DE10129745A1 - Optical arrangement for conducting solar light into buildings, directs focused light beams into a second light beam of reduced beam cross-section - Google Patents

Abstract

An optical arrangement for conducting a beam of sunlight through an aperture in a building, includes first optical device in the form a Fresnel lens (32) and a second optical device provided in the form of an off-axis parabolic mirror (28) for deflecting a parallel light beam (52), and arranged along the optical axis and spaced a smaller distance from the focal point (48) than the first optical device (32).

Description

Technical field

The invention relates to an optical arrangement for introducing a bundle of Sun rays through an opening in a building containing first optical means for Focusing a first bundle of incident sun rays with a first Bundle cross section in one focal point, and second optical means in a lesser Distance from the focal point are arranged as the first optical means for Aligning the beams focused in this way into a second parallel light beam from compared to the first bundle cross-section reduced bundle cross-section and means for Deflect the second light beam through the opening.

State of the art

Such arrangements are used to illuminate rooms without daylight or without providing sufficient daylight lighting with sunlight. Thereby the lighting quality compared to only artificially illuminated rooms improved and energy saved.

From US 4,349,245 an optical arrangement is known in which the sunlight is reflected on a further plane mirror by means of a trackable plane mirror  and from there through a roof opening in a building. The tracking takes place using a heliostat. However, the luminous flux that can be achieved with this arrangement is small and large openings and mirrors are necessary to allow sufficient light into the To initiate buildings.

It is known to introduce light into a building according to the Hemavari principle. It falls the parallel solar radiation on a first parabolic mirror, which the radiation on a smaller hyperbolic mirrors arranged on the optical axis are reflected. The Mirrors are arranged so that the focus of these two mirrors is there coincides. The resulting parallel beam with a smaller diameter is guided along the optical axis through a hole in the parabolic mirror and by there, for example, guided through the building opening by means of a plane mirror. By the reduction in cross section becomes a concentration of the incoming sunlight reached, whereby the building opening can be kept comparatively small.

From the subsequently published DE 199 08 383 A1 an optical arrangement for Introducing sunlight into a fiber optic cable known to be parallel Sunlight initially falls on a first parabolic mirror in the middle, then on one second, smaller parabolic mirror is reflected and from the second mirror to one Bundle of fiber optic cables, the ends of which are mounted in the middle of the large mirror are. The focal points of the two mirrors coincide.

From DE 196 04 995 A1 an optical arrangement is known in which the sunlight into a first, large and a second small parabolic mirror Optical waveguide is introduced. The light is then turned on by means of the optical waveguide distributed different parts of the building. In the event of low daylight is a Light generator provided, the radiation coupled in addition to daylight can be.

The known arrangements all use a particularly large parabolic mirror with a central suppression. The production of such a parabolic mirror with sufficient shape accuracy and surface quality is expensive. Goes on  due to the central suppression, a large proportion of the incident light is lost and it is with the large focal length of the necessary for the reduction of the cross section Parabolic mirror requires a high adjustment accuracy, so that the parallelized beam fits through the middle blanking. The required adjustment accuracy can only be reduce by increasing the center opening in the parabolic mirror, which in turn leads to a reduction in the luminous flux.

Disclosure of the invention

It is an object of the invention to provide an optical arrangement of the type mentioned to create improved efficiency that is easier and less expensive.

According to the invention the object is achieved in that the second optical means and the means for deflecting the second light beam along the optical axis on the same side of the first optical means are arranged. This eliminates the The need for center suppression with the associated radiation losses and high adjustment effort.

The first optical means are preferably formed by a lens, which is in a particularly preferred embodiment of the invention is designed as a Fresnel lens. Fresnel lenses are of sufficient quality even with large diameters Their versatility is commercially available and therefore form a special cost-effective variant of focusing.

The second optical means can also be from a lens, e.g. B. one Diverging lens or a converging lens and a plane mirror can be formed. The Scattering lens is placed in front of the focal point of the first optical means Converging lens behind the focal point of the first optical means. The one through this The lens parallelized beam is then deflected by means of a plane mirror.

In a particularly preferred embodiment, the second optical means are from a deflecting mirror are formed, which is designed as a parallel concave mirror.  

