EP1456497A1

EP1456497A1 - Sun protection device

Info

Publication number: EP1456497A1
Application number: EP02799738A
Authority: EP
Inventors: Peter Nitz; Christopher BÜHLER; Andreas Gombert; Benedikt BLÄSI
Original assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
Current assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
Priority date: 2001-12-17
Filing date: 2002-12-04
Publication date: 2004-09-15
Also published as: US20050068630A1; WO2003052232A1; DE10161938A1

Abstract

The invention relates to a sun protection device comprising at least one flat optical element (F) consisting of an at least partially transparent material and having two sides facing each other, one (E) of said sides being embodied in a non-structured flat manner, and the other (S) comprising parallel, linearly extending prismatic structural elements (SE) which periodically repeat themselves in the lateral direction. The structured side (S) comprises a surface (O) which is at least largely coparallel in relation to the unstructured flat side (E), the structural elements (SE) projecting past said surface. The inventive device is characterised in that the structural elements (SE) respectively comprise a triangular cross-sectional surface having a lateral edge (C) and two lateral flanks (A, B) which protrude above the surface, the lateral flank (A) being associated with a defining surface (A*) and the lateral flank (B) being associated with a defining surface (B*). Furthermore, at least two adjacent structural elements are laterally separated from each other by a section (D) of the surface (O), the lateral flank (A) forms an angle 90°-α with the surface, and forms an angle α + β with the lateral flank (B), and the lateral flank (B) forms an angle 90°-β with the surface.

Description

Sun protection device

Technical field

The invention relates to a sun protection device for light-transparent building openings against direct sunlight entering the building interior with at least one optical surface element consisting of at least partially light-transparent material, which can be attached in the area of the building opening and has two opposite surface element sides, one of which is flat in structure and the other provides prismatic structural elements running parallel to one another, linearly extending and periodically repeating in the lateral direction.

State of the art

In modern architecture, large glazed areas are increasingly being used, an architectural stylistic device that is desirable in principle, especially since the solar radiation / solar energy transmitted through the windows effectively contributes to covering the heating requirements during the heating season and the lighting situation due to increased lighting noticeably improved with daylight.

In the case of windows and glazing that transmits sunlight, however, undesirable effects can also occur. Intense, direct sunlight leads to glare in the interior of the room, especially in connection with VDU workstations. Add to that too high Solar energy inputs lead to uncomfortably high room temperatures, especially on warm summer days.

Especially in commercial property construction (administration and office buildings, ...), the primary energy requirement for cooling in summer often exceeds that for heating in winter. There is therefore a legitimate desire to avoid undesirable solar energy inputs in the summer as much as possible and, if screen workstations are located in the glazed room, to reduce glare effects.

In addition to classic solutions such as the provision of awnings or balconies in front of window surfaces, mechanical shading or sun protection systems with moving parts such as blinds and Venetian blinds, as well as technically complex optically switchable layers - all solutions that have various disadvantages, such as inflexible interior lighting, Too expensive or technically impossible to solve for large window areas - light-directing optical elements are known which work on the basis of optical refraction, reflection and / or internal total reflection and thus represent elements for sun and glare protection or also contribute to improving the daylight yield in interiors.

Such optical elements are typically designed as light-transparent surface elements and have, at least on one of their surfaces, prismatic structures which, depending on the angle of incidence, transmit, deflect, scatter or reflect the incident radiation. In the case of permanently installed surface elements of this type, the seasonally varying position of the sun means that direct sunlight during a certain time period, e.g. during the summer months, is reflected in a targeted manner, but during the remaining time the light deflection system can pass almost unhindered.

The function of light-guiding prisms can be expanded by attaching the structured surface so flexibly that the alignment of the structure to the Light source can be varied specifically. Such systems are known from DE 1 497 348, DE 31 38262 A1, US 4,773,733, DE 195 42 832 A1 or DE 19700 111 A1, in which structured lamellae or prismatic rods are rotatably mounted about an essentially horizontal axis, as a result of which the light-directing ones Align structures in a targeted manner or let them track the sun. However, the disadvantages of classic slatted blinds or external venetian blinds apply to these movable systems, in terms of expensive acquisition costs and susceptibility to faults due to mechanical failure.

In other systems, the light-directing or optically effective structure is applied stationary on a transparent pane, plate or glazing. The structure that influences the light path can lie either on the side facing the light source (“outside”) or on the side facing away from the light source (“inside”) of a transparent or translucent plate or glazing. Such systems with external prismatic structures are known from DE 831 449 or FR 2 463254, which fulfill the desired functions. Internal prismatic systems are known e.g. from DE 113391, US 2,812,691, US 4,519,675, DE 35 17 610 A1, DE 195 38 651 A1 or DE 198 34 050 A1. Systems with structures both inside and outside are also e.g. described in DE 1 50 365.

