DE29619113U1 - Lighting device with optical fibers - Google Patents

Description

Heinz-Jürgen Lokys 10967 Berlin

28 October 1996

LOK46.G1

Lighting device with optical fibres

13 pages description 5 pages with 17 claims 1 page summary 5 pages drawings

LOK46.G1 - 2 -

Description

The invention relates to a lighting device according to the preamble of claim 1.

In recent years, lighting equipment and systems using optical fibers or fiber bundles have been rapidly finding new areas of application in interior and, in particular, exterior lighting (especially in architectural, garden and water feature lighting) as well as in illuminated advertising and for light objects and effects. The main reasons for this are the wide range of design options that have been opened up, in particular, by the development of optical fibers and fiber bundles with controlled lateral light emission (so-called "sidelight fibers"), and the considerable installation and safety advantages that the transmission of light energy to the lighting point can bring compared to the transmission of electrical energy for subsequent conversion into light energy at the lighting point. This is particularly important when the lighting points are difficult to access and/or there are special safety requirements - such as in outdoor and underwater areas or in potentially explosive environments.

It is usual in such lighting devices to equip each branch formed by a fiber or fiber bundle with a lamp, with special coupling elements being provided for low-loss coupling of the lamp light into the fiber or fiber bundle end facing the lamp.

For example, the lamp can be placed in a focal point of an internally mirrored ellipsoid and the fiber end near the lamp

LOK4 6.G1 - 3 -

be arranged approximately at its other focal point. The dimensions of such a coupling ellipsoid must be tailored specifically to the lamp and fiber geometry, so that for different lamps and fibers, complete special coupling elements must be manufactured and kept in stock.

A complex coupling arrangement, which in its specific design is also only suitable for a precisely defined lamp and fiber geometry, in which an ellipsoidal reflection element is combined with a hyperboloidal reflection element, is described in DE 43 41 555 Al. This arrangement enables light from a lamp to be coupled into a maximum of two light guides.

The arrangements described in EP 0 650 011 Al and EP 0 711 951 Al can also be used to feed light from a lamp into two light guides. These two arrangements also use the light emitted by a curved lamp reflector into a half-space around the lamp and split it up using an angle mirror or a semi-transparent mirror or two curved mirrors or a combined concave mirror-lens arrangement. These arrangements incur relatively large losses and are only very flexible in use.

An arrangement specifically for coupling laser light into an optical fiber bundle is described in DE 41 05 98 9 Al. The core of this arrangement, which is not very practical for divergent lamp light, is a lens grid arrangement.

The commercially common arrangements, as soon as they reach a certain level of complexity (as in the case of luminous

LOK46.G1 - 4 -

lighting, effect lighting and architectural lighting), nor a large number of individual lamps, which inevitably leads to relatively high production costs and also means the presence of a correspondingly large number of sources of interference and thus a high level of maintenance effort.

The invention is therefore based on the object of specifying a lighting device of the above-mentioned type with reduced manufacturing and operating costs, the basic structure of which allows flexible adaptation to different applications.

The object is achieved by a lighting device having the features of claim 1.

The invention includes the technical teaching of feeding several branches of a lighting device, which supplies a plurality of lighting points via optical fibers, from a single lamp with low losses. It also includes the idea of providing a light distribution element that can be manufactured and handled in a variable manner with focusing optics arranged around the lamp for coupling the light into the fibers, which allows an unproblematic and inexpensive combination of different lamps (including the simple replacement of defective lamps) and fibers or fiber bundles.

In an embodiment of the lighting device that allows for an advantageous modular structure, the coupling elements for the optical fibers are designed as separate condenser elements, i.e. as essentially cylindrical sleeves or sleeve-like housing sections that have a simple focusing optic (e.g. simply consisting of two planar con-

• *

LOK4 6.G1 - 5 -

xex lenses, formed by a combination of plano-convex lens/asphere or by two aspheres).