With such a concave mirror, ie a curved deflecting mirror, two Functions fulfilled by an element. On the one hand, there is always the necessary Redirection and on the other hand, the beams are parallelized. On this way, higher efficiency can be achieved with fewer optical elements become.

The deflecting mirror can be designed as an off-axis paraboloid. That means that the Curvature of the mirror does not run through the entire parabola, but only a part. This allows the mirror to be produced inexpensively and precisely. Alternatively, the Deflecting mirror can also be designed as an off-axis ellipsoid or toroid. With shorter ones The second beam has a smaller focal length of the second optical means Diameter has that which originally strikes the optical arrangement Bundle of rays. The desired diameter can be determined, for example, by suitable ones Selection of the parabolic segment of a paraboloid. The advantage of one reduced cross section is that a smaller building opening is needed around the to achieve the same illuminance.

In a preferred embodiment of the invention there is a tracking device provided with which the arrangement or part of the arrangement of the sun run is trackable. The part of the optical arrangement that is the sun's path is trackable, be formed by a plane mirror that in the direct sun Redirected towards the means for focusing the bundle. Then only he needs The plan mirror can be updated. In an alternative embodiment of the invention the entire optics are mounted on a support that corresponds to the direction of the sun is tracked. This has the advantage that the plane table can be dispensed with and thus one optical component is used less. But it's also an off- Axis paraboloid can be used as a tracking mirror. Then the Fresnel lens to be dispensed with.

The better the focal point of the first optical means with the focal point of the second optical means coincides, the higher the image quality.  

In one embodiment of the invention, the cross section of the incident beam is focused by more than one focusing element and via a corresponding one Number of deflecting mirrors brought together again to form a parallel beam becomes. The focusing elements can be formed by several Fresnel lenses which are arranged in pairs one above the other and the incident beam of rays focus in a corresponding number of different focal points. Thereby Smaller optical components can be used that are significant in manufacturing are cheaper and their quality is usually better. Instead of in pairs the focussing elements also like a matrix to the external conditions be adjusted.

The Fresnel lenses can thus be offset in the direction of the optical axis each Fresnel lens located below that be arranged by the corresponding, curved deflecting mirror reflected parallel beams lie right next to each other. Then the rays from the top Deflecting mirrors are not shadowed by the ones below. But it is also conceivable to vary the deflection angle.

The light beam can be introduced into a building using light waveguides, Optical fibers, mirrors or a combination thereof. It is also possible to radiate the light directly freely. In the event of insufficient daylight Means for switching on artificial light are provided, which at corresponding arrangement in only one place have the advantage of central maintenance.

Embodiments of the invention are the subject of the dependent claims. Embodiments of the invention are below with reference to the attached drawings explained in more detail.

Brief description of the drawings

Fig. 1 shows a cross section through a building with an optical arrangement for introducing sunlight.

FIG. 2 shows the optical arrangement from FIG. 1 in detail.

FIG. 3 shows the beam path of the optical arrangement from FIG. 2.

FIG. 4 shows the beam path of two optical arrangements according to FIG. 2 lying one above the other.

FIG. 5 shows the beam path of two adjacent optical arrangements according to FIG. 2.

FIG. 6 shows the optical arrangement from FIG. 1, which as a whole can be tracked by the sun.

FIG. 7 shows an off-axis paraboloid mirror in three views . FIG. 8 shows the optical arrangement from FIG. 1, in which a converging lens with a plane mirror is used instead of a curved mirror.

FIG. 9 shows the optical arrangement from FIG. 1, in which a diverging lens with a plane mirror is used instead of a curved mirror.

Description of the embodiments

In Fig. 1, 10 denotes a building. The building 10 has three floors 12 , 14 and 16 , which are connected to one another by a staircase 18 . The staircase 18 is located in a stairwell 20 . An optical arrangement 24 for introducing sunlight into the building is provided on the roof 22 of the building 10 .

