Lighting Device for a Motor Vehicle, and Method for Producing Such a Lighting Apparatus

Abstract

A lighting apparatus for a motor vehicle comprises a light source to produce light, a planar light guide into which the light produced by the light source enters at least partially, the light guide having an output surface from which the light emerges at least partially, and a plurality of microstructure elements arranged on the output surface of the light guide to deflect the light emerging from the output surface of the light guide.

Claims

1. A lighting apparatus for a motor vehicle, comprising a light source to produce light; a planar light guide into which the light produced by the light source enters at least partially, the light guide having an output surface from which the light emerges at least partially; and a plurality of microstructure elements arranged on the output surface of the light guide to deflect the light emerging from the output surface of the light guide.

2. The lighting apparatus of claim 1, wherein the microstructure elements allow more than 80% of the light to emerge from the output surface.

3. The lighting apparatus of claim 1, wherein the microstructure elements allow more than 90% of the light to emerge from the output surface.

4. The lighting apparatus of claim 1, wherein the microstructure elements have a center-to-center distance varying stochastically between 0.03 mm and 0.20 mm.

5. The lighting apparatus of claim 1, wherein an incident surface of the light guide through which the light produced by the light source enters is an end face of the light guide.

6. The lighting apparatus of claim 1, wherein the light guide has a curved or angled light feed section for the light produced by the light source and/or input optics for the light produced by the light source.

7. The lighting apparatus of claim 1, wherein a thickness of the light guide decreases in a propagation direction of the light in the light guide, starting from the incidence surface, the propagation direction being perpendicular to the output surface.

8. The lighting apparatus of claim 1, wherein the light source comprises a light emitting diode or a laser diode.

9. The lighting apparatus of claim 1, wherein the microstructure elements comprise first microstructure elements and second microstructure elements designed differently from the first microstructure elements such that the first and second microstructure elements form a background pattern, a dividing line, text, and/or a logo.

10. The lighting apparatus of claim 1, wherein the microstructure elements are a component of an injection molded part.

11. The lighting apparatus of claim 1, further comprising a plurality of planar light guides each having an output surface.

12. The lighting apparatus of claim 1, wherein the lighting apparatus is a tail light, a brake light, a turn signal light, a daytime running light, or an interior light of the motor vehicle.

13. The lighting apparatus of claim 1, wherein the light guide is flat or curved.

14. A method for producing the lighting apparatus of claim 1, comprising: producing the microstructure elements by injection molding, together with the light guide.

15. The method of claim 14, further comprising: producing templates of the microstructure elements by a lithographic process; and transferring the templates by an electroplating process to an injection molding tool used to carry out the injection molding.

16. The lighting apparatus of claim 1, further comprising: a first substrate that serves as the light guide; and a second substrate containing the microstructure elements, wherein the first and second substrates are joined to one another by interlocking or by welding such that the microstructure elements abut the output surface of the light guide.

17. The lighting apparatus of claim 16, wherein the the first and second substrates are flat or curved.

18. A method for producing the lighting apparatus of claim 16, comprising: producing the microstructure elements by injection molding, together with the first and second substrates.

19. The method of claim 18, further comprising: producing templates of the microstructure elements by a lithographic process; and transferring the templates by an electroplating process to an injection molding tool used to carry out the injection molding.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The disclosure is explained in more detail below with reference to the attached drawings. The drawings show in:

[0029] FIG. 1 in schematic form a side view of a first implementation of a lighting apparatus, according to the disclosure, with a first implementation of a light guide;

[0030] FIG. 2 in schematic form a side view of the lighting apparatus, according to FIG. 1, with an exemplary beam path of the light coming from a light source;

[0031] FIG. 3 a view, according to the arrow III in FIG. 1;

[0032] FIG. 4 in schematic form a side view of a second implementation of a lighting apparatus, according to the disclosure, with the first implementation of a light guide;

[0033] FIG. 5 in schematic form a perspective view of a third implementation of a lighting apparatus, according to the disclosure, with a second implementation of a light guide;

[0034] FIG. 6 in schematic form a perspective view of a third implementation of a light guide of a lighting apparatus, according to the disclosure;

[0035] FIG. 7 in schematic form a perspective view of a fourth implementation of a light guide of a lighting apparatus, according to the disclosure;

[0036] FIG. 8 in schematic form a front view of a fourth implementation of a lighting apparatus, according to the disclosure, with a plurality of light guides of the first implementation of a light guide;

[0037] FIG. 9 in schematic form a front view of a fifth implementation of a lighting apparatus, according to the disclosure, with a plurality of light guides of the third implementation of a light guide;

[0038] FIG. 10 in schematic form a front view of a sixth implementation of a lighting apparatus, according to the disclosure, with a plurality of light guides of the fourth implementation of a light guide;

[0039] FIG. 11 in schematic form a front view of a seventh implementation of a lighting apparatus, according to the disclosure;

[0040] FIG. 12 in schematic form a side view of an eighth implementation of a lighting apparatus, according to the disclosure;

[0041] FIG. 13 in schematic form a side view of the lighting apparatus, according to FIG. 12, with an exemplary beam path of the light coming from a light source;

[0042] FIG. 14 in schematic form a side view of the lighting apparatus, according to FIG. 12, in an unassembled state;

[0043] FIG. 15 in schematic form a perspective view of a detail of the lighting apparatus, according to FIG. 1.

