Lighting device for a motor vehicle

Abstract

The present invention relates to a lighting device (100) for a motor vehicle, comprising at least: - a circuit board (1) with several light-emitting diodes (2), - a separator structure (3) arranged in front of the printed circuit board (1) which has a plurality of struts (30), wherein chambers are formed between the struts (30) and at least one light-emitting diode (2) is assigned to each chamber, and - an LC display (4) arranged in front of the separator structure (3) which is connected to the separator structure (3) by means of adhesive connections (5).

Description

The present invention relates to a lighting device for a motor vehicle and to a method for producing the same.PRIOR ARTIn the prior art, flat lighting devices based on a plurality of light emitting diodes are known as lighting means, which are used for carrying out signal functions in motor vehicles, for example as daytime running light, rear light, direction indicators or as front or rear signal light for generating complex, dynamic light signals.For example, the document DE 10 2021 129 672 A1 discloses a lighting device for a motor vehicle, comprising a printed circuit board having a plurality of light emitting diodes arranged thereon, an optical pane and a reflector element, wherein the reflector element is arranged between the printed circuit board and the optical pane, and a liquid crystal (LC) display arranged on the optical pane, which is configured for the selective switching of subareas ("pixels") between transparent and opaque states. The reflector element is divided into a plurality of segments, and each light-emitting diode is assigned a segment such that light emitted by the light-emitting diodes is reflected at the segments of the reflector element and backlights the LC display through the optical pane. In this case, the contour of the pixels of the LC display typically corresponds to the contour of the segments lying beneath it, and sharp and high-contrast light signals can be dynamically generated by matching the light-emitting diodes and the LC display.The individual components of such lighting devices are usually only connected or clamped to one another at the edge, so that undesirable gaps can occur between the components along the transverse planes of extension. In addition, "crosstalk" can take place between adjacent segments, i.e. light from an active segment is radiated into an adjacent inactive segment, in particular by multiple reflection, as a result of which sharpness and contrast depth of the displayed light signals are disadvantageously reduced.DISCLOSURE OF THE INVENTIONIt is the object of the present invention to propose an alternative embodiment of a lighting device for a motor vehicle, which can perform in particular a signal light function with particularly sharp and high-contrast light signals.This object is achieved by a lighting device according to claim 1. Advantageous further developments of the invention are specified in the dependent claims.The technical teaching of the invention discloses a lighting device for a motor vehicle, at least comprising:a printed circuit board having a plurality of light-emitting diodes,a separator structure arranged in front of the printed circuit board and having a plurality of struts, wherein chambers are formed between the struts and at least one light-emitting diode is associated with each chamber, andan LC display arranged in front of the separator structure, which is connected to the separator structure by means of adhesive bonds.The invention is based on the idea of sealing the individual chambers against one another and thus preventing undesired "crosstalk", in that the chambers are closed off on the light outlet side by means of adhesive connections to the LC display arranged in front of them. As a result, any gaps between the separator structure and the LC display are closed, for example on account of dimensional deviations of the struts, and a barrier for the lateral light emission is thus created. The light emerging from the chambers is prevented from passing into adjacent chambers, so that there is a sharply delimited transition and a high contrast between active and inactive chambers in the backlighting of the LC display.The separator structure is formed in particular from a plastic or a metal. The struts abut on the front side of the printed circuit board and each enclose one or more light emitting diodes, for example light emitting diodes of different light colors, forming the chambers. The struts have light absorbing or reflecting surfaces which form the walls of the chambers. The contours of the chambers provided by the arrangement of the struts can be suitably dimensioned and shaped, for example square, triangular or forming a more complex free shape. The struts preferably have front-side end faces which form joining faces of the adhesive bonds.The individually switchable subareas ("pixels") of the LC display have, for example, the same contour as the chambers of the separator structure located behind them, or the LC display has a finer subdivision. In particular, the LC display is designed as a passive matrix display, in which the pixels are controlled passively by means of matrix control, i.e. are controlled without additional electronic components at the individual pixels. The active liquid crystal layer of the LC display can be doped, for example, with black pigments, so that a black view results in the opaque state.In one embodiment of the lighting device according to the invention, the separator structure has a diffuser film arranged in front of the struts, which diffusion film bears approximately against the front-side end faces thereof, wherein the adhesive connections are formed between the diffuser film and the LC display. In particular, the adhesive joints are arranged overlapping the struts, so that the light exit surfaces provided by the contour of the chambers are not reduced by the adhesive joints. The light of the light emitting diodes emerging from the front side of the chambers is scattered during passage through the diffuser film, resulting in a two-dimensionally homogeneous light distribution which is sharply delimited by the contour of the chambers and which serves for backlighting the LC display. The diffuser film is formed from a polycarbonate, for example, and has a thickness in the range of 0.1-0.5 mm, for example.In the embodiment with diffuser film, the adhesive connections, in addition to the lateral sealing, also ensure that a gap necessary for the light injection is provided between diffuser film and light entry surface of the LC display, i.e. that the diffuser film does not come into direct body contact with the LC display.In particular, the adhesive joints are designed to be opaque and / or dust-proof. For example, the various adhesive bonds may include an opaque adhesive.Furthermore, the adhesive connections preferably surround all the chambers over the full circumference, so that a complete sealing of the chambers is formed.For example, the LC display has a non-planar, in particular curved, light entry surface. Such a design is made possible by the adhesive bonds introduced according to the invention, since these, in addition to the optical seal, also increase the structural integrity of the lighting device and a clamping effect for securing the separator structure and / or a diffuser film between the printed circuit board and the LC display is only necessary to a lesser extent. On the production side, an LC display with a curved light entry surface can preferably be realized by providing a separator structure with a corresponding front-side curvature. Such a separator structure provides between the planar printed circuit board and the LC display, which is initially likewise provided in planar fashion and which only assumes the curved contour of the separator structure during assembly under pressure, as a result of which a robust laminate structure is formed. Alternatively, a curvature of the LC display can be imposed during assembly with the aid of a separate device and fixed by the adhesive connections introduced.In particular, the lighting device is designed as a daytime running light, a tail light, a turn signal indicator, a front signal light or a rear signal light of a motor vehicle. In this case, the illumination device for the detailed embodiments offers great design freedoms with regard to the segmentation of the individual "pixels" in combination with the LC display. The lighting device can be designed as a signal light for displaying different light images such as writings, symbols and graphics, and for example generate light signatures that dynamically adapt to the driving modes of the motor vehicle.The invention additionally relates to a method for producing a lighting device according to one of the aforementioned embodiments, wherein adhesive connections are produced by means of screen printing (doctor blade), jet printing, pin transfer method or by means of tape (double-sided adhesive tape). For example, a UV curable adhesive may be used. A suitable prefixing can be produced, for example, by clamping the separator structure and the LC display on the edge side.EMBODIMENTS OF THE INVENTIONFurther measures improving the invention are presented below together with the description of exemplary embodiments of the invention on the basis of the figures. They show in schematic form: FIG. 1 a : Cross-sectional view of a first exemplary embodiment of the lighting device according to the invention, FIG. 1 b : detailed view of FIG. 1 a, FIG. 2 a : a cross-sectional detail view of a second exemplary embodiment, and FIG. 2 b : Top view of a part of the second exemplary embodiment.FIG. 1 ashows a cross-sectional view of a first exemplary embodiment of the lighting device 100 according to the invention, and FIG. 1 bshows an associated detailed view corresponding to the region marked with a dashed rectangle in FIG. 1 a.The lighting device 100 comprises the printed circuit board 1, which carries a plurality of light-emitting diodes 2 on the front side and is connected to the heat sink 6 on the rear side. The separator structure arranged in front of the printed circuit board 1 has the struts 30, wherein chambers are formed between the struts 30 and a light-emitting diode 2 is assigned to each chamber. The separator structure 3 furthermore comprises the diffuser film 31 arranged on the front side. the LC display 4 arranged in front of the diffuser film 31 is connected to the latter by means of the adhesive joints 5, wherein the adhesive joints 5 cover the struts 30. The LC display 4 comprises two glass or plastic sheets with a switchable liquid crystal layer lying therebetween.The adhesive joints 5 laterally seal the front area of the chambers formed between the struts 30, so that light emitted by the light emitting diodes 2 can, after passing through the diffuser film 31, pass into the adjacent chambers or their direct front area.The adhesive joints 5 are designed to be opaque and dust-proof, in particular using an opaque adhesive, and the chambers are surrounded over the full circumference by the adhesive joints 5, i.e. the adhesive joints 5 extend overlapping the entire end faces of the struts 30.FIG. 2 ashows a cross-sectional detail view of a second exemplary embodiment of the lighting device 100 according to the invention, wherein, in contrast to the first exemplary embodiment (cf. FIG. 1 b), no diffuser film is present, and the adhesive joints 5 are formed between the front-side end faces of the struts 30 and the light entry face of the LC display 4. In order to generate a diffuse backlighting, diffuser means can be integrated into the LC display 4, for example.FIG. 2 bshows a top view of part of the second exemplary embodiment, namely the separator structure 3 with the struts 30 forming the chambers and the associated light-emitting diodes 2. by the exemplary arrangement of the struts 30, the chambers have a triangular contour, i.e. the "pixels" formed for backlighting the LC display are triangular. When establishing the adhesive joints, the front-side end faces of the struts 30 exposed in FIG. 2 bare completely used as joining faces.List of reference characters100 Lighting device 1 Printed circuit board 2 Light-emitting diode 3 Separator structure 30 Strut 31 Diffuser foil 4 LC display 5 Adhesive connection 6 Heat sinkReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 10 2021 129 672 A1

[0003]

Claims

Lighting device (100) for a motor vehicle, at least comprising: - a printed circuit board (1) having a plurality of light-emitting diodes (2), - a separator structure (3) which is arranged in front of the printed circuit board (1) and has a plurality of struts (30), wherein chambers are formed between the struts (30) and at least one light-emitting diode (2) is assigned to each chamber, and - an LC display (4) which is arranged in front of the separator structure (3) and is connected to the separator structure (3) by means of adhesive bonds (5).Lighting device (100) according to Claim 1, characterized in that the struts (30) have front-side end faces which form joining faces of the adhesive bonds (5).Lighting device (100) according to Claim 1, characterized in that the separator structure (3) has a diffuser film (31) arranged in front of the struts (30), wherein the adhesive bonds (5) are formed between the diffuser film (31) and the LC display (4).Lighting device (100) according to one of the preceding claims, characterized in that the adhesive connections (5) are arranged overlapping the struts (30).Lighting device (100) according to one of the preceding claims, characterized in that the adhesive connections (5) are designed to be opaque.Lighting device (100) according to one of the preceding claims, characterized in that the adhesive bonds (5) comprise an opaque adhesive.Lighting device (100) according to one of the preceding claims, characterized in that the adhesive connections (5) are designed to be dust-proof.Lighting device (100) according to one of the preceding claims, characterized in that the adhesive connections (5) surround all the chambers over the full circumference.Lighting device (100) according to one of the preceding claims, characterized in that the LC display (4) has a non-planar, in particular curved, light entry surface.Lighting device (100) according to one of the preceding claims, designed as a daytime running light, a tail light, a turn signal lamp, a front signal lamp or a rear signal lamp.Method for producing a lighting device (100) according to one of the preceding claims, characterized in that the adhesive connections (5) are produced by means of screen printing, jet printing, pin transfer methods or by means of tape.

Images