Especially LED lighting devices for vehicles.

Abstract

A lighting device (1) for a vehicle includes at least one light source and an optical system (6), the at least one light source including an LED or a group of LEDs, the optical system being configured to collect at least one first beam (8) generated by the LED to project a second beam (9) having a predetermined illumination profile in a predetermined direction (D), wherein the optical system (6) includes a light guide (7) forming a flat strip (10) having a first end (13) and a second end (14); the light guide (7) is provided with at least one first collimating element (19) and at least one second collimating element (20) facing each other and operatively associated to generate a second beam (9) already within the light guide and toward the second end of the light guide, thereby determining the illumination profile, preferably an aesthetic appearance, of the second beam as it is emitted through an emission section (28) of the second end (14) of the light guide.

Description

[0001] Cross-reference to related applications

[0002] This patent application claims priority to Italian Patent Application No. 102020000002350, filed on February 6, 2020, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] The present invention relates to a lighting device for vehicles, particularly for headlights of vehicles such as automobiles, wherein the light source comprises LEDs or LED arrays. Background Technology

[0004] As is well known, headlights or lamps of vehicles, particularly automobiles, include a cup-shaped housing housing at least one light source, and a transparent element arranged to close the front opening of the cup-shaped housing. Inside the housing, an optical system is also arranged to orient and shape the light beam emitted by the light source according to a predetermined photometric profile. The simplest of these optical systems includes one or more reflectors, which may be assisted by one or more lenses or prisms formed on the transparent element or (in the case of lenses) housed within the cup-shaped housing.

[0005] If the light source includes LEDs or LED arrays to produce the necessary light output, the LEDs are placed very close to the lens, or, if that is not possible, the beam emitted by the LED light source is fed into a light guide that directs it to the intended emission area.

[0006] However, a drawback of current light guide-based optical systems is that the resulting light distribution is not always regular or uniform, and in general, they are not suitable or well-suited for producing the illumination profile required for vehicle headlights.

[0007] Therefore, current light guide-based optical systems are almost exclusively used for taillights, or at most for front DRLs.

[0008] This is the case in DE102010046022A, where the light guide section arranged between the light source and the collimation structure is not used as a collimation element, but guides the light without any construction or control.

[0009] FR2966223A1 discloses a light guide structure that can be dedicated to signal functions and is designed to use two different light sources instead, wherein a collimating element receives light by reflection.

[0010] US10288248B1 discloses an illumination device with a light guide that is only used to produce adjustable spotlights and also uses a complex and expensive construction based on an aspherical surface. Summary of the Invention

[0011] One object of the present invention is to provide a lighting device for a vehicle, particularly for headlights of vehicles such as automobiles, wherein the light source of the lighting device includes at least one LED or LED array, and the lighting device does not have the disadvantages of the prior art. In particular, the lighting device can provide highly uniform and consistent lighting and a light profile suitable for vehicle headlights, as well as high compactness, thereby having reduced volume, relatively low manufacturing and assembly costs, and high shape adaptability. Therefore, even vehicles with very different style profiles can be equipped with it, but by operating it according to a single operating principle.

[0012] Therefore, the present invention relates to a vehicle lighting device having the features set forth in the appended claims, particularly for headlights of vehicles such as automobiles.

[0013] In particular, the vehicle lighting device according to the invention preferably, but not exclusively, includes a vehicle headlight comprising: a cup-shaped housing housing at least one light source; a transparent element arranged to close a front opening of the cup-shaped housing; and an optical system also housed within the cup-shaped housing. The optical system is configured to focus at least one first beam generated by the light source and project a second beam having a predetermined illumination profile in a predetermined direction. The light source includes at least one LED or LED array, and the optical system includes a light guide comprising a flat strip demarcated between its front and back sides, the front and back sides being substantially flat and having first and second ends opposite to each other.

[0014] The first end is configured to focus at least one first beam generated by at least one LED or group of LEDs.