DE 26 15379 A1, DE 32 27 118 C2 and US 4,498,455 describe light-guiding systems in which the effect of a light-guiding prism system or prismatic slat system is further improved by including one or more flanks of the prism structure or slats in question are provided with a highly reflective, absorbent or highly scattering coating, for example are mirrored. Only the lamellar, rotatably mounted systems, such as lamellas, prism poles, allow a partial view through the glazing system between two adjacent lamellas / poles in certain positions. However, all of the above-mentioned surface-mounted systems have the disadvantage that the structuring makes it impossible to see through the surface systems. In the case of the flatly applied structures, use in facade areas is therefore prohibited, in which a view is desired or even absolutely necessary.

Another system, in which there is partial optical transparency, consists of complementary structures which take advantage of the fact that when passing through a thin, plane-parallel gap, only a minimally small parallel beam offset takes place. Thus, an element that fulfills a sun protection function due to total reflection at certain angles of incidence can be provided with see-through properties by adding a complementary structure to the element. Such systems are known, for example, from DE 1740553, DE 11 71 370, US 2,976,759, US 3,393,034, US 4,148,563, US 4,519,675, US 5,880,886, DE 19542 832 A1 or DE 196 22670. However, those complementary structures which are formed with inclined triangular prisms as the basic structure have the disadvantage that there are no joining surfaces available on which the structure and the complementary structure could be attached or glued to one another. In known structures, the basic structure of which is "quadrangular" in cross-section, as can be seen from DE 1740553 and DE 196 22 670, the end faces are suitable as adhesive surfaces. A possibility or a method of how structure and complementary structure can be joined and connected can be found in particular in DE 196 22 670.

Only US Pat. No. 5,880,886 (Milner, 1994) describes composite structures and complementary structures with a partial view that are suitable for surface mounting, inter alia, in vertical glazing. Compared to a triangular prism, the prism tip of the assembled structures is "replaced" by a partial surface, which is aligned plane-parallel to the continuous "rear" flat surface and allows a partial view. The viewing area or partial area that potentially allows partial viewing, is in any case on the "raised side" of the structure. The complementary structures listed in US Pat. No. 5,880,886, on the other hand, do not have an immediate viewing area, but (partial) viewing is achieved solely and exclusively through the complementary property of the two structures used.

The known complementary structures with optical see-through properties are complex to manufacture due to their two-component structure and accordingly cause additional costs in manufacture. In addition, they all only have light deflecting properties which are only able to deflect incident sunlight into the interior of the room, preferably to the ceiling area. A distraction to the outside, for example due to reflection to the outside, does not take place or only takes place to a limited extent.

Presentation of the invention

It is the task of specifying a sun protection device for light-transparent building openings to prevent direct sunlight from entering the interior of the building in such a way that effective sun protection is ensured with optical transparency properties, the sun protection device being designed to have the simplest possible geometry and simple construction, in order in this way to enable production keep associated production costs low. Sun protection should also make a decisive contribution to reducing the amount of light entering the interior of the building, especially when the sun is high, as is particularly the case in warm seasons.

The solution to the problem on which the invention is based is specified in claim 1. Features advantageously further developing the inventive concept are the subject matter of the subclaims and the entire description, in particular with reference to the exemplary embodiments. According to the invention, a sun protection device for light-transparent building openings against direct sunlight entering the building interior is provided with at least one optical surface element consisting of at least partially light-transparent material, which can be attached in the area of the building and has two opposite surface element sides, one of which is flat and the other unstructured Provided parallel to each other, linearly extending and periodically repeating prismatic structural elements in the lateral direction, designed such that the structured flat element side has a surface which is at least largely coparallel to the flat, unstructured flat element side and is surmounted by the individual structural elements. The individual structural elements each have a triangular cross-sectional area, which is enclosed by a side edge which coincides with the surface, and by two side flanks raised above the surface. The individual structural elements thus represent three-dimensional prismatic shaped bodies, which are defined by two free boundary surfaces, each of which is assigned to the two side flanks raised above the surface. In order to ensure the optical transparency properties of the surface element according to the invention, at least two adjacent structural elements are laterally separated from one another by a surface section of the surface. Each of these surface sections ensures an almost unobstructed view through the optical surface element consisting of light-transparent material. In addition, one of the two side flanks forms an angle of 90 ° -α with the surface. Both side flanks also form an angle α + β with one another and finally the other side flank forms an angle 90 ° -ß with the surface. In any case, α is not equal to β, which ensures that one side flank is always longer than the other. For reasons of effective light control, however, it is particularly advantageous here if the longer side flank is always arranged facing the incidence of sunlight.

