Light assembly comprising a side emitting light element

Abstract

An assembly comprising a substrate, light element disposed on the substrate, and optical element extending over the light element, wherein the light element is configured to emit light away from the substrate and to emit light sideways, preferably substantially parallel to the substrate, in an area extending between the substrate and plane parallel to the substrate and at distance of the substrate at same side as the light element, said distance being smaller than 1000 micrometer; wherein optical element is provided with at least one surface configured to reflect light rays, said at least one surface being inclined with respect to substrate and extending away from light element at least until said plane, said at least one surface being oriented so that the sideways light rays are reflected away from the substrate at angle (∂) of at least 30°, preferably at least 45°, with respect to plane parallel to substrate.

Description

[0001] LIGHT ASSEMBLY COMPRISING A SIDE EMITTING LIGHT ELEMENT

[0002] FIELD OF INVENTION

[0003] The field of the invention relates to a light assembly comprising a light element, and more particularly a side emitting light emitting diode. The field of the invention also relates to systems comprising such an assembly, to an optical element for use in such an assembly, to an optical plate for use in such a system and to methods for manufacturing an optical element or an optical plate.

[0004] BACKGROUND

[0005] Light sources, such as light emitting diodes (LEDs) with associated optical elements, such as lenses, comprised in standard light emitting devices may emit light at large angles, typically at angles of more than 80°. In the designs of conventional light emitting devices, such as LED devices, the light rays generated by the light source may have large angles, and in some cases light rays extend horizontally or even below the horizontal. The light emitted at such large angles may result in undesired glare, that would cause discomfort for the user, and / or would simply be lost because the light is not emitted in the direction of interest.

[0006] An example of a light source emitting light at large angles is a side-emitting LED. Because they do not comprise primary optics, side-emitting LEDs are thinner and cheaper than conventional LEDs and require less power to operate. However, they emit a significant amount of light sideways, i.e. at large angles. Appropriate optics are needed to manage the light output of such LEDs and limit the amount of light that would be lost in undesired directions, therefore increasing the efficiency of the light emitting device.

[0007] Often, light emitting devices, in particular outdoor luminaires, must comply with different glare classifications, usually abbreviated G or G* classifications. The G classification is defined in the CIE115:2010 standard, whereas the G* classification is defined by the EN 13201-2 standard. Such classifications are based on the maximal allowed ratio between the light intensity and the light flux at large angles below the horizontal, such ratio being generally expressed in cd / klm. The lowest G / G* classification, or Gl / G*l class, corresponds to the glariest situation for the user, causing the highest discomfort, whereas the highest G / G* classification, or G6 / G*6 class, corresponds to the most comfortable situation for the user. In prior art assemblies, in order to adapt the G / G* classification of a light emitting device, often different types of optical elements are required, each given type corresponding to a given G / G* classification. Finally, for each type of optical elements corresponding to each G / G* classification, additional categories of optical elements may be required depending on the road type, e.g. depending on the width of a road (residential road, traffic route, highway, pedestrian path, etc.), or depending on its location (inside a city, in the countryside, etc.). This has the effect of increasing the amount of different optical elements to be manufactured in order to answer every need from the customers. This solution may involve high development, manufacturing, and maintenance costs.

[0008] SUMMARY

[0009] The object of embodiments of the invention is to provide a light assembly allowing reducing the amount of light lost in undesired directions and hence increasing the efficiency, whilst keeping the number of components limited, and in particular to provide an assembly with a side emitting LED with a reduced amount of light at large angles.

[0010] According to a first aspect, there is provided an assembly comprising a substrate, a light element disposed on the substrate, and an optical element extending over the light element. The light element is configured to emit light away from the substrate and to emit light sideways, preferably substantially parallel to the substrate, in an area extending between the substrate and a plane parallel to the substrate, on the same side as the light element. The plane is located at a distance of the substrate, said distance being smaller than 1000 micrometer. The optical element is provided with at least one surface configured to reflect light rays. The at least one surface is inclined with respect to the substrate, and extends away from the light element at least until said plane. The at least one surface is oriented so that the sideways light rays are reflected away from the substrate at an angle 8 of at least 30°, preferably at least 45°, with respect to a plane parallel to the substrate.

[0011] An inventive insight underlying embodiments of the invention is that, by using at least one surface configured to reflect the sideways light rays away from the substrate, the directivity of the light output emitted by the assembly is improved, and the amount of light emitted in undesired directions is limited. Because the optical element is provided with the at least one surface, the cost of the assembly is cheaper than for an assembly where the optical element and the at least one surface are separate components.

[0012] Preferably, this angle 8 is smaller than 90°, more preferably smaller than 85°, even more preferably smaller than 80° with respect to a plane parallel to the surface. In this way, the light rays travel through the optical element, and preferably such that the light rays which exit the optical element travel towards a central axis of the lens element perpendicular on the support.

[0013] According to an embodiment, the at least one surface is a peripheral surface surrounding the light element.

[0014] This has the advantage that a larger portion of the light emitted sideways, is reflected, particularly when the light element emits sideways rays in a wide range of azimuthal directions, for example if the light element corresponds to a side-emitting LED that has a cylindrical or prism shape.

[0015] According to an embodiment the at least one surface is oriented at an angle y larger than 90°, measured from a plane parallel to the substrate and away from the light element, preferably larger than 95°, more preferably larger than 100°, e.g. larger than 105° or even larger than 110°. Preferably, the angle y is smaller than 175°, more preferably smaller than 165°, even more preferably smaller than 155°.

