COMPACT OPTICAL SYSTEM FOR VEHICLE INTERIOR LIGHTING

Description

technical field

[0001] The present invention is in the field of the automotive industry, and relates more particularly to interior lighting devices, especially those for the passenger compartments of motor vehicles. Prior art

[0002] US documents 2003 025002 Al, US 4453806 A, FR 3047946 A1 and WO 2005 116711 Al are representative of the prior art.

[0003] The passenger compartments of motor vehicles include numerous interior lighting devices to perform a variety of lighting functions. By way of non-limiting examples of known lighting functions, some interior lighting devices allow for the display of illuminated indications from or onto a wall of the passenger compartment; some interior lighting devices illuminate manual controls of the motor vehicle; and some other interior lighting devices are dedicated to illuminating a portion of an interior space within the passenger compartment of the motor vehicle.

[0004] A common characteristic of all these lighting systems is that they must meet strict dimensional constraints, stemming from the increasing number of electrical devices—lighting or otherwise—in vehicle interiors. Thus, while the lighting functionalities offered by interior lighting systems are expanding to meet the demands of vehicle manufacturers and users, the available space within the vehicle interior is simultaneously shrinking. This necessitates miniaturization to continue providing existing lighting functions and / or to enable the development of new lighting functions for vehicle interiors.

[0005] More specifically, the use of so-called pixelated, high-luminance light sources is known for integration into such interior lighting systems: these light sources are small and thus more easily meet some of the aforementioned dimensional constraints. Furthermore, they have a low acquisition cost, thereby reducing the manufacturing costs of these interior lighting systems. However, the combination of their small size and high luminance makes such pixelated light sources unsuitable for use inside a motor vehicle, as they present a potential risk to the human eye and compromise the comfort of the vehicle's occupants.

[0006] The present invention aims to address at least largely the previous problems and to lead to further advantages by proposing a new optical system for the passenger compartment of a motor vehicle.

[0007] Another objective of the present invention is to reduce the size of such an optical system compared to those implemented in known interior lighting devices.

[0008] Another objective of the present invention is to reduce the luminance of a pixelated light source while retaining its pixelation.

[0009] Another objective of the invention is to limit the manufacturing costs of such an optical system and of a lighting device comprising such an optical system. Description of the invention

[0010] According to the invention, at least one of the aforementioned objectives is achieved with an optical system for the passenger compartment of a motor vehicle as defined in claim 1, the optical system comprising (i) a diffuser configured to diffuse incident light rays from a light beam generated by a light source, and (ii) an optical assembly configured to project a real image of the light source onto the diffuser, a first geometric extent of the light beam measured at the level of the light source being less than a second geometric extent of the light beam measured at the level of an output face of the optical assembly.

[0011] Thus, the clever use of the diffuser allows the optical system according to the invention to reduce the luminance of the light source intended to interact with it. Furthermore, the optical system according to the invention is configured to preserve the pixelation of the light source. In other words, a shape and / or geometry of the light source intended to interact with the optical assembly is substantially preserved at the output of the optical assembly and / or the optical system. Consequently, the light rays entering the optical system according to the invention emerge with reduced luminance and with a spatial distribution substantially similar to that which they had at the input. In other words, the optical system is configured to perform a homothetic transformation of the light source with which it is intended to interact—and preferably a homothetic transformation of the magnification type.The use of the diffuser also allows for modification of the opening angle of the light rays passing through the optical system.

[0012] The diffuser of the optical system according to the first aspect of the invention is configured to diffuse—preferably without absorption—any light ray—called incident light rays—arriving at its surface. The light rays diffused by the diffuser of the optical system according to the invention are emitted in a plurality of directions from said diffuser, preferably without any preferred direction of propagation. In other words, the luminance of the diffuser is isotropic, regardless of the orientation of the incident light rays.

[0013] The optical assembly according to the invention is designed to work with the light source to project the light rays it generates onto the diffuser. For this purpose, the diffuser is located on the opposite side of the light source from the optical assembly when the optical system according to the first aspect of the invention is used with said light source.

[0014] According to the invention, the optical system makes it possible to increase the geometric extent of the light beam passing through said optical system, between (i) an input face located on the side of the light source intended to collaborate with the optical system and (ii) the output face of the optical system.

