NL2001486C2 - Lighting fixture for e.g. emergency lighting, has light guide around light source for capture of light from light source, where light guide is designed to emit light through substantial part of its outer surface - Google Patents

Abstract

The fixture (1) has a light source (2) e.g. LED, and a reflector (8) to form a focused beam, and a light guide (4) provided around the light source for the capture of light from the light source. The light guide is designed to emit light through a substantial part of its outer surface (7), where the luminance at an angle of about 60-70 degrees relative to a plane transverse to a longitudinal axis (L) of the light guide is substantially greater than the luminance in the plane transverse to the longitudinal axis of the light guide.

Description

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Title: Lighting fixture

The invention relates to a lighting fixture comprising a light source and a reflector to form a directed light beam.

Such lighting fixtures are known and are used for various applications, such as emergency lighting (for example escape route lighting or anti-panic lighting), as well as for night lighting in corridors, for example of hospitals, retirement homes, retirement homes and hotels. The focused light beam is hereby focused on a floor surface to be illuminated.

The light source is generally embodied as a gas discharge lamp, for example a fluorescent tube. However, the optical efficiency of gas discharge lamps is limited. A relatively large amount of light is also directed in a direction transverse to the longitudinal axis of the light source, while floor areas situated farther away are served with less light.

In addition, lighting fixtures are known in which the light source is designed as an LED. In practice, however, it appears to be complex to focus emerging light from a LED in a controlled manner.

German patent publication DE 103 59 182 describes a lighting fixture in which light is coupled in via an end of an elongated optical conductor, the light mainly coming out of the conductor in a direction transverse to the conductor. The European patent publications EP 1 443 265 and EP 1 078 816 also relate to an optical light guide in which the light exits substantially transversely of the longitudinal axis of the guide. Furthermore, the US patent publications US 2007/064418 and US 2002/126503, as well as the British patent publication GB 2 398 372 describe light guides in which light exits through the outer surface.

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The object of the invention is to provide a lighting fixture of the type mentioned in the preamble, wherein the above-mentioned disadvantage is obviated. In particular, it is an object of the invention to obtain a lighting fixture with a high lighting efficiency in which the light emerging from the light source is used efficiently. To that end, the lighting fixture further comprises a light guide arranged close to the light source for capturing light emerging from the light source, the light guide being adapted to radiate light through at least a substantial part of the outer surface.

By capturing light emerging from the light source in a light guide and radiating light over at least a substantial part of the light guide outer surface, a compact light source with a high optical efficiency, such as an LED, can be applied, while still being relatively A well-defined focusing can be realized in an inexpensive manner since the light guide can be made substantially larger than the light source. Due to the structure of the lighting fixture according to the invention, in which light exits via the light guide, tolerance requirements of the reflector profile are relatively low. A high lighting efficiency can thus be obtained.

Preferably, the polar diagram of the light guide exhibits a significant amplitude at a relatively large angle with respect to the normal of the longitudinal axis of the light guide. As a result, the lighting fixture can illuminate a region that is relatively far away, in the direction along the longitudinal axis of the light guide, since a large part of the available amount of light is not guided in a direction transverse to the longitudinal direction of the light guide, but precisely at a large angle thereof, so that a very long floor segment can be illuminated reasonably uniformly in an energy-efficient manner.

Further advantageous embodiments of the invention are shown in the subclaims.

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The invention will be further elucidated on the basis of exemplary embodiments shown in the drawing. In the drawing:

Figure 1 is a schematic perspective view of a first embodiment of a lighting fixture according to the invention;

Figure 2 shows a polar diagram of the lighting fixture of Figure 1; and

Figure 3 is a schematic perspective view of a second embodiment of a lighting fixture according to the invention.

The figures are only a schematic representation of a preferred embodiment of the invention. In the figures, identical or corresponding parts are indicated with the same reference numerals.

Figure 1 shows a schematic perspective view of a lighting fixture 1 according to the invention. The luminaire 1 comprises a light source 2 which is designed as an LED. The light source 2 is connected via a wiring 3 to an electrical supply (not shown). Furthermore, the luminaire 1 comprises a reflector 8 which has a parabolic profile in order to be able to emit a substantially parallel light beam. The fixture 1 also comprises a tubular light guide 5. The light source 2 is positioned near a first end 5 of the light guide 4, so that light emitted by the light source 2 can be easily captured in the light guide 4.