The sun protection device designed according to the invention, which can be titled synonymously with the terms light deflection or glare protection device, lies The idea is based on creating an optically effective surface structuring on an optical surface element consisting of light-transparent material, the structural elements of which are arranged in a periodic sequence on a surface of the surface element and are spaced apart from one another such that in the case of oblique illumination, the shadow cast by each individual structural element is the neighboring one Structural element is unable to cover. If the structural elements were lined up immediately adjacent to one another, the shadow of each individual structural element would fall on the adjacent structural element, as a result of which the optical effect of the structural element would be lost at least in this shaded area. However, if the individual structural elements are separated from each other in such a way that there is no or only a slight shadow coverage between the individual neighboring structural elements, and if the surface section that has been freed by the spacing of two immediately adjacent structural elements is unstructured and preferably left flat, this results in these surface sections the optical situation of two exactly or almost plane-parallel plates - if you look at the respective surface section and the back surface of the surface element, which has already been formed in any case - which enables an unobstructed and, above all, image-preserving view.

Even in embodiments of the sun protection device according to the invention, in which the respective two structural elements laterally spaced surface sections enclose a small angle with the flat rear surface of the surface element, the optical transparency properties are still retained, although the transparency image is shown slightly offset, which may be tolerable or is even desirable in some cases.

The surface element with its structured flat element side is advantageously to be attached in the area of the building opening in such a way that the structured flat element side faces the incidence of sunlight. As will be shown in detail, however, the surface element designed according to the invention is also capable of a desired anti-glare or protective effect in reverse installation, ie the structured flat element side faces the interior of the building.

Although the integration of the sun protection effect according to the invention into vertically oriented building openings is also the main interest and main area of application of such surface elements, for example by integrating the sun protection device in vertical window surfaces, its use is also fundamentally possible and also at inclined building openings, for example in roof areas or inclined facade flanks conceivable.

The exact geometric design and arrangement of the side flanks or boundary surfaces of the individual structural elements is fundamentally based on the type and purpose of their use, i.e. depending on whether it is a vertical or an obliquely inclined arrangement of the surface element or whether the structured surface element side faces or faces away from the sunlight. Particular attention must be paid to the local lighting conditions, which result from the sun orbits and sun positions depending on the latitude on earth and the seasons.

In consideration of the above-mentioned framework conditions to be taken into account individually, the side edges or boundary surfaces of the individual structural elements are preferably inclined to one another and to be oriented in relation to the incidence of sunlight such that the sunlight striking the structural elements, which strikes the individual structural elements from a certain angular range, is almost completely masked out , ie deflected to the outside by means of total internal reflection or thrown back into an outside area facing away from the inside of the building. If, however, sunlight strikes the corresponding structural elements from the other solid angle areas, the sunlight is passed on or redirected into the interior of the room. The sun protection device designed according to the invention, in which the structured side S faces the light source, is therefore characterized by a characteristic dip in its transmission properties hemispherical optical transmission for direct sunlight falling on the structural elements. Further details can be found below with reference to the exemplary embodiments.

Brief description of the invention

The invention is described below by way of example without limitation of the general inventive concept using exemplary embodiments with reference to the drawing. Show it:

1a, b are schematic sectional views for explaining the structural elements designed according to the invention (1a: state of the art), Fig. 2 lighting situation in which the structured flat element side faces the interior of the building, for explaining the function according to the invention Fig. 3 cross-sectional representation of a designed according to the invention

Sun protection device, Fig. 4 typical beam profiles (qualitative) within the

5, transmission diagram for the qualitatively shown in FIG. 4

Illumination situations, Fig. 6 cross-sectional view of a sun protection device with curved surfaces and rounded edges, Fig. 7, 8 sun protection devices in a complementary arrangement and

Fig. 9-11 diagram representations with regard to the transmission for different exemplary embodiments.

Ways of carrying out the Invention, Industrial Usability

FIG. 1a shows the situation according to the prior art, in which a surface element F structured on one side is irradiated by sunlight hv. The individual structural elements SE directly adjoin one another in the manner of a sawtooth structure and lead to mutual self-shading in the case of oblique irradiation (see hatched area). In areas in which self-shadowing occurs, however, the individual structural elements lose their visual effect. In contrast, in FIG. 1b, according to the invention, a surface element F is designed such that in areas in which mutual self-shading would occur, as in the case according to FIG. 1a, two adjacent structural elements SE are laterally spaced apart from one another by a surface section D. The surface sections are preferably arranged co-parallel to the flat element side E, which is otherwise flat. It is precisely in these areas of the surface element sections D, which are oriented coparallel to the surface element side E, that there are optical viewing conditions, so that a surface element F made in accordance with FIG. 1b and made of a light-transparent material for sun protection purposes can be integrated in the building facade area, in which the desire for there is at least partially existing optical transparency.