[0016] In that manner, the sideways emitted light rays are reflected away from the substrate. In the case where the at least one surface is not a flat surface, the at least one surface is oriented such that the angle created by each portion of said at least one surface and the substrate is larger than 90°, preferably larger than 95°, more preferably larger than 100°, e.g. larger than 105° or even larger than 110°.

[0017] The at least one surface may have a height and / or curvature and / or inclination (angle y) which varies between two points of the at least one surface, e.g. depending on the position with respect to the light element. In other words, the at least one surface is not limited to flat surfaces.

[0018] According to an embodiment, the optical element is a transparent body having a first side facing the substrate and a second side opposite said first side. The first side has a first flat face disposed on the substrate and a light incident surface that delimits a cavity surrounding the light element. Typically, the cavity is larger than the light element, but the cavity may also match the shape of the light element. Preferably, the second side has a second flat face parallel to the first flat face. Preferably, the second side has a light exit surface protruding outward of the second flat face and extending over the light incident surface. The light exit surface may be a convex surface, preferably a convex surface having a longest dimension which is longer than a shortest dimension thereof. The convex surface may be a substantially dome shaped surface, such as a substantially oval dome shaped surface. In that manner, the sideways light rays propagate within the cavity until reaching the light incident surface wherein the sideways light rays are refracted in the transparent body in the direction of the at least one surface. The refracted light rays are reflected by the at least one surface before exiting the optical element, preferably through the light exit surface. Preferably, the reflected light rays are directly refracted through the light exit surface, i.e. without further reflections, but in some cases the reflected light rays could be subject to a further reflection before being refracted through the light exit surface.

[0019] Preferably, the optical element comprises one or more lens elements. More preferably, the optical element is a lens element.

[0020] Preferably, when the assembly is used in a streetlight, the light exit surface has a longest dimension parallel to the driving direction and a shortest dimension perpendicular to the driving direction.

[0021] According to an embodiment the transparent body is formed with at least one recess in the first side, preferably in the first flat face, and at least one wall of the at least one recess forms the at least one surface.

[0022] Light rays emitted sideways from the light element and reaching said at least one wall of the at least one recess may be reflected through total internal reflection or any other reflection mechanism at the interface between the material of the optical element and the medium present in the recess, preferably air. By carefully choosing the shape of the recess and hence the orientation of the surface formed by the wall of the recess, the internally and totally reflected rays can be redirected towards the second side, and preferably toward the light exit surface of the optical element, e.g. a dome shaped surface of the optical element, hence increasing the amount of light emitted in a desired direction. The at least one recess may be covered with white painting or with painting of a different color, or with a reflective coating. A surface roughness of the at least one recess may correspond to any one of a coarse surface finish, a polished surface finish, or a combination thereof.

[0023] According to an embodiment the at least one recess comprises a recess surrounding the cavity.

[0024] If the light element is a side -emitting LED that has a cylindric shape or a prismatic shape, the light element emits sideways rays in a wide range of azimuthal directions. Having a recess that surrounds the cavity allows to reflect a significant amount of the light emitted in the sideways volume away from the substrate. According to an embodiment, the at least one recess comprises two first recesses arranged on opposite sides of the cavity, and optionally two second recesses arranged on opposite sides of the cavity and extending substantially perpendicular to the two first recesses. Preferably, when the assembly is used in a streetlight, the two first recesses extend in a direction perpendicular to a driving direction of the road.

[0025] For example, if the light element is a side-emitting LED that has a rectangular cuboid shape, defined by a height, a length and a width, most of the light emitted sideways, typically emitted with a Gaussian profile, will be emitted in the four sideways volumes defined by extruding the side faces of the cuboid in the direction of the edges of the rectangular base of the light element. By arranging four respective recesses in said four respective volumes, most of the light emitted in the sideways volumes can thus be reflected away from the substrate.

[0026] According to an embodiment the at least one recess has a height which is smaller than a distance between the first and second flat face.

[0027] Preferably, the height of the at least one recess is between 100 micron and 1000 micron, preferably between 200 micron and 500 micron. Preferably, the height of the at least one recess is larger than a height of the light element.

[0028] Such heights will typically allow to reflect a large portion of the sideways light rays whilst not disturbing other light rays that should not be reflected.

[0029] Preferably, the distance between the first and second flat face is between 1000 micron and 3000 micron, preferably between 1500 micron and 2500 micron.

[0030] Preferably, the at least one surface is oriented so that the sideways light rays are reflected and run through the optical element, adjacent of the cavity, preferably exiting the optical element through the light exit surface, e.g. the dome shaped surface.

[0031] Preferably, a distance between the incident light surface and the at least one surface is smaller than 2000 micron, preferably smaller than 1000 micron. Typically, this distance will be larger than 100 micron but the distance may also be zero.

[0032] In this way the distance travelled by the sideways light rays can be kept limited. According to an exemplary embodiment a material of the optical element comprises an optical grade polymer material, such as PMMA, PC or silicon, or a glass material. Preferably the material is moldable, e.g. injection moldable, and / or suitable for manufacturing the optical element by 3D printing. The at least one surface of the optical element is optionally covered with reflective painting or with a reflective coating.

[0033] According to an embodiment the light element comprises a side-emitting light emitting diode (LED).

