Lighting device for vehicle

Abstract

The invention relates to a lighting device for a vehicle, comprising: a flat light guide (1) comprising opposite flat sides (2, 2 ') and a narrow side (3) connecting the flat sides; a plurality of microstructure elements (7) which are arranged on one flat side (2) of the flat light guide (1); a plurality of light sources (4) arranged on one of the narrow sides (3) of the flat light guide (1); a number of optical films (8, 9) adjoining a flat side (2 ') of the flat light guide (1), which flat side (16) emits light (6), have optical structures (10, 11) for light deflection, and at least one optical film (8) has a capillary compensation structure (14) on a flat side (15) on which light (6) enters.

Description

Technical Field

[0001] The present invention relates to a lighting device for a vehicle, comprising: a flat light guide, the flat light guide comprising opposite flat sides and narrow sides connecting the flat sides; a plurality of microstructure elements, the plurality of microstructure elements being arranged on a flat side of the flat light guide; a plurality of light sources, the plurality of light sources being arranged on one of the narrow sides of the flat light guide; and a certain number (plurality) of optical films adjacent to the flat side of the flat light guide for light coupling out, the optical films having an optical structure for light deflection on the flat side of the emitted light. Background Art

[0002] DE 10 2019 133 693 A1 discloses a lighting device for a vehicle, which has a flat light guide and a light source arranged on a narrow side of the flat light guide, the flat light guide having a plurality of microstructure elements on the flat side for light coupling out. These microstructure elements couple the light coupled into the flat light guide out in the main emission direction on the light coupling out surface thus formed. Thus, a relatively large luminous surface can be produced to produce a signal light.

[0003] A lighting device for a vehicle is known from WO 2019 / 227688 A1, which has a flat light guide and a light source arranged on a narrow side of the flat light guide, wherein the flat light guide has a plurality of microstructure elements for coupling out light on the light coupling-out surface thus formed. A certain number of optical films having an optical structure are adjacent to the light coupling-out surface, so that the coupled-out light is scattered as preset. At least one optical film may have a prismatic element or a diffusion element as an optical structure, which is arranged on the front flat side of the corresponding film in the light emission direction. However, the optical scattering effect of the optical film is limited in the following way: due to the planar arrangement of the smooth flat sides of the film with respect to each other or the film relative to the flat light guide, an undesirable capillary effect may occur due to electrostatic charges. This leads to interference spots in the light coupling-out surface of the lighting device. Summary of the invention

[0004] It is therefore an object of the present invention to further develop a lighting device for a vehicle having a flat light guide and at least one film adjoining the flat light guide in such a way that a uniform, planar emission of light is ensured in a simple manner.

[0005] To achieve this object, the invention is characterized in that, in conjunction with the preamble of claim 1 , at least one optical film has a capillary compensation structure on the flat side through which light enters.

[0006] A particular advantage of the present invention is that films or flat light guides or optical lenses, which each have an optical structure only on a single flat side and a smooth and / or polished surface on the opposite flat side, can be easily contacted or laminated without adversely affecting the light deflection generated by the optical structure. This is because the capillary compensation structure is constructed on the smooth flat side itself, which prevents local interference or adverse effects on the effect to be achieved with the help of the optical structure due to capillary action when the flat sides of different films or flat light guides or optical lenses facing each other are abutted. The capillary compensation structure according to the present invention avoids the undesirable capillary effect that occurs when two smooth flat sides are abutted, and on the other hand, does not affect the optical effect of the other flat sides provided with the optical structure. This advantageously achieves an improved, uniform planar light emission, wherein undesirable local optical effects, such as local brightness increase, are avoided.

[0007] According to a preferred embodiment of the invention, the capillary compensation structure is formed by microstructure elements, which preferably have different dimensions and / or lateral extensions than the microoptical elements of the optical structure. This advantageously ensures that, on the one hand, the smooth flat sides do not directly abut against each other and, on the other hand, the optical effect of the optical structure is not changed or intensified. Preferably, the microstructure elements of the capillary compensation structure are designed such that the light entering the film and / or the optical lens is homogenized or parallelized.