In a specific embodiment of the lighting fixture according to the invention, an additional light source is positioned near a second end 6, opposite the first end 5, so that a large amount can be efficiently coupled into the light guide 4. However, the luminaire can also be designed without an additional light source, such as in the embodiment shown in Figure 1, wherein the second 4 end 6 is provided with a reflector designed as a mirror surface, preferably with a high degree of reflection. As a result, light loss is minimal and a system with a high optical efficiency is nevertheless obtained when a single light source is used.

The light guide 4 is adapted to radiate light through at least a substantial part 7 of the outer surface, preferably the entire outer surface of the light guide 4. Because the light guide is formed substantially elongated, rod-shaped, a very narrow strip, for example an escape route well lit.

By making the light guide substantially invariant in cross section, the amount and direction of the emerging light is more or less independent of the axial position on the outer surface of the light guide, so that the homogeneity of the light, seen in the longitudinal axis L of the light guide, is relatively high.

The embodiment of the lighting fixture 1 shown in Figure 1 is particularly suitable for escape route lighting in which a relatively narrow strip must be illuminated. The longitudinal axis L of the light guide 4 herein substantially coincides with the focal point of the parabolic reflector 8. For example, a strip with a length 20 of approximately 16 meters can pass through a single luminaire 1 with a more or less uniform light distribution in an energy-efficient manner, e.g. with a LED that consumes 2 watts. By using such an optic, the brightness in a direction which is substantially transverse to the longitudinal axis L can be very low relative to the brightness at an angle of approximately 60 ° or 70 ° with respect to the plane transverse to the lengteas L. This way glare can be prevented. Measurements show that the ratio of said brightnesses can be less than 1%. In another embodiment of the lighting fixture 1, the parabolic reflector 8 has been replaced by another type of reflector, for example 30 for focusing a wider light beam for illuminating a wider floor segment. This allows the fixture to be used, for example, as anti-panic lighting, whereby a relatively large floor area is more or less uniformly illuminated with a minimum number of fixtures.

It is noted here that the profile of the reflector can be determined in dependence on the height above a floor surface.

By using a lighting fixture 1 according to the invention, a very high optical efficiency and a very wide range can be achieved. Furthermore, the system is in principle suitable for various applications, whereby only the reflector needs to be adjusted. Furthermore, the light beam emitted by the armature 1 is only to a limited extent dependent on the angle-dependent light pattern of the light source itself.

The dimensions of the light guide 4 are larger than those of the light source. For example, the LED is realized on a surface of approximately 0.5 cm by approximately 0.5 cm, while the light conductor can have a length between approximately a few cm and a few dm or more.

The light conductor preferably comprises an optically transparent and low-absorption carrier material in which scattering particles are integrated, and wherein the refractive index of the carrier material differs from the refractive index of the scattering particles. The scattering particles are also preferably optically transparent and low in absorption. By distributing the scattering particles substantially uniformly in the carrier material, a uniform light emission from the light guide can be realized.

In a specifically applicable material for the light conductor, the weight percentage of the scattering particles relative to the carrier material is approximately in a range between approximately 1% and 5%.

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Preferably, the carrier material comprises acrylic glass (PMMA), polyethylene (PET) or a copolymer (PETG) thereof, so that a relatively inexpensive base material is available. Furthermore, the scattering particles are preferably made from a polystyrene (PS), a phenyl methacrylate or a butyl acrylate. The above materials are mentioned by way of example. The carrier material and / or the scattering particles can of course also be manufactured from other material.

The tubular light guide can be made as an extrusion profile. Of course, other production options are also available, such as sawing and / or milling. Furthermore, the light guide can not only be tubular, but also with a non-circular circumference, for example with a rectangular, square, triangular or elliptical cross-section.

The scattering particles are preferably spherical.

Furthermore, the diameter of the particles is preferably in a range between approximately 20 µm and approximately 75 µm. In a preferred form according to the invention, the scattering particles are arranged in a cross-linking structure in the carrier material.

Figure 2 shows a polar diagram 10 of the lighting fixture 1 of Figure 1. The polar diagram 10 shows a luminance curve 11 in the longitudinal axis L of the light guide 4. The polar diagram 10 is provided with lines 20a-d which have a specific indicate luminance amplitude. Furthermore, the diagram is provided with lines 21a-h which indicate specific angles with respect to the normal 12 of the longitudinal axis L of the light guide L. The curve 11 has a significant amplitude at a relatively large angle with respect to the normal 12 of the longitudinal axis L of the light guide 4. Thus, the curve 11 has lobes 13 around approximately +/- 70 °. Because the lobes 13 are at a relatively large angle with respect to the normal 12, a very wide-radiant effect is obtained. The normal 12 is located in a plane transverse to the longitudinal axis 7 L of the light guide 4. From the numerical data of Figure 2 it appears that the ratio of the luminances, also called brightness, at approximately ± 70 ° and 0 ° with respect to a plane transverse to the longitudinal direction L of the light guide 4 is greater than 100, in other words the luminance 5 at an angle in a range of approximately 60 ° to approximately 70 ° with respect to the plane transverse to the longitudinal axis L of the light guide 4 is more than one hundred times as large as the luminance in the plane transverse to the longitudinal axis L of the light guide, so that glare is advantageously prevented. Said luminance ratio is considerable and may even be more than 10, such as 150, or slightly less, for example 50 or 80. The polar diagram 10 furthermore shows an additional curve 14 of the luminance in a plane transverse to the longitudinal axis L of the light guide 4.

