DE102015007591A1 - Optical fiber for an interior or exterior light element of a motor vehicle - Google Patents

Abstract

The invention relates to a light guide (1) for an interior or exterior light element of a motor vehicle, with a light exit surface (4), from which light (2, 2 ') from the interior of the light guide (1) in an environment of the light guide (1) radiated is and with at least one fixedly connected to the light guide (1) fastening means (3), wherein the light guide (1) has a core region (6) made of a transparent first material having a first refractive index, and the core region (6) is designed, light (2, 2 ') in a main light propagation direction along the light guide (1), and wherein the fixing means (3) is made partly or entirely of a second material having a smaller second refractive index than the first one, 1) for an interior or exterior light element of a motor vehicle, which enables or has the most homogeneous possible brightness distribution at a light exit surface (4).

Description

The invention relates to a light guide for an interior or exterior light element of a motor vehicle, with a light exit surface from which light from the interior of the light guide in an environment of the light guide can be emitted, and with at least one fixedly connected to the light guide fastening means, wherein the light guide a core region of a transparent first material having a first refractive index, and the core region is configured to guide light in a main light propagation direction along the light guide.

In motor vehicles nowadays optical fibers for interior or exterior lighting elements are used in a variety of applications. The light guides are often arranged on corresponding inner or outer elements of the motor vehicle. For this you often have a fastener to attach to that inner or outer element.

So revealed the DE 10 2010 050 511 A1 a lighting device with at least one light source, a light guide and a support member for the light guide. The carrier part has a receiving groove for the light guide. The receiving groove here has an insertion opening for a holding projection of the light guide. In an assembly position, the at least one holding projection engages in the receiving groove, so that the light guide is fastened by the holding projection as a fastening means to the support part.

Also the EP 2 775 197 A1 shows a light guide, which has a projection which extends through a circuit board and thus fixes the light guide.

The US 2014/0029292 A1 discloses a linear lighting device with an elongate optical fiber and a light source at one end of the elongated optical fiber. The light guide is placed in a housing and held by fastening means in a Verbauposition.

The object is to provide a light guide for an interior or exterior light element of a motor vehicle, which allows or has a homogeneous distribution of brightness on a light exit surface.

This object is solved by the subject matter of the independent claim. Advantageous embodiments will become apparent from the dependent claims, the description and the figures.

The invention relates to a light guide for an interior or exterior light element of a motor vehicle. The light guide has a light exit surface, from which light can be emitted or decoupled from the interior of the light guide in an environment of the light guide. The light guide also has at least one fixedly connected to the light guide or fixed to the optical fiber mechanically coupled fastening means. The attachment means may also be non-positively connected to the light guide. The fastening means is thus an essential part of the light guide. The one or more attachment means may or may preferably also be arranged in one or two end regions of the light guide. The end regions of the light guide are advantageously located along a main extension of the light guide in opposite directions. The light guide has a core region of a transparent first material having a first refractive index. The core region is configured to guide light in a main light propagation direction along the optical fiber in its main extension. The light guide is designed in particular elongated. In order to achieve a homogeneous distribution of brightness at the light exit surface of the light guide, the fastening means is partially or entirely made of a second, in particular also transparent, material with a smaller compared to the first second refractive index.

This has the advantage that in the boundary region between the two materials a total reflection of the light conducted in the light guide light is promoted and entry of the guided light is prevented in the fastening means. As a result, the occurrence of multiple reflections within the light guide in the region of the fastening means is avoided. The multiple reflections otherwise lead to a local increase in the brightness occurring in the region of the fastening means in the light guide and thus also to a local increase in the brightness at an associated section of the light exit surface of the light guide. Consequently, the invention improves the homogeneity of the brightness distribution on the light exit surface.

In a preferred embodiment it is provided that the fastening means comprise a hook and / or an eyelet and / or a latching element and / or a pin and / or a pin and / or a clip and / or a clip and / or a recess and / or includes a recess. The said fasteners are particularly well suited for attaching a light guide in an interior or exterior light element of a motor vehicle and are also easy to implement or produce in one piece with the light guide. Thus, the mentioned geometries, which offer manufacturing and assembly advantages, are susceptible to the said multiple or multiple reflections. Accordingly, the problem of inhomogeneous is just in the aforementioned fasteners Brightness distribution on the light exit surface particularly pronounced. Moreover, said fasteners of the second material can be made well together with the remainder of the first material.