[0015] The geometric extent of a light beam characterizes the size of the entire range of light rays emitted by a light source, limited to the portion that reaches a given receiver. The geometric extent of the light beam corresponds to a geometric quantity (in m² .sr) characterizing the size and shape of the portion of light rays generated by the light source that reach the receiver. In other words, the geometric extent of the light beam characterizes how the beam of light rays is distributed across an emitting surface and the angular distribution of the light rays within that beam.As a rough example, in the case of a light source emitting within a hemisphere, such as a light-emitting diode (LED), the geometric extent of the light beam is obtained by multiplying the radiation cone of the light source—that is, the smallest cone encompassing all the light rays generated by said light source—by the emission surface area. Other calculation methods are applicable to other types of light sources and are well known to those skilled in the art.

[0016] Thus, thanks to the optical system according to the invention, the cone of radiation taken at the output of said optical system is greater than the cone of radiation of the light source located at the input of said optical system.

[0017] According to a key advantage of the invention, such an optical system is compact, thus reducing its size compared to those used in known interior lighting devices. Furthermore, the design of such an optical system reduces manufacturing costs.

[0018] According to the invention, the optical assembly comprises (i) a first part optically located between the light source and the diffuser, the first part being capable of anamorphosing the light source, and (ii) a second part optically located between the diffuser and the exit face of the optical assembly, the second part being a projection optic for the light rays diffused by the diffuser. The adverb "optically" here refers to the direction of propagation of the light rays within the optical system during its normal operation. The first part of the optical assembly makes it possible, in particular, to create a real image of the light source with which the optical system is intended to interact that is larger than its actual size; and the radiation cone of such a real image of the light source is smaller than that of the light source itself.The projection optics, forming the second part of the optical assembly, are configured to create a second real image of the real image—called the first real image—of the light source on the diffuser. Optionally, the projection optics create the second real image by means of an anamorphic distortion. The second real image created by the projection optics is located at a distance—finite or infinite—very large in front of the dimensions of the optical system conforming to the first aspect of the invention. By way of non-limiting example, the distance...

[0019] to which the second real image is created is located at least 30 times, and preferably 100 times, further than the dimensions of the optical system.

[0020] The optical system according to the invention may advantageously include one of the improvements below, the technical characteristics forming these improvements being able to be taken alone or in combination:The first part of the optical assembly advantageously offers a magnification greater than 1, and preferably greater than 2; the projection optics forming the second part of the optical assembly comprise one or more reflectors and / or one or more lenses and / or one or more light guides; the first part of the optical assembly is formed from a single material along with the diffuser, and / or the second part of the optical assembly is formed from a single material along with the diffuser. "Formed from a single material" means that the two parts in question are produced by the same manufacturing process and cannot be separated from one another without damaging or breaking one or both of these parts. Thus, according to a first embodiment, the first element is formed from a single material along with the diffuser, said diffuser being formed on one of the faces of said first element.According to a second embodiment, the projection optics are formed from a single piece of material along with the diffuser, said diffuser being formed on one of the faces of said projection optics. According to a third embodiment, the first element, the diffuser, and the projection optics are all formed from a single piece of material together; the first part of the optical assembly comprises a first reflector associated with a second reflector, the second reflector being configured to reflect light rays reflected by the first reflector. The first and / or the second reflector are preferably obtained by aluminizing a portion of the first element; the first reflector is configured to concentrate the light rays onto the second reflector.

[0021] According to the invention, the first optical axis associated with the first part of the optical assembly intersects a second optical axis associated with the second part of said optical assembly. This advantageous configuration makes it possible to propose an "angled" shape of the optical system conforming to the first aspect of the invention, thereby reducing its dimensional size. More particularly, the angle formed by the first optical axis and the second optical axis is between 70° and 110°. In the context of the invention, the optical axis is defined by a barycentric light ray emitted or shaped by the corresponding optical assembly or by the corresponding light source;