In contrast to the arrangement of the surface element F shown in FIG. 1b, in which the structured surface element side S faces the sunlight hv, FIG. 2 shows a situation in which the surface element F with its structured surface element side S faces away from the sunlight hv and the interior of the building is facing. In this case, too, the surface elements D between adjacent structure elements SE help the surface element F to be visually inspected. The hatched area indicates here that the structure elements SE can also be formed in this situation in such a way that no light exclusively occurs regularly through coparallel boundary surfaces is transmitted, but an impact on the flanks of the SE and thus an optical effect according to the invention is ensured despite the viewing area D. To understand the optical effect of the sun protection device designed according to the invention, it is shown in a cross-sectional illustration in FIG. 3 and provided with corresponding reference variables or symbols. As already mentioned above, the surface element F basically consists of a flat, unstructured surface element side E and a structured surface element side S located opposite it. On the side of the structured surface element side S, structural elements SE are provided in a periodic sequence, which have a triangular cross-sectional shape. Each individual structural element SE is delimited by two side flanks A, B, which rise above a surface O of the flat element side S. Only for reasons of geometric completeness should it be mentioned that each individual structural element SE is virtually delimited by a side edge C, the structural elements SE being, of course, connected and manufactured in one piece with the surface element F from the light-transparent material. Since the structural elements SE represent prism-like triangular bodies in their three-dimensional spatial shape, they are bounded by boundary surfaces or flank surfaces A * and B * corresponding to their cross-sectional side flanks A, B, respectively. Adjacent structural elements SE are also laterally spaced apart from one another by surface element sections D, the surface sections D at least largely coinciding with the surface O. The surface sections D are preferably flat and oriented coparallel with respect to the flat element side E. In special embodiments, however, the surface sections D can also be inclined slightly obliquely relative to the flat element side E. Typical angles of inclination are, for example, between 0 and 10 °.

Furthermore, it is assumed that the surface element F is preferably integrated vertically in a building facade opening and is oriented towards the south. In the same way, it is conceivable to orient the surface element F also in obliquely inclined positions and with orientations between southeast to southwest. Depending on the orientation and attachment of the sun protection device, the geometric designs and inclinations of the boundary surfaces A * and B * suitable to make. This is because they are decisively determined by the so-called sun profile angle αp, which corresponds to the angle between a surface normal with respect to a vertical surface and the projection of the direction of the sun onto the plane spanned by the surface normal and a vertical straight line. For example, the sun profile angle α _P assumes values between a minimum αp _u and a maximum angle αp ₀ for a vertical surface oriented exactly to the south, which each depend on the latitude and the ecliptic in the following way:

α _Pu = 90 ° - Φ - δ _max <α _P <90 ° - Φ + δ _max = α _Po

In the above relationship, Φ describes the latitude and δ _max = 23.45 ° the maximum declination or ecliptic, which results from the inclination of the earth's axis in relation to the orbit of the sun.

In order to be able to determine the design of the structural elements SE, the above-mentioned general conditions have to be taken into account. The sun protection device designed according to the invention is intended to almost completely avoid the direct incidence of sunlight into the interior of the room.

In the case of a vertical installation position of the surface element F and preferably an exact south orientation, the following design criteria can be defined with regard to the geometric design of each individual structural element: Assuming, as shown in FIG. 3, that the side flanks A and B depend on the angles α and β in 3 are included, they are to be selected in such a way that an effective light suppression when direct sunlight is incident on each of the boundary surface A ^* with increasing angles of incidence is to be selected such that a sunlight beam entering through the boundary surface A ^{* of} the structural element SE is such is broken, that this is totally reflected on the rear surface element side E. This is the case if the solar radiation takes at least the smallest solar profile angle αp _u ι, which is given by the following relationship:

α _pu ι = 90 ° - α + arcsin [n sin (arcsin (1 / n) - (90 ° - α))]

This case is shown in FIG. 4 and described by light path I. The light beam entering via the boundary surface A ^* is refracted at A ^{* in} such a way that the coupled-in light beam is totally reflected on the unstructured flat element side E which has just been formed and then emerges outward via the structured flat element side S.

The shadowing effect due to back reflection is also enhanced if a light beam that enters the surface element F through the upper boundary surface A ^{* is} subsequently totally reflected on the immediately adjacent boundary surface B *, so that the light beam is finally at an angle to the rear surface Flat element side E occurs, under which total reflection also occurs. Such a case exists if the solar radiation takes at least one lower solar profile angle in the following form:

α _pU2 = 90 ° - α + arcsinf n sin (arcsin (1 / n) + α + 2ß -90 °)]

The above condition is also shown in FIG. 4 with reference to the beam path II. The light beam deflected twice by means of total reflection likewise leaves the surface element F via the structured surface element side S without entering the interior of the room.

The upper limit of the masking area is determined by a beam path, which likewise enters the surface element F through the boundary surface A * and strikes the lower boundary surface B ^* from the inside. If, in contrast to the previous case, there is no longer any total reflection at the boundary surface B ^* , then a considerable part of the sunlight radiation is transmitted through the surface element. The upper limit angle in this regard thus takes the following form:

α _P o = 90 ° - α + arcsin [n sin (arcsin (α + ß - arcsin (1 / n)))].