In adaptation to the optical properties of the usual optical fibers, the coupling elements are expediently designed so that they feed lamp light at a coupling angle of essentially 60° into the ends of the optical fibers or fiber bundles near the lamp, whereby the light field or the filament of the lamp is essentially imaged onto the fiber end face.

A lighting device suitable for the uneven distribution of lamp light is designed in such a way that it has optical fibers or fiber bundles with different cross-sections and corresponding coupling elements with different cross-sections. In this way, significantly different luminances can be provided from a single lamp at different light exit points.

Designs with two to six coupling elements are particularly important in practice, but in principle a larger number of feed-in points can also be implemented, especially with high-performance lamps.

A lighting device that can be used advantageously for the application areas of "sidelight" fibers is characterized in that it has "sidelight" optical fibers or fiber bundles with two-sided feed arranged in a longitudinal direction, with at least one lamp with an associated light distribution element being provided in the row, which feeds light into at least two consecutive optical fibers or fiber bundles.

· O · i

LOK4 6.G1 - β -

A largely complete utilization of the light energy, even in designs with only a few coupled fibers or fiber bundles, is made possible by a design in which areas of the wall of the light distribution element between the coupling elements are mirrored and optionally also concavely curved, so that light reflected from there also reaches the coupling elements and via these into the fibers.

A design in which the coupling elements are firmly connected to the base body of the light distribution element, in particular integrally formed or glued to it, is suitable for standard applications. Sockets for the ends of the optical fibers can also be formed or glued to the distributor housing in this design.

The core of a modular system with significantly more variable application possibilities can be a light distribution element in which at least some of the coupling elements are detachably connected to the base body of the light distribution element, so that elements with different optical properties can be exchanged to adapt to different fibers or different desired luminance at the lighting point. In this case, the sockets for the fiber ends can also be attached to the distribution body in a modular manner.

The idea of a modular system reaches its full expression with a lighting device whose light distribution element can optionally accommodate different numbers of coupling elements and/or coupling elements with different cross-sections, in particular with a

LOK4 6.G1 - 7 -

The grid base body can be closed optionally by second frames or wall sections.

Since, for reasons of cost, lighting systems - unlike communication systems based on optical fibers - generally use plastic fibers that are temperature-resistant up to 100 ⁰ C at most, versions with more powerful lamps (lamps with a connected load of up to 1 kW are used in practice) have means for thermal decoupling between the lamp and the ends of the optical fibers or fiber bundles near the lamp. In a particularly simple and cost-effective version, these are air slots and optionally air baffles or ribs in the distributor housing for convective cooling. Alternatively or in addition to this, heat protection filter elements (dichroic or reflection-based) and/or high-temperature-resistant optical fiber sections with low thermal conductivity - made of quartz or quartz glass, for example - can be arranged between the lamp and the ends of the optical fibers or fiber bundles near the lamp.

A special design offers high flexibility with regard to the luminance and light colors available at the individual lighting points, or also the polarization states of the light, in which a gray, color or polarization filter element or a holder for optional insertion of such a filter element is provided in at least one part of the light paths.

Other advantageous developments of the invention are characterized in the subclaims or are described below together with the description of the preferred embodiment

LOK4 6.G1 - 8 -

The invention is illustrated in more detail with reference to the figures. They show:

Figure 1 is a sketchy representation of an embodiment in a specific practical application,

Figures 2a and 2b show a simplified horizontal and vertical sectional view of the structure of the light distribution element of another embodiment and

Figures 3a to 3d show various light distribution elements according to embodiments of the invention as elements of a modular system.

Fig. 1 shows an illuminated advertisement 1, which is designed as an arrangement of five sidelight optical fiber bundles 11 to 15 on a mirrored plastic carrier 10. The fiber bundle 11, like the fiber bundle 15, has a light feed from both ends, for which purpose a single discharge lamp 16 or 17 is provided, arranged in a protected manner behind the carrier 19. The much shorter fiber bundles 12 to 14 are fed by a single (third in the arrangement shown) discharge lamp 18. Normal plastic optical fibers 11a, 11b, 12a to 14a and 15a, 15b are spliced onto the sidelight fiber bundles at the points where they are held in the plastic carrier 10, which - also arranged behind the carrier 10 - take over the low-loss supply of light from the lamps 16 to 18 to the holding points in the carrier 10.