DETAILED DESCRIPTION

[0044] Identical or functionally identical parts are provided with the same reference numerals and symbols in the figures.

[0045] FIG. 1 to FIG. 3 and FIG. 15 show the implementation of a lighting apparatus of the present disclosure, comprising a light source 1 and a light guide 2. As can be seen in FIG. 3, the light source 1 has a plurality of light emitting diodes 3.

[0046] The light guide 2 is designed as a flat panel, where the light 4, coming from the light emitting diodes 3, is injected into an end face, serving as an incidence surface 5. In FIG. 1 and FIG. 2, the right side surface of the light guide 2 serves as an output surface 6 for the light 4.

[0047] It is quite possible to inject the light 4 into another narrow side of the light guide 2, for example, into the lower end face in FIG. 1 and FIG. 2 or into the right or left side surface in FIG. 1 and FIG. 2.

[0048] Furthermore, the lighting apparatus also comprises a plurality of microstructure elements 7 on the output surface 6 of the light guide 2. In FIG. 1 and FIG. 2 the microstructure elements 7 are indicated by a dashed line. The center to center distance between adjacent microstructure elements 7 can be less than 0.1 mm. As a result, it can be achieved that the microstructure optics, formed by the microstructure elements 7, can no longer be resolved as a structure when viewed with the human eye, so that the output surface 6 appears diffuse.

[0049] In FIG. 15 the microstructure elements 7 are not shown true to scale, but rather are significantly enlarged. The illustrated microstructure elements 7 have in each case the shape of a truncated cone, extending away from the output surface 6, wherein the microstructure elements 7 taper off, starting from the output surface 6. The base of the truncated cones may have a diameter of about 25 μm. The height of the truncated cones may also have a height of about 25 μm. The cone angle can be between 1° and 5°. The distance between the individual truncated cones on the incidence surface 3 may be between 30 μm and 150 μm; and, in particular, the distance can vary stochastically.

[0050] For physical reasons, the maximum of the distribution of light, emerging from the output surface 6, may not be oriented normal to the output surface 6 during extraction. Therefore, FIG. 4 shows a lighting apparatus, in which the light guide 2 is installed at an angle to the vertical. As a result, it can be achieved that the light 4 emerges horizontally from the output surface 6, so that the result is an improved perception and recognizability for a person, who is looking at the rear light of a vehicle from an upper field of vision and, thus, sees the output surface 6 as the surface, facing him.

[0051] FIG. 5 shows a light guide 2, the thickness of which changes in the direction of propagation of the light 4 in the light guide 2. In the area of the incidence surface 5, the light guide 2 has a comparable large first thickness d1 of, for example, 2 mm to 4 mm. This thickness d1 should be large enough to allow the light 4 to be fed through the incidence surface 5. A second thickness d2 in the end area of the light guide 2 is significantly smaller, so that the thickness d2 there is only about 1 mm to 2 mm.

[0052] FIG. 6 shows an example of a cylindrically curved light guide 2. FIG. 7 shows an example of a three dimensionally curved light guide 2.

[0053] FIG. 8 to FIG. 10 illustrate that a lighting apparatus, according to the disclosure, can have more than one light guide 2. In this case the light guides 2 can be arranged side by side or one above the other or offset from one another, in particular, also overlapping, in order to produce a desired appearance.

[0054] FIG. 11 shows an implementation of the lighting apparatus, in which a first plurality of microstructure elements is designed differently from a second plurality of microstructure elements, so that two different substructures 8a, 8b of the microstructure are formed. In this case the two substructures 8a, 8b, respectively, form structures of hexagons. The substructures 8a, 8b are, in particular, so different from one another that three-dimensional lighting effects are generated. In this case, the substructures 8a, 8b can be implemented, for example, by varying the height of the microstructure or, more specifically, the microstructure elements 7.

[0055] It is quite possible to use other geometric elements for the design of the substructures 8a, 8b, instead of a background pattern, consisting of hexagonal shapes. Such geometric elements may be, for example, rectangles, circles, triangles or honeycombs. As an alternative, it is also possible to implement other substructures, such as a dividing line and/or a text and/or a logo, instead of a repetitive background pattern.

[0056] The implementation of a lighting apparatus, according to FIG. 12 to FIG. 14, comprises a first and a second substrate 9, 10, through which the light 4 can pass. In this respect the first substrate 9 serves as a light guide 2, which has an incidence surface 5, which is formed as an upper end face in FIG. 13, for the light 4. On a surface 11, facing the first substrate, the second substrate 10 has microstructure elements 7 for extracting the light 4 from the output surface 6 of the first substrate 9.

[0057] In order to enable the extraction, the output surface 6 of the first substrate 9 and the surface 11 of the second substrate 10, on which the microstructure elements 7 are arranged, must abut each other. For this purpose, the two substrates 9, 10 are firmly joined to one another, for example, by interlocking or by welding. FIG. 14 shows the two substrates 9, 10 before the joining process.

[0058] If the output surface 6 of the first substrate 9, serving as the light guide 2, and the surface 11 of the second substrate 10, the surface being provided with the microstructure elements 7, lie flush against one another, then the light 4 emerges from the first substrate 9 through the output surface 6 and enters the second substrate 10 through the surface 11. Then the light 4 emerges from the second substrate 10 through the surface 12 opposite the surface 11 that is provided with the microstructure elements 7 (see FIG. 13).