With the help of the above three critical angles or equations, the anti-glare area of the sun protection device according to the invention can be individually adapted to different lighting situations via the choice of the angles α and β and the boundary surfaces A * and B *.

FIG. 6 shows a typical transmission diagram along the ordinate (semi-spatial or hemispherical) transmission values and along the abscissa the sun profile angles are provided. This shows that the transmission decreases significantly in the angular range of approximately 42 °. In the range of approximately 48 ° there is a further characteristic reduction in the transmission. The transmission of the surface element begins to increase in a characteristic manner only in the range of approximately 68 °, so that the bright zenith light is transmitted again and contributes to the illumination with daylight.

A further optimization possibility is the choice of the structural height h of the individual structural elements SE. If, for example, the surface element is to block out sunlight in the range between ocp _U2 and ocp _{0 with the} greatest possible partial transparency, the minimum height h of the individual structural elements SE is determined from the condition that self- _shading is still occurring at the _{lower limit} α _{Pu2 of} the _{masking area} , so the following formula applies:

h = P / [tan (α) + tan (α _pu2 )].

Here, P corresponds to the period length of each structural element SE, which results from the sum of the length of the side edge C and the clear width of the surface element D (see FIG. 3). A similar relationship can also be determined for the lower sun profile angle α _Pu ι.

If the height h of the structural elements SE is chosen to be smaller, the viewing area increases at the expense of the shading or dimming effect. If the height h is chosen larger, it may improve. the dimming effect even further, but in return the transparency decreases.

The selection of a suitable structure also depends on the refractive index of the material used (as can be seen from the aforementioned equations). In this regard, it can be noted that the greater the refractive index, the greater the scope in the design / implementation and the expected optical functionality and effect of the sun protection element. Typically, materials with approximately 1.4 <n <1.7 are available nowadays, preferably high-index plastics with n> 1.55 being suitable for a sun protection element according to the invention.

As mentioned at the beginning, the above explanations relate to a surface element whose structured surface element side S faces the incidence of sunlight. If, however, the structured side of the surface element faces away from the light source or from the incidence of sunlight, there are other critical angles which, however, are revealed to an expert on the basis of the above considerations by equivalent considerations.

With reference to the illustration according to FIG. 3, edge lines K, L, M are provided between the individual areas A *, B ^* , D, which are ideally straight-line or sharp-edged if an optimal shading effect is to be achieved. Likewise, it is ideally assumed that the boundary surfaces A *, B ^* and the surface sections D are formed exactly flat.

However, if you want the shading to be only moderate and, in return, much better room lighting with daylight, the edges can be used preferably rounded or one of the two inclined boundary surfaces A * or B ^* or both curved together. Such a structure with curved boundary surfaces and rounded edges can be seen in FIG. 6. As expected, the desired optical masking becomes less effective due to such roundings, especially since light is deflected or broken almost isotropically at the round edges K, L, M. These curves can also be designed as convex or concave or wavy surfaces using different production techniques. Such measures primarily improve the daylight effect of the sun protection device. Sunlight that is incident on conical or curved surfaces is deflected. In some cases, this light can lead to undesirable effects in the interior of the room, but with a suitable choice of such structures, the light deflected on curved or conical surfaces can also lead to better or more uniform illumination of the interior of the room due to the diffuser effect inherent in such a surface element.

Deflection of light on cones or curved surfaces generally leads to the appearance of a vertical gloss band in transmission, i. H. the horizontal component of the beam direction is not changed by deflection at the rounding, but the vertical component is definitely changed. This leads to the mentioned effect of a bright, i.w. vertical stripe band. This effect can nevertheless be weakened or completely prevented by the individual structural elements likewise not being exactly flat in the direction of their translation axis, but rather having a slight ripple or slight curvature along their translation axis. As a result, the light from the glossy tape is distributed over a larger angular range and the glare, which may be annoying, is reduced. The waviness of the structural elements along the translation axis preferably has a stochastic character, since otherwise oblique gloss bands or other brightly visible structures can form under certain circumstances.

The optical functionality of the individual structural elements SE can be improved compared to what has been described above in that one or more Boundary surfaces or partial surfaces of the structural elements SE are provided with an optically effective layer. Such an optically effective layer can, for example, have a reflecting, scattering or absorbing effect. To produce such optically effective layers, the structured flat element side S is exposed to a PVD (physical vapor deposition, for example vapor deposition or sputtering) or CVD (chemical vapor deposition) coating. In a particularly preferred manner, such a coating process can be carried out by means of oblique shading, so that only parts or partial surfaces of the structural elements SE are specifically surface-treated. This takes advantage of the fact that the particles of the deposition process in the gas phase (e.g. the vapor particles during vapor deposition, the sputtered particles during sputtering) have a preferred direction in their movement and thus shadows when coating structured surfaces, i.e. areas with less compared to neighboring areas Deposition rate.

