Lighting element with improved backlight, and use

Abstract

The invention relates to a lighting element (1) having: a light source assembly (2) with at least one light source (2a); a translucent panel (5) that has a visible surface (S), which is to be backlit, facing the observer (B) and a rear surface (R) facing away from the observer (B); a light-guiding body (4), a light decoupling surface (4b) of which adjoins the rear surface (R) of the panel (5) across a first air gap (7), said light-guiding body (4) having a light coupling surface (4a) positioned laterally to the light decoupling surface (4b) and a reflection surface (4c) opposite the light decoupling surface (4b); and a light guide (3) which has a light entry surface (3a) facing the light source assembly (2) and a light exit surface (3b) which faces the light coupling surface (4a) of the light-guiding body (4) and is spaced apart therefrom across a second air gap (8) in order to couple light (L) of the light source assembly (2) into the light-guiding body (4) while internally reflecting the light at least once in the light guide (3), said light guide (3) and light-guiding body (4) being designed in such a way that a first light coupled into the light-guiding body (4) is directed, as a reflection and / or a refraction, along a first optical beam path (I) in the direction of the reflection surface (4c) in order to be reflected, by means of an internal reflection, on the reflection surface (4c) in the direction of the light decoupling surface (4b) and a second light coupled into the light-guiding body (4) is directed, as a reflection and / or a refraction, along a second optical beam path (II) in the direction of the light decoupling surface (4b).

Description

[0001] Lighting element with improved backlighting and use

[0002] The invention relates to a lighting element, in particular for use in a passenger compartment of a motor vehicle. Lighting elements, in particular those used to generate ambient lighting in a motor vehicle, typically have a panel that forms a visible surface facing the viewer or occupant. For backlighting, several light sources of a light source arrangement are usually provided, whose light is intended to ensure the most uniform backlighting possible of the visible surface. This should be achieved with as low power consumption of the light sources as possible, thus saving electrical energy, installation space, and weight.The problem of inhomogeneity in illumination arises particularly when the color spectrum of the light emitted by the light sources can be adjusted by controlling the light sources. This occurs due to color mixing of adjacent light sources, so that their optical light path varies due to the offset up to the visible surface to be backlit, which in turn impairs the uniformity of the backlighting. While it is possible to counteract this by inserting a diffuser in the optical light path, this increases the installation space and also impairs the efficiency of light transmission. The aim is therefore not only to avoid inhomogeneities in the illumination of the visible surface to be backlit, but also to achieve this in a cost-, weight-, and space-saving manner, and to improve the efficiency of the backlighting.

[0003] Against this background, there was a need for a solution for a lighting element with improved uniformity of the backlighting of an associated visible surface, wherein in particular installation space, costs and weight are saved without at least compromising efficiency. This object is achieved by a lighting element according to claim 1. An equally advantageous use is the subject of the independent claim. Advantageous embodiments are each the subject of the dependent claims. It should be noted that the features individually listed in the claims can be combined with one another in any technologically expedient manner and demonstrate further embodiments of the invention. The description, particularly in conjunction with the figures, further characterizes and specifies the invention.The invention relates to a lighting element which has a light source arrangement with at least one light source, preferably a plurality of light sources. In a simple embodiment, the light source arrangement comprises only one light source, such as a light-emitting diode. The light source can be selectively activated and / or the light intensity can be adjusted, for example, by a control unit. These are preferably light sources, of which at least two, preferably three, light sources differ in the color spectra of the light they emit, wherein a distinction falling within the manufacturing tolerances is not regarded as a difference in the color spectrum according to the invention. For example, this is a light source arrangement comprising at least one RGB light-emitting diode that combines three light sources with different color spectra in a common module, for example in SMD construction.

[0004] According to the invention, a translucent panel is further provided, which has a visible surface to be backlit, facing the viewer, and a rear surface facing away from the viewer. The term "translucent" is to be regarded as a minimum requirement for certain areas. This does not exclude the possibility of the panel being partially opaque or partially translucent. The panel is, for example, formed from one or more parts. It preferably has a panel body made of a transparent material, such as a transparent thermoplastic, and a transmissive decorative layer forming the visible surface. For example, the decorative layer is a thin metallic film.

