Lighting device for vehicles

Abstract

The invention relates to a lighting device for vehicles comprising a flat light guide (1) with opposing flat sides (2, 2') and connecting narrow sides (3), with a plurality of microstructure elements (7) arranged on a flat side (2) of the flat light guide (1), with a number of light sources (4) arranged on one of the narrow sides (3) of the flat light guide (1), with a number of optical films (8, 9) adjoining a light-emitting flat side (2') of the flat light guide (1), which have an optical structure (10, 11) for light guidance on a flat side (16) emitting the light (6), wherein at least one optical film (8) has a capillary compensation structure (14) on a flat side (15) into which the light (6) enters.

Description

[0001] The invention relates to a lighting device for vehicles with a flat light guide comprising opposing flat sides and narrow sides connecting them, with a plurality of microstructure elements arranged on a flat side of the flat light guide, with a number of light sources arranged on one of the narrow sides of the flat light guide, with a number of optical films adjoining a light-emitting flat side of the flat light guide, which have an optical structure for light guidance on a light-emitting flat side.

[0002] From DE 10 2019 133 693 A1, a lighting device for vehicles is known, comprising a flat light guide and light sources arranged on one of its narrow sides. The light guide has a plurality of microstructure elements on a light-emitting flat surface. These elements cause the light coupled into the flat light guide to be coupled out in the main direction of emission at the light-emitting surface thus formed. This allows a relatively large illuminating area to be created for generating a signal light.

[0003] From WO 2019 / 227688 A1, a lighting device for vehicles is known, comprising a flat light guide and light sources arranged on one of its narrow sides. The flat light guide has a plurality of microstructure elements for coupling the light out at a light coupling surface thus formed. A number of optical films with an optical structure are connected to the light coupling surface, so that the coupled-out light is scattered according to a specified pattern. The at least one optical film can have prism elements or diffusion elements as its optical structure, which are arranged on a flat surface of the respective film facing forward in the direction of light emission. However, the optical scattering effect of the optical films is limited by the fact that, due to the planar arrangement of the smooth flat surfaces of the films relative to each other and of the films relative to the flat light guide, undesirable capillary effects can occur due to electrostatic charging.These lead to disturbing spots in the light output surface of the lighting device.

[0004] The object of the present invention is therefore to further develop a lighting device for vehicles with a flat light guide and with at least one film adjoining it in such a way that homogeneous planar light emission is ensured in a simple manner.

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

[0006] The particular advantage of the invention lies in the fact that films, flat light guides, or light disks, each having an optical structure on only one flat side and a smooth and / or polished surface on the opposite flat side, can be easily contacted or laminated without impairing the light guidance generated by the optical structure. This is because the capillary action on the otherwise smooth flat side, which incorporates a capillary compensation structure, prevents any local disturbance or impairment of the effect achieved by the optical structure due to capillary action when the facing flat sides of different films, flat light guides, or light disks are brought into contact.The capillary balancing structure according to the invention avoids an undesirable capillary effect that occurs when two smooth flat surfaces are in contact with each other, and furthermore does not affect the optical effect of the other flat surfaces provided with the optical structure. Advantageously, this results in improved, homogeneous, flat light emission, while avoiding undesirable local optical effects, such as the emission of increased local luminance.

[0007] According to a preferred embodiment of the invention, the capillary compensation structure is formed by microstructure elements that preferably have a different dimension and / or transverse extent than the micro-optical elements of the optical structure. This advantageously ensures that, firstly, the smooth flat sides do not lie directly against each other and, secondly, that the optical effect of the optical structure is not altered or enhanced. Preferably, the microstructure elements of the capillary compensation structure are designed such that light entering the film and / or light disk is homogenized or parallelized.

[0008] According to a further development of the invention, a plurality of microstructure elements are arranged on a rear flat surface opposite a flat surface serving as a light-emitting surface of the flat optical fiber, wherein the microstructure elements serve as extraction elements. They cause the coupled-in light to be deflected such that it strikes the light-emitting flat surface of the flat optical fiber at a relatively steep angle, with the effect that it is extracted. The light-emitting surface is smooth and free of scattering elements. The light-emitting surface can, for example, be designed as a polished surface.

[0009] In a further development of the invention, a reflector surface is attached to the rear of the flat optical fiber. This ensures that light coupled out on the rear of the flat optical fiber is reflected back into the fiber and can then exit at the light-emitting side. This improves the light output.

[0010] According to a further development of the invention, a two-part housing frame is provided for accommodating the flat light guide and the number of optical films. Optionally, a reflector surface and a light filter are also provided as optical components. Both a rear frame part and a front frame part of the two-part housing frame have a U-shaped frame section with a wall thickness adapted to the optical components it accommodates. The U-shaped frame section is connected by a recessed section with a thin wall thickness, so that a light source unit containing the light sources can be partially accommodated or attached. Advantageously, this creates a compact flat light guide module.

[0011] Exemplary embodiments of the invention are explained in more detail below with reference to the drawings.

[0012] They show: Fig. 1 a schematic side view of a first embodiment of the lighting device, wherein the optical components are arranged spaced apart from each other for illustrative purposes and Fig. 2 an exploded view of a second embodiment of the lighting device.

[0013] A lighting device according to the invention can, for example, be designed as a rear light for generating a taillight or brake light. Alternatively, the lighting device can also serve to generate a flashing light or daytime running light.

[0014] According to a first embodiment of the invention according to Fig. The lighting device comprises a flat light guide 1, which has opposing flat sides 2, 2' and connecting narrow sides 3. A plurality of light sources 4 are arranged on one of the narrow sides 3, arranged in a row or straight line on a circuit board 5.

[0015] The light sources 4 emit light 6, which is coupled into the flat optical fiber 1 at one of the narrow sides 3 and undergoes total internal reflection at the opposite flat sides 2, 2'. To enable the coupled light 6 to be coupled out at a front flat side 2' serving as a light-out surface, a opposite rear flat side 2 has an optical structure with a multitude of protrusions, which are designed as microstructure elements 7. The coupled light 6 striking the microstructure elements 7 undergoes total internal reflection, allowing it to exit at the front flat side 2' of the flat optical fiber 1.

[0016] The front flat side 2' (light output surface) is smooth. For example, the front flat side 2' is polished.

[0017] In the present embodiment, the flat light guide 1 is designed to be flat, with the front flat side 2' running parallel to the rear flat side 2.

[0018] On a light-emitting end or light-emitting end of the flat optical fiber 1, a first optical film 8 and a second optical film 9 are attached, each having an optical structure 10 or 11 on a light-emitting flat side for light guidance or light scattering, respectively. The optical structure 10, 11 can, for example, consist of a micro-optical structure with a plurality of microstructure elements 12. These can, for example, be prismatic and / or concave and / or convex.

[0019] In the direction of light emission, a light disc 13 is arranged in front of the first optical film 8 and the second optical film 9, which has opposite, smoothly formed flat sides. For example, the light disc 13 can be colored, for example red, if the lighting device is intended as a rear or brake light.

[0020] To avoid an undesirable capillary effect in the form of unwanted irregularities or inhomogeneities, or differently colored local spots on the light-emitting surface of the optical disk 13, the first optical film 8 has a capillary compensation structure 14 on a flat side facing the flat light guide 1. The capillary compensation structure 14 has the property that a plurality of protrusions are arranged distributed, preferably uniformly, over a rear flat side 15 of the first film 8. This prevents an otherwise smooth rear flat side 15 of the first film 8 from coming into full contact with a smooth front flat side 2'.

[0021] For example, the capillary balancing structure 14 can have a plurality of microstructure elements or a diffractive optic.

[0022] The capillary compensation structure 14 is arranged relative to the optical structure 10 located on a front flat surface 16 of the first film 8 such that the scattering effect of the light 6 caused by the optical structure 10 is not altered. The capillary compensation structure 14 is thus designed such that protrusions 29 are formed, preventing the first optical film 8 from lying flat against the flat optical fiber 1. The capillary compensation structure 14 therefore causes a base surface 27 of the rear flat surface 15 of the first optical film 8, from which the protrusions 29, designed as microstructure elements, rise, to be arranged at a distance a from the smooth surface of the flat optical fiber 1 in the assembled state, or from a plane 28 of the protrusion tips, which corresponds to the front flat surface 2' of the flat optical fiber 1 in the assembled state.

[0023] The capillary compensation structure 14 is designed such that the luminance emitted by the lighting device is not changed compared to an arrangement of microstructure elements 7 on the front flat side 2' as coupling elements and a smooth rear flat side 15 of the first foil 8.

[0024] According to an alternative embodiment of the invention, the capillary compensation structure 14 can have such a scattering effect that, in conjunction with the optical structure 10 formed on the front flat side 16 of the first optical film 8, a predetermined scattering effect of the light 6 is achieved.

[0025] For example, the elevations 29 of the rear flat side 15 can be arranged offset from the optical structure 10 or micro-optical elements 12 of the front flat side 16 of the optical film 8.

[0026] Preferably, the elevations 29 of the capillary compensation structure 14 have a different dimension and / or transverse extent than the microstructure elements 7, which are arranged on the front flat side 16 of the first optical film 8.

[0027] The microstructure elements 7, which serve as coupling elements, are preferably formed by injection molding of the flat light guide 1.

[0028] The capillary compensation structure 14 can be applied to the light-incident flat side (rear flat side 15), for example, by etching, laser cutting, or sandblasting. Alternatively, the capillary compensation structure 14 can be applied to the light-incident flat side or rear flat side 15 of the first film 8 by electrical discharge machining (EDM) or by electroplating.

[0029] In Fig. 2 shows a flat light guide module which, unlike the embodiment according to Fig.The flat optical fiber 1 has a reflector surface 18 on its rear flat side 2. The reflector surface 18 can, for example, be completely white and causes light coupled out at the rear flat side 2 of the flat optical fiber 1 to be reflected back towards the flat optical fiber 1, where it enters the flat optical fiber 1 and is coupled out in the direction of light emission by further total internal reflections or directly at the front flat side 2' of the flat optical fiber 1. This can improve the light output.

[0030] The optical components, namely the reflector surface 18, the flat light guide 1, the first optical film 8, the second optical film 9, and the light disk 13, are held in a two-part housing frame 19, the housing frame 19 being formed by a rear frame part 20 and a front frame part 21. Both frame parts 20 and 21 have a U-shaped frame section 22, which overlap or lie against each other when the frame parts 20 and 21 are assembled. The wall thickness w1 of the U-shaped frame section 22 is chosen to be such that the optical components 18, 1, 8, 9, and 13 lie against each other over their entire surface.

[0031] Furthermore, the rear frame part 20 and the front frame part 21 each have recessed sections 23 connecting the ends of the respective U-shaped frame section 22 for receiving a light source unit 24 comprising the light sources 4. The wall thickness w2 of the recessed section 23 is selected such that the light source unit 24 with the light sources 4 can be arranged between the recessed section 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 fastening means 25 for the preferably detachable fastening of the rear frame part 20 to the front frame part 21.

[0032] Fastening means 26 for attaching the light source unit 24 to the housing frame 19 are provided in the recess section 23.

[0033] The two-part housing frame 19 enables a compact design of the flat light guide module.

[0034] The light sources 4 are preferably designed as LED light sources, which are preferably arranged at an equidistant distance along a row. Reference symbol list 1 flat light guide 2.2' flat sides 3 narrow sides 4 light sources 5 circuit board 6 lights 7 microstructure elements 8 1. optical film 9 2. optical film 10 optical structure 11 optical structure 12 micro-optical elements 13 Light disc 14 Capillary compensation structure 15 rear flat side 16 front flat side 17 Base area 18 Reflector area 19 two-part housing frames 20 rear frame part 21 front frame part 22 U-shaped frame section 23 Recess section 24 light source units 25 Fasteners 26 Fasteners 27 Base area 28 Level 29 surveys a distance w1,w2 wall thickness QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2019 133 693 A1

[0002] WO 2019 / 227688 A1

[0003]

Claims

[1] Lighting device for vehicles with a flat light guide (1) comprising opposite flat sides (2, 2') and narrow sides (3) connecting the same, with a plurality of microstructure elements (7) arranged on a flat side (2) of the flat light guide (1), with a number of light sources (4) arranged on one of the narrow sides (3) of the flat light guide (1), with a number of optical films (8, 9) adjoining a light-coupling flat side (2') of the flat light guide (1), which have an optical structure (10, 11) for light guidance on a flat side (16) emitting the light (6), characterized by that at least one optical film (8) has a capillary compensation structure (14) on a flat side (15) into which the light (6) enters. [2] Lighting device according to claim 1, characterized bythat the capillary compensation structure (14) is designed such that a scattering effect of the optical structure (10, 11), which is arranged on a light-emitting flat side (16) of the optical film (8, 9), is not reduced. [3] Lighting device according to claim 1 or 2, characterized by that the capillary compensation structure (14) has a plurality of elevations (29) which have a dimension and / or transverse extent such that the degree of scattering is less than 25%, preferably less than 5%, compared to a degree of scattering of the optical structure (10) on the front flat side (16). [4] Lighting device according to one of claims 1 to 3, characterized bythat the capillary compensation structure (14) is designed as a diffractive optic which has a dimension and / or transverse extension such that the degree of scattering is less than 25%, preferably less than 5%, compared to a degree of scattering of the optical structure (10) on the front flat side (16). [5] Lighting device according to one of claims 1 to 4, characterized by that the capillary compensation structure (14) is attached to an optical film (8) which lies flat against a smooth front flat side (2') of the flat light guide (1). [6] Lighting device according to one of claims 1 to 5, characterized by that the microstructure elements (7) are formed by injection molding of the flat light guide (1). [7] Lighting device according to one of claims 1 to 6, characterized by that a reflector surface (18) is connected to the rear flat side (2) of the flat light guide (1). [8] Lighting device according to one of claims 1 to 7, characterized by that the micro-optical elements (12) of the optical structure (10, 11) are prism-shaped and / or concave-shaped and / or convex-shaped. [9] Lighting device according to one of claims 1 to 8, characterized by that the capillary compensation structure (14) is applied to the light-incident flat side (15) of the film (8) by etching or lasering or by sandblasting. [10] Lighting device according to one of claims 1 to 9, characterized by that the capillary compensation structure (14) is applied to the light-incident flat side (15) of the film (8) by erosion or by galvanic molding. [11] Lighting device according to one of claims 1 to 10, characterized bythat a two-part housing frame (19) is provided, wherein a rear frame part (20) and a front frame part (21) have a U-shaped frame section (22) with a wall thickness (w1) so that the flat light guide (1), the optical film (8) and at least the light disc (13) are enclosed on the circumference, and that a recess section (23) connecting one end of the U-shaped frame section (22) is provided for receiving a light source unit (24) having the light sources (4). [12] Lighting device according to one of claims 1 to 11, characterized by that fastening means (25) are arranged on the U-shaped frame part (22) for connecting the rear frame part (20) to the front frame part (21). [13] Lighting device according to one of claims 1 to 12, characterized bythat fastening means (26) are arranged on the recess section (23) for fastening the light source unit (24) to the housing frame (19). [14] Lighting device according to one of claims 1 to 13, characterized by that the plurality of light sources (4) are arranged in rows and / or in a straight line.

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