AT514573B1 - Light-guiding device and lighting unit with such a light-guiding device - Google Patents

Abstract

The invention relates to a device (1) for directing the light beams of a plurality of light sources (2) in at least one predetermined direction, comprising a flat optical element (3) of transparent material having an axis of symmetry (4), which optical element (3) has a light entrance side (5) with a substantially parabolic profile and a light exit side (6), wherein the light entrance side (5) of the optical element (3) in a plurality of light entry surfaces (7) and behind in a direction according to the predetermined direction the light beams corresponding to the angle arranged reflecting surfaces (8) is segmented and a lighting unit (15) with such a light-guiding device (1). According to the invention, each light entry surface (7) in the direction of the symmetry axis or plane (4) opposite edge (9) of the optical element, on which edge (9) the locations (10) for the arrangement of the light sources (2) are provided.

Description

Description: The invention relates to a device for directing the light rays of a plurality of light sources in at least one predetermined direction, comprising a flat optical element of transparent material with a plane of symmetry, which optical elements have a light entrance side with a substantially parabolic profile and a light The light inlet side of the optical element is segmented into a plurality of light entry surfaces and behind it in an angle arranged according to the predetermined direction of the light beams reflecting surfaces.

Furthermore, the invention relates to a lighting unit with a plurality of light sources and an above-mentioned light-guiding device.

Lichtlenkvorrichtungen and lighting units of the subject type have long been known in a variety of embodiments and are usually used to direct the Lichtstrah¬len one or a small number of light sources in a predetermined direction. For example, bundle Fresnel lenses, the light of a light source in Direction of the optical axis of the lens. In order to collimate the light of a point light source, one typically uses a parabolic mirror or a lens. This principle can be extended from a point light source to a small group of point light sources. However, if one wishes to collimate a large number of light sources, the known devices are no longer applicable without subdividing the light sources back into smaller groups and providing them with their own collimators. With the advent of light-emitting diodes as light sources, many lighting units today no longer consist of a few but of a large number of light sources whose light beams can not be directed in any suitable manner with conventional light-guiding devices.

DE 10 2010 028 755 A1 describes an optical lens element, which is suitable in principle only for a light source or arranged at one point array of light sources.

Also DE 10 2011 118 456 A1 describes an optical component for Beleuchtungszwecke, which is intended only for a single light source.

From US 8,235,556 B2, an optical element for collimating the light beams of many light sources has become known. However, the production cost of such an optical element is very large and increases with the number of light sources.

The object of the present invention is to provide a Lichtlenkvorrich¬tung the above type and a lighting unit with such a light-deflecting device, by which the light beams of a plurality of light sources can be directed in vorbe¬stimmte directions in a suitable manner. The constructive effort and the production costs for such a light-directing device or lighting unit should be as low as possible in order to enable a broad application for the most diverse fields of application. The disadvantages of the prior art should be avoided or at least reduced.

The object of the invention is achieved by an above-mentioned Lichtlenkvorrich tung, in which each light entrance surface in the direction of the symmetry axis or planar gegenŸberliegenden edge of the optical element has, at which edge the locations are provided for the arrangement of the light sources, so that the light beams of the light sources enter the light entry surfaces substantially normally, are reflected on the reflection surfaces disposed behind the light entrance surfaces, and are directed in the predetermined direction via the light exit side. Essentially, the present invention provides an optical element with which efficiently any number of light sources can be collimated. The light steering device is characterized by a simple and compact construction. The light sources are arranged at the edge of the optical element and transmit their light rays at a corresponding angle into the light entry surfaces of the optical element and are totally reflected at the reflection surfaces and exit via the light exit side in the desired direction. By exploiting the phenomenon of total internal reflection, the optical element or the light-guiding device or the lighting unit can be realized particularly cost-effectively.

Preferably, the light entry surfaces are formed with a circular cross section, wherein the center of the circular cross-section formed light entry surfaces substantially coincides with the locations for the arrangement of the light sources.

