COMPOSITE ELEMENT FOR LIGHT DIRECTION

Description

[0001] The invention relates to a composite surface element for light guidance, a window with such a composite surface element and a method for producing such a composite surface element.

[0002] Composite planar elements for light guidance are known in a wide variety of designs from the prior art. For example, WO 2013 / 012865 A2 shows substrates with light guidance layers that can be formed as window panes. To achieve such light guidance, the composite planar elements often have air-filled structures inside to enable total internal reflection.

[0003] There is a clear need for high-quality surface elements for light control: Electrical lighting in buildings contributes significantly to global energy consumption. Depending on the region, 10-20% of a commercial building's energy is used for lighting. More efficient use of daylight is therefore of great interest and leads to significant energy savings. Furthermore, natural daylight promotes people's well-being, health, and productivity.

[0004] However, numerous prior-art composite panels have the disadvantage that, due to the air-filled structures they contain, they are not completely transparent, but only diffusely transparent. Furthermore, an imprecise construction of the composite panels often leads to varying optical behavior in various areas of the composite panel. Finally, prior-art composite panels are often formed from multiple layers bonded together, which can lead to undesirable optical disturbances caused by the adhesive itself and variations in the thickness of the adhesive layer.

[0005] US 2002 / 159 154 A1 discloses an optical component consisting of two transparent flat bodies, each having depressions or other surface features on one of their sides that interpenetrate when the two bodies are arranged opposite each other. The shapes of the depressions or other surface features are selected such that they touch at some positions and are spaced apart at others to form cavities within the composite body. These cavities result in total internal reflection of incident light at specific angles. Composite bodies formed from two oppositely arranged optical components can be used as daylight screens to direct light onto an object or into the interior of a building.

[0006] WO 02 / 1 69 77 A1 relates to an optical component comprising two transparent bodies, each with a main surface interrupted by a plurality of cavities separated by cavity dividers. The cavity dividers of each body penetrate the cavities of the other body. The cavities are formed by the mutually facing side surfaces of the cavity dividers. Furthermore, the cavities and the cavity dividers are shaped such that a further cavity is also formed between the base of each cavity divider. The optical component finds particular application in the glazing of buildings and in the so-called "daylighting" of buildings.

[0007] DE 169 22 670 A1 discloses a device for redirecting light, in particular sunlight, having a flat light entry surface and a light exit surface, as well as boundary layers that refract and / or reflect the light and are provided between the flat surfaces. The light entry surface is a surface of a first planar element that has a surface structure on its side opposite the light entry surface. The light exit surface is further a surface of a second planar element that has a second surface structure on its side opposite the light exit surface. The surface structures of both elements are designed such that, when the elements are joined together, the surface structures interlock, forming gaps enclosed by both elements.

[0008] The object can be considered to be to provide a composite surface element which has good light-guiding properties and is, in particular, optically transparent and homogeneous, can be used advantageously in the area of ​​windows in buildings and can be manufactured in a simple manner.

[0009] The object is achieved according to the invention by a composite surface element for light guidance according to claim 1, a window with such a composite surface element according to claim 12, and a method for producing such a composite surface element according to claim 13. Advantageous developments of the invention are specified in the dependent claims.

[0010] The composite surface element according to the invention for light guidance has a first surface element with a first microstructure on a first inner surface and a second surface element with a second microstructure on a second inner surface, wherein the first and the second microstructure each have depressions and / or elevations. Furthermore, the surface elements in the composite surface element are arranged relative to one another such that the first and the second inner surfaces face one another and the first and second microstructures are arranged to engage one another such that internal micro-cavities are formed between the microstructures. The first and second microstructures have mutually corresponding locking sections for the positively locking attachment of the surface elements to one another, wherein the locking sections of the first and the second surface element are each formed as a corresponding pair comprising a locking receptacle and a locking element.

[0011] Furthermore, the invention relates to a window with a window pane and a composite surface element according to the invention applied thereto.