[0034] LEDs have numerous advantages such as long service life, small volume, high shock resistance, low heat output, and low power consumption. Further, side-emitting LEDs are thinner and cheaper than conventional LEDs and require less power to operate because they do not comprise primary optics.

[0035] According to a second aspect, there is provided a system comprising an assembly according to any of the embodiments described above, wherein the light element is part of an array of light elements arranged on the substrate. The optical element may be part of an optical plate extending over the array of light elements. It is noted that the array of light elements may comprise the same or different light elements. For example, side emitting LEDs without primary optic may be combined with standard LEDs with primary optic. It is noted that the optical plate may be integrally molded or may be a frame in which an array of optical elements is fixed. The optical elements may be the same or different. Alternatively, an array of distinct optical elements may be arranged over the array of light elements on the substrate.

[0036] Preferably, the array of light elements is a two-dimensional array of light elements, and the optical element is part of an array of optical elements aligned to form a two-dimensional array associated with the two-dimensional array of light elements. It is noted that the array of optical elements may comprise the same or different optical elements. For example, one or more optical elements as described above may be combined with other optical elements.

[0037] In an embodiment, two or more optical element of the array of optical elements are provided with at least one surface configured to reflect light rays, said at least one surface being inclined with respect to the substrate and extending away from the light element at least until said plane (P), said at least one surface being oriented so that the sideways light rays are reflected away from the substrate at an angle of at least 30°, preferably at least 45°, with respect to a plane parallel to the substrate.

[0038] In an embodiment the array of optical elements comprises a first and second row and a first and second column, the at least one surface comprises a first surface extending between the first row and the second row, a second surface extending along an opposite side of the first row, and a third surface extending along an opposite side of the second row; and optionally also a fourth surface extending between the first column and the second column, a fifth surface extending along an opposite side of the first column, and a sixth surface extending along an opposite side of the second column.

[0039] The optical plate or the individual optical elements may be fixed on the substrate by screwing, locking, clamping, clipping, gluing, welding or a combination thereof.

[0040] Screwing, locking, clamping, clipping, and the like correspond to releasable fastening means, thereby enabling the maintenance or the replacement of the optical plate or optical elements and / or of the substrate.

[0041] The optical plate may be integrally molded but may also be assembled by fixing optical modules or elements in a frame or by fixing optical elements and / or optical modules to each other, e.g. using a dovetail mechanism. The fixing in a frame may be done e.g. by any one or more of the following methods: welding, a heat and / or pressure treatment, a snap-fit mechanism, etc. Suitable assembly methods are disclosed in PCT application WO 2022 / 023441 Al and WO 2020 / 136197 Al in the name of the applicant, which are included herein by reference.

[0042] Also, a computer-implemented method for designing an optical unit comprising one or more optical matrices with one or more optical elements, may be used. The method may comprise the steps of: receiving data related to a desired light distribution for the optical unit, providing a database comprising a plurality of optical matrix models, each optical matrix model being associated with an optical matrix and comprising at least one light distribution of that optical matrix for at least one predetermined orientation, and an indication of further possible orientations, and using the database and the received data, determining at least one set of one or more optical matrix models amongst the plurality of optical matrix models for designing the optical unit. Exemplary embodiments of method for manufacturing an assembly by molding are disclosed in Dutch patent application N2030243 in the name of the applicant which is included herein by reference.

[0043] According to another aspect there is provided an optical element for use in an assembly of any one of the embodiments described above. The optical element may have any one of the features described above. According to yet another aspect there is provided an optical plate for use in a system of any one of the embodiments described above. The optical plate may have any one of the features described above.

[0044] According to yet another aspect there is provided a method for manufacturing an optical element or an optical plate of an assembly of any one of the embodiments described above by molding, e.g. injection molding, or by 3D printing.

[0045] Preferred embodiments relate to an assembly or system for use in an outdoor luminaire. By outdoor luminaire, it is meant luminaires which are installed on roads, tunnels, industrial plants, stadiums, airports, harbors, rail stations, campuses, parks, cycle paths, pedestrian paths or in pedestrian zones, for example, and which can be used notably for the lighting of an outdoor area such as roads and residential areas in the public domain, private parking areas and access roads to private building infrastructures, etc.

[0046] In a particular embodiment, preferably in an embodiment where the optical element includes one or more lens elements, one or more other optical elements may be provided to the one or more lens elements, such as reflectors, backlights, prisms, collimators, diffusors, and the like. For example, there may be associated a backlight element with one or more lens elements or with each lens element. Those one or more other optical elements may be formed integrally with the lens element, and e.g. integrally with a lens plate. In other embodiments, those one or more other optical elements may be mounted on the lens elements.

[0047] In the context of the invention, a lens element may include any transmissive optical element that focuses or disperses light by means of refraction. It may also include any one of the following: a reflective portion, a backlight portion, a prismatic portion, a collimator portion, a diffusor portion. For example, a lens element may have a lens portion with a concave or convex surface facing a light source, or more generally a lens portion with a flat or curved surface facing the light source, and optionally a collimator portion integrally formed with said lens portion, said collimator portion being configured for collimating light transmitted through said lens portion. Also, a lens element may be provided with a reflective portion or surface, referred to as a backlight element in the context of the invention, or with a diffusive portion.

