Device for grazing lighting of a road infrastructure

Abstract

A device for grazing lighting of a road infrastructure is described, comprising at least one light source and at least one reflector. The light source emits a plurality of light rays. The reflector reflects at least a part of the light rays emitted by the light source and defines an opening through which the light rays emitted by the light source exit from the device. When the device is installed to illuminate a section of the road infrastructure, the light source is at least partially positioned above a plane substantially parallel to the road surface of the section of the road infrastructure and superiorly tangent to the opening of the reflector. Furthermore, the reflector is conformed to, when the device is installed to illuminate the section of the road infrastructure, reflect the at least a part of the light rays emitted by the light source towards the road surface of the section of the road infrastructure.

Description

[0001] DEVICE FOR GRAZING LIGHTING OF A ROAD INFRASTRUCTURE

[0002] Technical field

[0003] The present invention generally relates to the field of devices and systems for the lighting of road infrastructures intended for the circulation of vehicles, such as road sections, motorway sections or tunnels. In particular, the present invention relates to a device for grazing lighting of a road infrastructure.

[0004] Prior art

[0005] The lighting of a road infrastructure is one of the elements that contribute most to the safety of the vehicles travelling on the infrastructure, both during the night-time and the daytime hours, if the road infrastructure is a tunnel. Sufficient lighting (in terms of luminance and uniformity of luminance) does, in fact, allow drivers to have optimal visibility of both the road route and of any obstacles (other vehicles or objects) present on the road surface. This allows drivers promptly to perform the manoeuvres (braking, steering, slowing down, etc.) necessary to drive the vehicles without getting into accidents or hazardous situations.

[0006] A known system of road lighting comprises a plurality of lighting devices, which comprise respective light sources (for example, gasdischarge lamps or LEDs) and which are positioned at a height typically comprised between 8 m and 12 m from the road surface. In general, installation at this height is performed by fixing the lighting devices at the upper end of poles (typically in steel or another suitable material) provided at the edges of the road surface.

[0007] As an alternative, road lighting systems are known that are the so- called “grazing” type. The known grazing lighting systems provide for a plurality of lighting devices that comprise respective light sources (typically LEDs) and that are positioned at a height typically not higher than 150 cm (for example 80 cm) from the road surface. Installation at this height is generally performed by fixing the lighting devices to structures already present on the edges of the road infrastructure, such as Jersey barriers, guardrails or side walls of the tunnel. The positioning of the lighting devices at such limited heights has numerous advantages, including simpler and safer maintenance, a lower probability of forming dark zones, the creation of less atmospheric luminance in the case of rain or fog, a greater adaptability to certain particular conditions, such as extreme weather conditions or proximity of airports, and a reduced visual and environmental impact.

[0008] Summary of the invention

[0009] In grazing road lighting systems, the luminous flux of each grazing lighting device is emitted precisely by substantially grazing the road surface, i.e. it points downwards starting from an extremely low height (the installation height of the device itself). Therefore, if the light beam emitted by the grazing lighting device has components pointed upwards or in other directions not useful for lighting of the road surface (due, for example, to diffusion phenomena inside the device itself), these components could result in a risk of dazzling for the drivers of the vehicles in transit, since the grazing lighting device is positioned substantially at a height that is typically slightly lower than the one of the eyes of the drivers of the vehicles in transit.

[0010] An object of the present invention is to provide a device for grazing lighting of a road infrastructure that solves the aforesaid problem.

[0011] In particular, an object of the present invention is to provide a device for grazing lighting of a road infrastructure that, when installed at grazing height (i.e. at a height no greater than 150 cm from the road surface), has a particularly reduced risk of dazzling of the drivers of the vehicles in transit. According to embodiments of the present invention, this object is achieved by a device for grazing lighting of a road infrastructure that comprises at least one light source and at least one reflector; the at least one light source emits a plurality of light rays; the at least one reflector reflects at least a part of the plurality of rays emitted by the light source and defines an opening through which the plurality of light rays emitted by the light source exits the device; in operating conditions (i.e. when the device is installed at grazing height to light a section of the road infrastructure), the light source is at least partially positioned above a plane substantially parallel to the road surface of the road infrastructure section and superiorly tangent to the opening of the reflector; the reflector is also conformed to reflect, in operating conditions (i.e. when the device is installed at grazing height to light the road infrastructure section), at least a part of the plurality of light rays emitted by the at least one light source towards the road surface of the road infrastructure section.

[0012] The device for grazing lighting of a road infrastructure according to embodiments of the present invention, when installed at grazing height (i.e. at a height no greater than 150 cm from the road surface), advantageously has a particularly reduced risk of dazzling of the drivers of the vehicles in transit.