[0022] The following improvements can also be advantageously incorporated into the optical system: The diffuser is configured to diffract incident light rays. In other words, the diffuser of the optical system is configured to deflect incident light rays coherently, potentially resulting in light interference. To this end, the diffuser may comprise a one-dimensional or two-dimensional array of patterns that protrude or are recessed relative to the diffuser's incidence surface. As a non-limiting example, such a diffractive diffuser may take the form of a holographic diffuser. The diffuser is configured to be at least partially reflective. In other words, the diffuser is configured to reflect at least some of the incident light rays. The diffuser includes a rough scattering surface. By "rough," we mean that the scattering surface has asperities that cause the incident light rays to scatter.Controlling the dimensions and / or density of the asperities determines the diffusive nature of the diffuser; the diffuser's rough diffusion surface is grained. As a non-limiting example, such a diffusion surface can be obtained by sandblasting; the diffuser includes a curved surface; the optical assembly is advantageously made of plastic and / or glass. Polycarbonate (PC), polypropylene carbonate (PPC), or polymethyl methacrylate (PMMA) are preferred.

[0023] According to an improvement of the invention, an interior lighting device for a motor vehicle ceiling light is proposed, the interior lighting device comprising: an optical system as defined above; a light source associated with the optical system and configured to generate light rays which the optical assembly of the optical system projects onto the diffuser of said optical system, the light rays passing through the output face of said optical system being intended to illuminate a part of a passenger compartment of the motor vehicle.

[0024] Thus, the lighting device according to the invention makes it possible to offer interior lighting for the passenger compartment of a motor vehicle which reduces the luminance of the light sources used and which thus makes the latter compatible with such use for a passenger compartment of a motor vehicle.

[0025] The interior lighting device according to the invention may advantageously include at least one of the improvements below, the technical characteristics forming these improvements being able to be taken alone or in combination: The light source is pixelated and comprises a plurality of light-emitting diodes (LEDs) arranged in a grid. Preferably, the LED grid is one-dimensional or, even more preferably, two-dimensional. This advantageous configuration makes pixelated light sources compatible with use in a motor vehicle interior without altering their electrical control, and in particular the intensity of the control current. The LEDs forming the pixelated light source are advantageously driven by an electrical signal with a high current intensity, for example, greater than 1 Ampere.

[0026] Various embodiments of the invention are envisaged, incorporating, according to all their possible combinations, the different optional features described herein. Description of the figures

[0027] Other features and advantages of the invention will become apparent from the following description on the one hand, and from several illustrative and non-limiting examples of embodiments given with reference to the attached schematic drawings on the other hand, in which: there FIGURE 1 illustrates a schematic view of a first embodiment of an optical system not conforming to the invention and implemented in an interior lighting device; the FIGURE 2 illustrates a schematic view of a second embodiment of an optical system according to the invention and implemented in an interior lighting device; the FIGURE 3 illustrates a third embodiment of the optical system conforming to the first aspect of non-conformity with the invention; the FIGURE 4 illustrates an exploded view detail of the first part of the optical assembly implemented in the optical system shown on the FIGURE 3 .

[0028] Of course, the features, variants, and different embodiments of the invention can be combined in various ways, provided they are not incompatible or mutually exclusive. In particular, provided it remains within the scope of the claims, variants of the invention may be conceived comprising only a selection of features, described hereafter in isolation from the other described features, if this selection of features is sufficient to confer a technical advantage or to differentiate the invention from the prior art.

[0029] In particular, all the variants and embodiments described can be combined with each other if there are no technical obstacles to this combination.

[0030] In the figures, elements common to several figures retain the same reference. Detailed description of the invention

[0031] With reference to FIGURES 1 to 3 , an optical system 1 is described in its characteristics common to each illustrated embodiment.

[0032] The specific features of each embodiment will be described in more detail later with reference to each of the FIGURES 1 to 4 .

[0033] In the FIGURES described below, the light ray tracings inside the optical system 1 are given for illustrative purposes only, to facilitate understanding of the operation of the invention.

