LIGHT EMITTING ARRANGEMENT FOR ILLUMINATED SURFACES

Abstract

A light emitting arrangement (100, 200, 300) is provided, comprising: a body (10) of solid material having a surface (11); a light guiding member (101, 110) partially embedded into said body, having a plurality of discrete light outcoupling regions (103) comprising light outcoupling means (230, 730, 830, 930) distributed along a longitudinal direction of the light guiding member, and a plurality of discrete, non-outcoupling regions (102) distributed along a longitudinal direction of the light guiding member, wherein said plurality of light non-outcoupling regions of the light guiding member are embedded by said body and said plurality of light outcoupling regions of the light guiding member are exposed on the surface of said body, wherein said non-outcoupling regions (102) form light incoupling regions comprising light incoupling means (220, 320, 420, 520, 620); and a plurality of solid state light sources (12) embedded within said body (10) of solid material arranged to emit light towards said light incoupling regions. The light emitting arrangement provides a body with an illuminated surface, and the plurality of light outcoupling regions enables efficient lighting, with no or little loss of light.

Claims

1. A light emitting arrangement comprising: a body of solid material having a surface; a light guiding member partially embedded into said body, said light guiding member having a plurality of discrete light outcoupling regions comprising light outcoupling means distributed along a longitudinal direction of the light guiding member, and a plurality of discrete, non-outcoupling regions distributed along a longitudinal direction of the light guiding member, wherein said plurality of light non-outcoupling regions of the light guiding member are embedded by said body and said plurality of light outcoupling regions of the light guiding member are exposed on the surface of said body, wherein said non-outcoupling regions (102) form light incoupling regions comprising light incoupling means; and a plurality of solid state light sources embedded within said body of solid material arranged to emit light towards said light incoupling regions.

2. A light emitting arrangement according to claim 1, further comprising at least one further light incoupling region comprising light incoupling means located at a lateral face of the light guiding member and at least one further solid state light source arranged to emit light towards said lateral face and said at least one light incoupling region.

3. A light emitting arrangement according to claim 2, wherein at least two further light incoupling regions are located at opposing lateral faces of the light guiding member, and at least two further solid state light sources are arranged on opposing sides of said light guiding member, each further solid state light source arranged to emit light towards a respective lateral face and one of said at least two further light incoupling regions.

4. A light emitting arrangement according to claim 1, wherein said non-outcoupling regions forming light incoupling regions are evenly distributed along the length of the light guiding member.

5. A light emitting arrangement according to claim 1, wherein at least one of said light incoupling means and further light incoupling means and said light outcoupling means comprises a wavelength converting material.

6. A light emitting arrangement according to claim 1, wherein said light incoupling means comprises a coating covering a part of the surface of the light guiding member.

7. A light emitting arrangement according to claim 1, wherein said light outcoupling means comprises a coating covering a part of the surface of the light guiding member.

8. A light emitting arrangement according to claim 1, wherein at least one of the light incoupling means and the light outcoupling means comprises a coating enclosing a longitudinal portion of the light guiding member.

9. A light emitting arrangement according to claim 1, wherein the light guiding member is an optical fiber core.

10. A light emitting arrangement according to claim 1, further comprising a protective cladding enclosing parts of the light guiding member not associated with light incoupling means or light outcoupling means.

11. A light emitting arrangement according to claim 1, wherein the surface of the body is planar and the light guiding member is at least partially curved.

12. A light emitting arrangement according to claim 1, wherein less than 70% by volume of the light guiding member is embedded by the solid body, such that at least 30% by volume of the light guiding member is exposed on the surface of said body.

13. A light emitting arrangement according to claim 1, wherein less than 50%, e.g. less than 30%, by volume of the light guiding member is embedded by the solid body, such that at least 50%, e.g. at least 70%, by volume of the light guiding member is exposed on the surface of said body.

14. A light emitting arrangement according to claim 1, wherein said body of solid material comprises, forms part of, or is adapted to be arranged on a wall, a ceiling, and/or a floor, or comprises or forms part of a piece of furniture or interior decoration.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] This and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing embodiment(s) of the invention.

[0027] FIG. 1 is a cross-sectional side view showing general structures of a light emitting arrangement according to embodiments of the invention.

[0028] FIG. 2 is a cross-sectional side view of a light emitting arrangement according to embodiments of the invention.