[0048] A lens element may comprise a lens portion having an outer surface and an inner surface facing the associated light source. The outer surface may be a convex surface and the inner surface may be a concave or planar surface. Also, a lens element may comprise multiple lens portions adjoined in a discontinuous manner, wherein each lens portion may have a convex outer surface and a concave inner surface. Lens elements are not limited to rotation-symmetric lenses such as hemispherical lenses, or to ellipsoidal lenses having a major symmetry plane and a minor symmetry plane, although such rotation-symmetric lenses could be used. Alternatively, lenses with no symmetry plane or symmetry axis could be envisaged.

[0049] In a particular embodiment, one or more further optical elements may be further provided such as one or more light shielding structures complying with different glare classifications, e.g. the G classification defined according to the CIE 115:2010 standard and the G* classification defined according to the EN13201-2 standard. The light shielding structures may be configured for reducing a solid angle of light beams of the light emitting elements by cutting off or reflecting light rays having a large incident angle, thereby reducing the light intensities at large angles and improving the G / G* classification of the luminaire system. The one or more light shielding structures may be mounted on any one of the optical element, the optical plate or the substrate by screwing, locking, clamping, clipping, gluing, welding or a combination thereof. Alternatively, the one or more light shielding structures may be integrally formed with any one of the optical element or the optical plate, for example by 3D printing or molding.

[0050] According to an embodiment, the light shielding structures may comprise one or more closed reflective barrier walls, each having an interior bottom edge disposed on a flat portion of an optical plate, an interior top edge at a height above said flat portion, and a reflective surface connecting the interior bottom edge and the interior top edge and surrounding one or more associated optical elements of the optical plate. According to another embodiment, the light shielding structures may comprise a plurality of reflective barriers, each comprising a base surface disposed on a flat portion of an optical plate, a top edge at a height above said base surface, and a first reflective sloping surface connecting the base surface and the top edge and facing one or more associated optical elements of an optical plate. Exemplary embodiments of shielding structures are disclosed in patent application WO 2020 / 249684 Al in the name of the applicant which is included herein by reference. Other exemplary embodiments of shielding structures are disclosed in patent application WO 2020 / 058282 Al in the name of the applicant, which is included herein by reference. Further examples of louver elements are disclosed in PCT patent application WO 2021 / 186058 Al in the name of the applicant, which is included herein by reference. Further, a spacer layer may be disposed between the carrier and the one or more optical elements. The spacer layer is provided with one or more holes through which one or more light emitting elements of the light source extend. Examples of spacer layers are disclosed in Dutch patent application N2025166 in the name of the applicant, which is included herein by reference. Furthermore, an optical element or optical plate may be movable and / or the control of the light elements may be selective. Examples of movable optics are disclosed in patent applications WO2019134875A1, W02020136202A1, W02020136200A1, W02020136205A1, W02020136203A1, W02020136204A1, WO2020136197A1, and WO2020136196A1 in the name of the applicant, which are included herein by reference. Examples of selective control of light elements are disclosed in patent applications W02019020366A1, WO2020165284A1, WO2020173836A1, and WO2021130275A1 in the name of the applicant, which are included herein by reference.

[0051] BRIEF DESCRIPTION OF THE FIGURES

[0052] This and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing exemplary embodiments. Like numbers refer to like features throughout the drawings.

[0053] Figure 1 illustrates schematically a longitudinal cut- view of an assembly according to an exemplary embodiment;

[0054] Figures 2A-2C illustrates schematically simulated light rays in an exemplary embodiment of the assembly, an isolux diagram and a polar diagram of the light distribution of the assembly of Figure 2 A, respectively;

[0055] Figures 3A-3B illustrate schematically a perspective view of two alternative embodiments of an optical element for use in an assembly;

[0056] Figures 4A-4H illustrate schematically eight exemplary embodiments corresponding to eight exemplary shapes of the at least one surface for use in an assembly;

[0057] Figure 5 illustrates schematically a further exemplary embodiment for which the light rays have been simulated; and

[0058] Figures 6A-6C illustrate three exemplary embodiments of a system with an array of light elements and an optical plate.

[0059] DESCRIPTION OF THE EMBODIMENTS

[0060] Figure 1 illustrates schematically a longitudinal cut-view of an assembly according to an exemplary embodiment.

[0061] As illustrated in Figure 1, the assembly 1 comprises a substrate 10, a light element 20 disposed on the substrate 10, and an optical element 30 disposed on the substrate 10 and extending over the light element 20. The light element 20 is configured to emit light LM away from the substrate 10, e.g. at an angle between 45° and 90° with respect to the substrate, and to emit light LI sideways, preferably substantially parallel to the substrate 10, in an area extending between the substrate 10 and a plane P parallel to the substrate 10, on the same side as the light element 20. The plane P is located at a distance D of the substrate 10, said distance D being smaller than 1000 micrometer. The optical element 30 is provided with at least one surface 310 configured to reflect light rays. The at least one surface 310 is inclined with respect to the substrate 10 and extends from the substrate 10 at least until said plane P. The at least one surface extends away from the light element 20. The at least one surface 310 is oriented so that the sideways light rays LI are reflected away from the substrate 10 at an angle 8 of at least 30°, preferably at least 45°, with respect to a plane parallel to the substrate 10. Preferably, the angle 8 is smaller than 90°, more preferably smaller than 85°, even more preferably smaller than 80°.