[0005] According to the invention, the luminous element comprises a light-guiding body arranged with its light-output surface adjacent to the rear surface of the diaphragm via a first air gap. The light-guiding body provided according to the invention comprises a light-input surface arranged laterally to the light-output surface and a reflection surface opposite the light-output surface. The light-guiding body is preferably made of a transparent thermoplastic, apart from optional additional surface coatings.

[0006] According to the invention, the luminous element further comprises a light guide having a light entry surface facing the light source arrangement and a light exit surface facing the light coupling surface of the light guide body and spaced apart by a second air gap, in order to couple the light from the light source arrangement into the light guide body with at least one internal reflection in the light guide. The first and second air gaps ensure optical decoupling, so that when viewed from above, the viewer cannot see through to the light source arrangement.

[0007] According to the invention, the light guide and the light guide body are designed in such a way that first light coupled into the light guide body is directed along a first optical beam path through the light guide in the direction of the reflection surface, such as being reflected and / or refracted, in order to be reflected by internal reflection at the reflection surface in the direction of the light output surface, i.e. to reach the aperture indirectly, while second light coupled into the light guide body is directed along a second optical beam path through the light guide in the direction of the light output surface, such as being reflected and / or refracted, in order to reach the aperture or at least directly to the light output surface of the light guide body.

[0008] This measure, which provides a multiple optical path for backlighting the visible surface, increases the uniformity of the backlighting without the need for an additional diffuser in the optical beam path between the light source arrangement and the visible surface of the panel. The different paths of the individual light beams allow for homogeneous illumination of the illuminated surface (regardless of color). At the same time, high luminous efficacy is achieved in a small installation space. This also saves costs, installation space, and weight.

[0009] Preferably, the second light of the second optical beam path is reflected at the light output surface of the optical fiber body in the direction of the reflection surface.

[0010] The light guide is preferably designed such that light from the light source arrangement is either reflected multiple times at an inner boundary surface of the light guide or at least once at an inner boundary surface of the light guide and is refracted upon exiting the light guide to be coupled into the light guide body. A reflective coating is preferably provided to provide the reflective surface of the light guide body. For example, this is a specular, non-transparent coating, such as a PVD or NCVM coating. However, it is also conceivable for the reflective coating to be further applied to a substrate, such as a film substrate, which is integrally bonded to a base body of the light guide body.

[0011] To avoid stray light, according to a preferred embodiment, a light shield made of opaque material is provided between the light source arrangement and the viewer, more preferably between the diaphragm and the light guide. It is also preferred that the diaphragm also covers the light shield.

[0012] The panel preferably comprises a panel body and a transmissive decorative layer applied to the visible surface or forming the visible surface. The decorative layer is preferably a metallic coating, applied, for example, as a thin layer using a PVD or NCVM process. This causes back-reflection of extraneous light from the passenger compartment of the motor vehicle to suppress unwanted light effects caused by extraneous light penetrating the panel.

[0013] The optical fiber preferably has a surface microstructure to generate internal reflection. For example, a facet-like microstructure is provided. Preferably, the surface normals of an individual facet enclose an angle of 4° to 12°.

[0014] Preferably, the light exit surface of the light guide is microstructured. It has, for example, a microlens-like, micropyramid-like, or microcylindrical structure.

[0015] Preferably, the light guide is designed to guide light from the light source arrangement to the light coupling surface of the light guide body by more than one internal reflection.

[0016] Preferably, the main emission direction of the light sources of the light source arrangement is not aligned with the rear surface of the aperture, and the light guide has the task, for example, of effecting a directional deflection of more than 270° of the original main light propagation direction of the light source arrangement.

[0017] The invention further relates to the use of the lighting element in one of the aforementioned embodiments in a motor vehicle, in particular as ambient lighting, preferably when arranged below the lower window edge of the vehicle door or in the dashboard. Due to the design according to the invention, the observer, in this case the driver or front passenger, sees the visible surface directly, while this is unimpaired by unwanted reflections.

[0018] The invention is explained in more detail with reference to the following figures. These figures are to be understood as examples only and represent only two preferred embodiments. They show:

[0019] Fig. 1 is a sectional view of a first embodiment of the lighting element 1 according to the invention;

[0020] Fig. 2 is a sectional view of a second embodiment of the lighting element 1 according to the invention.