[0015] Specifically, the first end of the light guide has a lateral edge on the side opposite to the second end, the lateral edge being shaped to define at least one first collimating element, which is formed, for example, by a concave lens or a convex lens, arranged facing at least one LED or LED group and configured to focus at least one first beam within the light guide and perform first collimation of the at least one first beam toward the second end of the light guide.

[0016] In combination, a first end of the light guide faces a second end and has at least one second collimating element on a side opposite to the lateral edge. This at least one second collimating element faces and is operatively associated with at least one first collimating element, and is configured to focus a first beam after first collimation and perform second collimation on the first beam, thereby generating a second beam already within the light guide downstream of the at least one second collimating element and toward the second end. The second beam already has an illumination profile and any desired shape or aesthetic appearance within the flat strip constituting the light guide, and is uniformly distributed over the entire height of the flat strip constituting the light guide, measured between the longitudinal upper edge and longitudinal lower edge of the flat strip.

[0017] The light guide also has a first intermediate section disposed between the first end and the second end and defined between two opposing converging portions on the front and back sides, such that the first intermediate section has a thickness that gradually decreases toward the second end, measured perpendicular to the first and second surfaces.

[0018] The light guide extends downstream of the first intermediate section and toward the second end with a cross-section having a constant thickness measured perpendicular to the front and back sides, wherein the term "downstream" refers to the trajectory of at least one first beam within the light guide.

[0019] The converging portions of the first intermediate section defining the front and back sides are continuously connected to the remainder of the front and back sides, and preferably have a continuous, straight or curved profile.

[0020] In addition to the first intermediate section having a converging surface, the light guide preferably also includes a second intermediate section disposed downstream of the first intermediate section, the term "downstream" referring to the trajectory of at least one first beam within the light guide.

[0021] The second intermediate section is also arranged on the second end side, and the second end is connected to the first intermediate section.

[0022] The second intermediate section has a constant thickness measured perpendicular to the front and back sides, and defines a bend in the light guide at least partially continuously, such that the first end and the first intermediate section are aligned linearly with each other and arranged at an angle relative to the second end, the first end and the first intermediate section being continuously connected to the second end through the second intermediate section.

[0023] The second intermediate section preferably, but not necessarily, has at least a plurality of grooves, engravings, or ribs formed on one or both of the front and back sides, and oriented perpendicular to the longitudinal upper and lower longitudinal edges of the flat strip constituting the light guide.

[0024] The grooves, grooves, or ribs are straight and preferably, but not necessarily, have a cylindrical profile, and are preferably formed only upstream of the curved portion of the second intermediate section on the side of the first intermediate section.

[0025] On the side opposite to the second end, the first end of the light guide is provided with at least one second collimating element, which is formed at a transverse through hole perpendicular to the front and back sides and passes through the flat strip constituting the light guide.

[0026] Therefore, at least one second collimating element is defined by at least one of the opposing transverse edges of a through hole extending between the longitudinal upper edge and the longitudinal lower edge of the flat strip.

[0027] In one embodiment, at least one second collimating element is formed on the lateral edge of the through-hole facing the second end, the edge being arranged toward the lateral edge of the first end of the light guide carrying at least one first collimating element.

[0028] According to one aspect of the invention, each of the first and second collimating elements, which are aligned side-by-side in the height direction of the flat strip (i.e., in the space between its upper and lower edges), is present in one or more, for example, two or three. Furthermore, they are configured to at least partially determine the aesthetic appearance of the emission segment of the second beam present on the front surface of the flat strip constituting the light guide.

[0029] In fact, the second end of the light guide has a light extraction element on the back side of the flat strip, such as a prism or other suitable type of optical device, which is configured to deflect the second beam from within the flat strip constituting the light guide through an emission section defined on the front side of the flat strip.

[0030] According to the invention, due to one or more pairs of collimating elements that face each other and are operatively associated, uniformity of the intensity of the second beam and other illumination characteristics, as well as a bright aesthetic appearance of the entire illumination device, have been achieved within the light guide. This bright aesthetic appearance is also defined by the shape of the emitting section located on the front side of the flat strip when the LED is turned on during use.