This circular or spherical design of the light entry surfaces ensures that the light beams originating from the light sources essentially occur normal to the surface of the optical element, whereby back reflections can be minimized and breakages of the incoming light beams can be prevented.

According to a further feature of the invention, the light exit side of the optical element is segmented into a plurality of light exit surfaces. Such a Segmentie¬rung the light exit side of the optical element, a material-saving design of the optical element and thus a more compact design can be achieved. The density and shape of the light exit surface segments can be configured essentially as desired.

If the light exit surfaces are inclined relative to the normal to the Symmetrieachse- or plane, the light emerging from the light exit side of the optical element light beams can be directed in desired directions. In this way, even more complex illumination patterns for certain applications without further optics and thus increased production costs can be realized.

The optical element is preferably made of optically transparent material, preferably plastic or glass, and is preferably produced by casting. As a result, the light-directing device or the lighting unit can be produced in large quantities in a very cost-effective manner, whereby a wide applicability can be ensured.

If lenses are arranged on the edge of the optical element in front of the locations for the arrangement of the light sources, the directional characteristic of the light sources can be changed accordingly.

Depending on the light sources used, it may be advantageous to change the directivity of the same by such lenses or adapt to the optical element of the Lichtlenkvorrich¬ tung. Often it will be cheaper to provide such lenses in front of standard light sources instead of using more expensive light sources with a specific directional characteristic. The objective light-guiding device has optimum properties if the light sources have flat or elliptical directional characteristics. As a result, scattered light can be avoided or at least reduced. As such, unless the light sources have such an elliptical or flat directivity, an improvement by the lenses in front of the light sources can be obtained.

The optical element and the lenses can also be made in one piece, whereby the manufacturing costs and the installation or installation effort can be reduced even further.

To achieve different lighting effects, the optical element and / or the lenses may be colored. In the case of the use of plastic or glass for the optical element and / or the lenses, such a coloring can take place in the same way as the production of the optical element. Alternatively, the coloring may also be achieved by applying color layers.

An antireflection coating can be arranged at the light entry surfaces of the optical element, at the light exit surfaces of the optical element and / or at the lenses, whereby reflection losses can be suppressed.

Preferably, the optical element is symmetrical, in particular rotationally symmetrical, formed about the axis of symmetry or plane. In such a symmetrical, in particular rotationally symmetrical design of the optical element of the Lichtlenkvorrich-tunq essentially any number of light sources along the edges of the optical

Elements are arranged along the circumference and whose light beams are directed in the desired direction on the light exit side of the optical element.

The object of the invention is also achieved by an above-mentioned lighting unit having a multiplicity of light sources and an above light-guiding device, wherein the light sources are arranged at least on a part of the edge of the optical element opposite the axis of symmetry or plane. Such a lighting unit is characterized by a particularly compact and inexpensive construction and high flexibility of both to be achieved luminous patterns. For further advantages, reference is made to the above description of the light-guiding element.

The light sources preferably have a narrow directional characteristic. As already mentioned above, it is advantageous with respect to an optimal function of the optical element or the total reflections occurring therein if the light sources have a narrow directional characteristic.

Furthermore, it is advantageous if the light sources aufwei¬sen elliptical directional characteristic. Due to such an elliptical directional characteristic stray light can be effectively suppressed.

Preferably, the light sources are formed by light emitting diodes. Light emitting diodes are currently available in different colors and with different power densities particularly cost-effective and also have a particularly small size. Although the power loss of light emitting diodes is relatively low, higher light output light emitting diodes may be required to cool the light sources. However, since the light sources are arranged at the edge of the optical element in the present illumination unit, a dissipation of the lost heat can be done relatively easily. A further advantage is provided by the fact that light emitting diodes with elliptical directional characteristics are available relatively inexpensively.

Alternatively, the light sources may also be formed by laser diodes. Compared to light-emitting diodes laser diodes have the advantage that they have a particularly narrow Richtcha¬rakteristik, whereby stray light can be prevented.

