LIGHTING DEVICE FOR A MOTOR VEHICLE

Abstract

A lighting device for a motor vehicle, has at least one light source, a flat light guide with an entry surface and at least one exit surface. At least one optical component is designed as an optical panel or optical film. The lighting device being configured so that the light generated by the at least one light source enters, at least in part, through the entry surface and into the light guide. The light entering through the entry surface exits, at least in part, from the at least one exit surface, and the light exiting the at least one exit surface of the light guide passes, at least in part, through the at least one optical component and/or is reflected by the at least one optical component. The flat light guide and/or the at least one optical component is made, at least in part, of silicone.

Claims

1. A lighting device for a motor vehicle, the lighting device comprising: at least one light source; a flat light guide with an entry surface and at least one exit surface, the entry surface being an end face-side surface of the light guide; at least one optical component that is designed as an optical panel or optical film, the lighting device being configured so that the light generated by the at least one light source enters, at least in part, through the entry surface and into the light guide, the light entering through the entry surface exits, at least in part, from the at least one exit surface, and the light exiting the at least one exit surface of the light guide passes, at least in part, through the at least one optical component and/or is reflected by the at least one optical component; and a housing at or in which the flat light guide and the at least one optical component are arranged, wherein the flat light guide and/or the at least one optical component are/is made of silicone, or the flat light guide and/or the at least one optical component includes silicone.

2. The lighting device according to claim 1, wherein the flat light guide and/or the at least one optical component are bendable.

3. The lighting device according to claim 1, wherein the flat light guide and/or the at least one optical component in the assembled state of the lighting device have at least one bend.

4. The lighting device according to claim 3, wherein the bending radius of the flat light guide is greater than three times a thickness of the light guide or is greater than four times the thickness of the light guide.

5. The lighting device according to claim 3, wherein the bending radius of the flat light guide is greater than 8 mm or greater than 12 mm.

6. The lighting device according to claim 1, wherein the light guide has structuring, wherein the light guide is configured so that the light propagating through the light guide is deflected, at least in part, by the structuring such that the light exits the light guide through the at least one exit surface.

7. The lighting device according to claim 1, wherein the at least one optical component has structuring, the optical component being configured so that the light exiting the light guide passes through the optical component.

8. The lighting device according to claim 1, wherein the at least one optical component has a reflective design, and wherein the optical component is configured so that the light exiting the light guide is reflected by the optical component.

9. The lighting device according to claim 1, wherein the light guide has a first exit surface and a second exit surface arranged opposite one another.

10. The lighting device according to claim 9, wherein the lighting device is configured so that light exiting the second exit surface of the light guide strikes the reflectively designed optical component is reflected by back to the second exit surface, and through the second exit surface at least partially re-enters the light guide before it exits from the first exit surface, and the light passing through another of the optical components.

11. The lighting device according to claim 1, wherein the at least one optical component or the reflectively designed optical component is connected to the light guide or connected thereto at one of the end-face sides of the light guide.

12. A method for manufacturing a lighting device according to claim 1, comprising: using an injection molding process to manufacture the light guide and/or the at least one optical component that is designed as an optical panel or optical film; introducing the light guide and the at least one optical component into the housing of the lighting device.

13. The method according to claim 12, wherein the structuring of the light guide and/or of the at least one optical component is produced during the injection molding process or wherein appropriate structuring of the injection mold takes place via a lithographic process or via laser machining.

14. The method according to claim 12, wherein the light guide and/or the at least one optical component are bent during the assembly of the lighting device.

15. The method according to claim 12, wherein the light guide and the optical component or the reflectively designed optical component are manufactured as a one-piece injection-molded part in which the light guide and the optical components adjoin one another in the longitudinal or transverse direction, during the introduction into the housing the optical component being folded over so that it rests on the at least one exit surface of the light guide.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

[0028] FIG. 1 shows an exploded view of an example of a lighting device according to the invention;

[0029] FIG. 2 shows a top view of a light guide and an optical component, connected thereto, of an example of a lighting device according to the invention;

[0030] FIG. 3 shows a side view of the light guide and the optical component of the lighting device according to FIG. 2;

[0031] FIG. 4 shows a view of the light guide corresponding to FIG. 3 and of the optical component of the lighting device according to FIG. 2, the folded-together state of the parts being indicated in this view;

[0032] FIG. 5 shows a perspective view of a plurality of adjacently situated light modules with an example of a lighting device according to the invention;

[0033] FIG. 6 shows a detail from FIG. 5 showing the example of a lighting device according to the invention;

[0034] FIG. 7 shows an exploded view of the lighting device according to FIG. 6;

[0035] FIG. 8 shows a schematic illustration of the bending of the light guide of the lighting device according to FIG. 6;

[0036] FIG. 9 shows a side view of the light guide of the lighting device according to FIG. 6 in the bent state;

[0037] FIG. 10 shows a detail from FIG. 9; and

[0038] FIG. 11 shows a side view of the light guide of the lighting device according to FIG. 6 in the bent state, the structuring being shown in an oversized illustration for explanation.