[0062] In Figure 1, the assembly 1 is shown with the light element 20 and the optical element 30 being disposed on an upper side of the substrate 10. The references "top" / "bottom" or "upper" / "lower" have only a relative value in relation to the depictions in the attached figures. It is understood that the assembly 1 can be used in any position and that what is up in the position shown here will not necessarily be up in use.

[0063] The sideways light rays LI generated by the light element 20 may be emitted in a volume (further referred to as a sideways -volume) extending between the upper surface of the substrate 10 and the plane P. The sideways light rays LI may be emitted with an angle a comprised between 70° and 110°, preferably between 80° and 100°, more preferably between 85° and 95°. The angle a is measured with respect to the axis perpendicular on the substrate 10.

[0064] The optical element 30 may correspond to a transparent body having a first side facing the substrate 10 and a second side opposite said first side. The first side has a first flat face 301a disposed on the substrate 10 and a light incident surface 301b that delimits a cavity 32 surrounding the light element 20. The second side may have a second flat face 302a parallel to the first flat face 301a and a light exit surface 302b protruding out of the second flat surface 302a and extending over the light incident surface 301b. The light exit surface 302b may be a convex surface, preferably a convex surface having a longest dimensions which is longer than a shortest dimension thereof.

[0065] The shape of the cavity 32 may depend on the shape of the light element 20 and / or on the desired light distribution. Typically, the cavity 32 is larger than the light element, but the cavity 32 may also match the shape of the light element 20. The light element 20 is preferably disposed in a central region of the cavity 32, more preferably at the center. Figure 1 shows an axis A which may correspond to an optical axis of the optical element 30. In other non-illustrated embodiments, the optical element 30 could be movable with respect to the light element 20, cf. the examples described in WO2019134875A1, W02020136202A1, W02020136200A1, W02020136205A1, W02020136203A1, W02020136204A1,

[0066] WO2020136197A1, and WO2020136196A1 in the name of the applicant, which are included herein by reference. Also, the light element 20 may comprise multiple side-emitting LEDs, and those LEDs could be selectively controlled. Examples of selective control of LEDs are disclosed in patent applications W02019020366A1, WO2020165284A1, WO2020173836A1, and WO2021130275A1 in the name of the applicant, which are included herein by reference.

[0067] The sideways light rays LI may propagate within the air inside the cavity 32, until reaching the interface between the air and the optical element 30, i.e. the light incident surface 301b. Upon reaching the light incident surface 301b, the sideways light rays LI are refracting inside the optical element 30 having a higher refractive index than air. Since the optical element 30 has a refractive index higher than the refractive index of air, the refracted light rays L2 are refracted at an angle closer, i.e. more acute, to an axis perpendicular to the interface between the air and the optical element 30.

[0068] The refracted light rays L2 propagate within the optical element 30 until they reach the at least one surface 310. Thus, when the refracted light rays L2 are reflected on the at least one surface 310, they are redirected away from the substrate 10. In that manner, the amount of refracted light rays L2 that would be emitted at large angles and may result in undesired glare and / or lost light is reduced. Reflected light rays L3 propagate within the optical element 30 until reaching the interface between the optical element 30 and the outside of the optical element 30, i.e. the light exit surface 302b, where the light rays L3 are further refracted. The output light rays L4 may be output with an angle P comprised between 0° and 50°, preferably between 0° and 40°. The angle is measured with respect to an axis substantially perpendicular to the substrate 10.

[0069] The at least one surface 310 may correspond to a peripheral surface surrounding the light element 20. This has the advantage to reflect a larger portion of the refracted light rays L2, particularly when the light element 20 emits sideways rays LI in a wide range of azimuthal directions, for example if the light element 20 corresponds to a side-emitting LED that has a cylindrical or a prismatic shape.

[0070] The at least one surface 310 may be oriented at an angle y larger than 90°, measured from a plane parallel to the substrate 10 and away from the light element 20. Preferably, the angle y is larger than 95°, more preferably larger than 100°, e.g. larger than 105° or even larger than 110°. In that manner, the refracted light rays L2 are reflected away from the substrate 10, as shown by reflected light rays L3 in Figure 1.

[0071] As shown in Figure 1 , the transparent body may be formed with at least one recess 31 in the first side 301, preferably in the first flat face 301a, and at least one wall of the at least one recess 31 forms the at least one surface 310. Refracted light rays L2 reaching the wall of the recess 31 may be reflected through substantially total internal reflection at the interface between the material of the optical element 30 and the medium present in the recess 31 , preferably air but other media, e.g. media overmolded into the optical element 30, are also possible, preferably media with a refractive index lower than the optical element 30. By carefully choosing the shape of the recess 31 and hence the orientation of the surface formed by the wall of the recess 31 , the internally and preferably totally reflected rays can be redirected towards the light exit surface 302b of the optical element 30, hence increasing the amount of light emitted in a desired direction.

[0072] The at least one recess 31 may comprise a recess which surrounds the cavity 32, see also Figure 3B which will be discussed below. In another embodiment the at least one recess 31 may comprise two first recesses arranged at opposite sides of the cavity 32, see also Figure 3A which will be discussed below. Optionally two second recesses 31 may be arranged on opposite sides of the cavity 32 and extending substantially perpendicular to the two first recesses, see also Figure 6B which will be discussed below.

