LIGHTING DEVICE AND METHOD FOR PRODUCING A LIGHTING DEVICE

Abstract

The invention relates to a lighting device (10) with a flat light guide (12) which has a protective layer (18) directly connected to a light guide core (16) on its light exit side (30) at least in a visible area (32), into which light (24) from at least one light source (22) can be coupled via the light guide core (16) via at least one coupling-in side (20), and which has a coupling-out structure (28) on its rear side (26) opposite the light exit side (30), which structure is set up to deflect light (24), as a result of which the deflected light (24) can be coupled into the light guide core (16) via at least one coupling-in side (20).

(24) emerges from the light guide (12) into the environment via the light exit side (30), and with a housing (14) which covers the rear side (26) at least in overlap with the entire visible area (32) of the light guide (12) on a side facing away from the light exit side (30) and is connected to the light guide (12) in a dust-proof and contamination-proof manner.

Claims

1. Lighting device (10), comprising: a flat light guide (12), which at its light emission side (30) at least in one viewing area (32) has a protective layer (18) directly connected to an optical fiber core (16), in which the optical fiber core (16) is connected via at least one coupling side (20), light (24) can be coupled in from at least one light source (22), and which is located on the opposite side (30) to the light emission side rear side (26) has a decoupling structure (28) which is arranged to deflect light (24), as a result of which the deflected light (24) emerges from the light guide (12) into the environment via the light exit side (30), and a housing (14), which covers the rear side (26) at least in overlap with the entire visible area (32) of the light guide (12) on a side facing away from the light exit side (30) and is connected to the light guide (12) in a dust-proof and dirt-proof manner.

2. Lighting device (10) according to claim 1, wherein the protective layer (18) provides an outer surface of the lighting device (10).

3. Lighting device (10) according to claim 1, wherein the light guide (12) is formed in one piece.

4. Lighting device (10) according to claim 1, wherein the protective layer (18) is provided by a film and/or by a film composite and/or by a protective coating.

5. Lighting device (10) according to claim 4, wherein the film or the film composite comprises a touch-sensitive layer which is covered by a protective film, in particular in the film composite towards the light emission side (30).

6. Lighting device (10) according to claim 4, wherein the film or the film composite is back-molded with the light guide core (16).

7. Lighting device (10) according to claim 1, wherein the decoupling structure (28) is provided by a raised or recessed microstructure of a rear surface of the light guide, in particular the decoupling structure (28) is molded onto the rear surface (26) and/or introduced by embossing on the rear surface (26).

8. Lighting device (10) according to claim 1, wherein the housing (14) is laser-welded and/or clipped and/or bonded and/or ultrasonically welded to the light guide (12).

9. Lighting device (10) according to claim 1, wherein the housing (14) has an inner side (15) facing the viewing area, which is partially absorbing or diffusely reflecting or scattering or weakly reflecting.

10. Method for producing a lighting device (10) according to claim 1, wherein the light guide (12) is produced in one piece from the light guide core (16) and the protective layer (18), the protective layer (18) being arranged on the light exit side (30) of the light guide (12) at least in the viewing area (32). and in which the housing (14) covers the rear side (26) of the light guide (12) towards the side facing away from the light exit side (30), at least in overlap with the entire viewing area (32). (32) of the light guide (12).

Description

SHORT FIGURE DESCRIPTION

[0025] The drawing shows in:

[0026] FIG. 1 a schematic sectional view of an illumination device with a one-piece light guide, into which light can be coupled from a light source via a coupling-in side, whereby the light can be deflected by a coupling-out structure of the light guide, as a result of which the deflected light can emerge from the light guide via a viewing area on a light exit side of the light guide, whereby arear side of the light guide opposite the light exit side is protected from dust and soiling from the outside by a housing, at least in the viewing area;

[0027] FIG. 2 a schematic sectional view of the lighting device as shown in FIG. 1, with soiling arranged in the viewing area on the light exit side of the light guide; and

[0028] FIG. 3 a schematic sectional view of the lighting device as shown in FIG. 1, with soiling arranged on the rear of the light guide.

[0029] Elements with the same function are assigned the same reference symbols in the figures.