[0029] FIG. 3 is a cross-sectional side view of a light emitting arrangement according to embodiments of the invention, showing a possible configuration of a light source.

[0030] FIG. 4 is a cross-sectional side view of a light emitting arrangement according to embodiments of the invention, showing a possible variant of the light incoupling means.

[0031] FIG. 5 is a cross-sectional side view of a light emitting arrangement according to embodiments of the invention, showing another variant of the light incoupling means.

[0032] FIG. 6 is a cross-sectional side view of a light emitting arrangement according to embodiments of the invention, showing another variant of the light incoupling means.

[0033] FIG. 7 is a cross-sectional side view of a light emitting arrangement according to embodiments of the invention, showing a possible variant of the light outcoupling means.

[0034] FIG. 8 is a cross-sectional side view of a light emitting arrangement according to embodiments of the invention, showing another variant of the light outcoupling means.

[0035] FIG. 9 is a cross-sectional side view of a light emitting arrangement according to embodiments of the invention, showing yet another variant of the light outcoupling means.

[0036] FIG. 10 is a cross-sectional side view of a light emitting arrangement according to embodiments of the invention.

[0037] As illustrated in the figures, the sizes of layers and regions are exaggerated for illustrative purposes and, thus, are provided to illustrate the general structures of embodiments of the present invention. Like reference numerals refer to like elements throughout.

DETAILED DESCRIPTION

[0038] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and fully convey the scope of the invention to the skilled person.

[0039] FIG. 1 illustrates general structures of a light emitting arrangement 100 according to embodiments of the invention. The light emitting arrangement 100 comprises a light guiding member 101, here in the form of an optical fiber. However, the light guiding member 101 may also be in the form of a sheet, seen from the side. In either case, the light guiding member, hereafter referred to as a light guide, has a longitudinal extension in at least one direction L.

[0040] The light guide 101 is partly embedded into a body 10 of solid material, such that parts or regions 102 of the light guide 101 are embedded or buried in the body 10, and other parts or regions 103 are exposed on the surface 11 of the body 10, e.g. protruding from the surface 11. As shown in the figure, the parts or regions 102 and the parts or regions 103 are alternatingly arranged in the longitudinal direction L. The regions 102 may be completely embedded in the body 10, whereas the regions 103 may be completely exposed. Thus, from a top view it would seem that the light guide 101 repeatedly appears on, or above, the surface 11 and repeatedly disappears from (or beneath) the surface 11. The body 10 may be made of a solid material, optionally non-transparent, for example metal, wood, mineral (e.g., stone), plastic, composites, textile, paper or combinations thereof.

[0041] Light is coupled into the light guide via light incoupling means (not shown) which may be located e.g. at the embedded regions 102 and in embodiments additionally at one or both of the lateral faces 104a, 104b of the light guide. Furthermore, the regions 103 form light outcoupling region and comprise light outcoupling means (not shown in FIG. 1) for extracting light from the light guide.

[0042] FIG. 2 shows a closer view of a light emitting arrangement according to embodiments of the invention. The light emitting arrangement 200 comprises a body of solid material 10 partly embedding a light guide 101 having alternating regions 102 and 103, where the regions 102 are embedded into the body 10 and the regions 103 are exposed on the surface of the body 10, as described above. Further, FIG. 2 shows a plurality of solid state light sources 12, typically light emitting diodes (LEDs), embedded in the body 10 in the vicinity of the region 102 of the light guide 101 and directed to emit light towards the light guide. The regions 102 of the light guide comprise light incoupling means 220, which facilitate coupling of light emitted by the LEDs 12 into the light guide 101. Thus, the regions 102 may form light incoupling regions. The regions 103 comprise light outcoupling means 230 which enable outcoupling of light from the light guide. Hence, light emitted by the LEDs 12 is coupled into the light guide 101 at multiple sites (light incoupling regions 102) and propagate through the light guide 101 by total internal reflection, according to Snell's law. However, instead of all light being guided to a distal end of the light guide, as is usually the case of with an optical fiber, light is coupled out of the light guide at multiple sites (the light outcoupling regions 103) distributed over the length, or longitudinal extension, of the light guide.

[0043] In some embodiments, each embedded region 102 of the light guide may be associated with a light source 12 and may thus represent a light incoupling region 102. However, it is also possible that some of the embedded regions 102 are not associated with a light source and thus do not constitute light incoupling regions. Hence, an embedded region 102 of the light guide 101 may or may not represent a light incoupling region.