[0012] In the method according to the invention for producing a composite surface element for light guidance, a first surface element with a first microstructure comprising elevations and depressions on a first inner surface and a second surface element with a second microstructure comprising elevations and depressions on a second inner surface are initially provided, wherein the surface elements are then subsequently arranged relative to one another such that the first and second inner surfaces face one another and the first and second microstructures are arranged in such an interlocking manner that internal microcavities are formed between the microstructures, wherein a positive-locking fixing of the surface elements to one another is achieved by means of mutually corresponding locking sections, wherein the locking sections of the first and second surface elements are each formed as a corresponding pair of a locking receptacle and a locking element.

[0013] The inventors have recognized that, particularly for redirecting daylight into the depths of rooms in window facades, for example in skylights, it is advantageous to provide microcavities, in particular microlouvres, inside a composite surface element, through which the incident light is totally reflected as long as the conditions for total reflection are met, so that the light redirection is thus essentially based on loss-free total reflection. By interlocking the first and second microstructures, particularly long and / or precise microcavities can be created. In particular, gaps with a very large aspect ratio (ratio of width to height) can be advantageously created, which are no longer technically feasible with conventional microstructuring of surfaces.Finally, in the composite panel element according to the invention, due to the positive attachment of the panel elements to one another, disruption of the microcavities by additional attachment means or methods is avoided or their influence reduced in a simple and advantageous manner, whereby, in particular, no adhesive is required to attach the panel elements to one another. Furthermore, complete transparency is particularly advantageous and of particular importance, especially when used in glass facades and windows.

[0014] The composite surface element according to the invention is initially formed from a composite of at least two parts, the surface elements, wherein the composite surface element is preferably formed over its entire surface from the two surface elements or the two surface elements extend over the entire surface of the composite surface element. The composite surface element can have any desired shape, with a design as a plate or as a disc being preferred. Furthermore, the composite surface element can have any desired thickness, wherein the composite surface element preferably has a thickness between 25 µm and 1 mm, more preferably a thickness between 50 µm and 500 µm, and most preferably between 100 µm and 250 µm.

[0015] The surface elements according to the invention can, in particular, be microstructured films or sheets and can be produced in various ways, for example, by UV embossing, hot stamping, injection molding, or other processes. The surface elements are preferably made of a highly transparent, weather-resistant, and / or UV-stable material. Suitable materials include, in particular, a wide variety of plastics, silicones, or glass, particularly preferably in combination with lacquer or silicone.

[0016] The composite surface element according to the invention is intended for light guidance, wherein the light guidance preferably occurs essentially and particularly preferably exclusively through total reflection at the interfaces of microcavities arranged in the interior of the composite surface element. These microcavities are preferably formed and / or arranged in the composite surface element in such a way that consistent light guidance occurs over the entire surface of the composite surface element.

[0017] According to the invention, both surface elements have a microstructure on an inner surface, which is preferably shaped and / or arranged uniformly over the entire surface of the surface element. The inner surface is understood to be the surface of the surface element which, in the case of the two surface elements arranged next to one another to form a surface composite element, is located in the interior of the surface composite element. The microstructure of the first and / or the second surface element preferably has numerous microstructure elements that are identical to one another and / or arranged periodically over the surface, each of which can have any desired shape and can be formed from any desired number of sections. The individual surfaces of the microstructure elements can be flat or non-curved, or can have a curved and / or angular profile.According to the invention, the microstructure is arranged at least on one side of each surface element, although an arrangement on both sides is also conceivable. However, the formation of microstructures on an exposed outer surface can also be undesirable, since, for example, in the outer area of ​​a window pane, there is a risk of scratching or clogging of the microstructures. Furthermore, such a microstructured outer surface can only be cleaned to a limited extent, which is why a coating or covering is preferred. In contrast, the microstructures located inside the composite surface element are protected against damage and, in particular, against mechanical influences.

[0018] The microstructure can be formed from both elevations and depressions. The microstructure is particularly preferably formed from depressions and elevations along at least one spatial direction, particularly preferably along at least one direction of the surface of the composite element, and particularly preferably from an alternating arrangement of depressions and elevations.