In order to further improve the optical see-through properties of the surface element F explained above, in particular in the case where a dielectric interface is provided along, for example, the boundary surface B ^* , a preferred exemplary embodiment according to FIG. 7 provides for the combination of a surface element F with a surface element F 'which is structured in a complementary manner thereto , The surface element F 'provides a surface element side S' which is structured in a complementary manner to the structured surface element side S of the surface element F. The joining of the two surface elements F 'and S' is preferably carried out in such a way that the joining of both elements F and F 'takes place along the surface sections D using an adhesion-promoting layer G.

In the embodiments shown in FIGS. 7 and 8, in addition to the see-through area D, see-through properties in view directions are achieved in particular in areas of the boundary areas A * and B *, in which light does not experience total reflection at the boundary areas B * and / or E. In the case of combinations with complementary surface element structures, however, it should be noted that the original surface element F is the first optical element in the light path and thus first optically effective for the incident light. As a result, the effect of such a system generally differs greatly from the anti-glare device on its own, as described above. The consequence of this is that a complementary surface element system F / F ', in which the complementary surface element F ¹ lies next to the light source, requires a special structural design. If the structural elements of the original surface element F were provided on the side facing away from the light source, the essential optical effects of the original surface element are not influenced when a complementary surface element is added.

In a preferred embodiment, one or both of the surface elements to be joined can be made of a light-transparent, flexible material, for example in the manner of a flexible film or thin plate. Suitable rolling or rolling processes are used to produce such flexible complementary surface elements, with which the complementary structures can be joined together.

For reasons of material savings, lower absorption effects and easier integration of the sun protection device, for example into an insulating glass composite, and ultimately for reasons of a noticeable cost reduction, it is particularly advantageous to miniaturize the light-guiding prismatic structural elements. Such a microstructured surface element can, for example, be laminated onto a glass pane in the form of a microstructured film. It is also conceivable to structure a pane, for example a window pane, directly on the surface. Another advantage of microstructures is that under certain circumstances they can no longer be resolved by the human eye, resulting in a quasi-homogeneous appearance.

This quasi-homogeneous appearance is particularly advantageous if the sun protection element is not to be used on a south-facing surface, but on a differently oriented surface or facade. Then a desired, from Sun protection angle-dependent sun protection function can also be guaranteed if the extended structural elements SE are no longer oriented horizontally, as in the south-oriented case, but tilted. If the sun protection element has a quasi-homogeneous appearance, then this necessary tilting no longer represents an architectural or aesthetic restriction on the possible use of the element.

Gray-tone lithography is particularly suitable for producing such microstructures, this method typically being limited to areas smaller than 10 cm ² . However, prismatic structures can also be produced by means of material-removing processes or precision machining, for example by micro-milling or micro-impacting. Larger areas are to be processed in such a method, but for desired area sizes of greater than 25 cm ² the associated procedural effort increases considerably. However, interference lithographic methods already offer the possibility of successfully structuring larger areas of up to 2500 cm2 in the desired manner.

If there is a miniaturized structure in the form of a master structure, this can be applied to large areas by molding processes, which enables the microstructure to be replicated. In this way, surface structures can be transferred or embossed in a wide variety of organic or inorganic materials, in molded parts or films of any type and surface. Possible replication processes to be mentioned in this context are, for example, the roller embossing process, stamp embossing process or injection molding processes. With the above methods, it is in particular possible to produce the structured surface inexpensively.

A particularly preferred form of use for the sun protection device according to the invention provides for integration into an insulating glass composite system. For example, a surface element or a film structured on the inward side is generally on the inside of the outer pane (or at Triple glazing on the inside of the middle pane), while an externally structured surface element is generally applied on the outside of an inside pane. Depending on the requirements, a third, fourth or further layer or pane in the insulating glass composite may also be necessary or can be implemented in individual cases.

Finally, FIGS. 9 to 11 show some transmission diagrams depending on the lighting situation for the following specific exemplary embodiments:

A vertically aligned sun protection device facing the light source with the parameters α = 48 °, β = 6 °, h / P = 0.5, n = 1.59 (refractive index of the light-transparent material) has the property that directional radiation that originates from a profile angle range between 57 ° and 66 ° inclusive occurs, only a maximum of 1.7% is transmitted. With such a structure, the amount of see-through is approximately 39% of the total area.

The dependence of the total transmission on the angle of incidence when irradiating in the profile plane (profile angle) for such a structure type is shown in FIG. The pronounced blanking area is clearly visible at high summer sun positions up to approx. 67 ° and a moderate reduction of around 50% in a transition area. At the same time, the transmission is very high for very high profile angles up to over 80 °, which has a positive effect on the illumination of the rear room due to the bright sky light in the zenith area. Likewise for angles of incidence of less than about 35 °.