If lenses are arranged in front of the light sources, the directivity of the light sources can be changed accordingly. As already mentioned above, the lenses can produce or improve the desirable narrow directivity of the light sources. Such lenses may also be made in one piece with the optical element.

Preferably, the light sources are designed to emit white light. For most applications, white light is required. Since low-cost light emitting diodes are already available in the white spectral range, cost-effective lighting units for emitting white light can thus also be produced.

For various lighting effects and applications, the light sources can also be designed to emit colored light. Such colored light sources may be used for certain applications, e.g. Tail lights of vehicles, turn signals of vehicles, traffic lights or stage lighting body, be necessary.

In front of the light exit side of the optical element, a cover element of at least partially transparent material may be arranged. With such a cover, pictograms or the like may be provided in the lighting unit in a stencil-like manner, as they are advantageous or desirable for many applications. For example, in such a cover element, pictograms of standing or walking persons of transparent material can be arranged, as is customary in pedestrian traffic lights.

To protect the lighting unit, especially in outdoor applications, it is advantageous if a preferably watertight housing is provided.

The present invention will be explained in more detail with reference to the attached drawings, in which Figure 1 shows a plan view of a circular device for directing the light beams of a plurality of light sources together with light sources; FIG. 2 shows a section through the circular light-guiding device according to FIG. 1 along the section line II-II; FIG. Fig. 3 is a detail view of a part of a light guiding device; Fig. 4 is a section through another embodiment of a circular

Light-guiding device with material-saving design of the light exit side of the optical element; Fig. 5 is a plan view of a device for directing the light rays of a

Variety of light sources including light sources as a line array; FIG. 6 shows a sectional view through a lighting unit with a light-guiding device as a line array according to FIG. 5 along the section line VI-VI; FIG. [0037] FIGS. 7A to 7C show examples of light-deflecting devices with a changed direction of the expiring light beams; and [0038] FIG. 8 is a plan view of a light-guiding device in the form of a polygon.

Fig. 1 shows a plan view of a circular device 1 for directing the Licht¬ rays of a plurality of light sources 2 together with light sources. The light-guiding device 1 comprises a flat, optical element 3 made of transparent material with an axis of symmetry or plane 4. In the example shown, the optical element 3 is arranged rotationally symmetrically about the axis of symmetry 4. At the edge 9 of the optical element 3, the light sources 2, which are formed for example by light emitting diodes, arranged so that the light beams of the light sources 2 radiate in the direction of the axis of symmetry 4. As better understood from the sectional view through the optical element 3 shown in FIG. 2, the optical element 3 has a light entrance side 5 and a light exit side 6. The light entry side 5 is segmented into a multiplicity of light entry surfaces 7 and reflection surfaces 8 arranged behind them. In the illustrated example, the light exit side 6 of the optical element 3 is planar and not segmented. The light entry surfaces 7 are preferably of circular or spherical design, the center 11 of the circles of the light entry surfaces 7 substantially coinciding with the locations 10 for the arrangement of the light sources 2. This ensures that the light beams emitted by the light sources 2 enter the light entry surfaces 7 substantially normal and that no losses occur due to partial reflections. At the rear of the light entry surfaces 7 arranged reflecting surfaces 8, a total reflection of the light rays in the direction of the light exit side 6 takes place. In the illustrated embodiment of the light guide device 1, all the light beams of all the light sources 2 are directed substantially parallel to each other and normal to the light exit side 6 of the optical element 3. Such a light guide device 1 can be manufactured relatively easily and inexpensively. The calculation of the radii of the circular or light entrance surfaces 7 and inclination of the reflection surfaces 8 and the number of segmentations must be adapted to the respective number of light sources 2 and the size of the optical element 3, which can be made relatively quickly and easily by various mathematical models and calculation programs.