[0031] Due to the aforementioned additional arrangements according to the invention, additional and greater illumination uniformity can be obtained, i.e., greater uniformity of the second beam emitted by the illumination device according to the invention. These additional arrangements can be used partially or entirely together and include a converging surface of the first intermediate section and a bend formed by the second intermediate section and the aforementioned grooves, notches, or ribs, which define a lens or obstruction that causes light to reflect between the front and back sides of the light guide until it is guided to the second end of the light guide, as well as the bend of the second intermediate section. The second end of the light guide defines an emitting section configured to emit a second beam, now having a predetermined illumination profile and a bright appearance, perpendicular to the front side, on the front side. This is because a light extraction element, such as a prism, is present on the back side of the second end of the light guide, which is configured to deflect the second beam formed within the light guide through the emitting section on the front side.

[0032] Using existing light guides, at least to the extent achievable by this invention, such a result cannot be obtained. In existing light guides, there are only one or more collimating elements arranged side by side at the light source, which are not arranged in pairs as in this invention.

[0033] In fact, in known light guides, the beam emitted by an LED is collimated, but remains stronger toward the center, causing the light emitted by the prism to be non-uniform, thus providing a non-uniform beam of light emanating from the lighting device. Attached Figure Description

[0034] Additional features and advantages of the invention will become more apparent from the following description of non-limiting embodiments thereof, which is made with reference to the accompanying drawings, wherein:

[0035] - Figure 1 The diagram schematically shows a three-quarters frontal perspective view of a vehicle lighting device, particularly a headlight, manufactured according to the present invention.

[0036] - Figure 2 The image is schematically shown at an enlarged scale, showing the contents of the device. Figure 1 Three-quarters of the frontal stereoscopic view of the optical system of the illumination device in the image;

[0037] - Figure 3 The diagram is schematically shown with an additional enlarged scale. Figure 2 A three-quarter rear-view perspective view of the same optical system, but rotated 90° to show its back side upwards and modified according to different implementations; and

[0038] - Figure 4 and Figure 5 Suggested schematically at a larger scale Figure 3 Two details of the optical system. Detailed Implementation

[0039] Reference Figure 1 Reference numeral 1 generally indicates a vehicle lighting device, which, in the non-limiting embodiment shown herein, consists of vehicle headlights.

[0040] It should be understood that the present invention is not limited to vehicle headlights, but extends to front or rear lights, but for the sake of simplicity, reference will be made to vehicle headlights in the following description.

[0041] The lighting device 1 includes: a cup-shaped housing 2 that houses at least one light source comprising at least one LED 3 or a group of LEDs 3 in a known manner. Figure 2 (In the non-limiting example shown, two pairs of LEDs 3 are included.) Figure 3 The transparent element 4 is arranged to close the front opening 5 of the cup-shaped housing 2; and an optical system 6 opposite to the transparent element 4, which is also housed within the cup-shaped housing 2. The optical system includes a light guide 7 configured to focus at least one first beam 8 generated by the light source defined by the LED 3. Figure 2 ), and in the preset direction D ( Figure 1 and Figure 2 (As indicated by the arrow in the image) a second beam 9 with a preset lighting profile is projected onto and through the transparent element 4.

[0042] According to one aspect of the invention, the light guide 7 includes a flat-profile strip 10 having a generally rectangular cross-section and a generally elongated parallelepiped shape, which, in the preferred embodiment shown, is curved. The strip 10 is preferably molded from a transparent synthetic plastic material and is defined between its front side 11 and back side 12, which are substantially flat and parallel to each other except along the middle section of the transparent strip 10 as will be seen.

[0043] The flat transparent strip 10 constituting the light guide 7 has a first end 13 and a second end 14 that are opposite to each other. Figure 2 ).