The optical arrangement 24 is shown again in detail in FIG. 2. An opening 26 is provided in the roof 22 . Four off-axis parabolic mirrors are arranged above the opening 26 , of which only the two front mirrors 28 and 30 are shown in the illustration in FIG. 2. Behind mirrors 28 and 30 are two more off-axis mirrors. The mirrors 28 and 30 have a high reflectivity in the visible spectral range (VIS) and a low reflectivity outside the visible spectral range. The mirror 28 is arranged somewhat above the mirror 30 . The mirror 30 is arranged somewhat to the right (in FIG. 2) of the mirror 28 . The mirrors, not shown, located behind the mirrors 28 and 30 are also offset in height and in the direction of the optical axis.

Four Fresnel lenses 32 and 34 are arranged in front of the four mirrors 28 and 30 at the same height and with the same optical central axis. Here, too, only the front Fresnel lenses are visible. The Fresnel lenses together have a total area of approximately 6 m ² and each have a focal length of 1.2 m. The Fresnel lenses are all the same distance from the associated off-axis parabolic mirror, ie the lower Fresnel lenses are also shifted to the right with respect to the upper Fresnel lenses.

A heliostat 36 with a plane mirror 38 is arranged on the roof 22 at a somewhat greater distance from the Fresnel lenses. The plane mirror is rotatably mounted about two axes and can be aligned in a known manner by means of a controlled drive so that the parallel sun rays are directed onto the Fresnel lenses 32 and 34 at all times. The tracking depending on the position of the sun is done by an electric motor. The plane mirror has a total area of 6.25 m ² and is therefore slightly larger than the area of the Fresnel lenses. As a result, the Fresnel lenses are fully illuminated.

To protect against environmental influences, part of the optical arrangement is arranged in a housing 40 which is provided with corresponding glazed openings for the passage of light. The mirrors are attached to a frame 44 . The beam path is shown in FIGS. 3 to 5. The light 44 emanating from the sun 42 is reflected on the plane mirror 38 in the direction of the Fresnel lens 32 . The parallel bundle 46 impinging there is focused on a focal point 48 .

The focal point 48 coincides with the focal point of the off-axis parabolic mirror 28 . The mirror 28 reflects the divergent radiation 50 and generates a parallel beam 52 deflected by an angle α. The beam 52 has a significantly smaller diameter than the beam 46 of the incident beam. The ratio of the diameters is determined by the ratio of the focal lengths of lens 32 and mirror 28 .

In FIG. 4, the beam path is shown from the side. The incident bundle consisting of two partial beams 54 and 56 is focused by the two Fresnel lenses 32 and 34 in two different focal points 58 and 60 . The mirrors 28 and 30 are correspondingly offset in height. Furthermore, the Fresnel lenses and the mirrors are arranged offset in the direction of the optical axis. As a result, the beam reflected at the upper mirror 28 can be directed past the lower mirror 30 . The two partial beams are focused and reflected by this arrangement with different lenses and mirrors, but combined again into a common beam.

In FIG. 5, the arrangement of the upper two Fresnel lenses is shown with the associated off-axis parabolic mirrors 32 and 62. The Fresnel lens 62 is arranged next to the Fresnel lens 32 . To summarize the beam, the beam is first reflected laterally by means of an off-axis parabolic mirror rotated through 90 ° about the optical axis and perpendicularly to the optical axis, and then downward by means of a plane mirror 66 , parallel to the partial beam which is reflected by the mirror 28 .

The partial beams brought together in this way are introduced into the building through the roof opening 26 ( FIG. 2). After the now concentrated and largely parallel sunlight has been introduced into the building, the light can be conveyed and coupled out inside the entire staircase 20 using a prismatic film (OLF = Optical Lighting Film). Depending on the sunlight available, sulfur lamp light is added in a mixing unit 70 . For this purpose, a sulfur lamp 72 can be controlled via an EIB bus and is dimmed depending on daylight via a brightness sensor. The variably composed light mixture is divided equally between two vertical hollow light guides 74 and 76 , which illuminate the stairwell evenly over three floors. Another deflecting module can turn a mirror into the beam path of a vertical hollow light guide, so that sunlight can be guided via a horizontal hollow light guide into a light ceiling of a nearby conference room 78 ( FIG. 1).

An alternative embodiment of the invention is shown in FIG . Here, the Fresnel lens is mounted together with the off-axis parabolic mirror 74 together in one assembly on the - not shown - heliostat. The assembly rotates about the common focal point 76 . With this arrangement, the first plane mirror can be omitted and the Fresnel lens can be aligned directly with the sun 78 . In this arrangement, the angle of incidence on the parabolic mirror is correspondingly steeper since, as before, the light is to be emitted vertically downwards. This structure needs two optical components.