3, some light entry surfaces 7 and reflection surfaces 8 of the optical element 3 are shown, and the respective radius for the circular or spherical design of the light entry surfaces 7 is entered from the detail view of a part of the light guide device 1. Accordingly, the light entrance surface 7 on the right side of FIG. 3 has a circular area of radius R1 from the center 11, which coincides with the locations 10 for the arrangement of the light sources 2. The radius R2 for the next light entry surface 7 is corresponding to the distance from the previous light entry surface 7 is smaller. After the number of segments of the light entrance surface 7 of the optical element 3 has been determined, the respective radii and inclinations of the reflection surfaces 8 can be easily calculated by software. Finally, the optical element 3 can be easily and quickly manufactured by milling from a plastic or glass block or by making a corresponding female mold and then casting it with plastic or glass.

4 shows a section through another embodiment of a circular Licht¬lenkvorrichtung 1 with material-saving design of the light exit side 6 of the optical element 3. Here, the light exit side 6 of the optical element 3 as the Lichteintrittssei¬te 5 is segmented into a plurality of light exit surfaces 12, which light exit surfaces 12 are all-around and arranged substantially normal to the axis of symmetry or plane 4. As will be explained below with reference to Figs. 7A to 7C, by tilting the light exit surfaces 12, a change in the illumination pattern can be achieved.

5 and 6 show a plan view and a section through a device 1 for directing the light beams of a plurality of light sources 2 together with light sources 2 as a line array. The light sources 2 are arranged on both edges 9 of the symmetrically arranged optical element 3 , In this way, any lengths of light steering devices 1bzw. Illuminating units 15 are produced, which can also exhibit any course (see Fig. 8). Theoretically, an asymmetrical design of the light-guiding device 1 is also conceivable in that one side of the optical element 3 adjacent to the plane of symmetry 4 is omitted. As can be seen from the sectional view according to FIG. 6, the optical element 3 can also be surrounded by a housing 17 and an at least partially transparent cover element 16, by means of which use of the illumination unit 15 also in the outer area is made possible. To change the light characteristic of the light sources 2, it is possible to arrange lenses 14 in front of the light sources 2, which may also be produced in one piece with the optical element 3.

In Figs. 7A to 7C, there are shown examples of light-deflecting devices 1 with changed direction of the outgoing light beams. FIGS. 7A to 7C show variants of the light-directing device 1 or illumination unit 15, whereby a change in the direction of the exiting light beams can be achieved by tilting the light exit surfaces 12. In the variant according to FIG. 7A, the light exit surfaces 12 have been inclined relative to the normal to the symmetry axis or plane 4 of the optical element 3, whereby the light rays exiting from the optical element 3 are directed away from the symmetry axis or plane 4 According to the variant according to FIG. 7B, all the light exit surfaces 12 are arranged substantially normal to the symmetry axis or plane 4 and all the light beams are arranged parallel in the direction of the symmetry axis or plane 4. In the variant according to FIG. 7C, the light exit surfaces 12 of the optical element 3 are inclined in the direction of the symmetry axis 4, whereby the light beams are directed in the direction of the symmetry axis or plane 4. By different inclination of the light exit surfaces 12 of the optical element 3 different light patterns and lighting effects can be achieved.

Finally, Fig. 8 shows a plan view of a light guide device 1 in the form of a polygon. As already mentioned above, the optical element 3 of the light-guiding device 1 can be arranged symmetrically with respect to a plane of symmetry 4 running along a traverse. In this way, illumination units 15 can be made to achieve individual illumination patterns. This opens up new possibilities in lighting technology.

The present invention increases the design possibilities in the lighting technology for simple lighting applications, such as the replacement of existing Leuchtstoffröh¬ren with LED linear arrays or appropriately adapted housing or Arbeitsbeleuch¬tungen. Also in the automotive industry, where high luminance with low power consumption and high reliability are required, such lighting units can be used. The use of a plurality of light sources also ensures a higher reliability of the lighting unit, since the failure of individual light sources has no or only a negligible influence on the function of the lighting unit.