[0034] Such an optical system 1 comprises (i) a diffuser 11 configured to diffuse incident light rays 8b arriving at said diffuser 11, and (ii) an optical assembly 10 configured to project onto the diffuser 11 a real image 4 - schematically represented on the FIGURE 1- of a light source 2 intended to be used with the optical system 1. According to the invention, a first geometric extent of the light beam measured at the level of the light source 2 is less than a second geometric extent of the light beam measured at the level of an output face 1021 of the optical assembly 10. In other words, the optical system 1 according to the first aspect of the invention is configured to reduce a geometric extent of the light beam measured at the level of the light rays 8a generated by the light source 2 intended to collaborate with it, the geometric extent of the light beam thus reduced being measured at or beyond the output face 1021 of the optical assembly 10, and formed by the light rays 8c exiting said optical system 1.

[0035] Such an optical system 1 is intended to be implemented in an interior lighting device 3 and used in a motor vehicle to illuminate a part of a passenger compartment. Such an interior lighting device 3 conforms to the second aspect of the invention and comprises (i) at least one optical system 1 conforming to the first aspect of the invention and (ii) a light source 2 associated with the optical system 1 and configured to generate light rays 8a which the optical assembly 10 of the optical system 1 projects onto the diffuser 11 of said optical system 1, the light rays 8c passing through the output face 1021 of said optical system 1 being intended to illuminate a part of a passenger compartment of the motor vehicle.

[0036] Advantageously, the light source 2 is optically coupled to the optical system 1, so that a majority - and preferably all - of the light rays 8a generated by the light source 2 pass through an entrance face 1011 of the optical system 1. For this purpose, the light source 3 is advantageously secured to the optical system 1, either by direct attachment to said optical system 1, or by means of a rigid support to which the optical system 1 and the light source 3 are attached.

[0037] The light source 2 is advantageously a pixelated light source comprising a plurality of light-emitting diodes arranged in a two-dimensional array. Thus, the optical system 1 is particularly suited for use in combination with a surface light source in which several light-emitting diodes form light rays 8a which are shaped by the optical system 1. As will be detailed later with reference to FIGURES 1 to 4 , the optical system 1 is configured to reduce the luminance of the light source 2 while preserving the spatial distribution of the different light-emitting diodes forming the pixelated light source.

[0038] More particularly, the optical assembly 10 of the optical system 1 comprises (i) a first part 101 located optically between the light source 2 and the diffuser 11, and (ii) a second part 102 located optically between the diffuser 11 and the exit face 1021 of the optical assembly 10. The first part 101 and the second part 102 are alternatively made from material or attached to one another by means of fixing, such as for example by gluing or fixed to a common support not shown in the FIGURES.

[0039] The first part 101 of the optical assembly 10 is capable of anamorphosing the light source 2 with which the optical system is intended to interact, in order to reduce the luminance of said light source 2. The magnification of the first part 1011 of the optical assembly 10 is advantageously greater than or equal to 2, and preferably equal to 2.5, in order to sufficiently reduce the luminance of a pixelated light source and make it compatible with use as interior lighting in a motor vehicle. Furthermore, the first part 101 of the optical assembly 10 is configured to project a real image of the light source 2 onto or near the diffuser 11. By "near" the diffuser, it is understood that the real image is formed at a distance of less than a few millimeters from the diffuser 11, preferably upstream of the diffuser 11 in the direction of propagation of the light rays 8a, 8b, 8c.

[0040] The second part 102 of the optical assembly 10 takes the form of a projection optic for the light rays scattered by the diffuser 11. In other words, the second part 102 of the optical assembly 10 is configured to create a second real image of the first real image of the light source 2 created at the diffuser 11 by the first part 101 of the optical assembly 10.

[0041] The first part 101 and / or the second part 102 of the optical assembly 10 are configured individually or collectively to maintain a pixelation of the light source 2 with which the optical system 1 is configured to collaborate when implemented in an indoor lighting device 3. In other words, when the light source 2 is composed of a plurality of light-emitting diodes, then the optical assembly 10 is configured to maintain a spatial dissociation of the light rays emitted by each light-emitting diode of said light source 2.

[0042] The diffuser 11 of the optical assembly 10 allows the incident light rays 8b to be diffused in a plurality of directions, isotropically or anisotropically, depending on the desired effects. As illustrated in the FIGURES 1 to 3, the diffuser 11 is advantageously located in an optically intermediate position between the entrance face 1011 and the exit face 1021 of the optical assembly 10 of the optical system 1.