[0019] According to the invention, the microstructures are formed and arranged on the inner surface of both surface elements in such a way that both surface elements can be brought together with their inner surfaces facing one another, wherein the two microstructures are then arranged one inside the other. In this case, the surface elements are arranged in particular in such a way that elevations of the first microstructure engage in depressions of the second microstructure and / or elevations of the second microstructure engage in depressions of the first microstructure. It is particularly preferred that in each case an elevation of the first surface element is arranged in a depression of the second surface element and in each case adjacent thereto a depression of the first surface element is arranged in an elevation of the second surface element.

[0020] Furthermore, according to the invention, microcavities for light guidance are formed by the interlocking of the microstructures of two surface elements. The formation of microcavities, which are well suited for light guidance, in the form of remaining gaps when the microstructures are interlocked, advantageously allows the microcavities to be formed and arranged very precisely, even with small dimensions. The formation of narrow, elongated microcavities, as well as microcavities arranged at a relatively large angle to the surface, i.e., a correspondingly smaller angle to the surface normal, is particularly achievable through the interlocking of the microstructures and is advantageous for light guidance.

[0021] In principle, the microcavities can have any shape, any arrangement, and any size. Furthermore, not all microcavities in the composite surface element need to be identical to one another, although this is preferred. Alternatively, an alternating arrangement of two different microcavities is also preferred.

[0022] Where reference is made to the dimensions of the microcavities, in particular the length, width, or height, this is to be understood with respect to a vertical surface formed by the surface elements, i.e., the foils or plates. The depth of the microcavities then refers to the dimension in the direction of the surface normal. This reference is chosen for clarity and is not to be understood as limiting; i.e., the composite surface element can, of course, also be used in a different orientation.

[0023] The microcavities and in particular microlamellae can in principle be arranged in a wide variety of ways to the surface of the surface elements in a free design of the microstructures: vertically, obliquely, curved, with a variable obliqueness or curvature over the surface, with different thicknesses and / or varying thicknesses, etc. The microlamellae can also be arranged horizontally or vertically, at any angle and / or in a curved manner in the plane of the surface elements.

[0024] In general, however, it is preferred that the microcavities have an elongated shape and are formed in particular as microlamellae or as microgaps, wherein particularly preferably an average depth of the microcavities is more than 2 times, very particularly preferably more than 5 times, and especially preferably more than 10 times an average height of the microcavities. Furthermore, the microcavities can extend in width over the entire surface or sections thereof. For example, the width of the microcavities can be at least 1 mm, preferably at least 1 cm, very preferably at least 5 cm, and very particularly preferably at least 10 cm. Finally, it is preferred that the microcavities have an angle to the surface normal of the first and / or the second surface element of less than 60°, very preferably less than 45°, and very particularly preferably less than 30° in a depth direction.

[0025] The internal microcavities formed between the microstructures can be gas-filled, evacuated, or filled with a medium that is optically less dense than the material of the surface elements or microstructures. As a result, total internal reflection occurs at the interfaces between the optically denser material of the surface elements and / or microstructures and the microcavities when light is incident at sufficiently shallow angles, which is used to direct the light.

[0026] According to the invention, the microcavities are internal, i.e. the microcavities are embedded in the interior of the composite surface element and are preferably neither open to the outside nor is the interior of the microcavities accessible, so that the composite surface element is insensitive to touch, cleaning, scratching or other external influences.

[0027] According to the invention, the two surface elements are connected to each other on the microstructure side and thus secured to each other, whereby this securing can be achieved by positive or non-positive locking. Furthermore, the connection of the surface elements, and in particular the microstructures—in addition to the positive or positive and non-positive locking—can also be achieved, for example, by adhesive bonding, ultrasonic bonding, chemical or thermal joining, or in any other way.

[0028] The locking sections corresponding to one another are also provided for a form-fitting hold and for this purpose have at least one section or a partial area with a corresponding shape corresponding to one another.