In another advantageous embodiment, it is provided that the optical waveguide has a cladding layer of the second material in an environmental region of the fastening means at an outer surface of the optical waveguide that is different from the light exit surface. The cladding layer can be made in one piece with the fastening means. This has the advantage that on the one hand the fastening means is attached over a large area to the remaining light guide and on the other hand, an interface between the first and the second material is increased. Accordingly, any optical effects such as reflections or refractions occur over a larger area. Thus, the homogeneity of the brightness distribution at the light exit surface is further improved.

In particular, the optical waveguide can comprise at least one elongated cable and / or ribbon-like optical waveguide region and / or a planar waveguide region. In the planar light guide region, the light exit surface is preferably expanded to a greater extent in an x and / or y direction parallel to the light exit surface than the light guide in a z direction perpendicular to the x and y directions. This should be referred to here as a flat light exit surface. Especially with a flat light exit surface, the described design is advantageous because there is an inhomogeneous brightness distribution is particularly noticeable.

In this case, provision may in particular be made for the cladding layer to extend continuously along the optical waveguide in the main light propagation direction, and in a sectional plane transverse to the main light propagation direction only on the outer surface different from the light exit surface or only on one or more further from the light exit surface different outer surfaces of the light guide extends. This has the advantage that the interface between the two materials extends over the entire light guide and thus reflections occurring at the interface occur homogeneously along the light guide. Accordingly, the resulting light distribution at the light exit surface is also homogeneous. On the one hand, the stability of the connection between the cladding layer and the core region is improved by the cladding layer at a plurality of outer surfaces of the light guide which are different from the light emergence surface, and the light is conducted more efficiently through the light guide via improved total reflection at the boundary surface. Accordingly, an increased brightness is achieved at the light exit surface.

Alternatively, in a further advantageous embodiment, the cladding layer may extend continuously along the optical waveguide in the main light propagation direction, thereby completely surrounding the core region of the optical waveguide in a sectional plane transverse to the main light propagation direction. This combines the advantages described in the paragraph with a simplified manufacturing method.

In a particularly advantageous embodiment it is provided that between the fastening means and the core region of the light guide or between the cladding layer and the core region of the light guide, a further layer of a material having a third refractive index is arranged. The third refractive index is in particular smaller than the first and greater than the second refractive index. In particular, the further layer may extend continuously along the light guide in the main light propagation direction. In this case, in a sectional plane transversely (in particular perpendicularly) to the main light propagation direction, it can either extend only between the outer surface different from the light exit surface and the core region or only between the one and more further outer surfaces of the light conductor different from the light exit surface.

Alternatively, the cladding layer may completely surround the core region of the optical waveguide. This has the advantage that the refractive behavior of the light in the optical waveguide can be optimized once again, so that once again improved homogeneity of the light distribution in the optical waveguide and thus also at the light exit surface is achieved.

In a further embodiment it is provided that the fastening means is designed in one piece with the light guide. So it is the light guide made in one piece. Thus, the attachment means is integral with the core portion. Especially in this field of application, the embodiment according to the invention is particularly advantageous since just one-piece production of the light guide with fastening means is cost-effective and thus particularly widespread in vehicle construction. However, the hitherto customary one-piece embodiments are particularly susceptible to the said multiple reflections, so that here the reduction of the multiple reflections leads to a particular increase in the homogeneity of the brightness distribution.

The invention also relates to an interior light element for a motor vehicle or for a motor vehicle component with a light guide according to one of the preceding claims. Especially for interior lighting elements, a homogeneous distribution of brightness is particularly desirable since they are generally arranged particularly close to a viewer, which is why inhomogeneous brightness distributions are particularly noticeable and disturbing.

The invention also relates to a motor vehicle with a light guide according to one of the described embodiments or with an inner light element of the last paragraph.