[0043] The diffuser 11 and the optical assembly 10 are advantageously made of optically transparent materials, particularly at the wavelengths of the light rays generated by the light source 2 with which the optical system 1 is likely to interact. By way of non-limiting example, the diffuser 11 and / or the optical assembly 10 are advantageously made of glass or of a plastic material such as, for example, polycarbonate (PC), polypropylene carbonate (PPC), or polymethyl methacrylate (PMMA).

[0044] The optical system 10 can be configured in several ways to meet the dimensional constraints imposed by different vehicle interiors, and in particular by the dimensions of the overhead lights in which the optical system is preferably intended to be integrated. By way of non-limiting examples, the FIGURES 1 to 4 will now be described in more detail through their specific characteristics.

[0045] There FIGURE 1 illustrates a schematic version of a first embodiment of the optical system 1 implemented in an interior lighting device 3, and in which the optical system 1 extends along a single optical axis O1.

[0046] The first part 101 of the optical assembly 10 is located at a distance from the light source 2 and has a wide admission angle, so that the majority - and preferably all - of the light rays 8a generated by the light source 2 enter the optical system 10 through the entrance face 1011 of the first part 101 of the optical assembly 10. The first part 101 is formed by one or more lenses and / or by one or more reflective surfaces in order to form the real image 4 of the light source 2 in a position optically intermediate between the first part 101 and the diffuser 11, along the single optical axis O1.

[0047] The set of incident light rays 8b which reach the diffuser 11 beyond the real image 4 of the light source 2 together form a cone whose opening angle is less than that of a cone formed by the set of light rays 8a generated by the light source 2.

[0048] The diffuser 11 of the optical system 10 illustrated on the FIGURE 1 is transparent so as to make it passable: the incident light rays 8b reaching the diffuser 11 pass through it axially along the optical axis O1 and are scattered in a plurality of directions around said optical axis O1, at the level of a face located on the side of the output face 1021 of the optical assembly.

[0049] The optical diffuser 11 illustrated on the FIGURE 1 is advantageously flat. In addition, it has at least one rough surface, for example grained, in order to diffuse the incident light rays 8b.

[0050] In this first embodiment, the diffuser 11 and at least a part 101, 102 of the optical assembly 10 are fixed rigidly to a support - not shown in the FIGURE 1 Alternatively, they can also be made entirely or partially from a single material in order to form a single optical piece and reduce the dimensional bulk of the optical system while facilitating its integration into an interior lighting device 3.

[0051] There FIGURE 2 illustrates a schematic version of a second embodiment of the optical system 1 implemented in an interior lighting device 3, and in which the optical system 1 has an angled configuration.

[0052] The first part 101 of the optical assembly 10 is located at a distance from the light source 2 and has a wide admission angle, so that the majority - and preferably all - of the light rays 8a generated by the light source 2 enter the optical system 10 through the entrance face 1011 of the first part 101 of the optical assembly 10. The first part 101 is formed by one or more lenses and / or by one or more reflective surfaces in order to form the real image of the light source 2 at the diffuser 11, along a first optical axis O2 which extends in a first direction.

[0053] The diffuser 11 of the optical system 10 illustrated on the FIGURE 2is reflective and is oriented with respect to the first optical axis O2 so as to form a non-zero angle, preferably between 20° and 70°. To make it reflective, the diffuser 11 includes at least one reflective surface, for example, obtained by aluminizing. The diffuser 11 is thus configured to reflect at least half of the incident light rays 8b, and to direct them towards a pupil of the projection optics forming the second part 102 of the optical assembly 10. In addition, the diffuser 11 includes at least one rough surface, for example, grained, in order to scatter the incident light rays 8b. The reflective surface is advantageously distinct from the rough surface. In the schematic example illustrated on the FIGURE 2The rough surface is that which the light rays 8b reach when they are shaped by the first part 101 of the optical assembly 10; and the reflective surface is that which is located opposite said rough surface with respect to a median plane of the diffuser 11. The optical diffuser 11 illustrated on the FIGURE 2 is advantageously flat.

[0054] The second part 102 of the optical assembly 10 of the optical system 1 illustrated on the FIGURE 2 is located downstream of the diffuser 11 according to the direction of propagation of the light rays 2 in the optical system 1. The second part 102 is oriented along a second optical axis O2 which forms a non-zero angle with the first optical axis O1, preferably between 20° and 160° depending on the applications sought, and preferably also equal to 90°.