[0029] The composite panel elements according to the invention can be used, in particular as composite films or composite panels with microlouvres, in windows and window facades, especially in skylights, to achieve the desired effect of directing daylight into the depths of rooms. The composite panel elements can be laminated, in particular, to the inside or outside of window panes or inserted into the space between insulating glazing units. Accordingly, it is preferred that the composite panel element be formed in such a way that it can be laminated, in particular as a light-conducting film, to a glass pane or other transparent body.

[0030] In a preferred development of the composite surface element according to the invention, the internal microcavities extend along a depth direction of the composite surface element over a first depth range or within a first depth range, and the first and second surface elements are fixed in at least a second depth range, which advantageously prevents any interaction with the microcavities. Accordingly, it is particularly preferred that the locking sections are arranged completely outside the first depth range containing the microcavities and / or completely inside the composite surface element, wherein an arrangement completely inside the composite surface element simultaneously achieves good protection of these areas and prevents the penetration of dirt.The depth direction is the direction normal to a surface of the composite surface element and thus typically the spatial direction with the smallest spatial extent of the composite surface element.

[0031] Although, in principle, any other fastening method is conceivable in addition to the form-fitting or form-fitting and force-fitting fastening of the two surface elements to one another, in a preferred embodiment of the composite surface element according to the invention, this fastening of the first and second surface elements to one another takes place exclusively form-fitting or form-fitting and force-fitting and, in particular, not by means of a material connection. The fastening is particularly preferably adhesive-free.

[0032] In order to achieve a particularly stable attachment of the two surface elements, the invention provides that, for the positive attachment of the surface elements to one another, the locking sections of the first and second surface elements are each formed as a corresponding pair consisting of a locking receptacle and a locking element. The locking receptacle is preferably arranged or formed on one surface element, and a corresponding locking element is arranged or formed on the other surface element.

[0033] The locking receptacle and the locking element can in principle be formed as desired and in particular have any desired shape. Preferably, the locking receptacle has two mutually facing and preferably mutually parallel locking inner surfaces and the locking element has two mutually facing and preferably mutually parallel locking outer surfaces, wherein in each case one locking inner surface and one locking outer surface are in surface contact with one another. Very particularly preferably, the fixing of the surface elements takes place by a press fit of the locking elements, wherein particularly preferably the distance between the two locking outer surfaces is greater than the distance between the locking inner surfaces. The distance between the two locking outer surfaces is preferably between 0.01% and 10%, particularly preferably between 0.1% and 5% and very particularly preferably between 0.5% and 2% greater than the distance between the locking inner surfaces.This distance generally exists between the corresponding surfaces and / or surfaces belonging to a locking receptacle and / or a locking element.

[0034] Also advantageous is an embodiment of the composite surface element according to the invention in which the two surface elements are secured to one another by locking, with at least one locking lug preferably being arranged on the locking element or on the locking receptacle to secure the two surface elements against being pulled apart. This can involve a detachable connection between the two surface elements or an irreversible locking connection that cannot be opened without at least partially destroying the microstructures.

[0035] The height of the microcavities in the height direction of the surface composite element and the depth of the microcavities in the depth direction of the surface composite element must be selected such that, on the one hand, the greatest possible light guidance is achieved and, on the other hand, the good optical properties of the surface composite element are maintained so that it is not perceived as disturbing by a user. Accordingly, an advantageous embodiment of the surface composite element is preferred in which the height of the microcavities is between 100 nm and 20 µm, particularly preferably between 1 µm and 10 µm, and very particularly preferably between 3 µm and 8 µm, and / or the depth is between 20 µm and 1 mm, particularly preferably between 50 µm and 500 µm, and very particularly preferably between 100 µm and 300 µm.

[0036] A particularly advantageous development of the composite surface element according to the invention provides that the surface elements, and in particular the entire composite surface element, are completely transparent. Completely transparent means, in particular, without any clouding, inclusions, discoloration, and / or cavities visible to the eye, i.e., the composite surface element(s) are not diffuse and / or essentially translucent without restriction. In particular, it is preferred that the two surface elements, and thus most preferably also the composite surface element, be formed as transparent and / or flexible films.