This type of structure is therefore ideally suited as seasonal sun protection for south-facing facades in geographical latitudes in which the highest summer sun levels are less than 67 °, e.g. the geographical latitude of Freiburg i.Br. (Φ = 48 °). In a period from May 2nd to August 11th, more than 98% of the direct solar radiation is reflected or absorbed by the element. In the transition times from 12.3.-1.5. and 12.8.-30.9. only a maximum of 40-50% of the direct radiation is transmitted through the element. At the same time, high transmission and thus a contribution to space heating through solar energy inputs during the winter is guaranteed. At all times in a rear room there is good daylight illumination due to the high transmission at high angles of incidence.

The next example, shown in Figure 10, relates to a seasonal, i.e. Temporary sun protection with partial transparency, with the structure on the side facing the light source and a continuously increasing shading taking place in the shading period with the profile angle.

FIG. 10 shows the transmission diagram for a sun protection device which has a vertically oriented structure facing the light source with the parameters α = 60 °, β = 1.5 ° and h / P = 0.27 and has the property that directed radiation which falls from a profile angle range between 43 ° and 67 ° with increasing incidence angle is weakened more and more. With this ideal structure, the percentage of transparency is approx. 52% of the total area. 10 clearly shows the onset at 42 ° (Equinoxe) and steadily increasing up to the maximum position of the sun of approx. 67 ° and a moderate reduction of about 50% in a transition area. At the same time, the transmission is very high for very high profile angles from around 80 °, which has a positive effect on the illumination of the rear space due to the bright sky light in the zenith area. The element also shows very high transmission for angles of incidence less than 42 °, which means that light and heat can be introduced during the heating season and the transition seasons.

Finally, FIG. 11 shows a transmission diagram of a sun protection device with rounded or curved edges (K, L, M) and curved flanks (A *, B ^* ), which can be used as a diffuser or diffusing screen to improve room illumination with partial transparency and seasonal sun protection function is. The flanks and edges are curved or rounded in such a way that a part of the incident radiation is no longer blanked out exactly as in the previous cases, but that part of the radiation is always present in every irradiation situation, i.e. also in the angle of incidence range in which there is in principle a shading effect incident light is scattered into the depth of the rear room. The level of the transmission depends strongly on the type and extent of the curvatures and undulations compared to a flat and sharp-edged structure.

The element on which FIG. 11 is based is suitable, for example, for use in northern Central Europe due to its specific cut-off angle range. Examples include: Berlin with φ = 52.5 ° and a maximum sun angle of 61 °, Hamburg with φ = 53.5 ° and a maximum sun angle of 60 ° or Moscow with φ = 56 ° and a maximum sun angle of 57.5 °. Alternatively, the element can be used in south facades that are slightly inclined to the north in central and southern Central Europe.

LIST OF REFERENCE NUMBERS

F, P surface element

E unstructured flat surface element side

S Structured flat element side

SE structural element

0 surface

A, B side flanks

A ^* , B * boundaries

D surface section

K, L, M edges

P period length

Claims

claims

1.Sun protection device for light-transparent building openings against direct sunlight entering the building interior with at least one optical surface element (F) consisting of at least partially light-transparent material, which can be attached in the area of the building opening and has two opposite surface element sides, one of which (E) is unstructured and flat and the other (S), which runs parallel to one another, extends linearly and repeats itself periodically in the lateral direction, prismatic structural elements (SE), characterized in that the structured flat element side (S) is at least largely an unstructured flat element side (E) Co-parallel surface (O), which is surmounted by the structural elements (SE), that the structural elements (SE) each have a triangular cross-sectional area with a side edge (C), which coincides with the surface (O), and two over r have raised side flanks (A, B), the side flank (A) being assigned a boundary surface (A ^* ) and the side flank (B) a boundary surface (B ^* ), and in that at least two adjacent structural elements are defined by a surface section (D ) of the surface (O) are laterally separated from each other, and that the side flank (A) with the surface forms an angle 90 ° -α, with the side flank (B) an angle α + β and that the side flank (B) with the surface encloses an angle 90 ° -ß, where α is not equal to β.

2. Device according to claim 1, characterized in that the optical surface element is mounted in the area of the building opening in such a way that the structured surface element side faces the incidence of sunlight.

3. Device according to claim 1 or 2, characterized in that α is greater than β.

4. Device according to one of claims 1 to 3, characterized in that the side flank (A) with the surface via an edge (M), the side flank (A) and the side flank (B) via an edge (K) and the side flank (B) are connected to the surface via an edge (L).

5. Device according to one of claims 1 to 4, characterized in that the surface element (F) is integrated in a vertically extending building opening and the surface element sides (E) and (S) are vertically oriented.