DETAILED DESCRIPTION

[0039] The lighting device depicted in the figures comprises a light source that is designed as a light-emitting diode (LED), or multiple light sources that are designed as light-emitting diodes (LEDs). FIG. 1 illustrates a circuit board 1 on which the light sources designed as light-emitting diodes are situated. The multiple light-emitting diodes may also have different colors, for example in order to implement a twofold function or a threefold function. These functions may be, for example, a navigation light, a daytime running light, and a travel direction indicator, or a navigation light, a daytime running light, and an autonomous driving function, wherein the autonomous driving function requires a cyan color.

[0040] The lighting device further comprises a flat light guide 2 having an entry surface 3 and a first and a second exit surface 4, 5 (see FIGS. 1, 3, and 7). The entry surface 3 is designed as an end face-side surface of the light guide 2, whereas the exit surfaces 4, 5 are designed as a front side and a rear side of the light guide 2.

[0041] The lighting device further comprises a first optical component 6, designed as an optical panel, situated in front of the first exit surface 4 of the light guide 2, and a second optical component 7, designed as an optical panel, situated in front of the first optical component 6 (see FIGS. 1 and 7). The second optical component 7 is optional and may also be omitted. Alternatively, the optical components 6, 7 may be designed as optical films. The at least one optical component 6, 7 may have structuring, which may contribute to the diffusion and homogenization of the light emitted from the lighting device.

[0042] The lighting device further comprises a housing 8 in which the at least one light source 1, the light guide 2, and the optical components 6, 7 may be at least partially accommodated (see FIGS. 1, 6, and 7). The housing 8 may have a two-part design for simplified installation of the optical components, and may have a rear and a front housing part 8a, 8b (see FIGS. 1 and 7). The light guide 2 and the optical components 6, 7 may then be positioned between these housing parts 8a, 8b, and may be held and fixed when the two housing parts 8a, 8b are joined together. The housing parts 8a, 8b may be latched together, or screwed or welded from the rear side.

[0043] The rear housing part 8a may have a rear wall having a reflective design, at least in part (see FIG. 7). Alternatively, a reflectively designed optical component 9 may be provided (see FIG. 1) which, for example, is a reflective optical film having a white surface in order to diffusely reflect the light. The reflectively designed optical component 9 is bent at the edges. The second exit surface 5 of the light guide 2 and also the lateral edges of the light guide 2 are thus covered in order to ideally reflect exiting light back into the light guide 2.

[0044] The lighting device further comprises an optical component 10, designed as an outer panel, that is illuminated as homogeneously as possible by the light exiting the light guide 2 (see FIGS. 1 and 7). The outer panel may be used as an illuminated exit surface of the lighting device. There is an option for the optical component 10, designed as an outer panel, to be provided as a two-component part in a one-piece design with the front housing part 8b.

[0045] During operation of the lighting device, light emitted from the light sources is coupled in to the end face-side entry surface 3 of the light guide 2. A portion of the coupled-in light directly exits the first exit surface 4, at the right in FIG. 1, and leaves the lighting device after passing through the optical components 6, 7 and the outer panel. In addition, a portion of the light propagating in the light guide 2 exits the second exit surface 5 of the light guide 2 and strikes the reflectively designed optical component 9. The light is reflected from the optical component 9 back to the second exit surface 5, so that, at least in part, it enters through the second exit surface 5 and back into the light guide 2 before it exits the first exit surface 4 and leaves the lighting device through the optical components 6, 7 and the outer panel.

[0046] The light guide 2 and/or the optical components 6, 7, 9, 10 may be made of or may include silicone. The light guide 2 and/or the optical components 6, 7, 9, 10 may in particular be manufactured using an injection molding process. Due to the design of the light guide 2 and/or the optical components 6, 7, 9, 10 as silicone components, the lighting device may have a bent design (see FIG. 7). In addition, the manufacture may be simplified due to the fact that the manufacture of various parts may be combined.

[0047] FIGS. 2 through 4 show an example in which the light guide 2 and the reflectively designed optical component 9 are manufactured as a one-piece injection-molded part. In the unmounted state, the optical component 9 adjoins the light guide 2 (see FIG. 3). The optical component 9 has a first section 9a, which in the mounted state covers the second exit surface 5 of the light guide 2. The optical component 9 also has three second sections 9b, which in the mounted state rest against the side faces 2a of the light guide 2 not used as an entry surface 3, and cover them.