[0037] Several embodiments of a composite surface element according to the invention for light guidance are explained in more detail below with reference to the drawings. The figures show: Fig. 1 a schematic sectional view of a window pane with a composite surface element; Fig. 2 a front view of theFig. 1illustrated window pane; Fig. 3 shows a schematic longitudinal section of a first and a second surface element with a microstructure according to a first embodiment; Fig. 4 shows a schematic longitudinal section of a composite surface element composed of the surface elements according to the first embodiment; Fig. 5 shows a schematic longitudinal section of a first and a second surface element with a microstructure according to a second embodiment; Fig. 6 shows a schematic longitudinal section of a composite surface element composed of the surface elements according to the second embodiment; Fig. 7 shows a schematic longitudinal section of a first and a second surface element with a microstructure according to a third embodiment; Fig. 8 shows a schematic longitudinal section of a composite surface element composed of the surface elements according to the third embodiment;9 shows a schematic longitudinal section of a first and a second surface element with a microstructure according to a first embodiment, which is not part of the claimed invention; Fig. 10 shows a schematic longitudinal section of a composite surface element composed of the surface elements according to the first embodiment, which is not part of the claimed invention; Fig. 11 shows a schematic longitudinal section of a first and a second surface element with a microstructure according to a fourth embodiment; Fig. 12 shows a schematic longitudinal section of a composite surface element composed of the surface elements according to the fourth embodiment; Fig. 13 shows a schematic longitudinal section of a first and a second surface element with a microstructure according to a fifth embodiment; Fig.Fig. 14 shows a schematic longitudinal sectional view of a composite surface element composed of the surface elements according to the fifth embodiment; Fig. 15 shows a schematic longitudinal sectional view of a first and a second surface element with a microstructure according to a second embodiment, which is not part of the claimed invention; and Fig. 16 shows a schematic longitudinal sectional view of a composite surface element composed of the surface elements according to the second embodiment, which is not part of the claimed invention.

[0038] The various embodiments of a composite surface element 1 are each formed as a composite of two transparent surface elements 11, 21, wherein the surface elements 11, 21 are preferably each formed as films and / or plates. Furthermore, the surface elements 11, 21 each have a microstructure 12, 22 on at least one side. The two surface elements 11, 21 are connected on the microstructure side by superimposed inner surfaces 13, 23, so that defined microcavities 2, in particular microgaps or microlouvres, are formed between the microstructures 12, 22. The composite surface elements 1 can in particular be used to be arranged on the surface of a window pane 9 and thus achieve improved light guidance of obliquely incident light into the room (see Fig. 1 ).

[0039] The microstructures 12, 22 of a composite surface element 1 are interlocked, so that a protrusion 14 of the first microstructure 12 is positioned in a depression 25 of the second microstructure 22 and a protrusion 24 of the second microstructure 22 is positioned in a depression 15 of the first microstructure 12. By interlocking the microstructures 12, 22, gaps can be formed as microcavities 2 with a very large aspect ratio (ratio of width to height) (see Fig. 2 ) which cannot be manufactured using conventional microstructuring of surfaces or cannot be easily realized.

[0040] The microcavities 2 created by the microstructure-side connection and embedded between the microstructures 12, 22 are filled with air, causing the light incident on the microcavities 2 to be totally reflected as long as the conditions for total reflection are met. The light redirection is thus essentially based on loss-free total reflection.

[0041] In the film / plate plane of the composite surface element 1, the microcavities 2 can be arranged horizontally or vertically, at any angle or even in a curved manner. Fig. 3 - 16 show some examples of microstructure combinations and the resulting cross-sectional profiles of the microcavities 2, particularly microlamellae, when the two surface elements 11, 21 are joined together. For better understanding, the depth, width, and height directions in the drawings are indicated with reference to a vertically positioned surface element.

[0042] By means of a suitable profile geometry, the two microstructured inner surfaces 13, 23 of the two surface elements 11, 21 can be fixed to one another in a force-fitting manner and / or locked into one another.