[0013] Since the light source is positioned at least partially above a horizontal plane superiorly tangent to the opening of the reflector, it is in an at least partially raised positioned with respect to the opening. Therefore, the light rays emitted by the portion of light source positioned above the horizontal plane along directions comprised within the angle having vertex in the light source and sides that join the source itself with the two lower and upper ends of the opening (also referred to hereinafter as the “direct emission angle on the transverse plane”, or also simply the “direct emission angle”), exit directly from the device through the opening defined by the reflector (i.e. without undergoing any reflection), pointing directly towards the road surface (i.e. downwards). The reflector therefore does not intervene in any way on the direction of these rays as emitted by the light source, since the latter is already such as to avoid upwards light emission and then, as a consequence, dazzling, thanks only to the position of the light source with respect to the opening.

[0014] The light rays emitted by the light source along directions outside the direct emission angle on the transverse plane are intercepted by the reflector and reflected one or more times before exiting the device. However, according to the present invention, the reflector is conformed also to reflect these rays towards the road surface (i.e. downwards).

[0015] The positioning of the light source with respect to the opening of the reflector and the shape of the reflector itself are therefore advantageously able to ensure that substantially all the rays emitted by the light source point towards the road surface (i.e. downwards) and therefore do not result in risks of dazzling and upwards emitted light.

[0016] It should be noted that this result may be obtained without using lenses or other refractive elements to correct the direction of the rays emitted by the light source, in particular without refractive elements interposed between the light source and the reflecting surface of the reflector. These refractive elements generally lead to diffusion phenomena, which could give rise to direct rays parallel to the road surface (i.e. in a substantially horizontal direction) or also upwards, with a consequent risk of dazzling for the drivers of the vehicles in transit. Avoiding these refractive elements therefore allows these diffusion phenomena to be avoided, and therefore the risk of dazzling for the drivers of the vehicles in transit substantially to be eliminated.

[0017] The possibility of avoiding refractive elements also makes the grazing lighting device particularly compact and also economical.

[0018] According to an aspect of the present invention, a device for graz- ing lighting of a road infrastructure is provided, comprising:

[0019] - at least one light source suitable for emitting a plurality of light rays; and

[0020] - at least one reflector suitable for reflecting at least a part of the plurality of light rays emitted by the at least one light source, said at least one reflector defining an opening through which said plurality of light rays emitted by the at least one light source exits the device, wherein, when the device is installed to illuminate a section of said road infrastructure, the at least one light source is at least partially positioned above a plane substantially parallel to a road surface of said section of said road infrastructure and superiorly tangent to the opening of the reflector; and wherein the reflector is conformed to, when the device is installed to illuminate said section of said road infrastructure, reflect said at least a part of the plurality of light rays emitted by the at least one light source towards the road surface of said section of the road infrastructure.

[0021] The shape of the reflector is preferably calculated by a software to which a plurality of requirements on the light beam emitted by the device are provided as constraints, said requirements comprising that said at least part of the plurality of light beams emitted by the at least one light source be directed towards the road surface of the road infrastructure section. Optionally, the plurality of requirements may also include one or more additional requirements defined by the lighting regulations applicable to the road infrastructure section.

[0022] According to an advantageous embodiment, when the device is installed to illuminate the section of said road infrastructure, the at least one light source is positioned entirely above the plane substantially parallel to the road surface of said section of said road infrastructure and superiorly tangent to the opening of the reflector. According to an advantageous embodiment, a portion (63) of the reflector located below said plane has a profile comprising at least one concave part.

[0023] Preferably, said at least a part of the light rays impinges on the reflector along respective incidence directions which coincide with respective emission directions of said at least a part of the light rays from the at least one light source.

[0024] According to some embodiments, the device comprises:

[0025] - a plurality of light sources arranged along a direction and capable of emitting a plurality of light rays; and

[0026] - a plurality of reflectors suitable for reflecting at least a part of said plurality of light rays emitted by the plurality of light sources.

[0027] Optionally, the plurality of reflectors is formed by a single reflecting surface.

[0028] For example, the plurality of light sources comprises two light sources, the plurality of reflectors comprises two reflectors, the two light sources are placed in symmetrical positions with respect to a plane substantially perpendicular to said direction, and the two reflectors are symmetrical with respect to said plane.

[0029] Optionally, a portion of each of the two reflectors adjacent to said plane has a profile comprising at least a concave part.

[0030] Preferably, the reflector has a reflecting surface with reflectance greater than 0.9.

[0031] Preferably, the reflector has a hole and at least one light source is positioned substantially in correspondence with the hole.

[0032] Brief description of the drawings

[0033] Features and advantages of the present invention will be clearer from the following detailed description, provided by way of nonlimiting example, to be read with reference to the appended drawings, in which:

[0034] - Figures 1 a and 1 b are respectively a perspective view of a device for grazing lighting according to an embodiment of the present invention, and a schematic side view of the device installed to light a road infrastructure section;

[0035] - Figure 2 is a cross-sectional view on a transverse plane of a lighting unit comprised in the device of Figure 1 , according to an embodiment of the present invention;

[0036] - Figures 3a, 3b and 3c show functioning of the reflector for rays having different directions on the transverse plane;

[0037] - Figure 4 is a cross-sectional view on a horizontal plane of a lighting unit comprised in the device of Figure 1 , according to a further embodiment of the present invention; and

[0038] - Figures 5a, 5b and 5c show functioning of the reflector of Figure 4 for rays having different directions on the horizontal plane.