[0008] According to a further development of the present invention, a plurality of microstructure elements are arranged on a rear flat side opposite to the flat side of the flat light guide serving as a light coupling-out surface, wherein the microstructure elements serve as coupling-out elements. The microstructure elements deflect the coupled-in light so that the light is irradiated at a relatively steep angle onto the flat side of the flat light guide from which the light is emitted, thereby achieving the effect of coupling out the light. The light coupling-out surface is smooth and free of scattering elements. The light coupling-out surface can be constructed, for example, as a polished surface.

[0009] According to a further development of the invention, the reflective surface adjoins the rear side of the flat light guide, thereby ensuring that the light coupled out at the rear side of the flat light guide is reflected back into the flat light guide and can then be output on the light coupling-out side, thereby improving the light output.

[0010] According to a further development of the present invention, a two-part housing frame is provided for accommodating a flat light guide and a plurality of optical films. If necessary, a reflective surface and an optical lens are also provided as optical components. Both the rear frame portion and the front frame portion of the two-part housing frame have a U-shaped frame section having a wall thickness adapted to the optical components to be accommodated. The U-shaped frame sections are connected by a vacant section having a smaller wall thickness, so that a light source unit having a light source can be partially accommodated or fixed. Advantageously, a compact flat light guide module is provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Embodiments of the present invention will be described in more detail below with reference to the accompanying drawings.

[0012] Figure 1 A schematic side view of a first embodiment of a lighting device is shown, wherein the optical components are arranged at a distance from one another for illustration purposes, and

[0013] Figure 2 An exploded view of a second embodiment of the lighting device is shown. DETAILED DESCRIPTION

[0014] The lighting device according to the present invention can be configured as a rear light, for example, to produce a tail light or a brake light. Alternatively, the lighting device can also be used to produce a flash light or a daytime running light.

[0015] According to Figure 1 In the first embodiment of the present invention, the lighting device has a flat light guide 1 having opposite flat sides 2, 2' and narrow sides 3 connecting the flat sides. A plurality of light sources 4 arranged in a row or straight line on a circuit board 5 are arranged on one of the narrow sides 3.

[0016] The light source 4 emits light 6, which is coupled into the flat light guide 1 on one of the narrow sides 3 and is totally reflected on the opposite flat sides 2, 2'. In order to couple the coupled light 6 out on the front flat side 2' serving as a light coupling-out surface, the opposite rear flat side 2 has an optical structure with a large number of protrusions, which are configured as microstructure elements 7. The coupled light 6 impinging on the microstructure elements 7 is totally reflected so that it can be output on the front flat side 2' of the flat light guide 1.

[0017] The front flat side 2 ′ (optical coupling exit surface) is configured to be smooth, for example, the front flat side 2 ′ is configured to be polished.

[0018] In the present exemplary embodiment, the flat light guide 1 is of planar design, wherein the front flat side 2 ′ extends parallel to the rear flat side 2 .

[0019] A first optical film 8 and a second optical film 9 are adjacent to the light output side or light exit side of the flat light guide 1, and the first optical film and the second optical film respectively have an optical structure 10 or 11 on their flat sides from which light is emitted, for light deflection or light scattering. The optical structures 10 and 11 can be made, for example, as micro-optical structures with a plurality of microstructure elements 12. These microstructure elements can be configured, for example, as prismatic and / or concave and / or convex.

[0020] In front of the first optical film 8 and the second optical film 9 along the light emission direction, an optical lens 13 is arranged, which has opposite flat sides that are respectively smoothly constructed. For example, if the lighting device is set as a taillight or a brake light, the optical lens 13 can be colored, such as red.

[0021] In order to avoid the occurrence of undesirable capillary effects in the form of undesirable irregularities or unevenness or local spots of different colors on the light exit surface of the optical lens 13, the first optical film 8 has a capillary compensation structure 14 on the flat side facing the flat light guide 1. The capillary compensation structure 14 has the following characteristics: a plurality of ridges are distributed, preferably uniformly distributed, on the rear flat side 15 of the first film 8. This prevents the otherwise smooth rear flat side 15 of the first film 8 from being in planar contact with the smooth front flat side 2'.

[0022] For example, the capillary compensation structure 14 may have a plurality of microstructure elements or a diffractive optical mechanism.