The features and feature combinations mentioned above in the description, as well as the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figures, can be used not only in the respectively specified combination but also in other combinations or in isolation, without the frame to leave the invention. Thus, embodiments of the invention are to be regarded as encompassed and disclosed, which are not explicitly shown and explained in the figures, however, emerge and can be produced by separated combinations of features from the embodiments explained. Embodiments and combinations of features are also to be regarded as disclosed, which thus do not have all the features of an originally formulated dependent or independent claim.

Embodiments of the invention are explained in more detail below with reference to schematic drawings. Showing:

1 a light guide with a fastening means, as known from the prior art, in a schematic sectional view in a main light propagation direction;

2 an exemplary embodiment of a light guide according to the invention with a fastening means in a schematic sectional view in the main light propagation direction;

3 a second exemplary embodiment of a light guide in a schematic sectional view perpendicular to the main light propagation direction;

4 a third exemplary embodiment of a light guide according to the invention with a fastening means in a schematic sectional view perpendicular to the main light propagation direction and

5 a fourth exemplary embodiment of a light guide with a fastening means in a schematic sectional view in the main light propagation direction.

Identical and functionally identical elements are provided in the different figures with the same reference numerals.

In 1 For example, an optical fiber for an interior or exterior light member of a motor vehicle according to the prior art is shown schematically in a sectional view in a main light propagation direction along the light guide. The light guide 1 In this case, it extends mainly in an x-direction, which also corresponds to the main light propagation direction, and along which a light 2 through the light guide 1 is directed. The light guide 1 in this case has a fastener 3 which is present in the form of a pin. The light guide 1 here has a light exit surface 4 on, on which light 2 from the inside of the light guide 1 as light 2 ' in an environment of the light guide 1 exit. The fastener 3 is here at one of the light exit surface 4 different outer surface 5 formed. The outer surface 5 and thus the fastener 3 lies in the example shown, the light exit surface 4 diametrically opposite. Accordingly, the light becomes 2 inside the light guide 1 on the geometry of the fastener 3 broken several times, what s the fastener 3 opposite side (in the present case in the negative x-direction opposite) to an increased exit of the light 2 ' in the environment of the light guide 1 leads. Thus, at the light exit surface 4 an inhomogeneous brightness distribution exists.

In 2 Now, a first exemplary embodiment of a light guide according to the invention is shown. The light guide 1 is here in a sectional view analogous to that in 1 shown light guide 1 shown schematically. Again, this is the fastener 3 designed as a pin and from one of the light exit surface 4 opposite, here diametrically opposite outer surface 5 formed. However, this is a core area 6 of the light guide 1 made of a first material having a first refractive index and a cladding layer 7 of the light guide 1 of a second material having a smaller second refractive index than the first one. It is also the fastener 3 from this second material. The coat layer 7 encases the core area 6 along the main light propagation direction present completely (see. 4 ). The coat layer 7 and the fastener 3 are made in one piece in this example. It can also be the entire light guide 1 including sheath layer 7 and core area 6 and the fastener 3 be made in one piece. This can be z. B. be realized by an injection molding process.

Because between the cladding layer 7 and the core area 6 now a boundary layer 8th is present, which is independent of the fastener 3 is designed, and in the present straight line, the light 2 inside the light guide 1 at this boundary layer 8th reflected. Multiple reflections on the fastener 3 which is determined by the geometry of the fastener 3 are conditional account for that. This is at the light exit surface 4 achieves a homogeneous or substantially homogeneous brightness distribution. In an alternative embodiment, the cladding layer 7 also at the light exit surface 4 be omitted (cf. 3 ). Accordingly, the cladding layer 7 then only on one or more of the light exit surface 4 different outer surfaces 5 arranged.

In 3 a third exemplary embodiment of a light guide is shown, in this case in a schematic sectional view perpendicular to the main light propagation direction. In the example shown, the light guide 1 at opposite sides of the light guide in the y-direction 1 arranged fasteners 3 on. These are together with the cladding layer 7 made of the second material. In the core area 6 however, the light guide is 1 also made here from the first material. Because the cladding layer 7 not here on the light exit surface 4 extends here especially a lot of light 2 ' in the environment of the light guide 1 issued. At the same time, through the boundary layer 8th a multiple reflection on the fasteners 3 avoided, so that the brightness distribution at the light exit surface 4 is homogeneous.