[0021] The invention relates to a lighting element 1, which is shown in a first embodiment in Figure 1 and has a light source arrangement 2 with a plurality of light sources 2a which differ with respect to the respective color spectrum. This is an RGB light-emitting diode module in SMD design mounted on a circuit board, the light sources 2a of which can be selectively activated by a control unit (not shown) and the respective light intensity can be adjusted. On the viewer B side, a translucent aperture 5 is also provided, which has a visible surface S to be backlit, facing the viewer B, and a rear surface R facing away from the viewer. The term translucent is to be regarded as a minimum requirement for certain areas. This does not exclude the possibility of the aperture 5 being opaque or translucent in some areas. The aperture 5 can, for example, be designed in one piece or in several parts.In the first embodiment shown, it comprises a visor body 5a made of a transparent material, such as a transparent thermoplastic, and a transmissive decorative layer 5b forming the visible surface S. The decorative layer 5b is a thin metallic layer. More precisely, the decorative layer 5b is a metallic coating, applied, for example, as a thin layer using a PVD or NCVM process. This causes extraneous light L* from the passenger compartment of the motor vehicle to be reflected back in order to suppress unwanted light effects caused by extraneous light L* penetrating the visor 5. The first air gap 7 represents a further reflection barrier for the extraneous light L*.

[0022] The luminous element 1 further comprises a light guide body 4, which is arranged with its light output surface 4b adjacent to the rear surface R of the diaphragm 5 via a first air gap 7. The light guide body 4 provided according to the invention has a light input surface 4a arranged laterally to the light output surface 4b and a reflection surface 4c opposite the light output surface 4b. The light guide body 4 is formed from a transparent thermoplastic, apart from a reflection coating 4d. To provide the reflection surface 4c of the light guide body 4, the latter has a reflection coating 4d made of a specular, non-light-permeable coating, such as a PVD or NCVM coating. However, it is also conceivable for the reflection coating 4d to be further applied to a substrate, such as a film substrate, which is integrally bonded to a base body of the light guide body 4.

[0023] In order to couple the light L from the light source arrangement 2 into the light guide body 4, the luminous element 1 further comprises a light guide 3, which has a light entry surface 3a facing the light source arrangement 2 and a light exit surface 3b facing the light entry surface 4a of the light guide body 4 and spaced apart by a second air gap 8. The light guide 3 is provided to couple the light L from the light source arrangement 2 into the light guide body 4 with at least one internal reflection in the light guide 2. The first air gap 7 and the second air gap 8 ensure optical decoupling, so that when viewed from above, the viewer B cannot see through to the light source arrangement 2.

[0024] The light guide 3 and the light guide body 4 are designed such that first light coupled into the light guide body 4 is directed, for example deflected and / or refracted, along a first optical beam path I through the light guide 3 in the direction of the reflection surface R in order to be reflected by internal reflection at the reflection surface 4c in the direction of the light output surface 4b, i.e. to reach the aperture 5 indirectly, while second light coupled into the light guide body 4 is directed, for example reflected and / or refracted, along a second optical beam path II through the light guide 3 in the direction of the light output surface 4b in order to reach the aperture 5 or at least the light output surface 4b of the light guide body 4. The second light of the second optical beam path II is reflected at the light output surface 4b of the light guide body 4 back in the direction of the reflection surface 4c.

[0025] To ensure a suitable light-refracting effect, the light exit surface 3b of the light guide 3 is microstructured. It has, for example, a microlens-like, micropyramid-shaped, or microcylindrical structure.

[0026] This measure, which provides a multiple optical path for backlighting the visible surface S, increases the uniformity of the backlighting without requiring an additional diffuser in the optical beam path between the light source arrangement 2 and the visible surface S of the aperture 5. The different paths of the individual light beams allow for homogeneous illumination (regardless of color) of the illuminated surface. This also saves costs, installation space, and weight.

[0027] In order to avoid stray light, a light diaphragm 6 made of opaque material is further provided between the light source arrangement 2 and the viewer b, more precisely between the diaphragm 5 and the light guide 3, wherein the diaphragm 5 further covers the light diaphragm 6.