[0023] The capillary compensation structure 14 is arranged relative to the optical structure 10 arranged on the front flat side 16 of the first film 8 so that the scattering effect of the light 6 caused by the optical structure 10 is not changed. Therefore, the capillary compensation structure 14 is designed so that the protuberance 29 is formed to prevent the first optical film 8 from being flat against the flat light guide 1. Therefore, the capillary compensation structure 14 causes the base surface 27 of the rear flat side 15 of the first optical film 8 (the protuberance 29 configured as a microstructure element protrudes from this base surface) to be arranged at a distance a from the smooth surface of the flat light guide 1 in the installed state or the plane 28 of the tip of the protuberance (the plane corresponds to the front flat side 2' of the flat light guide 1 in the installed state).

[0024] The capillary compensation structure 14 is designed in such a way that the brightness emitted by the lighting device does not change compared to an arrangement of the microstructure elements 7 as decoupling elements on the front flat side 2 ′ and the smooth rear flat side 15 of the first film 8 .

[0025] According to an alternative embodiment of the present invention, the capillary compensation structure 14 may have a scattering effect that cooperates with the optical structure 10 formed on the front flat side 16 of the first optical film 8 to achieve a predetermined scattering effect of the light 6 .

[0026] For example, the elevations 29 of the rear flat side 15 may be arranged offset with respect to the optical structures 10 or micro-optical elements 12 of the front flat side 16 of the optical film 8 .

[0027] Preferably, the elevations 29 of the capillary compensation structure 14 have a different size and / or lateral extension than the microstructure elements 7 arranged on the front flat side 16 of the first optical film 8 .

[0028] The microstructured element 7 serving as decoupling element is preferably formed by injection molding the flat light guide 1 .

[0029] The capillary compensation structure 14 can be applied, for example, by etching, laser or sandblasting, to the flat side on which the light is incident (rear flat side 15 ).

[0030] Alternatively, the capillary compensation structure 14 can be applied by etching or electroplating to the light incident flat side or rear flat side 15 of the first film 8 .

[0031] Figure 2 shows a flat light guide module, according to Figure 1 Different from the embodiment of the flat light guide module, the flat light guide module has a reflective surface 18 on the rear flat side 2 of the flat light guide 1. For example, the reflective surface 18 can be colored white on the entire surface and reflect the light coupled out on the rear flat side 2 of the flat light guide 1 back in the direction of the flat light guide 1, wherein the light enters the flat light guide 1 and is coupled out in the light emission direction by further total reflection or directly on the front flat side 2' of the flat light guide 1. In this way, the light output can be improved.

[0032] The optical components, namely the reflective surface 18, the flat light guide 1, the first optical film 8, the second optical film 9 and the optical lens 13 are held in a two-part housing frame 19, wherein the housing frame 19 is composed of a rear frame part 20 and a front frame part 21. Both frame parts 20, 21 have a U-shaped frame section 22, which overlap or abut against each other in the installed position of the frame parts 20, 21. The wall thickness w1 of the U-shaped frame section 22 is selected to be so large that the optical components 18, 1, 8, 9 and 13 abut against each other in a planar manner.

[0033] Furthermore, the rear frame part 20 and the front frame part 21 each have a cutout section 23 connecting the ends of the respective U-shaped frame section 22 for accommodating a light source unit 24 having a light source 4. The wall thickness w2 of the cutout section 23 is selected such that the light source unit 24 having a light source 4 can be arranged between the cutout sections 23 of the rear frame part 20 and the front frame part 21. The U-shaped frame sections 22 of the rear frame part 20 and the front frame part 21 have a fastening device 25 for preferably releasably fastening the rear frame part 20 to the front frame part 21.

[0034] A fastening device 26 is provided on the recess section 23 for fastening the light source unit 24 to the housing frame 19 .

[0035] The two-part housing frame 19 allows a compact design of the flat light guide module.

[0036] The light sources 4 are preferably designed as LED light sources, which are preferably arranged equidistantly along a row.