[0039] The Figures are not to scale.

[0040] Detailed description of embodiments of the invention

[0041] Figures 1 a and 1 b show a device 100 for grazing light of a road infrastructure according to an embodiment of the present invention.

[0042] The device 100 preferably comprises an external casing 1. The external casing 1 preferably has a box shape comprising a front face 1 a, a rear face 1 b and two side faces 1 c, 1 d (the side face 1d is not visible in Figure 1 a, but is preferably symmetrical to the face 1c). The side faces 1 c, 1 d preferably have a trapezoidal shape with larger base turned towards the front face 1 a and smaller base turned towards the rear face 1 b. The rear face 1 b also extends along the sides of the trapezoid up until it joins with the front face 1 a. When the device 100 is installed, the casing 1 is positioned so that the front face 1 a of the casing 1 is directed towards the road infrastructure section to be illuminated. The front face 1 a may have a flat shape or be at least partially curved, as shown in Figure 1 a.

[0043] The casing 1 preferably has an elongated shape in a direction y parallel to the front face 1 a, so that the front face 1 a extends along direction y. When the device 100 is installed (for example as shown in Figure 1b), the casing 1 is positioned so that the direction y is substantially parallel to the road surface 200 of the road infrastructure section to be illuminated, and parallel to the direction along which the road infrastructure section to be illuminated extends. This is why direction y will also be called the “longitudinal direction” below in this description and in the claims. The longitudinal direction y is shown in Figure 1 a together with another two directions x and z (respectively parallel to the road surface 200 and perpendicular to it), together with which the longitudinal direction y forms a triplet of orthogonal directions. In the detailed description that follows, it is assumed that the road surface 200 is substantially horizontal, so the directions x and y are substantially horizontal, while the direction z is substantially vertical. The longitudinal direction y and the horizontal direction x identify a plane xy, which will also be referred to hereinafter as “horizontal plane”, whereas the horizontal direction x and the vertical direction z identify a plane xz perpendicular to the longitudinal direction y, which will also be referred to hereinafter as “transverse plane”. This is not limiting, since the road surface 200 could, for example, correspond with a sloping section of the road infrastructure. In this case, the triplet of orthogonal directions x, y and z is rigidly rotated so that the plane xy is maintained, in any case, substantially parallel to the road surface 200.

[0044] The casing 1 is preferably in metal, for example aluminium or stainless steel. The casing 1 preferably has dimensions, along each of the three directions x, y and z, respectively comprised between 5 cm and 10 cm, between 15 cm and 40 cm, and between 8 cm and 12 cm.

[0045] According to an advantageous embodiment, the casing 1 has a plurality of tabs 2 for dissipation of the heat produced by the compo- nents of the device 100 during their functioning. The tabs 2 are, for example, situated at upper portions of the front face 1a and the rear face 1 b of the casing 1 .

[0046] The device 100 further preferably comprises a fixing member (not shown in the drawings) configured to allow fixing of the device 100 to a support structure. The fixing member is preferably fixed to the rear face 1 b of the casing 1. It may, for example, comprise a threaded member, such as a screw or a bolt, suitable to engage a corresponding hole provided in the support structure. The support structure may be a structure dedicated to support of the device 100, or may be a surface of a structure that performs another function. For example, in the case in which the road infrastructure section to be illuminated is bordered by a Jersey barrier or by a guardrail, the device 100 may be fixed by means of the fixing member to a surface of the Jersey barrier or a section of the guardrail 300, as shown schematically in Figure 1b. If, on the other hand, the road infrastructure section to be illuminated is a section of tunnel, the device 100 may be fixed by means of the fixing member to a side wall of the tunnel.

[0047] In any case, the device 100 is preferably suitable for being positioned at a height H with respect to the road surface 200 of the road infrastructure section to be illuminated. The height H is measured along the vertical direction z. The height H is preferably not greater than 150 cm, more preferably is comprised between 50 cm and 120 cm, for example it is around 80 cm.

[0048] The fixing member is preferably also suitable for allowing, after the device 100 has been fixed to the support structure, the orientation of the device 100 to be adjusted (for example manually) around at least one of the three directions x, y and z, for example around the longitudinal direction y (i.e. on the transverse plane xz), as indicated schematically by arrow A on Figure 1 b.

[0049] The device 100 also comprises a lighting unit configured to pro- duce a light beam apt to illuminate a road infrastructure section, when the device 100 is installed at grazing height, i.e. at the height H in the range described above.