[0073] The recess 31 may have a height H2 which is smaller than a distance Hl between the first flat face 301a and the second flat face 302a. Preferably, the height H2 is between 100 micron and 1000 micron, preferably between 200 micron and 500 micron. Preferably, the distance Hl between the first and second flat face is between 1000 micron and 3000 micron, preferably between 1500 micron and 2500 micron. Preferably, the height H2 is larger than a height H of the light element 20. Preferably, the at least one surface 310 is oriented so that the sideways light rays L2 are reflected through the optical element 30, adjacent of the cavity 32, cf. light rays L3, preferably exiting the optical element 30 through the dome shaped surface 302b, cf. light rays L4. Preferably, a distance d between the cavity 32 and the at least one surface 310 is smaller than 2000 micron, preferably smaller than 1000 micron.

[0074] The material of the optical element 30 may comprise plastic, preferably a plastic with good reflective properties. The optical element may also comprise other materials than plastic. The at least one surface 310 is optionally covered with reflective painting or with a reflective coating. The light element 20 may comprise one or more side-emitting light emitting diodes (LED). Sideemitting LEDs are thinner and cheaper than conventional LEDs because they do not comprise primary optics. Therefore, the assembly 1 may be more compact than a traditional light assembly.

[0075] Figure 2A-2C illustrate schematically light rays in an exemplary embodiment of the assembly, an isolux diagram and a polar diagram of the light distribution of the assembly of Figure 2A, respectively. The isolux diagram and polar diagram were simulated for the exemplary embodiment of Figure 2A with recesses 31 extending parallel to each other along opposite sides of the cavity as in the embodiment of Figure 3 A. In Figure 2A, the light rays LI, L2, L3 and L4 discussed above in connection with Figure 1 can be distinguished. Further light rays LM from the main beam coming from an upper surface of the light element 20 are illustrated. Typically, the road extends parallel to the longest dimension DI of the light exit surface 302b, see also Figure 6A which will be discussed below, as indicated with arrow R in Figure 2B and Figure 6A.

[0076] Figure 2C depicts polar diagrams DI, D2, D3, respectively showing the light distribution in C-plane 0°-180°, i.e. in a plane extending typically perpendicular on the road in a driving direction, in C- plane 90°-270°, i.e. in a plane extending typically perpendicular on the road perpendicular on a driving direction, and in C-plane 10°-170°. It is noted that the light rays of Figure 2C are simulated light rays and are only intended to give an idea about the principles of embodiments of the invention.

[0077] From Figure 2C, it can be clearly seen that polar diagrams DI, D2 and D3 represent a cone of light whose emission angle is contained below 80°. DI and D3 shows two first extrema between 60° and 70° corresponding to refracted light rays LM from the upper surface of the light element which were not reflected by the at least one surface 310. Additionally, DI and D3 show two second extrema between 30° and 40°, which are caused by additional light rays L4 which originate from the light rays LI emitted at large angles and redirected by the at least one surface 310. The first and second extrema can also be seen in the isolux diagram of Figure 2B (showing lines of equal light intensity in a plane parallel to the road, i.e. perpendicular on the C-planes), see the indications L4 and LM. The reflective property of the at least one surface 310 and / or the angle y may be chosen depending on the desired light distribution. Therefore, it may be concluded that some part of the light intensity at large angles has been redirected in the direction of interest.

[0078] Figures 3A-3B illustrate schematically a perspective view of two alternative embodiments of an optical element for use in an assembly. As shown in Figure 3 A, the optical element 30 may be formed with a recess 31 in the first side 301, preferably in the first flat face 301a. A wall of the recess 31 forms the at least one surface 310a and 310b. If the light element is a side-emitting LED that has a rectangular cuboid shape, defined by a height, a length and a width, most of the light emitted sideways will be emitted in the four sideways volumes defined by extruding the side faces of the cuboid in the direction of the edges of the rectangular base of the LED. For typical applications the light emitted at large angles is preferably limited in at least two directions, typically the directions parallel to a road. In that case, as shown by Figure 3 A, the recess 31 may extend parallel to the length direction of the cuboid and preferably perpendicular on the longest dimensions DI of the light exit surface 302 (note that DI typically corresponds with the road direction), such that the recess 31 intercepts substantially all of two of the four above-mentioned volumes. Thus, most of the light emitted in the two sideways volumes can thus be reflected away from the substrate 10. In the embodiment of Figure 3 A, the recess 31 defines two surfaces 310a and 310b as illustrated also in Figure 5. However, in another embodiment, the recess 31 could be shaped as in the example of Figure 1 or as in any of the examples discussed below in connection with Figures 4A-4H.

[0079] Figure 3B illustrates another exemplary embodiment where the at least one surface 310 may be a single peripheral surface surrounding the light element 20. If the light element is a side-emitting LED that has a substantially round or square top surface, the light element 20 emits sideways rays in a wide range of azimuthal directions. Having a recess 31 that surrounds the cavity 32 allows to reflect a significant amount of the light emitted in the sideways volume away from the substrate 10. The cross section of the recess 31 could be shaped as in the example of Figure 1 or 5, or as in any of the examples discussed below in connection with Figures 4A-4H.

[0080] Figures 4A-4H illustrate schematically eight exemplary embodiments corresponding to eight exemplary shapes of the at least one surface for use in an assembly.

[0081] The optical element 30 may be formed with a recess 31 in the first side, preferably in the first flat face 301a, and a wall of the recess 31 may form the at least one surface 310. As illustrated in the embodiments of Figures 4A-4H, the at least one surface 310 may comprise any one of a concave surface, a convex surface, a flat surface, or a combination thereof. The shape of the at least one surface 310 varies from one embodiment of Figures 4A-4H to another. In the first embodiment, illustrated in Figure 4 A, the at least one surface 310 is flat. In the second embodiment, illustrated in Figure 4B, the at least one surface 310 is concave, i.e. the angle y between the substrate and a first portion of the at least one surface 310 is smaller than the angle between the substrate and a second portion of the at least one surface 310 closer to the substrate than the first portion. In the third embodiment, illustrated in Figure 4C, the at least one surface 310 is convex, i.e. the angle y between the substrate 10 and a first portion of the at least one surface 310 is larger than the angle between the substrate 10 and a second portion of the at least one surface 310 closer to the substrate 10 than the first portion. In some embodiments, the shape of the surface 312 opposite to the at least one surface 310 is not restricted to any particular shape or angle since the surface 312 is not intended to receive the light rays L. However, in other embodiments, where an array of optical elements is present, both surfaces 310 and 312 may be used to reflect sideways light rays, cf. Figure 6B and 6C which are discussed below. It is further noted that, seen in a cross section, the shape and / or dimensions of the at least one surface may vary depending on the position where the cross section is taken.

[0082] The at least one surface 310 may be oriented at an angle y larger than 90°, measured from a plane parallel to the substrate and away from the light element. In the case where the at least one surface 310 correspond to a single flat surface, as illustrated in Figure 4A, the angle y may be measured at the junction between the substrate and the at least one surface 310. In the case where the at least one surface 310 is not totally flat, as illustrated in Figures 4B-4H, the angle between each portion of the at least one surface 310 and the substrate may be larger than 90°. In this manner, the light rays L may be reflected away from the substrate.

[0083] Figure 5 illustrates a further exemplary embodiment of an assembly, where the recess 31 is formed with two distinct surfaces 310a and 310b oriented at respective angles yl and y2. In this way a more uniform light distribution may be obtained. More in particular, the additional extrema shown in Figures 2B and 2C may be smoothened so as to de reduced or even not to be noticeable. The number of surfaces 310a, 310b and the angles yl, y2 may be further optimized to obtain a desirable light distribution. Optionally a curvature may be used as illustrated in Figures 4B-4G. It should be clear for the skilled person that embodiments illustrating other combinations of surfaces may be envisaged.

[0084] The sideways light rays may be reflected by the at least one surface 310 by total internal reflection or any other reflection mechanism. The at least one surface 310 may be covered with white painting or with painting of a different color, or with a reflective coating. A surface roughness of the at least one surface 310 may correspond to any one of a coarse surface finish, a polished surface finish, or a combination thereof.

[0085] Figures 6A-6C illustrate three embodiments of an optical plate 300 with an array of four optical elements 30, looking at the second side of the optical plate 300, i.e. at the light exit surfaces 302b, but wherein also the position of the light elements 20, the light incident surfaces 301b and the recesses 31 have been indicated for clarity purposes. Although four optical elements 30 are illustrated, the skilled person will understand that the same principles apply for arrays with more or less optical elements 30. Further, the road direction R has been indicated.

[0086] In the embodiment of Figure 6A each optical element 30 is provided with a peripheral recess 31 defining a peripheral surface configured to reflect sideways light rays, in a way as has been described above. Seen in a top view of the optical plate 300, the recess 31 may be located between the respective light incident surface 301b and light exit surface 301a.

[0087] In the embodiment of Figure 6B the array of optical elements 30 comprise a first and second row and a first and second column. Here multiple recesses are provided per optical element 30, extending in straight lines in between and adjacent the optical elements 30 as follows. First recesses 31b extends between the first row and the second row, a second recess 31a extends along an opposite side of the first row, and a third recess 31c extends along an opposite side of the second row. Further, fourth recesses 31e extends between the first column and the second column, a fifth recess 3 Id extends along an opposite side of the first column, and a sixth recess 3 If extends along an opposite side of the second column. Here two recesses 31b and two recesses 31e are provided but in an alternative embodiment one recess 31b and one recess 31e could be used each formed with two reflective surfaces 310, 312 as shown in Figures 4A-4H. The light exit surface 302b is a convex surface having a longest dimension DI which is longer than a shortest dimension Ds thereof, and the longest dimension is typically oriented parallel to the road direction R. The recesses 31a-f are arranged partially below the light exit surfaces 302b.

[0088] In the embodiment of Figure 6C, only recesses 31a-31c are provided in a similar way as in Figure 6B, e.g. because most sideways light rays are emitted in one direction and / or because it is mainly interesting to reduce light at large angles in the road direction R.

[0089] Although the principles of the invention have been set out above in relation to specific embodiments, it should be understood that this description is merely illustrative and does not constitute a limitation on the scope of protection which is determined by the attached claims below.

Claims

CLAIMS1. An assembly (1) comprising a substrate (10), a light element (20) disposed on the substrate (10), and an optical element (30) extending over the light element (20), wherein the light element (20) is configured to emit light away from the substrate (10) and to emit light sideways, preferably substantially parallel to the substrate (30), in an area extending between the substrate (10) and a plane (P) parallel to the substrate and at a distance (D) of the substrate (10) at the same side as the light element (20), said distance (D) being smaller than 1000 micrometer; wherein the optical element (30) is provided with at least one surface (310; 310a-310b) configured to reflect light rays, said at least one surface being inclined with respect to the substrate and extending away from the light element at least until said plane, said at least one surface being oriented so that the sideways light rays are reflected away from the substrate (10) at an angle (5) of at least 30°, preferably at least 45°, with respect to a plane parallel to the substrate (10).