[0044] Also refer to other Figures 3 to 5 The first end 13 is configured to converge at least one first beam 8 generated by at least one LED 3 or LED group 3 (in this case, a single beam 8 generated by LED 3) to transmit the at least one first beam within the light guide 7. As will be seen, these first beams are mixed in the light guide and undergo a series of total internal reflections on their inner sides at faces 11 and 12, and are transmitted within the light guide 7 along the light guide from end 13 toward the other end 14 according to trajectory F (by... Figure 2The arrow in the diagram indicates the movement, and the trajectory F follows (i.e., parallel to) the longitudinal profile of the flat band 10 defined by faces 11 and 12.

[0045] For this purpose, the first end 13 of the light guide 7 is provided with a transverse edge 15 on the side opposite to the second end 14. The transverse edge 15 is substantially perpendicular to the surfaces 11, 12 and substantially perpendicular to the transparent flat strip 10 or the corresponding longitudinal upper edge 16 and longitudinal lower edge 18 of the light guide 7.

[0046] Edge 15 is shaped to define at least one first collimating element 19, in this case a pair of collimating elements 19, each collimating element facing a pair of LEDs 3 arranged side by side. Figure 3 ), and in the non-limiting example shown, it consists of a corresponding lens.

[0047] In this context and below, "collimating element" should be understood as an optical element that not only focuses and distributes light, but also performs such light distribution in a controlled manner, thereby shaping individual light rays into beams with a predetermined shape and intensity, i.e., producing collimated beams (in this case, within the light guide 7).

[0048] The lens 19 constituting the first collimating element can be concave or convex (in the non-limiting example shown, both lenses 19 are convex, but other configurations are also possible).

[0049] In summary, each lens or collimating element 19 is arranged to face at least one LED 3 or LED group 3, and is configured to focus each first beam 8 emitted by the LED 3 within the light guide 7 and perform first collimation on the first beam. Figure 5 ).

[0050] Additionally, the first end 13 of the light guide 7 faces the second end 14 and has at least one second collimating element 20 on the side opposite to the lateral edge 15. In this case, there are two collimating elements 20 of a known type, each collimating element arranged to face a pair of LEDs 3 across a pair of lenses 19.

[0051] Therefore, the collimating element 20 is arranged one in front of the other in the direction F relative to the corresponding collimating element 19.

[0052] The at least one second collimating element 20 (i.e., a pair of collimating elements 20 side by side) is parallel to the front side 11 and the back side 12 and oriented perpendicular to the longitudinal upper edge 16 and the longitudinal lower edge 18.

[0053] In fact, each second collimating element 20 is bounded by one of the two opposing and radially inward lateral edges 30 and 31 of the transverse through-hole 21 formed by the light guide 7, which are perpendicular to the surfaces 11 and 12.

[0054] At least one second collimating element 20 (a pair next to collimating element 20 in the illustrated example) is configured to focus the first beam 8 after the first collimation and perform a second collimation of the first beam 8, thereby generating a second beam 9 with a predetermined illumination profile downstream of at least one second collimating element 20 and toward the second end 14. This second beam has been uniformly distributed within the light guide 7 over the entire height of the flat strip 10 constituting the light guide 7, measured perpendicularly to the longitudinal upper edge 16 and longitudinal lower edge 18 between the longitudinal upper edge 16 and longitudinal lower edge 18. Figure 5 ).

[0055] In the example shown, the edges 30, 31 of the through hole 21 are parallel to each other and parallel to the lateral edge 15 of the end 13, and extend perpendicularly to the longitudinal upper edge 16 and longitudinal lower edge 18 between the longitudinal upper edge 16 and longitudinal lower edge 18 of the flat strip 10 constituting the light guide 7.

[0056] In the non-limiting example shown, a single through-hole or window 21 drilled laterally through the transparent strip 10 constituting the light guide 7 defines and shapes a pair of second collimating elements 20.