[0050] With reference to Figure 2, the lighting unit (indicated with reference number 4) preferably comprises a light source 5 and a reflector 6. The light source 5 may, for example, comprise one or more LEDs, in particular one or more white-light LEDs. The luminous intensity of the source 5 is preferably adjustable, for example by adjusting the power supply current of the light source 5 (in particular, by varying the intensity and / or waveform of the power supply current).

[0051] The reflector 6 is conformed so as to reflect at least part of the rays emitted by the light source 5.

[0052] More in particular, the reflector 6 has a reflecting surface that encloses a space 60, which is in communication with the exterior of the reflector 6 through an opening 61. The opening 61 is closed by an optically transparent window 7, i.e. such as to allow the passage of the light radiation emitted by the light source 5 towards the exterior of the lighting unit 4 and, therefore, towards the exterior of the device 100.

[0053] The window 7 can, for example, be in glass, or in a plastic material. The window 7 has a substantially constant thickness. The thickness of the window 7 is preferably comprised between 2 mm and 6 mm. The material and the thickness of the window 7 are preferably chosen so as to give the window 7 suitable mechanical properties, for example in terms of resistance to impacts and / or abrasion due to atmospheric dust and / or the action of periodic cleaning devices of the outer surface of the window 7.

[0054] Optionally, the outer surface of the window 7 may be treated so as to minimize abrasion and / or yellowing and / or clouding and / or fouling phenomena that can occur over time and that can compromise the performance of the device 100. For example, the outer surface of the window 7 may be treated with TiC>2 (titanium dioxide). Advantageously, when the window 7 is subjected to ultraviolet light (for example, the ultraviolet component of sunlight, or the ultraviolet light emitted by a UV lamp intentionally brought close to the device 100 to perform a cleaning operation), this triggers a photocatalytic oxidation reaction of any organic or inorganic compounds present on the outer surface of the window 7. Titanium dioxide advantageously acts as a photocatalyst or photo-promoter of this reaction, i.e. it facilitates the reaction without changing its own structure or its own state.

[0055] The window 7 is preferably positioned at the front face 1 a of the casing 1. For this purpose, a dedicated opening may be provided in the casing 1 , inside which the window 7 is inserted. In order to seal the casing 1 and protect it against infiltrations of water, humidity, dust, etc., the edges of the window 7 may be fixed sealed to corresponding edges of the opening in the casing 1 , for example by means of gluing and / or by means of a gasket (not shown on the drawings).

[0056] The reflecting surface of the reflector 6 (i.e. the inner surface of the reflector 6, turned towards the space 60) preferably has a reflectance greater than 0.9 (90%). The reflecting surface of the reflector 6 also preferably has a surface processing treatment suitable for minimizing the presence of diffuse radiation in non-specular directions, not useful for purposes of illuminating the road surface 200. The Applicant has indeed observed that, as the reflectance of the reflecting surface of the reflector 6 increases, there is advantageously an increase in the light output ratio of the grazing lighting device 100, i.e. the ratio between the luminous flux emitted by the grazing lighting device 100 and the luminous flux emitted by the source 5. In any case, a processing treatment of said reflecting surface reduces the intensity of the non-specular diffusion phenomenon to which the rays emitted by the light source 5 and striking the reflecting surface of the reflector 6 are subject. In order to obtain the reflectance values indicated here above, for example, the reflecting surface may be made of aluminium, sheet metal or glass. Optionally, in order further to increase the reflectance and reduce the diffusion, the inner surface of the reflecting surface of the reflector 6 (or at least part of it) may be processed with treatments that reduce its surface roughness, such as lapping, polishing, metallisation or sputtering.

[0057] Figure 2 shows a plane P that, when the device 100 is in operating conditions (i.e. it is installed at grazing height and oriented to illuminate the road infrastructure), is substantially parallel to the road surface 200 and superiorly tangent to the opening 61 of the reflector 6. Since, by way of non-limiting example, it has been assumed that the road surface 200 is substantially horizontal, the plane P is also substantially horizontal. Therefore, in the detailed description that follows, it will also be called “horizontal plane P”.

[0058] The plane P preferably divides the reflector 6 into two portions, i.e. an upper portion 62 and a lower portion 63. The two portions 62 and 63 are therefore reciprocally adjacent at the plane P.

[0059] The light source 5 is at least partially positioned above the horizontal plane P, i.e. at the upper portion 62 of the reflector 6. According to advantageous embodiments, the light source 5 is entirely positioned above the horizontal plane P. For example, as shown in Figure 2, the upper portion 62 of the reflector 6 may have a hole 66, at which the light source 5 is positioned. The light source 5 need not necessarily be positioned flush with the reflecting surface of the reflector 6; the light source 5 may, in fact, be situated in a different position, provided that it is at least partially above the horizontal plane P that delimits below the upper portion 62 of the reflector 6. For example, the light source 5 may be positioned in the portion of space 60 enclosed between the plane P and the upper portion 62 of the reflector 6. As an alternative, the light source 5 may be positioned at least partially at the upper portion 62 of the reflector 6, but outside the space 60, for example at the hole 66, but in a position outside the space 60.