[0030] FIGS. 1 to 3 each show a lighting device 10 which is designed in particular to be used in a vehicle, especially a motor vehicle, in an interior area. The lighting device 10 comprises a one-piece flat light guide 12 and a housing 14, which covers the light guide 12 at least in some areas. The light guide 12 comprises a light guide core 16 and a protective layer 18 arranged directly on the light guide core 16. In the present case, the protective layer 18 is a protective coating and/or a film composite and/or a single-layer film. In particular, the film composite can comprise a touch-sensitive film which is set up to receive a user input represented by a touch from a person. Alternatively or additionally, the film composite may comprise a protective film which is designed to protect the light guide core 16 and/or the touch-sensitive film from damage. For this purpose, the protective film can be arranged in the film composite on a side of the touch-sensitive film facing away from the optical fiber core 16. In particular, the film composite can be provided from several layered films, one of which can be designed as a protective film. The touch-sensitive film can comprise at least one transparent or partially transparent conductor track for electrical functions, in particular touch sensitivity.

[0031] In order to be able to form the flat light guide 12 in one piece, the protective coating can be applied as a protective layer 18 by spray coating to the light guide core 16 for providing the light exit side 30 of the light guide 12. If the film composite or the single-layer film is provided as a protective layer 18, the light guide core 16 can be sprayed onto the film composite or the single-layer film, in particular as part of an injection molding process. In this way, loose elements of the light guide 12 can be avoided.

[0032] The planar light guide 12 has at least one coupling side 20, via which light 24 from at least one light source 22 can be coupled into the light guide 12.

[0033] In particular, the light 24 is fed from the light source 22 into the light guide core 16 of the light guide 12. The injected light 24 is propagated within the optical fiber core 16. For this purpose, the light 24 can be guided within the light guide core 16 by total internal reflection. To decouple the light 24 from the optical fiber core 16, the light 24 must be redirected. In order to be able to decouple light 24 from the light guide core 16 and furthermore from the light guide 12, the light guide 12 has a decoupling structure 28 on its rear side 26. The decoupling structure 28 on the rear side 26 of the light guide 12 is kept free of the protective coating. In the present case, the decoupling structure 28 is characterized by protrusions are provided on the surface of the light guide 12 at the rear side 26. For arranging the decoupling structure 28 on the rear side 26 of the light guide 12, the protrusions can be formed on the rear side 26 by an injection molding process or the protrusions can be formed on the rear side 26 by an embossing process when the light guide core 16 is provided. In this way, the projections and the optical fiber core 16 are formed from the same material. Alternatively or in addition to providing the decoupling structure 28 by projections, the decoupling structure 28 can be provided by indentations on the rear side 26 of the light guide 12. In particular, these depressions can be provided by embossing the light guide core 16 on the rear side 26. In the present case, the rear side 26 of the light guide 12 is provided by the light guide core 16.

[0034] As a result of the deflection of the light 24 in the light guide core 16 via the decoupling structure 28, the light 24 can emerge from the light guide 12 via a light exit side 30 of the planar light guide 12, in particular in a viewing area 32. At least over the entire viewing area 32, the flat light guide 12 is covered outwardly at its rear side 26 by the housing 14, in particular in a direction facing away from the light exit side 30 starting from the rear side 26. A function of the housing 14 is explained below in particular in connection with FIGS. 2 and 3, in which soiling 34 is arranged on respective surfaces of the light guide 12.

[0035] FIG. 2 shows how the contamination 34 is arranged on the light exit side 30 of the flat light guide 12. In this case, the contamination 34 is a fingerprint. The soiling 34 on the light exit side 30 of the light guide 12 causes a deflection of the light 24 and consequently an exit of the light 24 at the rear side 26 of the light guide 12. Due to a not highly reflective, in particular not specularly reflective design of the inside of the housing 15 in the viewing area 32, the light 24 exiting from the light guide 12 at the rear side 26 is partially absorbed and scatteringly reflected by the inside of the housing 15 in the viewing area 32.