[0057] According to one aspect of the invention, as already mentioned, the second collimating element 20 is paired with the first collimating element 19 formed on the lateral edge 15, i.e., operatively associated, to facilitate the collimation of the beam 8, which, after being collimated by the second collimator, produces a second beam 9 with desired illumination characteristics, which is downstream of the element relative to the direction F and already within the light guide 7. The second collimating element also improves the uniformity of the second beam that could be obtained solely by the first collimating element 19, such as in… Figure 5 The image is illustrated with dashed lines, though it is merely illustrative and makes no claim to realism.

[0058] According to the invention, the light guide 7 also has a first intermediate section 22 between the first end 13 and the second end 14, the first intermediate section being arranged downstream of at least one second collimating element 20 relative to the trajectory F of at least one first beam 8.

[0059] The first intermediate section is defined between two opposing converging portions 23 of the front side 11 and the back side 12, such that the first intermediate section 22 has a thickness that gradually decreases toward the second end 14, measured perpendicular to the first surface 11 and the second surface 12, but has a constant height measured perpendicular to the longitudinal upper edge 16 and the longitudinal lower edge 18.

[0060] Experiments show that this method is useful for improving the uniformity and homogeneity of the emitted beam 9 when needed (e.g., when the LED group 3 is spaced further apart), because it increases the internal reflection of the light generated by the LED 3 and propagates along the light guide 7 in direction F and causes it to intersect.

[0061] Furthermore, the light guide 7 extends toward the second end 14 upstream and downstream of the first intermediate section 22 of the trajectory F defined by at least one first beam 8 and defined by the shape of the light guide 7 with a cross section having a constant thickness measured perpendicular to the front side 11 and the back side 12, so that the front side 11 and the back side 12 are always parallel to each other except for the portion of the light guide formed by the intermediate section 22.

[0062] The opposing converging portions 23 that define the front 11 and back 12 of the first intermediate section 22 are continuously connected to the rest of the front 11 and back 12 and have a continuous straight profile (in the example shown) or a curved profile defined, for example, by a parabola, hyperbola or complex curve segment.

[0063] According to a preferred aspect of the invention, the light guide 7 further includes a second intermediate section 24, which is arranged downstream of the first intermediate section 22 and on the side of the second end 14 relative to the trajectory of the light beam 8.

[0064] The second intermediate section 24 connects the second end 14 to the first intermediate section 22 and has a constant thickness measured perpendicular to the front side 11 and the back side 12; additionally, at the second intermediate section 24, the front side 11 and the back side 12 of the flat strip 10 are at least partially curved and have matching curvatures so as to always remain parallel to each other and such that the second intermediate section 24 defines a bend 25 at least partially and substantially continuously in / along the light guide 7. Figure 2 and Figure 3 The first end 13 and the first intermediate section 22 are aligned in a straight line with each other and are arranged at a certain angle to the second end 14. The first end 13 and the first intermediate section 22 are substantially continuously connected to the second end 14 through the second intermediate section 24.

[0065] The second intermediate section 24, whether or not it forms a bend 25, preferably has at least partially a plurality of grooves or notches or ribs 26 formed on one or both of the front side 11 and the back side 12 (in a preferred embodiment, only on the back side 12), and oriented perpendicular to the longitudinal upper edge 16 and longitudinal lower edge 18 of the light guide 7.

[0066] The grooves, engravings, or ribs 26 are straight and preferably have a cylindrical profile.

[0067] The cross-sectional variations of these cylindrical optics 26 and the first intermediate segment 22 obtained through the converging surfaces 11, 12 are used to better “mix” the light guided along the light guide 7. Without these additional elements, especially under certain conditions (e.g., LEDs 3 arranged far apart), a strong but poorly controlled beam can be obtained.

[0068] When a bend 25 exists on the optical guide 7, it is preferable to form a groove, groove, or rib 26 only on the side of the first intermediate section 22 upstream of the bend 27 of the second intermediate section 24. This bend 27 defines the aforementioned bend 25 of the flat strip 10 located on the side of the first intermediate section 22.

[0069] Here, above, and below, the terms “upstream” and “downstream” are intended, as already indicated, to refer to the linear propagation direction F of the beam 8 within the light guide 7, so as to form a beam 9 with a predetermined illumination profile at its exit.

[0070] exist Figure 3 and Figure 5 In the non-limiting example shown, at least one second collimating element 20 is formed at a single edge 30 on the side of the first end 13 of the transverse through-hole 21.

[0071] In this embodiment, in Figure 3 and Figure 5 In this configuration, at least one second collimating element 20 (a pair of collimating elements 20 arranged side by side in a direction perpendicular to the edges 16, 18) faces the second end 14 and is thus formed on the edge 30 arranged on the side of the edge 15.

[0072] On the other hand, Figure 2 In the non-limiting embodiment shown, the collimating element 20 is always formed on the edge 30 facing the interior of the through-hole 21, while the opposite edge 31 is provided with an optical mixer 32, which consists, for example, a cylindrical lens or notch of the type of element 26, with the aim of increasing the mixing and uniformity of the collimated light moving within the light guide 7. Therefore, the optical mixer 32 is a preferred but optional element, such as... Figure 3 and Figure 5 As in the implementation method, it can be omitted.

[0073] In any of the embodiments described, the collimating element 20 may include a concave lens or a convex lens or other suitable optical device (e.g., Fresnel or holographic).

[0074] The through-hole 21 is an important aspect of the invention because it enables the production of the second collimating element 20 in a simple and economical manner, with a reduced overall size and in the most suitable position, thereby achieving the desired emission uniformity in the beam 9.

[0075] At least the first collimating element 19 and the second collimating element 20 are configured to further at least partially define the emission segment 28 of the second beam 9. Figure 2 In terms of aesthetic appearance, according to the present invention, the emitting section 28 is arranged on the front side 11 of the flat strip 10 constituting the light guide 7, that is, represented by a predetermined portion of the surface 11.

[0076] In fact, the second end 14 of the light guide 7 is provided with a light extraction element 29 on the back side 12 of the flat strip 10. The light extraction element 29 is configured to deflect the second beam 9 to the emission section 28 of the front side 11 in the direction D, which is substantially perpendicular to the surfaces 11 and 12.

[0077] Due to the configuration and distribution of light received via collimating elements 19 and 20, light emitted by LED 3 propagates within light guide 7 via total internal reflection and a series of refractions and reflections, eventually reaching end 14 of light guide 7. This series of refractions and reflections is first caused by intermediate section 22 with a gradually decreasing thickness measured perpendicular to surfaces 11, 12 (i.e., perpendicular to the emitting section 28) (i.e., parallel to direction D), then by obstacles including grooves / scratches or ribs 26, and finally by bend 25.

[0078] The second end 14 of the light guide 7 defines the emission section 28 of the light guide 7 on the front side 11. The emission section 28 is configured to emit a second beam 9 with a preset illumination profile and a preset aesthetic appearance in the direction D.

[0079] For this purpose, the second end 14 of the light guide 7 is provided with a light extraction element 29 on its back side 12 side. In the non-limiting example shown, the light extraction element 29 consists of an array of prisms and is configured to deflect the second beam 9, which is now uniform and conforms to the desired illumination profile due to reflections caused by the lenses or collimating elements 19 and 20, as well as by the intermediate section 22, rib 26 and bend 25 (and optical mixer 32, if present), through the emitting section 28 of the front side 11 and from there through the transparent element 4 in direction D, thereby forming, for example, a low beam or anti-fog beam.

[0080] Collimation is performed to illuminate the barrier over its entire height between edges 16 and 18, the barrier being visible through a colorless lens or transparent element 4 and including the end 14 of a light guide 7 formed by a flat strip 10.

[0081] The input light generated by LED 3 has a Lambertian distribution, and the output light (beam 9 pointing in the D direction) is produced by the described configuration and, in particular, by the functional pairing of the collimating elements 19 and 20 arranged one in front of the other along direction F. Figure 1The output light defined by beam 9 is uniform. Therefore, even when the end 14 is viewed from different angles (e.g., from the front or from the side), the shape or aesthetic appearance of the emitting section 28 is substantially the same.

[0082] Lenses 19 and 20 work together and can achieve collimation and uniformity within an enclosed space.

[0083] Another advantage of the described scheme is that the LEDs 3 can be arranged side by side with a greater distance between them compared to the usual configuration used in known light guides.

[0084] Therefore, the described scheme proposes to use a reduced number of LEDs, but with high efficiency, to create a so-called "barrier" optical system.

[0085] Especially when using collimators with improved efficiency, the large number of LEDs commonly used in known schemes can have a function that is uniform when lit (typically only emitting a signal). However, the necessary spacing between the LEDs must be kept small (e.g., 6.5 mm in slide 7), otherwise “spots” will form in terms of lighting that impair the function.

[0086] Conversely, using two collimators, one in front of the other (working together), according to the present invention allows for a larger spacing (e.g., 25 mm), as it produces a more uniform (fewer aesthetic defects) and more collimated (higher efficiency) beam. This saves significant structural space and reduces LED heat generation during use—heat that typically must be removed by a heat sink, which is a particularly bulky component if the LED generates a large amount of heat.

[0087] Variations in the sections and cylindrical optics are elements that improve the bright, aesthetically pleasing appearance in the side view.

[0088] All the objectives of this invention have been achieved.

Claims

1. A lighting device (1) for vehicles, comprising a cup-shaped housing (2) which houses at least one light source, a transparent element (4) arranged to close a front opening (5) of the cup-shaped housing (2), and an optical system (6) also housed in the cup-shaped housing and configured to collect at least one first light beam (8) generated by the light source and to project a second light beam (9) having a preset illumination profile in a preset direction (D), wherein the light source comprises at least one LED (3) or a group of LEDs (3), wherein the optical system (6) comprises a light guide (7) consisting of a flat strip (10) which is delimited between a flat front face (11) and a back face (12) thereof and has a first end (13) and a second end (14) opposite each other, the first end (13) being configured to collect the at least one first light beam (8) generated by the at least one LED (3) or group of LEDs, and wherein the first end (13) of the light guide is provided on the side opposite the second end (14) with a lateral edge (15) shaped to define at least one first collimation element (19) arranged facing the at least one LED (3) or group of LEDs and configured to concentrate the at least one first light beam (8) within the light guide (7) and perform a first collimation of the at least one first light beam towards the second end (14) of the light guide; and wherein the front face (11) of the flat strip (10) which constitutes the light guide comprises, on the front face (11) itself, an emission section (28) of the second light beam (9), the second end (14) of the light guide (7) being provided on the side of the back face (12) of the flat strip (10) with a light extraction element (29) configured to deflect the second light beam (9) through the emission section (28) of the front face to make the emission direction of the second light beam (9) perpendicular to the front face (11); characterized in that in combination: i) - the first end (13) of the light guide is provided towards the second end (14) and on the side opposite the lateral edge (15) with at least one second collimation element (20) facing and operatively associated with the at least one first collimation element (19) and configured to concentrate the first light beam after the first collimation and perform a second collimation of the first light beam, producing downstream of the at least one second collimation element and towards the second end the second light beam (9) having the preset illumination profile which has been within the light guide and uniformly on the entire height of the flat strip (10) which constitutes the light guide, measured perpendicularly to the longitudinal upper edge (16) and to the longitudinal lower edge (18) of the flat strip between the longitudinal upper edge (16) and the longitudinal lower edge (18) in the longitudinal direction thereof; ii) - the back face (12) of the flat strip (10) which constitutes the light guide is provided with a plurality of light extraction elements (29) arranged in correspondence with the emission section (28) of the second light beam (9) and configured to extract the second light beam (9) from the light guide (7) and to make the emission direction of the second light beam (9) perpendicular to the back face (12) of the flat strip (10) which constitutes the light guide. ii) - said second collimating element (20) is oriented parallel to said front face (11) and to said back face (12) and perpendicular to said longitudinal upper edge (16) and to said longitudinal lower edge (18); iii) - between said first end portion (13) and said second end portion (14), said light guide (7) has a first intermediate section (22) arranged downstream of said second collimating element (20) with respect to the trajectory of said at least one first light beam (8) and delimited between two opposite converging portions (23) of said front face (11) and of said back face (12), so that said first intermediate section (22) has a thickness measured perpendicularly to said front face (11) and to said back face (12) which gradually decreases towards said second end portion (14), but has a constant height measured perpendicularly to said longitudinal upper edge (16) and to said longitudinal lower edge (18), said light guide (7) extending downstream of said first intermediate section (22) and towards said second end portion (14) with a cross section having a constant thickness measured perpendicularly to said front face and to said back face.

2. The illumination device of claim 1, wherein Said opposite converging portions (23) of said front face (11) and of said back face (12) which delimit said first intermediate section (22) are continuously connected to the rest of said front face (11) and of said back face (12) and have a continuous, straight or curved profile.

3. The illumination device of claim 1, wherein Said light guide (7) comprises a second intermediate section (24) arranged downstream of said first intermediate section (22) with respect to the trajectory of said at least one first light beam (8) and on the side of said second end portion (14), connecting said second end portion (14) with said first intermediate section (22); said second intermediate section (24) has a constant thickness measured perpendicularly to said front face and to said back face, and, in correspondence with said second intermediate section, said front face (11) and said back face (12) are at least partially curved and have matching bends, so that said second intermediate section defines at least partially and continuously a bend (25) in said flat band (10) which constitutes said light guide (7), so that said first end portion (13) and said first intermediate section (22) are aligned linearly with each other and arranged at an angle with respect to said second end portion (14), said first end portion (13) and said first intermediate section (22) being connected continuously with said second end portion (14) by said second intermediate section (24).

4. The illumination device of claim 3, wherein Said second intermediate section (24) is provided at least partially with a plurality of grooves or scores or ribs (26) formed on one or both of said front face and of said back face and oriented perpendicularly to said longitudinal upper edge (16) and to said longitudinal lower edge (18) of said flat band (10) which constitutes said light guide.

5. The illumination device of claim 4, wherein, Said grooves or scores or ribs (26) are straight.

6. The illumination device of claim 4, wherein Said grooves or scores or ribs (26) have a cylindrical profile.

7. The illumination device of claim 4, wherein Said recesses or scores or ribs (26) are formed only upstream of said first intermediate section (22) upstream of the curved portion (27) of said second intermediate section (24) defining said bend (25) in said flat strip (10).

8. The illumination device of claim 1, wherein, Said at least one second collimating element (20) is formed in correspondence with a transverse through hole (21) formed through said flat strip (10) constituting said light guide (7) perpendicularly to said front face (11) and to said back face (12); said at least one second collimating element (20) is defined by one or both of the opposite transverse edges (30, 31) of said through hole (21) extending between said longitudinal upper edge (16) and said longitudinal lower edge (18) of said flat strip (10).

9. The illumination device of claim 1, wherein, Said at least one second collimating element (20) faces said second end portion (14).

10. The illumination device of claim 1, wherein, Said first collimating element (19) and said second collimating element (20) are configured to also at least partially determine the aesthetic appearance of the emission section (28) of said second light beam (9) on said front face (11) of said flat strip (10) constituting said light guide.

11. The illumination device of claim 1, wherein, Said lighting device is a headlight for a motor vehicle.

12. The illumination device of claim 1, wherein, Said first collimating element (19) is a concave lens or a convex lens.

13. A vehicle comprising a lighting device (1) according to claim 1.

14. The vehicle of claim 13, wherein, Said lighting device is a lamp.

15. The vehicle of claim 13, wherein, Said lighting device is a headlight.

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