[0060] The device 100, when installed at grazing height H with the front face 1 a provided with the window 7 turned towards the road infrastructure section to be illuminated, advantageously has a particularly reduced risk of dazzling of the drivers of the vehicles in transit.

[0061] Since the light source 5 is at least partially positioned above the horizontal plane P superiorly tangent to the opening 61 , it is in an at least partially raised position with respect to the opening 61. Therefore, as shown in Figure 3a (which shows the advantageous case in which the light source 5 is entirely positioned above the horizontal plane P), the light rays R1 , R2 emitted by the light source 5 along directions comprised within an angle a having vertex in the light source 5 and sides that join the source 5 itself respectively with the lower end 65 and the upper end 66 of the opening 61 (also referred to hereinafter as the “direct emission angle on the transverse plane”), exit from the device 100 through the opening 61 without undergoing any reflection, pointing directly towards the road surface 200 (i.e. downwards). The reflector 6 therefore does not intervene in any way on the direction of these rays R1 and R2, which is already such as to avoid dazzling, due only to the raised position of the light source 5 with respect to the opening 61 .

[0062] As to the light rays emitted by the light source 5 along directions outside the direct emission angle a on the transverse plane, these are intercepted by the reflector 6 and reflected one or more times.

[0063] Preferably, the shape of the reflector 6, together with the precise position of the light source 5 at least partially above the horizontal plane P, is determined so that the reflected rays also exit from the device 100 through the opening 61 , pointing towards the road surface 200 (i.e. downwards). For this purpose, the reflector 6 may comprise one or more convex parts and / or one or more concave parts, where “convex part” means that, taking any pair of points of that part of the reflector 6, the segment that joins the two points of the pair is entirely contained in the space 60; where “concave part” means, on the other hand, a part of the reflector 6 that does not have said property that defines the convex part. Furthermore, the upper portion 62 and the lower portion 63 of the reflector 6 preferably have different shapes, i.e. different combinations of at least one convex part and / or at least one concave part.

[0064] The shape of the reflector 6 can, for example, be calculated by an optical simulation software, which is provided, as constraints, with one or more requirements that the light beam emitted by the lighting unit 4 must satisfy. Said one or more requirements comprise the fact that the rays intercepted by the reflector 6 and reflected one or more times are emitted pointing towards the road surface 200 (i.e. downwards). Optionally, other constraints may also be provided (for example, on the progress of division of the light intensity of the light beam in longitudinal direction y and for angles measured on the plane xz, as will be described in greater detail below), depending on the regulations on lighting applicable to the road infrastructure section to be illuminated.

[0065] By way of non-limiting example, such constraints may, for example, be one or more of the requirements defined in CIE 115:2010, second edition, “Lighting of roads for motor and pedestrian traffic,” ISBN 978 3 901906 86 2, p. 11 , Table 2, namely: luminance requirements, luminance uniformity requirements, and glare requirements toward the driver of the vehicle passing along the road infrastructure. The requirements on these parameters typically vary as the lighting category changes, which in turn is determined by the traffic conditions along the roadway infrastructure and its classification. In order to meet the requirements for luminance, luminance uniformi- ty and glare, the luminous intensity of the light beam emitted by the lighting unit 4 and incident on a given point on the road surface 200 must be such that the fraction of light reflected from the road surface 200 back to the driver is contained within a defined range of variability, which also depends on the reflecting features of the road surface 200. Shape and size of the range of variability can be used as constraints for calculating the shape of the reflector 6.

[0066] By way of non-limiting example, the reflector 6 may have the shape shown in Figure 2. In particular, Figure 2 shows the section of the reflector 6 on a plane parallel to the transverse plane xz (and therefore also transverse) and passing through the light source 5. On this transverse plane, the upper portion 62 of the reflector 6 has a convex profile; the lower portion 63 of the reflector 6, on the other hand, has a profile comprising both a convex part and a concave part. In particular, a part 64 of the lower portion 63 of the reflector 6 adjacent to the lower end 65 of the opening 61 preferably has a concave profile.

[0067] As shown in Figure 3b, the rays R3 directed towards the upper portion 62 of the reflector 6 are reflected once before exiting from the device 100 towards the opening 61. Also the rays R4 directed towards the convex part of the lower portion 63 of the reflector 6 are reflected before exiting from the device 100 through the opening 61. In any case, both the rays R3 (i.e. those emitted by the source 5 upwards and that do not exit directly from the opening 61 ) and the rays R4 (i.e. those emitted by the source 5 downwards and that do not exit directly from the opening 61 ) exit from the device 100 through the opening 61 pointing towards the road surface 200 (i.e. downwards).