[0036] As a result, the light 24 emerging from the light guide 12 at the rear side 26 after its partial absorption and scattering on the inside of the housing 15 cannot be clearly perceived by an observer viewing the light guide 12 from the light exit side 30 and, in particular, cannot be assigned to the soiling 34. The inside of the housing 15 thus makes it possible for scattered light due to soiling 34 on the light-emitting side 30 of the light guide 12 not to be perceived as brightly illuminated areas.

[0037] FIG. 3 shows soiling 34 on the rear side 26 of the flat light guide 12. In the present case, the soiling 34 is a fingerprint. The soiling 34 on the rear side 26 of the light guide 12 can cause a deflection of the light 24 in the light guide core 16, whereby scattered light on the light exit side 30 caused by the soiling 34 could escape from the light guide 12 and, in particular, the soiling 34 is thus recognizable as a bright area. The housing 14 is designed to protect the rear side 26 of the light guide 12 from soiling 34 in that the housing 14 encloses the rear side 26 in a dust-proof manner, at least in overlap with the viewing area 32. in order to prevent soiling 34 from accumulating on the rear side 26 of the light guide 12. For this purpose, the housing 14 can be laser-welded or otherwise connected to the light guide 12.

[0038] Due to the non-highly reflective, in particular non-specularly reflective design of the inner side 15 of the housing in the viewing area 32, the light 24 emerging from the light guide 12 at the rear side 26 is partially absorbed and scattered by the inner side 15 of the housing in the viewing area 32. As a result, the light 24 emerging from the light guide 12 at the rear side 26 cannot be clearly perceived by an observer viewing the light guide 12 from the light exit side 30 after its partial absorption and scattering on the inside of the housing 15 and, in particular, cannot be assigned to the soiling 34. The inside of the housing 15 thus makes it possible for scattered light due to soiling 34 on the light-emitting side 30 of the light guide 12 not to be perceived as brightly illuminated areas.

[0039] Due to its particularly compact design, the lighting device 10 described above makes it possible to save on vehicle installation space. Furthermore, the lighting device 10 enables costs to be saved compared to conventional lighting devices, as particularly few components are required for the lighting device 10 and, in particular, a cover lens can be dispensed with.

[0040] The lighting device 10 comprises a directly accessible flat light guide 12. In the lighting device 10, it is intended that the rear side 26 of the light guide 12 should be protected. The decoupling structure 28 on the rear side 26 of the light guide 12 is designed such that it decouples the light 24 from the light guide 12 directly in the direction of a viewer. The rear side 26 of the light guide 12 can be protected from dust and fingerprints as soiling 34 by the housing 14.

[0041] Fingerprints or dust on the rear side 26 of the flat light guide 12 scatter light 24 incident on the fingerprint or on the dust in the direction of the light-emitting side 30 of the light guide 12. This makes a luminous fingerprint or luminous dust visible to an observer. In order to avoid the accumulation of dust and fingerprints on the rear side 26 of the light guide 12, the flat light guide 12 and the housing 14 are welded and/or glued together in particular.

[0042] The front of the flat light guide 12 must be protected from scratches. The protective coating can be provided to protect the light-emitting side 30 of the light guide 12 from scratches. In order to avoid changing the optical properties of the decoupling structure 28, the rear side 26 of the light guide 12 is kept free of paint.

[0043] Scratches on the light-emitting side 30 of the light guide 12 can make polished, high-quality surfaces appear inferior and cause significant light losses in the light guide 12. In the present case, only the light-emitting side 30 of the light guide 12 is painted. For this purpose, the protective coating can be applied to the light guide core 16 after a welding process of welding the housing 14 to the light guide 12. By means of the protective coating 18, the light guide 12 can be protected from scratches on its light-emitting side 30 and, if necessary, also on its light guide edges.

[0044] Overall, the invention shows how a lighting module can be provided with the flat light guide 12 and without a cover lens.

REFERENCE LIST

[0045] 10 Lighting device [0046] 12surface light guide [0047] 14 Housing [0048] 15 Inside of housing [0049] 16 Fiber optic core [0050] 18 Protective layer [0051] 20 Coupling side [0052] 22 Light source [0053] 24 Light [0054] 26 Back [0055] 28 Decoupling structure [0056] 30 Light emission side [0057] 32 Visibility range [0058] 34 Pollution