[0044] Furthermore, not all parts of the light guide exposed on the surface must comprise light outcoupling means. Hence, there may be parts of the light guide 101 exposed on the surface that do not represent, or comprise, light outcoupling regions.

[0045] To improve light distribution uniformity, the light incoupling regions 102 may be arranged at regular intervals along the length of the light guide 101. The distribution of the light outcoupling regions 103 may be regular or irregular, and can be adapted to provide a desired pattern of extracted light.

[0046] As mentioned above, the light source 12 may be an LED, for example a blue or violet LED, although LEDs of other colors are of course equally possible. The light source may be embedded into the body of solid material adjacent a light incoupling region of the light guide and in optical contact with the light incoupling means. The light source is typically arranged on a printed circuit board or lead frame (not shown) and connected to an external power supply and control circuitry via electrical leads, as appreciated by a person of skill in the art. A PCB or lead frame and any electrical leads may be at least partly embedded in the body 10.

[0047] The light source may be in more or less direct physical contact with the light guide via the light incoupling means. Optionally however the light source may be arranged at a distance from the light guide, as long as it is still in optical contact with the light incoupling means of the light guide.

[0048] FIG. 3 shows an embodiment of a light emitting arrangement where the light source, in the form of a direct phosphor converted LED, is physically and optically coupled to the light guide 101 via the light incoupling means 320, here a layer of optical coupling material, such as silicone. Thus, the LED 12 may comprise a wavelength converting layer 313 applied on the LED, which wavelength converting layer 313 is in direct contact with the silicone material 320. In other embodiments such as illustrated in for example FIG. 2, the light source may be arranged at a distance from the light guide 101. In such embodiments however a transparent medium, such as an optically coupling material, may be provided to establish optical contact between the light source and a light incoupling region of the light guide.

[0049] Although FIGS. 2 and 3 show LEDs positioned beneath the light guide as seen from the surface 11, it is contemplated that the light source may also be positioned at the same depth as the light incoupling region of the light guide and beside it.

[0050] In some embodiments, in addition to light sources arranged along the length of the light guide e.g. as shown in FIGS. 2 and 3, solid state light sources, such as LEDs or laser light sources, may be arranged at lateral faces of the light guide, such as at the ends 104a, 104b of an optical fiber, and in optical contact with light incoupling means provided at said lateral faces, such that additionally light can be coupled into the light guide from one or both ends of the fiber. The lateral faces 104a, 104b and the light source(s) may in such cases either be embedded in the body 10 or solid material, or may be provided outside of the body 10, e.g. on a surface of the body. When light is coupled into the light guide from a lateral face or end, the light intensity may decrease along the light guide with increasing distance from the light source, and it may then be advantageous to compensate for this decrease by adapting the number and/or spatial distribution of the light outcoupling means in order to provide more even light output along the length of the light guide. The light source used in these embodiments may for example be a phosphor converted LED similar to the light source 312 of FIG. 3. Furthermore, in embodiments where the light incoupling regions are provided at one or both of the lateral faces of 104a, 104b, the light guide may optionally comprise a wavelength converting material mixed with the material of the light guide.

[0051] The light incoupling means may be provided as a coating, for example a wavelength converting coating or a transparent optical material. The coating may be adhesive and may attach the light source to the light guide, e.g. as shown in FIG. 3. In some embodiments, the light incoupling means may be etched into the material of the light guide, during manufacture thereof or later.

[0052] FIGS. 4-6 illustrate different configurations of the light incoupling means. In some embodiments, represented in FIG. 4, the light incoupling means 420 are provided on the surface of the light guide 101 to completely cover, or enclose, a portion thereof. The light incoupling means may thus form a sleeve around a portion of the light guide, in particular in embodiments where the light guide is an optical fiber core. In other embodiments, e.g. as illustrated in FIG. 5, light incoupling means 520 may be provided as a coating primarily on one side of the light guide, typically the side thereof facing the light source. Thus, in such embodiments the light incoupling means 520 does not enclose or encircle the light guide.

[0053] In yet other embodiments, represented schematically in FIG. 6, the light incoupling means may be represented by a pattern 620 of light coupling material applied on the surface of the light guide. The light incoupling pattern 620 may be provided primarily on a surface of the light guide facing the light source, although it is also contemplated that a pattern could be provided all around a portion of the light guide in a manner corresponding to the embodiment shown in FIG. 4.

