14 are arranged symmetrically about the central axis C1-C1’. Thus, the offset between the optical axis L1-L1’ and the central axis C1-C1’ creates a vertical asymmetrical distribution of light emitting elements 16 of the light source 14 about the optical axis L1-L1’. In said embodiment, the number of light emitting elements 16 arranged above the optical axis L1-L1’ is unequal to the number of the light emitting elements arrange below the same optical axis L1-L1’. The same is achieved due to the combined effect of the vertical offset and the light emitting elements 16 being arranged symmetrically about the central axis C1-C1’. Further, the number of light emitting elements 16 arranged below the optical axis L1-L1’ are greater than the number of rows above the optical axis L1-L1’. In the luminous device 10, 12, the light source 14 are offset vertically such that the central axis C1-C1’ and the optical axis L1-L1’ are separated by a predetermined distance α. The predetermined distance α may be calculated based on the design of the lighting emitting element 16, the optical element 18 and/or the intensity of the light sources. In a preferred embodiment the predetermined distance α for offsetting the at least one light source 14 ranges preferably between 2 and 30 rows. It could be understood that the offsetting can be created for n number of rows based on the design of luminous device. In the exemplary embodiment, the distance traveled by the light beam generated by the light emitting elements 16 arranged above the optical axis L1-L1’ travels relatively less distance and are subjected to relatively lesser divergence by the optical element 18. Due to the same, the images formed by said light emitting elements 16 that are projected towards the ground surface S are sharper. This may enable the luminous device 10, 12 to project a clear image in road writing function. Further, the low beam function may provide better illumination near the field of view of the driver. Similarly, the distance travelled by the light beam produced by the light emitting elements 16 arranged below the optical axis L1-L1’ is relatively more and due to this are subjected to more relatively increased divergence thus forming a blurring image. This enables the light sources 14 to produce a light beam with an increased spread. Further, it is envisioned a lighting system comprising a right-hand luminous assembly and a left-hand luminous assembly. According to an embodiment, the right-hand luminous assembly includes a right luminous device 10 and the left-hand luminous assembly includes a left luminous device 12, each luminous device 10, 12 including a vertical offset between the central axis C1-C1’ of the light source 14 and the optical axis L1-L1’ of the optical elements 18. The right luminous device 10 and the left luminous device 12 may work simultaneously to produce a combine light beam 300 that is projected to illuminate the road surface. Unless stated otherwise, dimensions and geometries of the various structures depicted herein are not intended to be restrictive of the invention, and other dimensions or geometries are possible. Plural structural components can be provided by a single integrated structure. Alternatively, a single integrated structure might be divided into separate plural components. A luminous device (10, 12) for a vehicle comprises : an optical element (18) presenting an optical axis (L1-L1’); at least one light source (14) comprising: - a substrate (15) extending at least along a vertical axis (A1-A1’); - a plurality of light emitting elements (16) extending from the substrate (15) and disposed in an array of at least one column and/or at least one row, otherwise called a light-emitting elements array, in such a way that the plurality of light-emitting elements are disposed symmetrically about a central axis (C1-C1’) perpendicular to the substrate (15); wherein the at least one light source (14) is arranged on a focal zone of the optical element (18) and disposed such that the central axis (C1-C1’) is orientated substantially parallel to the optical axis (L1-L1’); characterized in that the at least one light source (14) is eccentrically arranged with respect to the optical element (18) in such a way that the optical axis (L1-L1’) and the central axis (C1-C1’) are offset along the vertical axis (A1-A1’) to create vertical asymmetrical distribution of light emitting elements (16) of the at least one light source (14) about the optical axis (L1-L1’). The luminous device (10, 12) as claimed in claim 1, wherein the number of light emitting elements (16) arranged above the optical axis (L1-L1’) is unequal to the number of the light emitting elements arrange below the same optical axis (L1-L1’). The luminous device (10, 12) as claimed in claim 2, wherein the number of light emitting elements (16) arranged below the optical axis (L1-L1’) are greater than number of light emitting elements (16) above the optical axis (L1-L1’). The luminous device (10, 12) as claimed in any of the preceding claims, wherein the light emitting elements (16) arranged above the optical axis (L1-L1’) are configured to project light beam towards a ground surface. The luminous device (10, 12) as claimed in claim 4, the light beam projected towards the ground surface is for low beam lighting and/or road projection function. The luminous device (10, 12) as claimed in claim 2, wherein the light emitting elements (16) arranged below the optical axis (L1-L1’) are configured to project the light beam away from the ground surface. The luminous device (10, 12) as claimed in claim 1, wherein the at least one light source offset vertically such that the central axis (C1-C1’) and the optical axis (L1-L1’) are at a predetermined distance (α). The luminous device (10, 12) as claimed in any of the preceding claims, wherein the light emitting elements (16) are arranged in an array having plurality of rows and columns. A lighting system (100) comprising a right –hand luminous assembly and a left-hand luminous assembly, at least one of the right-hand luminous assembly and the left-hand luminous assembly including a luminous device as claimed in any of the preceding claims. A vehicle comprising a lighting system as claimed in claim 9 and presenting a longitudinal axis (L), wherein said at least one of the right-hand luminous assembly and the left-hand luminous assembly is arranged such that the projection axis of the luminous device is misaligned with the vehicle longitudinal axis (L) to orientate the luminous device outwardly.