The supply fiber bundles 11a to 15b each lead into one of three light distribution elements 16a to 18a. The light distribution element 16a, which is designed as a double distributor

LOK4 6.G1 - 9 -

directs the light of the lamp 16 into the supply fiber bundles 11a and 11b, the element 18a designed as a triple distributor directs the light of the lamp 18 into the supply fiber bundles 12a, 13a and 14a, and the double light distributor element 17a directs the light of the lamp 17 into the supply fiber bundles 15a and 15b. The lamps 16 to 18 are supplied with power via a supply line 19 from a (not shown) power source or control unit or are controlled according to pre-programmed time effects.

The light distribution elements 16a to 18a can contain identical or different color filters, which makes it very easy to achieve color effects with different differentiations using a small number of (in particular identical) light sources. In one embodiment, filters of the same transmission curve (color) can be arranged between each lamp and the ends of all of the supply fibers leading into the associated light distributor. Alternatively, different filters can also be provided for the different light outputs in an individual light distributor. If, for example, in the arrangement according to Fig. 1, a red or blue filter is provided in the light distribution element 16a at the ends of the two fiber bundles 11a and 11b facing the (approximately "white") lamp 16, a display color that gradually changes from red to blue in the course of the letter "A" is achieved, since, as a result of the weakening of the light streams fed into the sidelight fiber bundle 12 from both ends and conducted therein, the red component of the light emitted from the side decreases from left to right, while the blue component decreases from right to left.

LOK46.G1 - 10 -

Fig. 2a and 2b are schematic representations (in horizontal and vertical sectional planes, respectively) of the structure of a four-way light distribution element 100 in a design for feeding light from a high-performance discharge lamp 101 into four essentially identical plastic optical fibers 102 to 105. Fig. 2a refers to the sectional plane marked A-A in Fig. 2b, and Fig. 2b refers to the sectional plane marked B-B in Fig. 2a.

A carrier plate 106, which is circular in plan view and has a central hollow-cylindrical socket section 107, has a lamp base 101a in the center, into which the lamp 101 is inserted with its glass body vertically aligned. The base 107a of the socket section 107 has air slots 107a.1, and the upper end face 107b has a circular central opening 107b.1 for convection cooling of the lamp 101. The socket section 107 has - with the center axes offset by 90° from one another - four condenser sections 108 to 111, which are also essentially hollow-cylindrical but are injection-molded together and with the socket section 107. Two aspherical lenses 108a, 108b; 109a, 109b; 110a, 110b or purple, 111b. Between both lenses' there is a dichroic heat protection filter plate 108c to 111c and on the flat surface of the lens furthest from the lamp there is a color filter plate 108d to 111d. (The latter can be omitted in a simplified version, as can the heat protection filters if necessary - especially with lamps that are not very bright.)

The diameter of the condensers 108 to 111 and the radius of curvature of the lenses 108a to 111 near the lamp are so

LOK46.G1 - 11 -

dimensioned so that lamp light enters each condenser from a solid angle range of approximately 90°, and the radius of curvature of the lenses 108b to 111b remote from the lamp is selected so that the light is emitted outward from the condensers essentially at a focusing angle of 60°, so that it enters the end faces of the fibers 102 to 105 in this entry angle range - which is preferred for plastic optical fibers.

In extension of the optical axes of the condensers, a slot 106a to 106d is incorporated into the carrier plate 106. In each of the slots, a fiber holder 102a to 105a, in which the end of the associated fiber 102 to 105 closest to the lamp is fixed, is guided in a radially displaceable and fixable manner in order to be able to optimally adjust the position of the fiber end faces relative to the condenser with regard to the precise lamp geometry and the optical fiber parameters. (In a simplified version of the device, these adjustment means - which can also be designed in a different way within the scope of expert action - are also dispensable.)