6. The device according to claim 5, characterized in that the side flank (A) is inclined relative to the vertically oriented surface such that from a smallest sun profile angle α _pu ι, which corresponds to an angle between the surface normal to the surface and the projection of the direction of the sun a plane that is spanned by the surface normal and a precisely vertical straight line, the radiation transmitted by the device is reduced by rays that enter through the boundary surface (A *) and then strike the unstructured surface (E) and are totally reflected there , where the following relationship applies:

α _pu ι = 90 ° - + arcsin [n sin (arcsin (1 / n) - (90 ° - α))]

with n: refractive index of the light-transparent material.

7. The device according to claim 5, characterized in that the side flanks (A, B) are inclined relative to the vertically oriented surface such that from a smallest sun _profile angle α _pU2 , which corresponds to an angle between the surface normal to the surface and the projection of the direction of the sun to a plane spanned by the surface normal and a vertical straight line, the radiation transmitted by the device is reduced by rays which enter through the boundary surface (A ^* ) then hit the boundary surface (B ^* ), are totally reflected there and then hit the unstructured surface (E) and be totally reflected there again, whereby the following relationship applies:

α _pu2 = 90 ° - α + arcsin [n sin (arcsin (1 / n) + α + 2ß -90 °)]

with n: refractive index of the light-transparent material.

8. The device according to claim 6 or 7, characterized in that the side flanks (A, B) are inclined relative to the vertically oriented surface such that up to a largest sun profile angle α _po , the angle between the surface normal to the surface and the projection the direction of the sun to a plane spanned by the surface normal and a vertical straight line that reduces radiation transmitted through the device by rays that pass through the boundary surface (A *) subsequently striking the boundary surface (B ^* ) there are still totally reflected and then hit the unstructured surface (E) and are totally reflected there again, with the following relationship:

α _po = 90 ° - α + arcsinf n sin (arcsin (α + ß - arcsin (1 / n)))]

with n: refractive index of the light-transparent material.

9. Device according to one of claims 6 to 8, characterized in that the side flanks (A) and (B) have a common point of intersection, which provides a distance h from the surface, for which:

h »P / [tan (α) + tan (α _pu1 )] or h« P / [tan (α) + tan (α _pu2 )].

with P: = period length of a structural element or a repetition unit = length of the side edge (C) + clear width of the surface section (D)

10. The device according to claim 4, characterized in that the edges (M, K, L) are at least partially formed as sharp edges, or at least partially rounded concavely or convexly.

11. The device according to claim 10, characterized in that the edges (M, K, L) at least partially have a stochastic or periodic surface ripple.

12. Device according to one of claims 1 to 11, characterized in that the side flanks or boundary surfaces (A) and / or (B), the surface section (D) and / or the unstructured flat element side (E) at least partially as optically effective surfaces are formed on which light is reflected, scattered or absorbed.

13. Device according to one of claims 1 to 12, characterized in that the boundary surfaces (A, B) are flat or as at least partially convex, concave, convex-wavy or concave-wavy curved surfaces.

14. Device according to one of claims 1 to 13, characterized in that the surface section (D) is flat or as an at least partially curved surface, and that the surface section (D) is oriented co-parallel to the unstructured flat element side (E) or to this an angle between 0 ° and about 10 ° is arranged inclined.

15. Device according to one of claims 1, 3 to 5 or 10 to 14, characterized in that the optical surface element (F) is mounted in the region of the building opening in such a way that the structured surface element side (S) faces the interior of the building.

16. Device according to one of claims 1 to 15, characterized in that the structured surface element side (S) of a first surface element (F1) is provided with a complementarily structured surface element side of a second surface element (F ¹ ).

17. The apparatus according to claim 16, characterized in that the joining of the two surface elements (F1, F ¹ ) takes place in each case on those surfaces by means of a joining agent which correspond to the surface sections (D) of the first surface element (F1).

18. Device according to one of claims 1 to 17, characterized in that the surface element (F) is made of a flexible material which can be applied like a film to a flat light-transparent support structure.

19. Device according to one of claims 1 to 17, characterized in that the surface element (F) is designed as a window pane.

20. Device according to one of claims 1 to 19, characterized in that the surface element (F) is designed as part of a multi-pane insulating glazing.

21. Device according to one of claims 1 to 4 or 10 to 20, characterized in that the surface element (F) can be integrated into a building opening inclined relative to the vertical.

22. A method for producing a device according to claim 12, characterized in that the optically functional surfaces are produced by means of a PVD or CVD process.

23. The method according to claim 22, characterized in that by vapor deposition with preferred direction of movement of the steam particles by way of self-shading at least partial areas of the structured flat element side (S) are surface-treated.

24. Use of the sun protection device according to one of claims 1 to 21 as a light deflection or as a glare protection device.