Claims (20)

Device (1) for directing the light beams of a plurality of light sources (2) in a predetermined direction, with a flat optical element (3) made of transparent material with a symmetry axis or plane (4), which optical element (3) has a light entrance side (5) with a substantially parabolic profile and a light exit side (6), wherein the light entry side (5) of the optical element (3) into a plurality of light entry surfaces (7) and behind in the predetermined Direction of the light rays corresponding angles arranged reflecting surfaces (8) is segmented, characterized in that each light entrance surface (7) in the direction of the Symmet¬rieachse or plane (4) opposite edge (9) of the optical element (3), at which Edge (9) the locations (10) for the arrangement of the light sources (2) are provided so that the light rays of the light sources (2) substantially normal in the Li enter the reflecting surfaces (8) arranged behind the light entry surfaces (7) and directed in the predetermined direction via the light exit side (6). 2. Light-guiding device (1) according to claim 1, characterized in that the light entry surfaces (7) are formed with a circular cross section, wherein the center (11) of the formed with a circular cross-section light entry surfaces (7) substantiallywith the points (10) for the arrangement of the light sources (2) coincides. 3. Light-guiding device (1) according to claim 1 or 2, characterized in that the light exit side (6) of the optical element (3) is segmented into a plurality of light exit surfaces (12). 4. light guide device (1) according to claim 3, characterized in that the Lichtaus¬trittsflächen (12) are inclined relative to the normal to the axis of symmetry or plane (4). 5. light-guiding device (1) according to one of claims 1 to 4, characterized in that the optical element (3) made of optically transparent material, preferably plastic or glass, and is preferably made by casting. 6. Light-guiding device (1) according to one of claims 1 to 5, characterized in that at the edge (9) of the optical element (3) before the locations (10) for the arrangement of the light sources (2) lenses (14) for changing the directional characteristic the light sources (2) are arranged an¬. 7. A light guiding device (1) according to claim 6, characterized in that the optical element (3) and the lenses (14) are made in one piece. 8. Light-guiding device (1) according to claim 6 or 7, characterized in that the optical element (3) and / or the lenses (14) are formed colored. 9. light guide device (1) according to one of claims 1 to 8, characterized in that at the light entry surfaces (7) of the optical element (3), and / or at the light exit surfaces (12) of the optical element (3) and or or an antireflection coating (13) is arranged on the lenses (14). 10. Light-guiding device (1) according to one of claims 1 to 9, characterized in that the optical element (3) is formed symmetrically, in particular rotationally symmetrical, about the symmetry axis or plane (4). 11. Lighting unit (15) with a plurality of light sources (2) and a device (1) for directing the light beams of the light sources (2) according to one of claims 1 to 10, characterized in that the light sources (2) at least at one part of the symmetrical axis or plane (4) opposite edge (9) of the optical element (3) are arranged. 12. Illumination unit (15) according to claim 11, characterized in that the light sources (2) have a narrow directional characteristic. 13. Illumination unit (15) according to claim 12, characterized in that the light sources (2) have elliptical directional characteristics. 14. Lighting unit (15) according to any one of claims 11 to 13, characterized in that the light sources (2) are formed by light-emitting diodes. 15. Lighting unit (15) according to any one of claims 11 to 13, characterized in that the light sources (2) are formed by laser diodes. 16. Lighting unit (15) according to any one of claims 11 to 15, characterized in that in front of the light sources (2) lenses (14) for changing the directional characteristic of the Licht¬quellen (2) are arranged. 17. Lighting unit (15) according to any one of claims 11 to 16, characterized in that the light sources (2) are designed to emit white light. 18. Lighting unit (15) according to any one of claims 11 to 17, characterized in that the light sources (2) are designed to emit colored light. 19. Lighting unit (15) according to any one of claims 11 to 18, characterized in that in front of the light exit side (6) of the optical element (3) a cover (16) is arranged at least partially transparent material. 20. Lighting unit (15) according to any one of claims 11 to 19, characterized in that a preferably waterproof housing (17) is provided. For this 3 sheets of drawings