[0043] In a first, in the Figures 3 and 4In the embodiment shown, in the area of ​​the depressions 15 of the first microstructure 12, the two surface elements 11, 21 are fastened to one another exclusively by force via two flat adhesive sections 16, 26 of the two microstructures 12, 22, while in the area of ​​the depressions 25 of the second microstructure 22, a positive fastening additionally takes place, with a locking section 17 at the end of the elevations 14 of the first microstructure 12 engaging with a corresponding locking section 27 in the interior of the depressions 25 of the second microstructure 22. The first locking section 17 is formed as a male locking element 6, while the second locking section 27 is formed as a female locking receptacle 5. Micro-cavities 2 are formed between the microstructures 12, 22, which run at right angles to the surface of the surface composite element 1.

[0044] Another one in the Figures 5 and 6The embodiment shown differs from the first embodiment only in that in the area of ​​the depressions 15, 25 of both microstructures 12, 22, the two surface elements 11, 21 are fixed to one another in a force-fitting and form-fitting manner, so that the two surface elements 11, 21 have a mirror-symmetrical structure to one another and are merely arranged offset from one another.

[0045] Another one in the Figures 7 and 8 The embodiment shown differs from the first embodiment only in that the micro cavities 2 no longer run parallel to the depth direction, but alternately inclined in the height direction.

[0046] The locking can also be designed such that microcavities 2 are created only on one side of the microstructure 12, 22, while a force-fitting material bond takes place on the other side. This may require a slightly adhesive surface, which can be achieved, for example, by selecting a slightly adhesive material in the microstructure 12, 22 or a corresponding coating. Two first surfaces 3 of each of the two microstructures 12, 22 are spaced apart and preferably arranged parallel to each other, so that they form a microcavity 2, while two second surfaces 4 of the two microstructures 12, 22 are in full contact and form an adhesive section 16, 26 (see Figs. 9 and 10 ).

[0047] One in the Figures 11 and 12 The version shown differs from the previous version of the Figures 9 and 10, which is not part of the claimed invention. This is significantly due to the fact that, in addition to the force-fitting fastening by means of adhesive sections 16, 26, a form-fitting fastening by means of locking sections 17, 27 is also carried out. Furthermore, the micro-cavities 2 formed as micro-lamellae have a curved course in the depth direction. It is also possible in principle that the micro-cavities 2 do not extend over the entire depth of the depressions 15, 25, as is the case, for example, in the Figures 15 and 16 is shown.

[0048] A locking action can also be achieved in particular by the width of the locking receptacle 5 being slightly smaller than the width of the locking element 6 in the region of the locking section 17, 27, resulting in a press fit. For this purpose, the preferably parallel inner locking surfaces 7 of the locking receptacle 5 are spaced apart by a smaller distance than the two outer locking surfaces 8 of the locking element 6 (see Figs. 13 and 14 ).

[0049] The composite surface elements 1 formed as composite films or panels with micro-louvres as micro-cavities 2 can be used in windows, on window panes 9, and on window facades, particularly in skylights, to achieve the desired effect of directing daylight into the depths of rooms. Films can be laminated to the inside or outside of window panes or inserted into the space between insulating glazing units. The micro-cavities 2 are embedded within the film or panel, making the film resistant to contact, cleaning, scratching, or other external influences. List of reference symbols

[0050] 1Surface composite element 2Microcavities 3First surface 4Second surface 5Locking receptacle 6Locking element 7Internal locking surface 8External locking surface 9Window pane 11First surface element 12First microstructure 13First inner surface 14Elevations of the first microstructure 15Depressions of the first microstructure 16Adhesive section of the first microstructure 17Locking section of the first microstructure 21Second surface element 22Second microstructure 23Second inner surface 24Elevations of the second microstructure 25Depressions of the second microstructure 26Adhesive section of the second microstructure 27Locking section of the second microstructure T1First depth range T2Second depth range