In Fig. 3a to 3d (in a sketch-like representation based on Fig. 2a with the designation of the elements also based on this) further components of a modular system of light distribution elements are shown.

Fig. 3a shows a light distribution element 100A for feeding the light of a lamp 101 into two optical fibers 104, 105, whose end face normals are aligned at an angle of 90° to each other. The element 100A is formed similarly to the base body of the four-way distribution element 100 according to Fig. 2a and 2b, with the base being essentially

LOK4 6.G1 - 12 -

chen is open (number 107a.2) and in the sleeve sections 108 and 109, which are not required here for coupling into a fiber, a spherical concave mirror ("ball mirror") 108e or 109e is arranged. Fig. 3b shows a similar triple distributor element lOOB, with which a feed into three fibers 103 to 105 is realized and in which therefore only the sleeve section 108 is closed with a spherical concave mirror 108e.

Fig. 3c shows a double distributor element lOOC consisting of a single continuous cylindrical condenser sleeve 112, which contains two opposing lens heat protection filter sets 109a to 109c or l11 to 111c for coupling the light of a lamp 101 into two opposing optical fibers 103, 105. In the modification lOOD shown in Fig. 3d, one exit surface of the sleeve is closed with a concave mirror 109e, and the light of the lamp 101 is coupled into a single fiber 105 via the remaining exit surface. The lamp holder and cooling openings are not shown here in accordance with the sketch-like character.

Overall, the invention is not limited in its implementation to the preferred embodiments given above. Instead, a number of variants are conceivable which also make use of the solution presented in other types of implementation.

Thus, instead of individual fibers, in an arrangement similar to Fig. 2a and 2b, fiber bundles can also be mounted on the light distribution element. The fiber or fiber bundle mounts

LOK4 6.G1 - 13 -

can be arranged separately from the actual light distribution element.

Instead of the condenser arrangements shown with two plano-convex lenses, the light output elements can comprise arrangements with biconvex lenses or aspherical arrangements. The light distribution elements can also have output elements with different dimensions for coupling light into fibers or fiber bundles with different diameters, which will then usually be located at different distances from the fibers/fiber bundles. For standard applications, such a configuration will provide a predetermined fixed fixation of the elements, while for flexible solutions, configurations are more suitable that have adjustment options in the manner of the means shown in Fig. 2a and 2b for radially shifting the fiber ends and/or means for changing the focal length of the condensers.

In addition to the arrangement shown in Fig. 2a and 2b with the optical axes of the condensers lying in one plane, depending on the spatial radiation characteristics of the lamp, arrangements in which the condensers are spatially grouped around the lamp in order to make optimum use of the emitted light are also conceivable as an embodiment of the invention. For the same reason, in arrangements with only two or three coupling points - as shown in Fig. 1 - sections of the housing wall of the light distribution element may be mirrored and possibly designed with a suitable curvature (in particular as a spherical mirror) in order to feed reflected light into the condensers in addition to the light emitted directly in the opening area.

LOK4 6.G1 - 14 -

To implement the modular structure mentioned above, the arrangement according to Fig. 2a and 2b can be modified so that the condensers 108 to 111 are not manufactured together, but separately as standard elements with different internal diameters and/or focal lengths and are only assembled on the carrier. Advantageously, such a system can also comprise separately manufactured curved and mirrored wall parts, which are inserted instead of a condenser if only two or three coupling-out points are required.