[0048] The connection region between the light guide 2 and the optical component 9 has two bent edges 11 that simplify folding over the optical component 9 onto the light guide 2. FIG. 4 shows in dashed lines the optical component 9 folded onto the light guide 2. In the folded state, the optical component 9 rests against the second exit surface 5 and the side faces 2a of the light guide 2 not used as an entry surface 3, and effectively covers them.

[0049] The lighting device may be used as a single light module for a signal function, or as part of an arrangement of multiple light modules for a signal function. Multiple such light modules placed side by side, also with partial overlapping, may together form a signal function. This may be, for example, a daytime running light or a travel direction indicator or also a combination of both functions, in particular when the light sources have a first light-emitting diode with the color white and a second light-emitting diode with the color yellow.

[0050] FIG. 5 shows a corresponding example with an arrangement of multiple light modules, of which the third example of a lighting device according to the invention is the middle light module 12 which is used as a bent corner element. A signal function that is designed with multiple flat light modules, as an illuminating area, may be guided around the corner of a lighting device designed as a taillight, for example, and the illuminating area may continue in the side region of the taillight. Due to the design of the light guide 2 and/or of the optical components 6, 7, 9, 10 as silicone components, the light module 12 used as a corner element and illustrated in FIG. 6 and in the exploded view in FIG. 7 may also be provided with a comparatively homogeneously illuminating outer panel.

[0051] The light guide 2 and/or the optical components 6, 7, 9, 10 as a planar implementation may be manufactured as injection-molded parts, and brought into the bent shape only when the lighting device and the light module 12 are put together, as indicated in FIG. 8 for various bending radii.

[0052] Large bending radii are not critical, whereas for excessively small bending radii there is a risk that undesirable outcoupling of the light from the light guide 2 may occur, which would result in disturbance of the homogeneity of the illuminated outer panel 10 of the lighting device. It may be provided that the bending radius of the light guide 2 is greater than three times the thickness of the light guide 2, preferably greater than four times the thickness of the light guide 2. Undesirable outcoupling of the light from the light guide is avoided with radii of this magnitude.

[0053] For example, it may be provided that the bending radius of the light guide 2 is greater than 8 mm, preferably greater than 12 mm. This ensures that for wall thicknesses or thicknesses of the light guide 2 between 2 mm and 3 mm, which are typically provided for flat light modules, no undesirable outcoupling of the light from the light guide 2 occurs. It is certainly possible to use larger radii, for example radii between 15 mm and 25 mm, in order to create an attractive geometric course in the corner region, and so that an excessively sharp or pointed corner is not provided.

[0054] The optical components 6, 7, 9, 10 and the housing parts 8a, 8b may have the same curvature or the same bend as the light guide 2 (see FIG. 7).

[0055] On its second exit surface 5, the light guide 2 bears structuring 13 that is used as outcoupling optics. Alternatively or additionally, it may be provided that structuring, is also provided on the first exit surface 4. For the homogeneous illumination that is to be produced in flat light modules, it is meaningful for the optics to be designed as micro-optics with sizes smaller than 200 m, in particular smaller than 100 m. The structuring 13 may be designed in the light guide 2 either as a recessed optical structure, or as a concave, elevated, or convex structure.

[0056] As an example, FIG. 11 shows structuring 13 designed as a recessed optical structure with small planar surfaces 14 between the individual optics. The distribution of the optics over the exit surface 5 of the light guide 2 varies, and is suitably selected in order to achieve the desired homogeneous illumination of the optical component 10 used as an outer panel.

[0057] It may be provided that the structuring of the light guide 2 and/or of the at least one optical component 6, 7 is produced during the injection molding process. Appropriate structuring of the injection mold may take place via a lithographic process or via laser machining.

[0058] For a lithographic process, for example UV lithography or laser interference lithography, a planar master optic is produced, from which a thin nickel shim is then galvanically molded. The nickel shim is either inserted directly into a mold, or after it is molded it is galvanically further built up to form a thicker mold insert.

[0059] Also, direct laser machining of the mold offers advantages with regard to time and costs for producing the structuring. Furthermore, in the event of possible repairs, the mold may be re-lasered, while for the lithographic method a completely new nickel shim or thicker electroplating must be produced. The laser machining of the mold is therefore the preferred method.

[0060] By use of laser machining of the mold, for micro-optics having an elevated or convex design, and also micro-optics having a recessed or concave design, on the mold side suitable structurings may be produced on the at least one exit surface 4, 5 of the light guide 2.

[0061] A corresponding design or adaptation may likewise be provided for the structurings of the optical components 6, 7, which may be designed as micro-optics or diffuser optics.

[0062] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.