In 4 a third exemplary embodiment of a light guide is shown schematically and also in a sectional view perpendicular to the main light propagation direction. Unlike the in 3 illustrated embodiment, the jacket surrounds 7 the core area 6 now complete, so that the boundary layer 8th around the core area 6 is trained. Again, by the cladding layer 7 the multiple reflection at the fasteners 3 prevented and thus at the light exit surface 4 achieved a homogeneous light distribution. This embodiment is particularly easy to manufacture.

In 5 Fig. 12 is a schematic illustration of a fourth exemplary embodiment of a light guide in a sectional view parallel to the main light propagation direction. In this example, the cladding layer is 7 along the main light propagation direction of the light guide 1 present, and only at one of the light exit surface 4 different outer surface 5 of the light guide 1 , Between the cladding layer 7 and the core area 6 Here is another layer 9 arranged. This has a refractive index which is between the refractive index of the first and the second material of the core region 6 and cladding layer 7 lies. In the example shown, the further layer is 9 also between the light exit surface 4 and the core area 6 of the light guide 1 arranged. However, this does not necessarily have to be the case. Of course, the cladding layer 7 also in the present representation on the lying in the negative y direction underside of the light guide 1 are located, so the core area 6 then perpendicular to the main light propagation direction first of the further layer 9 and then from the cladding layer 7 is surrounded. Through the further layer 9 the optical reflection properties are further optimized so that at the light exit surface 4 a homogeneous brightness distribution is achieved.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102010050511 A1 [0003]
• EP 2775197 A1 [0004]
• US 2014/0029292 A1 [0005]

Claims (9)

Optical fiber ( 1 ) for an interior or exterior light element of a motor vehicle, having - a light exit surface ( 4 ), from which light ( 2 . 2 ' ) from the inside of the light guide ( 1 ) in an environment of the light guide ( 1 ) is radiatable; and - at least one fixed to the light guide ( 1 ) connected fastening means ( 3 ); the light guide ( 1 ) a core area ( 6 ) of a transparent first material having a first refractive index, and the core region ( 6 ) is designed to light ( 2 . 2 ' ) in a main light propagation direction along the light guide (FIG. 1 ), characterized in that the fastening means ( 3 ) is made partially or entirely of a second material having a smaller second refractive index than the first. Optical fiber ( 1 ) according to claim 1, characterized in that the fastening means ( 3 ) comprises a hook and / or an eyelet and / or a latching element and / or a pin and / or a pin and / or a clamp and / or a recess. Optical fiber ( 1 ) according to one of the preceding claims, characterized in that the light guide ( 1 ) in a surrounding area of the fastener ( 3 ) at one of the light exit surface ( 4 ) different outer surface ( 5 ) of the light guide ( 1 ) a cladding layer ( 7 ) of the second material. Optical fiber ( 1 ) according to claim 3, characterized in that the cladding layer ( 7 ) in the main light propagation direction continuously along the light guide ( 1 ) extends, and thereby in a sectional plane transverse to the main light propagation direction only on the one of the light exit surface ( 4 ) different outer surface ( 5 ) or only on one side and at least one further one of the light exit surface ( 4 ) different outer surface ( 5 ) of the light guide ( 1 ). Optical fiber ( 1 ) according to claim 3, characterized in that the cladding layer ( 7 ) in the main light propagation direction continuously along the light guide ( 1 ), and in a sectional plane transverse to the main light propagation direction, the core region (FIG. 6 ) of the light guide ( 1 ) completely surrounds. Optical fiber ( 1 ) according to one of the preceding claims, characterized in that between the fastening means ( 3 ) or the cladding layer ( 7 ) and the core area ( 6 ) of the light guide ( 1 ) another layer ( 9 ) is arranged from a material having a third refractive index, which is in particular smaller than the first and greater than the second refractive index. Optical fiber ( 1 ) according to one of the preceding claims, characterized in that the fastening means ( 3 ) in one piece with the light guide ( 1 ) is executed. Interior light element for a motor vehicle or for a motor vehicle component with a light guide ( 1 ) according to any one of the preceding claims. Car with a light guide ( 1 ) according to one of claims 1 to 7 or an inner luminous element according to claim 8.

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