[0055] In this second embodiment, the diffuser 11 and at least a part 101, 102 of the optical assembly 10 are fixed rigidly to a support - not shown in the FIGURE 2 Alternatively, they can also be made entirely or partially from a single material in order to form a single optical piece and reduce the dimensional bulk of the optical system while facilitating its integration into an interior lighting device 3.

[0056] There FIGURE 3 illustrates a schematic version of a third embodiment of the optical system 1 according to the first aspect of the invention and in which the optical system 1 extends along a single optical axis O1. In order to better understand this third embodiment, the FIGURE 4 illustrates a schematic exploded view of the first part 101 of the optical assembly.

[0057] The first part 101 of the optical assembly 10 is formed by a first optical part 101A and a second optical part 101B which are advantageously brought together at their contact faces 1015A, 1015B. They are preferably glued together at their contact faces 1015A, 1015B.

[0058] The first optical element 101A has a generally conical shape, the light source 2 being intended to be placed near or against a vertex 1016 of said conical surface. The first optical element 101A is configured to collect the light rays generated by the light source 2. The conical surface is thus delimited by linear outer walls 1017 extending around the optical axis O1 between the vertex 1016 and the contact surface 1015A. The outer walls 1017 of the first optical element 101A are advantageously transparent in order to allow the light rays generated by the light source to pass through. The outer walls 1017 thus form the entrance face 1011 of the optical assembly 10 of the optical system according to this embodiment.

[0059] The light rays that pass through the outer walls 1017 of the conical surface reach a concave surface 1012 located between said outer walls 1017 and around the optical axis O1. Collectively, the outer walls 1017 and the concave surface 1012 form a lens for shaping the light rays generated by the light source: the outer walls 1017 and the concave surface 1012 of the first optical piece 101A offer a positive vergence.

[0060] The concave surface 1012 is transparent so that light rays can pass through it.

[0061] The light rays passing through the first optical part 101A are projected out of the first optical part 101A towards the second optical part 101B. These light rays - propagating inside the first optical part 101A - then reach the second optical part 101B, through whose contact surface 1015B they pass.

[0062] The second optical element 101B has a concave shape: the outer walls 1014 of said second optical element 101B are nonlinear, and preferably parabolic. The outer walls 1014 of the second optical element are made reflective, for example by means of an aluminum coating on their surface. Consequently, the outer walls 1014 of the second optical element 101B form a second concave reflector configured to reflect the light rays from the first optical element 101A back towards said first optical element 101A and convergently towards the optical axis O1.

[0063] These light rays reach the first optical piece 101A at a proximal region of the optical axis O1, forming a first convex reflector 1013. It should be noted that the first convex reflector 1013 is made of material with the conical surface: it extends outward from the concave surface 1012 located inside the conical surface of the first optical piece 101A, symmetrically around the optical axis O1. The first convex reflector 1013 is obtained by a metallic deposit on its surface, for example, aluminum.

[0064] The light rays reaching the first convex reflector 1013 are again reflected towards the second optical piece 101B, at a proximal region of the optical axis O1, relative to the outer walls 1014 of the second optical piece 101B. Thus, the first convex reflector 1013 of the first optical piece 101A contributes to forming a real image of the light source that can be associated with the present optical assembly 10.

[0065] The actual image thus formed is formed at the proximal region of the optical axis O1 of the second optical element 101B. For this purpose, the second optical element comprises a transparent domed surface 1018 that projects from the outer walls 1014 of the second optical element 101B. More specifically, the transparent domed surface 1018 takes the form of a dome that extends symmetrically around the optical axis 101B and projects from the outer walls 1014.

[0066] The transparent curved surface 1018 here forms the diffuser 11 of the optical system 1 according to the first aspect of the invention. For this purpose, the transparent curved surface 1018 is advantageously roughened so as to be able to diffuse the incident light rays 8b in a plurality of directions around the optical axis O1.

[0067] Thus, the first optical piece 101A and the second optical piece 101B together make it possible to create, near the transparent curved surface 1018, a real image of the light source intended to collaborate with the optical system 1. The real image thus formed is magnified compared to its real dimensions, so as to reduce its luminance.

[0068] Consequently, as can be seen on the FIGURE 4 , the first part 101 of the optical assembly 10 is associated with a second part 102 in order to project the real image of the light source beyond the output face 1021 of the optical system 1.

[0069] The optical system illustrated in this third embodiment is particularly compact and economical to manufacture, because it results from the assembly of the two optical parts 101A, 101B and their combination with the second part 102 of the optical assembly 10.

[0070] In summary, the invention relates in particular to an optical system 1 and an interior lighting device 3 for a motor vehicle and comprising a light source 2 coupled to such an optical system 1. The optical system 1 comprises a first part 101 of an optical assembly 10 which allows a real image 4 of the light source 2 to be projected near a diffuser 11 of the optical system 1. The optical assembly 10 of the optical system 1 also comprises a second part 102 which acts as a projection optic in order to project out of said optical system 1 a real image of the real image of the light source 2 formed near the diffuser 11.The optical system 1 according to the invention makes it possible to reduce the luminance of the light source 2 of the interior lighting device 3 while retaining its pixelation, thus making it possible to use in motor vehicle interiors light sources based on light-emitting diodes and driven by a high amperage electric current without risk to the occupants of said interiors.

[0071] Of course, the invention is not limited to the examples just described and many modifications can be made to these examples without departing from the scope of the claims.

[0072] In particular, the different features, forms, variants and embodiments of the invention can be combined with each other in various ways insofar as they are not incompatible or mutually exclusive.

Claims

1. Optical system (1) for interior lighting of a motor vehicle cabin, the optical system (1) comprising: - a diffuser (11) configured to diffuse incident light rays (8b) of a light beam generated by a light source (2); - an optical element (10) configured to project a real image of the light source (2); a first geometric extent of the light beam measured at the light source (2) being less than a second geometric extent of the light beam measured at an exit face (1021) of the optical element (10), the optical element (10) comprising: - a first part (101) optically located between the light source (2) and the diffuser (11), the first part (101) being able to anamorphose the light source (2) and create a first real image of the light source (2) near or on the diffuser (11); - a second part (102) optically located between the diffuser (11) and the exit face (1021) of the optical element (10), the second part (102) being an optical projection of the light rays diffused by the diffuser (11) and being configured to create a second real image of the first real image created at the diffuser (11) wherein a first optical axis (01) associated with the first part (101) of the optical element (10) intersects a second optical axis (02) associated with the second part (102) of said optical element (10), the angle formed by the first optical axis (01) and the second optical axis (02) being between 70° and 110°; the diffuser (11) being configured to be at least partially reflective.

2. Optical system (1) according to claim 1, wherein the first part (101) of the optical element (10) is formed of the same material as the diffuser (11), and / or the second part (102) of the optical element (10) is formed of the same material as the diffuser (11).

3. Optical system (1) according to any one of the preceding claims, wherein the diffuser (11) is transmissive, the incident light rays (8b) on an incident face of the diffuser (11) being diffused at a face opposite to the incident face with respect to the first part (101) of the optical element (10).

4. Optical system (1) according to any one of the preceding claims, wherein the diffuser (11) comprises a rough diffusion surface.

5. Optical system (1) according to the preceding claim, wherein the rough diffusion surface of the diffuser (11) is grained.

6. Optical system (1) according to any one of the preceding claims, wherein the diffuser (11) is configured to diffract the incident light rays (8b).

7. Optical system (1) according to any one of the preceding claims, wherein the diffuser (11) comprises a curved surface.

8. Interior lighting device (3) for a motor vehicle ceiling light, the interior lighting device (3) comprising: - an optical system (1) according to any one of the preceding claims; - a light source (2) associated with the optical system (1) and configured to generate light rays that the optical element (10) of the optical system (1) projects onto the diffuser (11) of said optical system (1), the light rays passing through the exit face (1021) of said optical system (1) being intended to illuminate a part of a cabin of the motor vehicle.

9. Interior lighting device (3) according to the preceding claim, wherein the light source (2) is pixelated and comprises a plurality of light-emitting diodes organized in an array.