[0037] Reference numerals list

[0038] 1 Flat light guide

[0039] 2, 2' flat side

[0040] 3 Narrow side

[0041] 4 Light Source

[0042] 5 Circuit Board

[0043] 6 Light

[0044] 7 Microstructure elements

[0045] 8. The first optical film

[0046] 9 Second optical film

[0047] 10 Optical structure

[0048] 11 Optical structure

[0049] 12 Micro-optical components

[0050] 13 Light lenses

[0051] 14 Capillary compensation structure

[0052] 15 Rear flat side

[0053] 16 Front flat side

[0054] 17 Base

[0055] 18 Reflective surface

[0056] 19 Two-part housing frame

[0057] 20 Rear frame section

[0058] 21 Front frame section

[0059] 22 U-shaped frame sections

[0060] 23 Vacant Section

[0061] 24 Light source units

[0062] 25 Fastening device

[0063] 26 Fastening device

[0064] 27 Base

[0065] 28 Plane

[0066] 29 Uplift

[0067] a Distance

[0068] w1, w2 wall thickness

Claims

1. A lighting device for a vehicle, comprising: a flat light guide (1), the flat light guide comprising opposite flat sides (2, 2') and a narrow side (3) connecting the flat sides; a plurality of microstructure elements (7), the plurality of microstructure elements being arranged on a flat side (2) of the flat light guide (1); a plurality of light sources (4), the plurality of light sources being arranged on one of the narrow sides (3) of the flat light guide (1); a certain number of optical films (8, 9) adjacent to the flat side (2') of the flat light guide (1) for light coupling out, the optical films having an optical structure (10, 11) for light deflection on the flat side (16) of the emitted light (6), characterized in that: At least one optical film (8) has a capillary compensation structure (14) on the flat side (15) through which the light (6) enters.

2. The lighting device according to claim 1, characterized in that: The capillary compensation structure (14) is configured not to reduce the scattering effect of the optical structure (10, 11) arranged on the flat side (16) of the optical film (8, 9) from which light is emitted.

3. The lighting device according to claim 1 or 2, characterized in that: The capillary compensation structure (14) has a plurality of protrusions (29) having such a size and / or lateral extension that the scattering is less than 25%, preferably less than 5%, compared to the scattering of the optical structure (10) on the front flat side (16).

4. The lighting device according to any one of claims 1 to 3, characterized in that: The capillary compensation structure (14) is designed as a diffractive optical element having such dimensions and / or lateral extension that the scattering degree is less than 25%, preferably less than 5%, compared to the scattering degree of the optical structure (10) on the front flat side (16).

5. The lighting device according to any one of claims 1 to 4, characterized in that: The capillary compensation structure (14) is arranged on an optical film (8) which is in flat contact with the smoothly formed front flat side (2') of the flat light guide (1).

6. The lighting device according to any one of claims 1 to 5, characterized in that: The microstructure element (7) is formed by injection molding the flat light guide (1).

7. The lighting device according to any one of claims 1 to 6, characterized in that: The reflective surface (18) adjoins the rear flat side (2) of the flat light guide (1).

8. The lighting device according to any one of claims 1 to 7, characterized in that: The micro-optical elements (12) of the optical structure (10, 11) are prismatic and / or concave and / or convex.

9. The lighting device according to any one of claims 1 to 8, characterized in that: The capillary compensation structure (14) is applied by etching or laser or sandblasting to the flat side (15) of the membrane (8) on which the light is incident.

10. The lighting device according to any one of claims 1 to 9, characterized in that: The capillary compensation structure (14) is applied by etching or electroplating to the flat side (15) of the membrane (8) on which light is incident.

11. The lighting device according to any one of claims 1 to 10, characterized in that: A two-part housing frame (19) is provided, wherein the rear frame portion (20) and the front frame portion (21) include a U-shaped frame section (22) having a wall thickness (w1), so that the flat light guide (1), the optical film (8) and at least the optical lens (13) are surrounded on the peripheral side, and a vacant section (23) connecting the ends of the U-shaped frame section (22) is provided for receiving a light source unit (24) having a light source (4).

12. The lighting device according to any one of claims 1 to 11, characterized in that: A fastening device (25) is arranged on the U-shaped frame section (22) for connecting the rear frame part (20) to the front frame part (21).

13. The lighting device according to any one of claims 1 to 12, characterized in that: A fastening device (26) is arranged on the recessed section (23) for fastening the light source unit (24) to the housing frame (19).

14. The lighting device according to any one of claims 1 to 13, characterized in that: The plurality of light sources (4) are arranged in a row and / or in a straight line.

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