The material from which the light guide is preferably constructed is, for example, known from the European patent publication EP 0 893 708 for the realization of information carriers. Furthermore, the material from which the light guide can be constructed is commercially available from BWF Kunststoffe GmbH & Co. KG. KG in Offingen, Germany, under the name "SATLITE".

Figure 3 shows a schematic perspective view of a second embodiment of a lighting fixture 1 according to the invention, in which the light guide 4 is designed otherwise, namely as a plate, so that a wider strip can be illuminated. In combination with the reflector 8, a fixture 1 can thus be designed that is optimized for a floor area to be illuminated. A block or plate-shaped light guide is particularly suitable for installation in a ceiling or wall or for steps. Furthermore, the radiation pattern, in particular for a block or plate-shaped light conductor, can be adjusted by a specific reflector geometry, optionally in combination with a specific length and width ratio of the light conductor, for example a symmetrical or disymmetrical radiation pattern.

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The invention is not limited to the exemplary embodiments described here. Many variants are possible.

Instead of designing the light source as an LED, the light source can also be designed differently, for example as a compact gas discharge lamp.

Furthermore, the luminaire according to the invention can not only be used as escape route lighting or anti-panic lighting, but also in other ways, for example as night lighting and decorative lighting. To this end, a horizontal segment of floor or ceiling, but also a wall segment can be illuminated.

In addition, the reflector can be substantially mirrored or diffuse.

Such variants will be clear to those skilled in the art and are understood to be within the scope of the invention as set forth in the following claims.

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Claims (14)

A lighting fixture, comprising a light source and a reflector to form a directed light beam, further comprising a light conductor arranged near the light source for capturing light emerging from the light source, the light conductor being adapted to emit light via at least a substantial part of the outer surface, wherein the luminance at an angle with respect to the plane transverse to a longitudinal axis of the light guide is considerably larger than the luminance in the plane transversely to the longitudinal axis of the light guide. 2. The luminaire as claimed in claim 1, wherein the luminance 10 at an angle in a range of approximately 60 ° to approximately 70 ° with respect to the plane transverse to the longitudinal axis L of the light guide is considerably greater than the luminance in the plane transverse to the longitudinal axis of the light guide. 3. Lighting fixture as claimed in any of the foregoing claims, wherein the light guide is formed substantially elongated. 4. Lighting fixture according to one of the preceding claims, wherein the light guide is substantially invariant in cross-section. 5. Lighting system according to any one of the preceding claims, wherein the light guide comprises an optically transparent and low-absorption carrier material in which scattering particles are integrated, and wherein the refractive index of the carrier material differs from the refractive index of the scattering particles. 6. A lighting fixture according to any one of the preceding claims, wherein the scattering particles are optically transparent and low in absorption and are substantially uniformly distributed in the carrier material. 7. Lighting fixture as claimed in any of the foregoing claims, wherein the outer surface of the light guide is rough. 2 00 1 4 86 * * A lighting fixture according to any one of the preceding claims, wherein the weight percentage of the scattering particles relative to the carrier material is approximately in a range between approximately 1% and 5%. The lighting fixture according to any one of the preceding claims, wherein the polar diagram of the light guide exhibits a significant amplitude at a relatively large angle with respect to the normal of the longitudinal axis of the light guide. 10. Lighting fixture as claimed in any of the foregoing claims, wherein the support material comprises acrylic glass, polyethylene or a copolymer thereof. A lighting fixture according to any one of the preceding claims, wherein the scattering particles are made from a polystyrene, a phenyl methacrylate or a butyl acrylate. 12. Lighting fixture according to one of the preceding claims, wherein the light source is positioned near a first end of the light guide. 13. Lighting fixture as claimed in any of the foregoing claims, further comprising an additional light source or a reflector which is positioned near a second end of the light guide. A lighting fixture according to any one of the preceding claims, wherein the reflector is parabolic. 2 fifl 1 i au