In FIG. 7, one of the off-axis parabolic mirror used is shown in different side views. Fig. 7a shows a section through the parabolic segment. Fig. 7b and Fig. 7c show respectively a plan view and a side view. It can be seen that a sixth is cut out of the 3-dimensional "parabola bowl" and used as a mirror.

An alternative embodiment is shown in FIG . The arrangement shown corresponds in all details to the arrangement described above. Instead of an off-axis paraboloid 28 , however, the beam is parallelized by means of a lens 80 and then deflected at a plane mirror 82 .

In Fig. 9, a further alternative embodiment is shown. Here, as in FIG. 8, the second optical means are formed by a lens 84 and a plane mirror 86 . However, the lens 84 is designed as a diverging lens and is arranged in front of the focal point of the Fresnel lens 32 .

The Fresnel lenses 32 used can be made from, for example, four partial lenses, of which the lens center of each partial lens is not in the center but on a corner. The advantage of using these partial lenses is that in the manufacturing process, lower forces have to be applied when pressing the lens in order to generate the same pressure.

Claims (12)

1. An optical arrangement ( 24 ) for introducing a bundle ( 44 ) of sun rays through an opening ( 26 ) into a building ( 10 ), comprising first optical means ( 32 ) for focusing a first bundle ( 46 ) of incident sun rays with a first Bundle cross section in a focal point ( 48 ), and second optical means ( 28 ), which are arranged at a closer distance from the focal point ( 48 ) than the first optical means ( 32 ), for directing the beams focused in this way into a second parallel light bundle ( 52 ) of reduced bundle cross-section compared to the first bundle cross-section and means ( 28 ) for deflecting the second light bundle through the opening ( 26 ), characterized in that the second optical means and the means ( 28 ) for deflecting the second light bundle ( 52 ) along the optical Axis are arranged on the same side of the first optical means ( 32 ). 2. Optical arrangement ( 24 ) according to claim 1, characterized in that the first optical means are formed by a lens ( 32 ). 3. Optical arrangement according to claim 2, characterized in that the lens is a Fresnel lens ( 32 ). 4. Optical arrangement according to one of the preceding claims, characterized in that the second optical means ( 28 ) are formed by a lens. 5. Optical arrangement according to one of claims 1 to 3, characterized in that the second optical means are formed by a deflecting mirror ( 28 ) which is designed as a parallel concave mirror. 6. Optical arrangement according to one of the preceding claims, characterized by a tracking device ( 36 ) with which the arrangement ( 24 ) or a part ( 38 ) of the arrangement can be tracked the sun. 7. Optical arrangement according to claim 5 or 6, characterized in that the deflecting mirror ( 28 ) is designed as an off-axis paraboloid or as an off-axis elipsoid. 8. Optical arrangement according to one of claims 5 or 7, characterized in that the part of the optical arrangement which can be tracked by the sun is formed by a plane mirror ( 38 ) which the direct sun beam ( 44 ) towards the means ( 32 ) deflected to focus the bundle. 9. Optical arrangement according to one of the preceding claims, characterized in that the cross section of the incident beam of more than one focusing element ( 32 , 34 , 62 ) is focused and again via a corresponding number of deflecting mirrors ( 28 , 30 , 64 ) a parallel bundle of rays is brought together. 10. Optical arrangement according to claim 9, characterized in that the focusing elements are formed by a plurality of Fresnel lenses ( 32 , 34 , 62 ) which are arranged in pairs one above the other and the incident beam in a corresponding number of different focal points ( 58 , 60 ) focus. 11. Optical arrangement according to claim 10, characterized in that the Fresnel lenses ( 32 ) in such a way in the direction of the optical axis ( 54 ) are arranged offset to the underlying Fresnel lenses ( 34 ) that the curved by the corresponding Deflecting mirror ( 28 , 30 ) the reflected parallel beams are directly next to each other. 12. Optical arrangement according to one of claims 3 to 11, characterized characterized in that the Fresnel lens consists of several partial lenses with one common lens center exists.