Claims (17)

LOK46.G1 - 15 - Claims 1. Lighting device (1) for transmitting the light generated by at least one lamp (16 to 18; 101) to a plurality of lighting points for interior or exterior lighting or lighting design, which has a plurality of optical fibers (11a to 15b; 102 to 105) or optical fiber bundles (11 to 15), in particular of the "sidelight" fiber type, leading to one or more lighting points, characterized in that a light distribution element (16a to 18a; 100; 100A to 100D) is assigned to the lamp or to a lamp, which has a socket (101a) for the exchangeable insertion of the lamp and a plurality of focusing coupling elements (108 to 111) arranged at substantially equal angular intervals around the lamp for bundling a portion of the lamp radiation onto the end of an optical fiber (102 to 105) or an optical fiber bundle near the lamp. 2. Illumination device according to claim 1, characterized in that the coupling elements are designed as condenser elements (108 to 111) with a sleeve section and a focusing optics (108a, 108b to 111b) accommodated in this. 3. Lighting device according to claim 1 or 2, characterized in that it comprises optical fibers or LOK4 6.G1 - 16 - -fiber bundles with different cross-sections and corresponding coupling elements with different cross-sections. 4. Lighting device according to one of the preceding claims, characterized in that the light distribution element (100) has two to six coupling elements (108 to 111). 5. Lighting device according to one of the preceding claims, characterized in that the longitudinal axis of the lamp holder (101a) is substantially perpendicular to a plane containing the optical axes of the coupling elements (108 to 111). 6. Lighting device according to one of the preceding claims, characterized in that it has "sidelight" optical fibers or fiber bundles (11, 15) with two-sided feed, wherein a lamp (16, 18) with associated light distribution element (16a, 18a) is provided for feeding into both ends. 7. Lighting device according to one of the preceding claims, characterized in that the coupling elements (108 to 111) are designed such that they feed lamp light at a coupling angle of substantially 60° into the ends of the optical fibers (102 to 105) or fiber bundles near the lamp. LOK46.G1 - 17 - 8. Lighting device according to one of the preceding claims, characterized in that the coupling elements (108 to 111) are designed such that they receive lamp energy from a solid angle range between 60° and 120°. 9. Lighting device according to one of the preceding claims, characterized in that regions (108e, 109e) of the wall of the light distribution element (100A; 100B, 100D) lying between the coupling elements are mirrored. 10. Lighting device according to one of the preceding claims, characterized in that at least some of the coupling elements (108 to 111) and/or mounting elements for the ends of the optical fibers or fiber bundles are firmly connected to the base body (106, 107; 112) of the light distribution element (100), in particular are integrally formed or glued thereto. 11. Lighting device according to one of the preceding claims, characterized in that at least some of the coupling elements and/or mounting elements (102a to 105a) for the ends of the optical fibers (102 to 105) or fiber bundles are detachably connected to the base body (106, 107; 112) of the light distribution element (100). 12. Lighting device according to one of the preceding claims, characterized in that the light distribution element (100 to 100) is designed to selectively accommodate different LOK4 6.G1 - 18 - lent of many coupling elements and/or coupling elements with different cross-sections, in particular with a grid base body that can be closed optionally by second frames or wall sections {108e, 109e). 13. Lighting device according to claim 10 or 11, characterized in that a holder (106a to 106d, 102a to 105a) connected to the base body (106, 107) of the light distribution element (100) is provided with a socket for the end of an optical fiber (102 to 105) or an optical fiber bundle near the lamp. 14. Lighting device according to one of the preceding claims, characterized in that the optical fibers (Ha to 15b; 102 to 105) or fiber bundles (11 to 15) are made of plastic and means (107a.1, 107a,2, 108c to 111c) for thermal decoupling between the lamp (101) and the ends of the optical fibres or fibre bundles near the lamp. 15. Lighting device according to claim 13, characterized in that air slots (107a.1) and optionally air guiding devices for convective cooling of the light distribution element (100) are provided as means for thermal decoupling. 16. Lighting device according to claim 13 or 14, characterized in that as means for thermal dissipation. · LOK4 6.G1 - 19 - coupling heat protection filter elements (108c to 111c) and/or high temperature resistant light guide sections with low thermal conductivity are arranged between the lamp and the ends of the optical fibers or fiber bundles near the lamp. 17. Lighting device according to one of the preceding claims, characterized in that a gray, color or polarization filter element (108d to 111d) or a holder for the optional insertion of such a filter element is provided between the lamp (101) and the end of at least one of the optical fibers or fiber bundles (102 to 105) near the lamp.