[0054] The light incoupling means of any embodiment of the light emitting arrangement described herein may optionally comprise a wavelength converting material. For example, a wavelength converting material may be dispersed in the form of particles or molecularly dissolved in an optical coupling material.

[0055] Further, the light outcoupling means of any embodiment may optionally comprise a wavelength converting material. For example, a wavelength converting material may be dispersed in the form of particles or molecularly dissolved in an optical coupling material.

[0056] Wavelength converting materials, also referred to as luminescent materials or phosphors, are inorganic or organic compounds capable of converting primary light, e.g. light emitted by a light source such as an LED, to secondary light having a different spectral distribution (usually light of longer wavelengths). The type of wavelength converting material used in the light emitting arrangements of the invention may be selected with due regard to the spectral properties of the light emitted by the light source and the desired spectral composition of the output light (i.e. the light extracted from the light guide via the light outcoupling regions). It is possible to use a combination of wavelength converting materials providing different colors of light in order to achieve output light having a desired color or other spectral property.

[0057] Examples of suitable inorganic wavelength converting material include cerium (Ce) doped yttrium aluminum garnet, YAG (Y.sub.3Al.sub.5O.sub.12) or lutetium aluminum garnet, LuAG (Lu.sub.3Al.sub.5O.sub.12). Ce doped YAG emits yellowish light, whereas Ce doped LuAG emits yellow-greenish light. Examples of other inorganic phosphors materials which emit red light may include, but are not limited to ECAS and BSSN; ECAS being Ca.sub.1-xAlSiN.sub.3:Eu.sub.x wherein 0<x≦1, preferably 0<x≦0.2; and BSSN being Ba.sub.2-x-zM.sub.xSi.sub.5-yAl.sub.yN.sub.8-yO.sub.y:Eu.sub.z wherein M represents Sr or Ca, 0≦x≦1, 0≦y≦4, and 0.0005≦z≦0.05, and preferably 0≦x≦0.2. Inorganic phosphors may be provided in particle form, dispersed in a matrix.

[0058] Examples of suitable organic wavelength converting materials for use in the present invention include organic luminescent materials based on perylene derivatives, for example the compounds sold under the name Lumogen® by BASF. Examples of suitable compounds include, but are not limited to, Lumogen® Red F305, Lumogen® Orange F240, Lumogen® Yellow F083, and Lumogen® F170. Organic wavelength converting materials have among other thing the advantage that their molecular structure can be designed such that the spectral peak position can be tuned. Another prominent feature of organic wavelength converting materials is that they may be molecularly dissolved in a matrix material and thus be transparent, i.e. non-scattering.

[0059] Alternatively, the wavelength converting material used in embodiments of the invention may be based on quantum dots, which are small crystals of semiconducting material generally having a width or diameter of only a few nanometers. When excited by incident light, a quantum dot emits light of a color determined by the size and material of the crystal. Light of a particular color can therefore be produced by adapting the size of the dots. Most known quantum dots with emission in the visible range are based on cadmium selenide (CdSe) with a shell such as cadmium sulfide (CdS) and zinc sulfide (ZnS). Cadmium free quantum dots such as indium phosphide (InP), and copper indium sulfide (CuInS2) and/or silver indium sulfide (AgInS2) can also be used. Quantum dots show very narrow emission band and thus they show saturated colors. Furthermore the emission color can easily be tuned by adapting the size of the quantum dots. Any type of quantum dot known in the art may be used in embodiments of the present invention. However, it may be preferred for reasons of environmental safety and concern to use cadmium-free quantum dots or at least quantum dots having very low cadmium content.

[0060] A light incoupling means comprising the wavelength converting material may be transparent, that is, essentially non-scattering. For example, an inorganic nano-sized phosphor may be used, such as quantum dots, or an organic phosphor which is molecularly dissolved in an optical coupling material.

[0061] Turning to FIGS. 7-9, different variants of the light outcoupling means are shown. Generally, the light outcoupling means of the light outcoupling regions 103 of the light guide 101 may comprise a wavelength converting material, or a light diffracting, refracting or scattering material or structure. The light outcoupling means may be provided as a coating. In some embodiments, the light outcoupling means may be etched into the material of the light guide, during manufacture thereof or later.