[0028] The second embodiment shown in Figure 2 differs essentially from the first in the relative arrangement of the light source arrangement 2 and the design of the light guide 3. While in the first embodiment of the lighting element 1 shown in Figure 1 the main emission direction of the light source arrangement 2 is directed towards the rear surface R of the aperture, this is not the case in the second embodiment shown in Figure 2 and the light guide 3 has the task of effecting a directional deflection of more than 270° of the original main light propagation direction of the light source arrangement 2. The second embodiment thus also differs in that the light guide 3 is designed to guide light from the light source arrangement 2 to the light coupling surface 4a of the light guide body 4 by more than one internal reflection. For this purpose, the light guide 3 has a surface microstructuring 3c for generating an internal reflection.For example, a facet-like microstructuring is provided. Preferably, the surface normals of a single facet enclose an angle of 4° to 12°.

Claims

Claims 1. Lighting element (1), comprising: a light source arrangement (2) with at least one light source (2a); a translucent diaphragm (5) which has a visible surface (S) to be backlit and facing the viewer (B), and a rear surface (R) facing away from the viewer (B); a light guide body (4) which is arranged via a first air gap (7) adjacent to the rear surface (R) of the diaphragm (5) with a light output surface (4b) of the light guide body (4), wherein the light guide body (4) has a light input surface (4a) arranged laterally to the light output surface (4b) and a reflection surface (4c) opposite the light output surface (4b); a light guide (3) having a light entry surface (3a) facing the light source arrangement (2) and a light exit surface (3b) facing the light coupling surface (4a) of the light guide body (4) and spaced apart by a second air gap (8),to couple light (L) from the light source arrangement (2) into the light guide body (4) with at least one internal reflection in the light guide (3), wherein the light guide (3) and the light guide body (4) are designed such that first light coupled into the light guide body (4) is directed along a first optical beam path (I) through the first light guide (3) in the direction of the reflection surface (4c), such as being reflected and / or refracted, in order to be reflected by internal reflection at the reflection surface (4c) in the direction of the light output surface (4b), and second light coupled into the light guide body (4) is directed along a second optical beam path (II) through the light guide (3) in the direction of the light output surface (4b), such as being reflected and / or refracted.

2. Lighting element (1) according to the preceding claim, wherein the reflection surface (4c) of the light guide body (4) is formed by a reflection coating (4d).

3. Lighting element (1) according to one of the preceding claims, wherein light (L) of the light source arrangement (2) is either reflected multiple times at an inner boundary surface of the light guide (3) or at least once at an inner boundary surface of the light guide (3) and is refracted upon exiting the light exit surface (3b) of the light guide (3) in order to be coupled into the light guide body (4).

4. Lighting element (1) according to one of the preceding claims, wherein the second light of the second optical beam path (II) is reflected at the light output surface (4b) of the light guide body (4) in the direction of the reflection surface (4c).

5. Lighting element (1) according to one of the preceding claims, wherein a light diaphragm (6) made of opaque material is provided between the light source arrangement (2) and the viewer (B), preferably between the diaphragm (5) and the light guide (3).

6. Lighting element (1) according to the preceding claim, wherein the aperture (5) further covers the light aperture (6).

7. Lighting element (1) according to one of the preceding claims, wherein the cover (5) has a cover body (5a) and a transmissive decorative layer (5b) applied on the side of the visible surface (S) or forming the visible surface (S).

8. Lighting element (1) according to the preceding claim, wherein the decorative layer (5b) is a metallic coating.

9. Lighting element (1) according to one of the preceding claims, wherein the light source arrangement (2) comprises at least two, preferably three, light sources (2a) with differing color spectra.

10. Lighting element (1) according to one of the preceding claims, wherein the light guide (3) has a surface microstructuring (3c) for generating an internal reflection.

11. Lighting element (1) according to one of the preceding claims, wherein the light exit surface (3b) of the light guide (3) is microstructured.

12. Lighting element (1) according to one of the preceding claims, wherein the light guide (3) is designed to guide light from the light source arrangement (2) to the light coupling surface (4a) of the light guide body (4) by more than one internal reflection.

13. Lighting element (1) according to one of the preceding claims, wherein the main radiation direction of the light sources (2a) of the light source arrangement (2) is not aligned with the rear surface (R) of the diaphragm (5).

14. Use of the lighting element (1) according to one of the preceding claims in a motor vehicle.

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