[0068] Lastly, as shown in Figure 3c, some rays R5 emitted by the light source 5 along directions outside the direct emission angle a on the transverse plane can be directed towards the concave part 64 of the lower portion 63 of the reflector 6. These rays R5 are reflected a first time towards the upper portion 62 of the reflector 6, and from there they can undergo other reflections before exiting from the device 100 through the opening 61 . In any case, the rays R5 also exit from the device 100 through the opening 61 pointing towards the road surface 200 (i.e. downwards).

[0069] The shape of the reflector 6 and the positioning of the light source 5 with respect to it are therefore advantageously able to ensure that substantially all the rays emitted by the light source 5 (or all the rays emitted by the light source 5, according to the advantageous embodiment shown in the Figures, in which the light source 5 is entirely positioned above the horizontal plane P) point towards the road surface 200 (i.e. downwards, so that the rays R1-R5 are completely below the plane P from the point at which they exit from the opening 61 as far as the road surface 200), and therefore do not result in any risks of dazzling.

[0070] In principle, in order to avoid risks of dazzling, it is sufficient that substantially all the rays emitted by the device 100 are directed downwards along directions that form with the horizontal plane P any non-zero angle. In particular operating conditions (for example, if the road infrastructure to be illuminated is sloping, or has a bend, etc.), it is nonetheless preferable that substantially all the rays emitted by the device 100 are directed downwards along directions that form with the horizontal plane P an angle greater than a certain, predefined minimum angle, the amplitude of which depends on the specific operating conditions.

[0071] It should be noted that this result can be obtained without using lenses or other refractive elements to correct the direction of the rays emitted by the light source 5, in particular without refractive elements interposed between the light source 5 and the reflecting surface of the reflector 6. These refractive elements generally lead to diffusion phenomena, which could give rise to direct rays upwards, with a con- sequent risk of dazzling for the drivers of the vehicles in transit. Avoiding these refractive elements therefore allows diffusion phenomena to be minimized, and therefore the risk of dazzling for the drivers of the vehicles in transit substantially to be eliminated.

[0072] The possibility of avoiding refractive elements also makes the device 100 particularly compact and also economical.

[0073] Although avoiding refractive elements is possible and advantageous, optionally, according to embodiments not shown in the drawings, the window 7 can be configured to induce a refraction on at least part of the rays emitted by the light source 5. For example, the window 7 could have a portion with a curved inner surface and / or outer surface (for example, concave or convex). The curvature basically forms a lens that, if crossed by a ray, alters its direction as a result of the refraction. According to a variant, the refraction may be obtained by varying the refractive index of the material of which the window 7 is made.

[0074] The device 100 can comprise multiple light sources and / or reflectors arranged along the longitudinal direction y, in order to provide a lighting with substantially constant intensity or variable in a desired manner along the longitudinal direction y.

[0075] For example, the device 100 may comprise multiple separate lighting units, arranged in the casing 1 and aligned along the longitudinal direction y. Each lighting unit may comprise a respective light source and a respective reflector. The reflectors of the different lighting units can be closed by separate windows, or by a single window of elongated shape in the longitudinal direction y that covers all their openings.

[0076] According to other embodiments, the reflectors of the lighting units can be reciprocally integrated, for example by shaping a single reflecting surface in a manner that it forms two or more reflectors.

[0077] For example, Figure 4 shows a lighting unit 4’ comprising two light sources 51 , 52 and two reciprocally integrated reflectors 62’, 63’, according to a non-limiting embodiment of the present invention.

[0078] Each light source 51 , 52 may, for example, comprise one or more LEDs, in particular one or more white-light LEDs. The reciprocally integrated reflectors 62’, 63’ are conformed so as to reflect at least part of the rays emitted by the light sources 51 , 52. More in particular, the reflecting surface that forms the reciprocally integrated reflectors 62’, 63’ encloses an inner space 60’, which is in communication with the outside through a single opening 6T common to the two reflectors 62’, 63’ and closed by the optically transparent window 7 described above.

[0079] The shape of the section of each of the reflectors 62’, 63’ on the respective planes substantially parallel to the transverse plane xz (and therefore also transverse themselves) and passing through the sources 51 , 52 is preferably calculated by applying a procedure similar to the one described above with reference to the reflector 6 shown in Figure 2. The detailed description of the section of each of the reflectors 62’, 63’ on these transverse planes will therefore not be repeated.

[0080] Furthermore, the two reflectors 62’, 63’ are preferably symmetrical with respect to the plane P’, substantially parallel to the transverse plane xz (and therefore also transverse itself) and passing through the median position of the window 7 along the longitudinal direction y. Hereinafter, the reflectors 62’, 63’ will also be referred to respectively as the left reflector and the right reflector.

[0081] Figure 4 also shows two further planes PT and P2’, also substantially parallel to the transverse plane xz (and therefore also transverse themselves) and tangential to the opening 6T at its two opposite ends. Each plane PT, P2’ preferably divides a respective reflector 62’, 63’ into two portions, i.e. an outer portion 621 , 631 and an inner portion 622, 632. The outer portion 621 , 631 and the inner por- tion 622, 632 are therefore reciprocally adjacent at the transverse plane P1 P2’.

[0082] Preferably, each light source 51 , 52 is at least partially positioned externally to a respective transverse plane P1 ’, P2’, i.e. at the outer portion 621 , 631 of a respective reflector 62’, 63’. According to advantageous embodiments, each light source 51 , 52 is entirely positioned externally to the respective transverse plane P1 ’, P2’. For example, as shown in Figure 4, the outer portion 621 , 631 of each reflector 62’, 63’ may have a respective hole 662, 663 at which the light source 51 , 52 is positioned. Each light source 51 , 52 need not necessarily be positioned flush with the reflecting surface of the respective reflector 62’, 63’; each light source 51 , 52 may indeed be situated in a different position, provided that it is at least partially outside the plane P1 ’, P2’ that delimits the outer portion 621 , 631 of each reflector 62’, 63’. For example, each light source 51 , 52 may be positioned in the portion of space 60’ enclosed between the plane P1 ’, P2’ and the outer portion 621 , 631 of each reflector 62’, 63’. As an alternative, each light source 51 , 52 may be positioned at least partially at the outer portion 621 , 631 of the respective reflector 62’, 63’, but outside the space 60’, for example at the hole 662, 663, but in a position outside the space 60’. In any case, the light sources 51 , 52 are preferably situated in symmetrical positions with respect to the transverse plane P’.

[0083] Each reflector 62’, 63’ may comprise one or more convex portions and / or one or more concave portions. The shape of each reflector 62’, 63’, together with the precise position of the respective light source 51 , 52 at least partially outside the respective plane PT, P2’ can, for example, be calculated by an optical simulation software, which is provided, as constraints, with one or more requirements that the light beam emitted by the lighting unit 4’ must satisfy. Such one or more requirements comprise, for example, the fact that the light beam emitted by the lighting unit 4’ has division of the light intensity with a desired trend (constant or variable) in longitudinal direction y and for different angles measured on the transverse plane xz, depending on the regulations on lighting applicable to the road infrastructure section to be illuminated.

[0084] By way of non-limiting example, each reflector 62’, 63’ may have the shape shown in Figure 4. In particular, in the non-limiting embodiment shown in Figure 4, the outer portion 621 , 631 of each reflector 62’, 63’ has a convex profile; on the other hand, the inner portion 622, 632 of each reflector 62’, 63’ has a profile comprising both a convex part and a concave part. In particular, a part of the inner portion 622, 632 of each reflector 62’, 63’ adjacent to the transverse plane P’ preferably has a concave profile. The concave profile parts of the two inner portions 622, 632 therefore join together at the transverse plane P’, thus forming a single concavity.

[0085] Advantageously, the symmetrical shape of the reflectors 62’, 63’ and the symmetrical positioning of the light sources 51 , 52 with respect to the transverse plane P’ allow a lighting with division of the light intensity that is substantially constant or variable in the desired manner along the longitudinal direction y to be provided.

[0086] As shown in Figure 5a, indeed, the light rays R1 ’ emitted by the light source 51 along directions comprised within an angle 0 having vertex in the light source 51 and sides that join the source 51 itself respectively with the left end 67’ and the right end 68’ of the opening 6T (also referred to hereinafter as the “direct emission angle on the horizontal plane”), exit from the device 100 through the opening 6T without undergoing any reflection, pointing directly towards the right. Functioning of the light source 52 is symmetrical with respect to the transverse plane P’, so it will directly emit rays that point to the left with a direction symmetrical to the one of the rays R1 ’ with respect to the transverse plane P’. As to the light rays emitted by the light source 51 along directions outside the direct emission angle 0 on the horizontal plane, these are intercepted by the reflector 6 and reflected one or more times.

[0087] In particular, as shown in Figure 5b, the rays R2’, R3’ emitted by the light source 51 and directed towards the left reflector 62’ are reflected once by the latter, before exiting from the device 100 through the opening 61 ’ pointing to the right. Functioning of the light source 52 (not shown in Figure 5b) is symmetrical with respect to the transverse plane P’, so it emits rays directed towards the right reflector 63’, which are reflected once before exiting from the device 100 through the opening 61 ’ pointing to the left with a symmetrical direction to the one of the rays R2’, R3’ with respect to the transverse plane P’.

[0088] Lastly, as shown in Figure 5c, the rays R4’ emitted by the light source 51 and directed towards the right reflector 63’ are reflected once by the latter, before exiting from the device 100 through the opening 61 ’ pointing to the left. Functioning of the light source 52 (not shown in Figure 5c) is symmetrical with respect to the transverse plane P’, so it emits rays directed towards the left reflector 62’, which are reflected once before exiting from the device 100 through the opening 61 ’ pointing to the right with a symmetrical direction to the one of the rays R4’ with respect to the transverse plane P’.