[0062] FIG. 7 illustrate an embodiment in which the light guide 101 comprises light outcoupling means 730 provided on the surface of the light guide 101 to completely cover, or enclose, a portion thereof, the enclosed portion thus forming a light outcoupling region 103. The light outcoupling means may thus form a sleeve around a portion of the light guide, in particular in embodiments where the light guide is an optical fiber core. In other embodiments, e.g. as illustrated in FIG. 8, light outcoupling means 830 may be provided as a coating primarily on one side of the light guide, typically on a side thereof facing away from the surface 11 of the body and in the viewing direction of an observer. Thus, in such embodiments the light outcoupling means does not enclose or encircle the light guide. In yet other embodiments, represented schematically in FIG. 9, the light outcoupling means may be represented by a pattern 930 of light coupling material applied on the surface of the light guide. The light outcoupling pattern 930 may be provided primarily on a surface of the light guide facing away from the surface 11 and in the direction of an observer, although it is also contemplated that a pattern could be provided all around a portion of the light guide in a manner corresponding to the embodiment shown in FIG. 7.

[0063] The light outcoupling means of any embodiment of the light emitting arrangement described herein may optionally comprise a wavelength converting material. For example, a wavelength converting material may be dispersed in the form of particles or molecularly dissolved in an optical coupling material as described above with reference to the light incoupling means. Suitable wavelength converting materials include those mentioned above with reference to the light incoupling means. In embodiments where the light incoupling means as well as the light outcoupling means comprise wavelength converting material, the wavelength converting materials of the light incoupling means and the light outcoupling means, respectively, may be the same or different.

[0064] For the purpose of light outcoupling it may be preferable in some embodiments to use either a scattering wavelength converting material, such as wavelength converting particles of a sufficient size, for example at least 100 nm, or to combine non-scattering (transparent) wavelength converting particles or a molecularly dissolved organic wavelength converting material with inorganic scattering elements.

[0065] Thus, the light outcoupling means may comprise scattering elements, optionally in combination with a wavelength converting material. For instance scattering elements in the form of particles of reflective material, such as TiO.sub.2, Al.sub.2O.sub.3 or BaSO.sub.4, or combinations thereof, may be incorporated in an optically coupling material such as silicone or another material as described above.

[0066] The light guiding member described herein may be made of any suitable material, for example glass or plastic, and may optionally be flexible. Usually, the light guiding member is at least partly covered by a cladding which protects the light guiding material and which prevents undesired leakage of light from the light guide at its interfaces with other materials, such as the material of the solid body 10. However, the cladding is absent from any portions of the light guide covered by light incoupling means or light outcoupling means. Hence, the cladding of e.g. an optical fiber may need to be removed at portions that are to be covered or coated with light incoupling means or light outcoupling means, such that the light incoupling means and the light outcoupling means are in optical contact with the optical fiber core.

[0067] The light emitting arrangement according to embodiments of the invention thus provides a light guide emitting light at selected portions along its length, partly embedded into the surface of a body of solid material. For example, at least 30% by volume of the light guide is not embedded into the body and thus exposed on the surface and thus available for light extraction. In some embodiments, at least 50%, or at least 70% by volume of the light guide is exposed and available for light extraction. FIG. 10 shows an example embodiment of a light emitting arrangement in which more than 50% by volume of a light guide 110 is exposed on the surface 11 of the body 10. Embedded regions 102, which here form light incoupling regions, constitute a lesser part, by volume, of the light guide as compared to the light outcoupling regions 103, which are exposed to the surroundings and visible to an observer.

[0068] The body 10 may be optionally non-transparent and may comprise any suitable material, synthetic or natural, and may form or form part of any kind of object, for example an object or material used for interior decoration or design. For instance, the body 10 may form or form part of a wall or a wall segment, a wallpaper, a ceiling or a ceiling tile (for suspended ceilings), a floor or a floor tile, a carpet, or a piece of furniture such as a table, a desk, a cupboard, a screen, a door, a chair or seat, etc.

[0069] The light guide may be manufactured by known methods, and it may subsequently be partly embedded or integrated into the surface of the solid body by insertion into holes or recesses in the body formed by any suitable means, e.g. drilling, cutting or the like, or by molding during production of the body itself The light guide may optionally be joined with the body during manufacture of the body.

[0070] The person skilled in the art realizes that the present invention by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims. For example, although all figures show a planar surface and a curved, undulating light guide it is contemplated that the surface as well as the light guide may have any shape.

[0071] Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage.