DE102014015592A1 - Production of a light-guiding element with a coupling-out structure - Google Patents

Abstract

The invention relates to a method and a device for producing a light-guiding element with a coupling-out structure, by means of which light with a predetermined luminance distribution L _{v, is to be} coupled out. The proposed method comprises the following steps: generating (101) a photoconductive substrate; Applying (102) a coupling-out structure A _i to the substrate; Coupling (103a) light into the substrate and determining (103b) the luminance distribution L _v (A _i ) coupled out by the coupling-out structure A _i ; depending on a difference D of the luminance distributions D = L _v, - L _v (A _i ) determining (104) a coupling-out structure A _{i + 1} such that after application of the coupling-out structure A _{i + 1} to the coupling-out structure A _i reduces the difference D. becomes; and repeating (105) steps 1.2. to 1.4. for i = i + 1 until the difference D satisfies a given limit condition.

Description

The invention relates to a method and a device for producing a light-guiding element with a coupling-out structure, by means of which light coupled into the light element can be coupled out of the light guide element with a predetermined luminance distribution.

Such light-guiding elements can be used, for example, as lighting elements, as decorative elements or as optical display or output elements. In particular, such light elements are used in or on vehicles, for example, for ambient lighting, for illumination or backlighting of decorative elements, or for design or information purposes.

The term "light-guiding element" is understood here to mean an element or a component into which light can be coupled, for example by means of one or more LED's, which conducts the coupled-in light, and the coupled-in light to points or surface elements defined by the coupling-out structure is coupled to the element / component.

In the present case, the term "luminance" in [cd / m ² ] is understood to mean the luminous flux emitted by an infinitely small local area element in terms of solid angle. The term "luminance distribution" L _v is understood above to mean the areal distribution of the luminance of the luminous flux decoupled from the light-conducting element.

Generic light guide elements are known in the art. So revealed the DE 10 2008 017 345 A1 Lighting devices in which the light of one or more light sources is received by means of optical fibers and by arranging the optical fibers on surfaces, for example in the interior of a vehicle, an ambient light distribution takes place. The light guide elements are provided with a thin layer of a material which is chosen so that it provides on the one hand with the light source (tag design) with other surfaces in the vehicle interior an optically harmonious overall impression, on the other hand by the very thin layer or by special surface structuring at least locally enough light from the lighting element (night design) can emerge. This is realized for example by a coating of the light guide with a thin lacquer layer, preferably a lacquer with metallization effect (vehicle paint) or a thin metallization. By locally different thickness of the layer thickness and / or structuring light emission sites of the light guide or points can be defined with reduced transmission, which may also have predetermined geometric shapes. It can also be used to display symbols (arrows, stars, etc.) or pictograms and labels.

Furthermore, the disclosure DE 10 2009 030 684 A1 a decorative element and a method for its production, with at least one partially transparent decorative film, which is applied to a flat support member known. In this case, a first layer of a transparent plastic is arranged between the carrier element and the decorative film, and between the carrier element and the first layer, a second layer of a further plastic is provided. A transparent cover layer of a material which can be hardened in situ by means of a supplied energy is arranged on a side of the decorative film which is remote from the first layer.

Since the luminous flux within a light-guiding element can vary greatly in terms of location, which depends on the distance from the light-incoupling light source, on the geometry of the component and on the concrete coupling over a surface, it is particularly difficult to produce a surface-emitting light-conducting element which is provided with a light guide predetermined surface luminance distribution (homogeneous or inhomogeneous) should shine.

The object of the invention is to specify a cost-effective method and a device for producing a light-guiding element with a coupling-out structure, wherein light can be coupled out with a predetermined desired luminance distribution from the light-guiding element through the coupling-out structure. The method should in particular make it possible to produce compact planar light guides with a large bandwidth of spatial design freedom such that they have a decoupled desired luminance distribution.

The invention results from the features of the independent claims. Advantageous developments and refinements are the subject of the dependent claims.

The procedural aspect of the object is achieved with a method for producing a light-guiding element having a coupling-out structure, by means of which light with a predetermined luminance distribution L _{v, is to be} coupled out. In a preferred embodiment, the predetermined luminance distribution L _{v, should be} constant area. Of course, the luminance distribution L _{v, soll} can indicate any distribution of the locally emitted luminous flux.

The proposed method comprises the following steps.

In a first step, a generating or providing a photoconductive substrate takes place. The substrate is preferably flat educated. The generating of the photoconductive substrate is advantageously carried out by means of a primary molding process, such as an injection molding or an extrusion process, or by means of a forming process, such as by deep drawing. The substrate itself is advantageously a plastic material.

In a second step, a coupling-out structure A _{i is} applied to the substrate. The coupling-out structure A _i is advantageously made of a plastic material. The coupling-out structure A _i furthermore advantageously consists of a light-transparent material with a refractive index comparable to the substrate. The light-transparent material may have, for example, opaque, reflective and / or luminescent inclusions. The coupling-out structure A _i is furthermore advantageously applied to the substrate by means of a printing technique, for example by means of a suitably modified ink-jet printing method, or by means of a tampon or transfer printing method. For this purpose, the material to be applied to the substrate as coupling-out structure A _i must first be sufficiently flowable and thus printable. After application of the material, curing of the applied coupling-out structure A _i advantageously takes place.

The first decoupling structure A _{i = 0} applied to the substrate is advantageously determined with regard to its structure and / or its application thickness as a function of the predetermined luminance distribution L _{v, soll} . Alternatively, the first coupling-out structure A _{i = 0 to} be applied to the substrate can be applied as a homogeneous material layer having a predetermined constant layer thickness. As an alternative, the first coupling-out structure A _{i = 0 to} be applied to the substrate can be applied as a predetermined material layer pattern with a homogeneous or predetermined inhomogeneous layer thickness.

Advantageously, the coupling-out structure A _{i = 0 is selected} such that the following applies for a resulting luminance distribution L _v (A _{i = 0} ): for all surface elements, the luminance distribution L _v (A _{i = 0} ) is smaller than the predetermined luminance distribution L _{v, should} , that is, it is coupled out less light than the luminance distribution L _{v, should} correspond. By iteratively applying further decoupling structures, as described below, the decoupled luminous flux can finally be increased, and thus ultimately the predetermined luminance distribution L _{v, soll is to be} achieved.

In a third step, light is coupled into the substrate and the luminance distribution L _v (A _i ) decoupled by the coupling-out structure A _{i is} determined. The coupling of light is advantageously carried out by means of a light source, in particular one or more LEDs, which are / is connected to the substrate for conducting light. The determined by the coupling-out structure A _i decoupled luminance distribution L _v (A _i ) is advantageously carried out with an image-resolving luminance measurement system, eg. A CCD luminance measurement camera, which detects the local and / or direction-dependent decoupled from the respective surface elements of the light guide luminous flux is set up.

In a fourth step, depending on a difference D of the luminance distributions D = L _{v, soll} - L _v (A _i ), a coupling-out structure A _{i + 1 is} determined such that after applying the coupling-out structure A _{i + 1} to the already applied (n) Coupling-out structure (s) A _i the difference D (prognostically) is reduced. The difference D, like the luminance distributions, preferably has the dimension 2 or 3. The calculations to be carried out to determine the coupling-out structure A _{i + 1} depend, in particular, on the material of the coupling-out structure A _{i + 1 to be applied} and the difference D.

In a fifth step, the steps two to four are repeated for i = i + 1 until the difference D satisfies a predetermined limit condition. The limit condition indicates, for example, that the method is terminated when, for all surface elements F _{k of} the light guide element, the light decoupling is that D _Fk <G1, where G1 is a predetermined limit value. It is advantageous for the boundary condition in the context of a given measurement inaccuracy when determining the luminance distribution L _v (A _i ): D = 0.

The material of the decoupling structures iteratively applied to the substrate may be identical, but may also differ from a decoupling structure A _i to a next decoupling structure A _{i + 1} .

The proposed method makes it possible, in particular, to produce different luminance distributions with the same geometry / shape of a light-guiding element. According to an advantageous further development, at least one decorative layer and / or one reflector layer and / or one layer has a lower refractive index and / or one compared to the substrate Applied light filter layer. These layers can be applied to the substrate as required or desired effect to be achieved.

An apparatus-related aspect of the object is achieved by a device for producing a light-conducting element, which has a coupling-out structure, by means of which light with a predetermined luminance distribution L _{v, should be able to be} coupled out.

The proposed device comprises a first means for generating or providing a photoconductive substrate, a second means for applying a coupling-out structure A _i to the substrate, a third means for coupling light into the substrate and for determining the output coupled by the coupling-out structure A _i luminance distribution L _v (A _i ), a fourth means, with the depending on a difference D of the luminance distributions D = L _v, - L _v (A _i ) a decoupling structure A _{i + 1} can be determined in such a way that after applying the decoupling structure A _{i + 1} to the decoupling structure A _i the difference D is reduced, and a control means for driving the first to fourth means such that the application of decoupling structures A _i iteratively carried out on the substrate until the difference D satisfies a predetermined boundary condition.

In an advantageous development, the second means is designed and arranged such that the application of the coupling-out structures A _i takes place by means of a printing technique. The second means is advantageous designed and set up in particular as an inkjet printer or pad printer or to the transfer printer.

Further advantages, features and details will become apparent from the following description in which - where appropriate, with reference to the drawings - at least one embodiment is described in detail. The same, similar and / or functionally identical parts are provided with the same reference numerals.

Show it:

1 a schematic flow diagram of a proposed method, and

2 a schematic structure of a proposed device.

1 shows a schematic flow diagram of a proposed method for producing a light-guiding element with a coupling-out structure, by the light with a predetermined luminance distribution L _{v, should be} auskoppelbar. The method comprises the following steps. In a first step 101 a photoconductive substrate made of a plastic material is produced by an extrusion process. In a second step 102 a decoupling structure layer A _{i = 0 is} applied to the substrate by means of a pad printing process. For this purpose, the plastic material to be applied is initially sufficiently fluid for the pad printing process and is hardened after application of the coupling-out structure A _{i = 0} . The curing takes place here by means of UV light. The goal is to achieve a homogeneous luminance distribution L _{v, soll} by the decoupling structure to be applied.

After application, light can be coupled out of the substrate by the coupling-out structure layer A _{i = 0} . However, it is questionable whether this already takes place with the desired homogeneous luminance distribution L _{v, soll} . In order to check this, coupling takes place in a third step 103a of light into the substrate and a detecting 103b the output coupled by the coupling-out structure A _{i = 0} luminance distribution L _v (A _{i = 0} ). The luminance distribution L _v (A _{i = 0} ) indicates the current luminance distribution caused by the coupling-out structure A _{i = 0} .

In a fourth step 104 is carried out as a function of a difference D of the luminance distributions D = L _{v, soll} - L _v (A _i ) determining a coupling-out structure A _{i + 1} such that after application of the coupling-out structure A _{i + 1} to the coupling-out structure A _i, the difference D is reduced , For this purpose, first the difference D of the luminance distributions D = L _{v, soll} - L _v (A _i ) is determined. Let it be assumed that the shape of the substrate is substantially planar, so that the difference D and the luminance distributions are two-dimensional fields, ie dependent on, for example, the location coordinates x, y. Determining the decoupling structure A _{i + 1} is done numerically by a corresponding forecasting model.

In a fifth step 105 Repeat steps two to four for i = i + 1 until the difference D satisfies a given limit condition. As a result of the iterative application of decoupling structure layers A _i effected in this way, it is possible to inexpensively produce compact planar light guides with a large bandwidth of spatial design freedom in such a way that they have a decoupled desired luminance distribution.

2 shows a schematic structure of a proposed device for producing a light-guiding element with a coupling-out structure, by the light with a predetermined luminance distribution L _{v, should be} auskoppelbar. The proposed device comprises a first means 201 for generating or providing a photoconductive substrate, a second means 202 for applying a coupling-out structure A _i to the substrate, a third means 203 for coupling light into the substrate and for determining the luminance distribution L _v (A _i ) coupled out by the coupling-out structure A _i , a fourth means 204 in which a coupling-out structure A _{i + 1} can be determined in such a way that, after applying the coupling-out structure A _{i + 1} to the coupling-out structure A _i, the difference D is determined as a function of a difference D of the luminance distributions D = L _{v, soll} -L _v (A _i ) is reduced, and a control means 205 for driving the first to fourth means in such a way that the application of decoupling structures A _i to the substrate takes place iteratively until the difference D satisfies a predetermined boundary condition.

Although the invention has been further illustrated and explained in detail by way of preferred embodiments, the invention is not limited by the disclosed examples, and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention. It is therefore clear that a multitude of possible variations exists. It is also to be understood that exemplified embodiments are really only examples that are not to be construed in any way as limiting the scope, uses, or configuration of the invention. Rather, the foregoing description and description enable the skilled artisan to practice the exemplary embodiments, and those of skill in the knowledge of the disclosed inventive concept may make various changes, for example, to the function or arrangement of particular elements recited in an exemplary embodiment. without departing from the scope defined by the claims and their legal equivalents, such as further explanation in the specification.

LIST OF REFERENCE NUMBERS

101-105

steps

201

first means

202

second means

203

third means

204

fourth means

205

control means

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102008017345 A1 [0005]
• DE 102009030684 A1 [0006]

Claims (9)

Method for producing a light-guiding element with a coupling-out structure, by means of which light with a predetermined luminance distribution L _{v, is to be} coupled out _, comprising the following steps: 101 ) of a photoconductive substrate, applying ( 102 ) of a coupling-out structure A _i on the substrate, coupling ( 103a ) of light into the substrate and determining ( 103b ) the luminance density L _v (A _i ) decoupled by the decoupling structure A _i , dependent on a difference D of the luminance distributions D = L _{v, soll} - L _v (A _i ) determining ( 104 ) of a coupling-out structure A _{i + 1 in} such a way that, after applying the coupling-out structure A _{i + 1} to the coupling-out structure A _i, the difference D is reduced, repeating ( 105 ) of steps 1.2. to 1.4. for i = i + 1 until the difference D satisfies a given limit condition. Method according to Claim 1, characterized in that the generation ( 101 ) of the photoconductive substrate by means of a primary molding process, such as an injection molding or an extrusion process, or by means of a forming process, such as by deep drawing takes place. A method according to claim 1 or 2, characterized in that the substrate is formed flat. Method according to one of claims 1 to 3, characterized in that the application ( 102 ) of the coupling-out structures A _i takes place by means of a printing technique. Method according to one of claims 1 to 4, characterized in that on the substrate additionally at least: a decorative layer and / or a reflector layer and / or a layer is applied to a lower refractive index compared to the substrate and / or a light filter layer. Method according to one of claims 1 to 5, characterized in that the predetermined luminance distribution L _{v, should be} constant surface. Method according to one of Claims 1 to 6, characterized in that, for the boundary condition in the context of a given measurement inaccuracy in determining the luminance distribution L _v (A _i ), the following applies: D = 0. Apparatus for producing a light-conducting element with a coupling-out structure, by means of which light with a predetermined luminance distribution L _{v, is to be} decoupled, and for carrying out a method according to the preceding claims, comprising: a first means ( 201 ) for generating or providing a photoconductive substrate, a second means ( 202 ) for applying a coupling-out structure A _i to the substrate, a third means ( 203 ) for coupling light into the substrate and for determining the luminance distribution L _v (A _i ) coupled out by the coupling-out structure A _i , a fourth means ( 204 ), with which depending on a difference D of the luminance distributions D = L _{v, should} - L _v (A _i ) a coupling-out structure A _{i + 1} can be determined such that after applying the coupling-out structure A _{i + 1} to the coupling-out structure A _i, the difference D is reduced, and a control means ( 205 ) for driving the first to fourth means in such a way that the application of decoupling structures A _i to the substrate takes place iteratively until the difference D satisfies a predetermined boundary condition. Device according to claim 8, characterized in that the second means ( 202 ) is designed and arranged such that the application of the decoupling A _i takes place by means of a printing technique.

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