Claims

1. Composite panel element (1) for guiding light, with - a first panel element (11) with a first microstructure (12) on a first inner surface (13), wherein the first microstructure (12) has elevations (14) and / or recesses (15), - and a second panel element (21) with a second microstructure (22) on a second inner surface (23), wherein the second microstructure (22) has recesses (24) and / or elevations (25), - wherein the panel elements (11, 21) are arranged relative to one another such that the first and second inner surfaces (13, 23) face one another and the first and second microstructures (12, 22) are arranged in an interlocking manner such that internal micro cavities (2) are formed between the microstructures (12, 22), characterized in that - the first and second microstructures (12, 22) have snap-in sections (17, 27) corresponding to one another for form-fit fastening of the panel elements (11, 21) to one another, and - the snap-in sections (17, 27) of the first and second panel elements (11, 21) are each formed as a corresponding pair of a snap-in catch (5) and a snap-in element (6).

2. Composite panel element according to claim 1, characterized in that the internal micro cavities (2) extend along a depth direction of the composite panel element (1) over a first depth section (T1) and the fixing of the first and second panel elements takes place in at least a second depth section (T2).

3. Composite panel element according to claim 1 or 2, characterized in that the snap-in sections (17, 27) are arranged completely outside the first depth section (T1) and / or completely inside the composite panel element (1).

4. Composite panel element according to at least one of the preceding claims, characterized in that the first and second panel elements (11, 21) are fixed to one another exclusively in a form-fitting or form- and force-fitting manner.

5. Composite panel element according to at least one of the preceding claims, characterized in that the snap-in catch (5) has two snap-in inner surfaces (7) facing one another and parallel to one another and the snap-in element (6) has two snap-in outer surfaces (8) facing one another and parallel to one another, wherein one snap-in inner surface (7) and one snap-in outer surface (8) are in planar contact with one another in each case.

6. Composite panel element according to at least one of the preceding claims, characterized in that the panel elements (11, 21) are fixed by a press fit of the snap-in sections (17, 21), the distance between the two snap-in outer surfaces (7) preferably being greater than the distance between the snap-in inner surfaces (8).

7. Composite panel element according to at least one of the preceding claims, characterized in that the two panel elements (11, 21) are fixed to one another by snap-in, at least one snap-in lug preferably being arranged on the snap-in element (6) or on the snap-in catch (5) in order to secure the two panel elements (11, 21) against being pulled apart.

8. Composite panel element according to at least one of the preceding claims, characterized in that the composite panel element (1) is completely transparent.

9. Composite panel element according to at least one of the preceding claims, characterized in that the two panel elements (11, 21) are formed as transparent and / or flexible films.

10. Composite panel element according to at least one of the preceding claims, characterized in that the micro cavities (2) have a height of between 100 nm and 20 µm, preferably between 1 µm and 10 µm and particularly preferably between 3 µm and 8 µm.

11. Composite panel element according to at least one of the preceding claims, characterized in that the micro cavities (2) have a depth of between 20 µm and 1 mm, preferably between 50 µm and 500 µm and particularly preferably between 100 µm and 300 µm.

12. Window with - a window pane (9) and - a composite panel element (1) applied thereto according to one of the preceding claims.

13. Method of manufacturing a composite panel element (1) for guiding light, comprising - providing a first panel element (11) with a first microstructure (12) on a first inner surface (13), wherein the first microstructure (12) comprises elevations (14) and recesses (15), - providing a second panel element (21) having a second microstructure (22) on a second inner surface (23), wherein the second microstructure (22) comprises elevations (24) and recesses (25), - arrangement of the panel elements (11, 21) relative to one another such that the first and second inner surfaces (13, 23) face one another and the first and second microstructures (12, 22) are arranged in an interlocking manner such that internal micro cavities (2) are formed between the microstructures (12, 22), - wherein a form-fit fixing of the panel elements to one another (11, 21) is achieved by means of corresponding snap-in sections (17, 27) of the first and second microstructure (12, 22), - wherein the snap-in sections (17, 27) of the first and second panel elements (11, 21) are each formed as a corresponding pair of a snap-in catch (5) and a snap-in element (6).