2. The assembly of claim 1 , wherein the optical element is a lens element.

3. The assembly of claim 1 or 2, wherein the angle (5) is smaller than 90°, more preferably smaller than 85°, even more preferably smaller than 80°.

4. The assembly of any one of the previous claims, wherein the at least one surface (310; 310a- 310b) is a peripheral surface surrounding the light element (20).

5. The assembly of any one of the previous claims, wherein the at least one surface (310; 310a- 310b) is oriented at an angle (y; ya-yb) larger than 90°, measured from a plane parallel to the substrate (10) and away from the light element (20), preferably larger than 95°, more preferably larger than 100°, e.g. larger than 105° or even larger than 110°, and preferably smaller than 175°.

6. The assembly of any one of the previous claims, wherein the optical element (30) is a transparent body having a first side facing the substrate (10) and a second side opposite said first side, wherein the first side has a first flat face (301a) disposed on the substrate (10) and a light incident surface (301b) that delimits a cavity (32) surrounding the light element (20).

7. The assembly of the previous claim, wherein the second side has a second flat face (302a) parallel to the first flat face (301a) and a light exit surface (302b) protruding out of the second flat surface and extending over the light incident surface.

8. The assembly of the previous claim, wherein the light exit surface is a convex surface, preferably a convex surface having a longest dimension which is longer than a shortest dimension thereof.

9. The assembly of any one of the claims 6-8, wherein the transparent body is formed with at least one recess (31) in the first side, preferably in the first flat face (301a), and wherein at least one wall of the at least one recess (31) forms the at least one surface (310; 310a-310b).

10. The assembly of claim 7 and 9, wherein the at least one recess is arranged at least partially below the light exit surface.

11. The assembly of claim 9 or 10, wherein the at least one recess (31) comprises a recess which surrounds the cavity (32).

12. The assembly of any one of the claims 9-11, wherein the at least one recess comprises two recesses arranged on opposite sides of the cavity, and optionally two further recesses arranged on opposite sides of the cavity and extending substantially perpendicular to the other two recesses.

13. The assembly of any one of claim 9-12 and claim 7, wherein the at least one recess (31) has a height (H2) which is smaller than a distance (Hl) between the first and second flat face (301a, 301b).

14. The assembly of the previous claim, wherein the height (H2) is between 100 micron and 1000 micron, preferably between 200 micron and 500 micron.

15. The assembly of claim 13 or 14, wherein the distance (Hl) between the first and second flat face is between 1000 micron and 3000 micron, preferably between 1500 micron and 2500 micron.

16. The assembly of any one of the claims 13-15, wherein the height (H2) is larger than a height (H) of the light element.

17. The assembly of any one of the claims 6-16, wherein the at least one surface is oriented so that the sideways light rays which pass through the light incident surface are reflected through the optical element, adjacent of the cavity.

18. The assembly of claim 7 and 17, wherein the at least one surface is oriented so that the sideways light rays which are reflected at said at least one surface exit the optical element through the light exit surface.

19. The assembly of any one of the claims 6-18, wherein a distance (d) between the light incident surface (301b) and the at least one surface (310) is smaller than 2000 micron, preferably smaller than 1000 micron.

20. The assembly of any one of the previous claims, wherein the light element (20) comprises a side-emitting light emitting diode, side-emitting LED.

21. A system comprising the assembly of any one of the previous claims, wherein the light element is part of an array of light elements arranged on the substrate.

22. The system of the previous claim, wherein the array of light elements is a two-dimensional array of light elements, and wherein the optical element is part of an array of optical elements aligned to form a two-dimensional array associated with the two-dimensional array of light elements.

23. The system of the previous claim, wherein two or more optical elements of the array of optical elements are each provided with at least one surface (310) configured to reflect light rays, said at least one surface being inclined with respect to the substrate and extending away from the respective light element at least until said plane (P), said at least one surface being oriented so that the sideways light rays are reflected away from the substrate at an angle of at least 30°, preferably at least 45°, with respect to a plane parallel to the substrate.

24. The system of claim 22 or 23, wherein the array of optical elements comprise a first and second row and a first and second column, the at least one surface comprises a first surface (31b) extending between the first row and the second row, a second surface (31a) extending along an opposite side of the first row, and a third surface (31c) extending along an opposite side of the second row; and optionally also a fourth surface (3 le) extending between the first column and the second column, a fifth surface (3 Id) extending along an opposite side of thefirst column, and a sixth surface (3 If) extending along an opposite side of the second column. The system of any one of the claims 21-24, wherein the optical element is part of an optical plate extending over the array of light elements. The system of the previous claim, wherein the optical plate is integrally molded. The system of claim 25, wherein the optical plate is a frame comprising the optical element, and optionally also further optical elements. The system of any one of claims 25-27, wherein the optical plate is fixed on the substrate by screwing, locking, clamping, clipping, gluing, or a combination thereof. Optical element for use in an assembly of any one of the claims 1-20. Optical plate for use in a system of any one of the claims 25-28. A method for manufacturing an optical element of an assembly according to any one of claims 1-20 or an optical plate of a system according to any one of the claims 25-28, said method comprising the step of 3D printing or molding, preferably injection molding, the optical element or the optical plate, respectively.

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