[0089] Assuming that the device 100 is installed on the right-hand side of the road infrastructure section to be illuminated, direct rays propagating to the left looking frontally at the device 100 (i.e., moving away from the driver of a vehicle traveling along the road infrastructure section) are thus directed in favor of the flow of vehicles passing along the road infrastructure section (and thus provide lighting called “pro-flow” in the following), while direct rays that propagate to the right looking frontally at the device 100 (i.e., approaching the driver of a vehicle traveling along the road infrastructure section) are therefore directed against the flow of vehicles passing along the road infrastructure section (and thus provide lighting called in the following “counter flow”).

[0090] If, therefore, the two light sources 51 , 53 emit with the same light intensity, the symmetry of the reflector 6’ and of the arrangement of the sources 51 , 52 with respect to the plane P’ allows providing of a pro flow lighting and a counter flow lighting that are substantially balanced, i.e. a lighting with division of the light intensity that is substantially symmetrical along the longitudinal direction y.

[0091] However, in certain situations it may be necessary to provide lighting with an intensity having a variable trend along the longitudinal direction y. For example, it may be necessary to provide a pro flow lighting with a higher intensity than the intensity of the counter flow lighting. In this case, it is possible to obtain this result by increasing the light intensity of the source 51 and / or by altering the shape of the reflector 6’, making it asymmetrical with respect to the transverse plane P’, so that most of the rays emitted by both light sources 51 and 52 are directed towards the left looking frontally to the device 100.

[0092] By similar but symmetrical reasoning, counter flow lighting of higher intensity than pro-flow lighting intensity can be achieved.

Claims

CLAIMS1. Device (100) for grazing lighting of a road infrastructure, comprising: at least one light source (5; 51 , 52) suitable for emitting a plurality of light rays (R1 -R5); and at least one reflector (6; 62', 63') suitable for reflecting at least a part (R3-R5) of the plurality of light rays (R1 -R5) emitted by the at least one light source (5; 51 , 52), said at least one reflector (6; 62', 63') defining an opening (61 ; 61 ') through which said plurality of light rays (R1 -R5) emitted by the at least one light source (5; 51 , 52) exits the device (100), wherein, when the device (100) is installed to illuminate a section of said road infrastructure, the at least one light source (5; 51 , 52) is at least partially positioned above a plane (P) substantially parallel to a road surface (200) of said section of said road infrastructure and superiorly tangent the aperture (61 ; 61 ') of the reflector (6; 62', 63'); and wherein the reflector (6) is conformed to, when the device (100) is installed to illuminate said section of said road infrastructure, reflect said at least a part (R3-R5) of the plurality of light rays (R1 -R5) emitted by the at least one light source (5; 51 , 52) towards the road surface (200) of said section of the road infrastructure.

2. Device (100) according to claim 1 wherein, when the device (100) is installed to illuminate said section of said road infrastructure, the at least one light source (5; 51 , 52) is positioned entirely above the plane (P) substantially parallel to a road surface (200) of said section of said road infrastructure and superiorly tangent the aperture (61 ; 61 ') of the reflector (6; 62', 63').

3. Device (100) according to claim 1 or 2, wherein a portion (63) of the reflector (6, 62', 63') located below said plane (P) has a pro-file comprising at least one concave part.

4. Device (100) according to any of the preceding claims, wherein said at least a part of the light rays (R3-R5) impinges on said reflector (6; 62', 63') along respective directions of incidence which coincide with respective directions of emission of said at least a part of the light rays (R3-R5) from the at least one light source (5; 51 , 52).

5. Device (100) according to any one of the preceding claims, comprising:- a plurality of light sources (51 , 52) arranged along a direction (y) and capable of emitting a plurality of light rays (R1 '- R4'); and- a plurality of reflectors (62', 63') suitable for reflecting at least a part of said plurality of light rays (R1'-R4') emitted by the plurality of light sources (51 , 52).

6. Device (100) according to claim 5, wherein the plurality of reflectors (62', 63') is formed by a single reflecting surface.

7. Device (100) according to claim 5 or 6, wherein the plurality of light sources (51 , 52) comprises two light sources and the plurality of reflectors (62', 63') comprises two reflectors, wherein the two light sources are placed in symmetrical positions with respect to a plane (P') substantially perpendicular to said direction (y) and wherein the two reflectors (62', 63') are symmetrical with respect to said plane (P').

8. Device (100) according to claim 7, wherein a portion (622, 632) of each of the two reflectors (62', 63') adjacent to said plane (P') has a profile comprising at least one concave part.

9. Device (100) according to any of the preceding claims, wherein the reflector (6, 6') has a reflecting surface with reflectance greater than 0.9.

10. Device (100) according to any of the preceding claims, whereinthe reflector (6; 62', 63') has a hole (66, 662, 663) and wherein the at least one light source (5; 51 , 52) is positioned substantially in correspondence with the hole (66; 662, 663).

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