EP2249076A1 - Street lamp with punctiform light sources, in particular LED light - Google Patents

Abstract

The light has a set of point-shaped LEDs (2) provided with lenses that are arranged in a layer of LEDs (4). The LEDs are provided with half-spherical radiation characteristic with maximum intensity along a direction in a sectional plane perpendicular to the layer. The sectional plane is inclined opposite to a perpendicular bisector of the layer at non-zero angle. A light scattering plate (12) is arranged at the layer in a distance, where distance between the layer of the LEDs and light scattering plate is about 10 mm.

Description

The present invention relates to luminaires for lighting purposes indoors or outdoors, in particular street lights for the illumination of tunnels, with a plurality of punctiform light sources, which may be formed in particular of light emitting diodes (LEDs).

The advances in the technical development of LEDs as light sources, in particular the development of particularly high-intensity LEDs, has made it possible to use such light sources in outdoor luminaires, in particular as street lights. In this case, a plurality of LEDs is provided. To achieve certain light distribution curves, the LEDs are arranged on a correspondingly shaped surface or the light of the LEDs is deflected by optical means. In particular, relatively wide-beam lights are desired for illuminating streets.

An example of a lighting device made of LEDs, which is set up as tunnel lighting, is in FIG EP 1 498 656 A2 disclosed. This tunnel light has a plurality of LEDs arranged one behind the other in one direction. In order to increase the emission angle of the light-emitting diodes (eg 40 ° instead of 20 ° emission angle), each light-emitting diode is assigned a scattering lens.

However, a disadvantage of such luminaires is that a viewer of the luminaire, e.g. a motorist approaching the lamp along the road is blinded at certain distances from the lamp, each corresponding to a certain angle of view of the lamp, by the plurality of punctiform light sources with very high luminance.

It is the object of the present invention to provide a luminaire, in particular an interior or exterior luminaire, with a plurality of punk-shaped light sources, which is improved with regard to the light distribution properties and the diaphragm properties.

The invention solves the problem by a luminaire with a plurality of punk-shaped light sources, in particular LEDs, which are arranged in a plane, wherein the light sources each have a hemispherical emission characteristic which is perpendicular in a sectional plane to said plane has at least a maximum in the light intensity along a direction which is inclined relative to the mid-perpendicular on the plane by a non-zero angle γ, as well as with a light-scattering plate arranged at a distance to the plane.

In the luminaire according to the invention, a wide-beam light distribution, which is particularly suitable for illuminating a road, in particular a tunnel, is produced in that the main maximum of the luminous intensity is not emitted downwards, but in a vertical sectional plane through the luminaire (C-plane). inclined at an angle to the mid-perpendicular of the luminaire. This makes it possible to illuminate this relatively evenly despite the distances between the street lights and tunnel lights along the roadway. However, a motorist would perceive the variety of punctiform bulbs, depending on the angle of view to the lamp, as dazzling, because the individual points of light with very high luminance are resolved separately by the viewer and at a viewing angle of the lamp, which corresponds to the angle γ, blind him directly. According to the invention, this glare is prevented by arranging a light-scattering plate at a defined distance from the point-shaped light-emitting means. By the light-diffusing plate, a luminance reduction for the individual point-like light sources is achieved, because the effective emission area, which generates each of the point-like light sources in the plane of the light-diffusing plate, increases compared to the emission surface of the point-like light source itself by the defined distance of the light-scattering plate is. In general, it is a circular or elliptical radiating surfaces, which are generated in the light-scattering plate of the light sources. The driver no longer perceives the punk-shaped light sources as a dazzling point because he only sees the punctiform light sources as luminous circular areas or ellipses with a correspondingly reduced luminance. Due to the defined distance of the light-scattering plate to the punctiform light source, the radiation characteristic of the individual semispherical radiation characteristic punctiform light sources is not completely resolved, so that the desired light distribution of the overall light, for the uniform illumination of a road section, still guaranteed.

A preferred distance between the plane of the point-shaped light sources and the light-diffusing plate is at least 10 mm, preferably between 30 mm and 50 mm. Preferably, a maximum distance of about 70 mm is not exceeded. Within the specified ranges, the semi-spherical light emission characteristic of the point light sources is largely retained, but the glare is effectively reduced to an acceptable level. The light diffusing plate not only effectively increases the emission area of the point light sources, but at the same time increases the halfway angle defining the width of the at least one maximum in the light distribution curve of the luminaire (i.e., the maximum is broadened in the luminous intensity distribution curve). In addition, the position of one maximum (i.e., the angle γ) can be slightly shifted from a lamp without a light-diffusing plate.

According to an embodiment of the luminaire according to the invention, the distance between the plane in which the punk-shaped light sources are arranged and the light-diffusing plate is constant over the entire plane. In an alternative embodiment, which is particularly preferred for luminaires having an asymmetric light distribution curve in a C-plane, the light-scattering plate is wedge-shaped with respect to the plane in which the point-shaped light sources are arranged. In this embodiment, for example, the distances between the point light sources and the light diffusing plate can be adjusted according to the asymmetry of the semi-spherical radiation characteristic of the light sources, particularly with respect to the angle γ of a single maximum. In point-shaped light sources with symmetrical hemispherical radiation characteristic can be achieved by the wedge-shaped inclination of the plane of the light sources with respect to the light-scattering plate Lichtbandknickung.

In one embodiment, the angle γ, which defines the position of the maximum with respect to the mid-perpendicular of the luminaire in the C-plane, is always greater than or equal to 45 ° for each one of the light sources. This also achieves a maximum in the luminous intensity distribution of the entire luminaire at an angle γ of more than 45 °.

According to a preferred embodiment, the intensity value of each of the point-shaped light sources in the maximum is at least twice as large as the intensity value along the perpendicular bisector. The light distribution curve of the entire luminaire may have a minimum in the direction of the mid-perpendicular.

In one embodiment of the luminaire, the punctiform light sources each have two maxima, preferably two identical maxima, which are arranged symmetrically with respect to the mid-perpendicular in said sectional plane with angles of ± γ. This embodiment of the luminaire is advantageously suitable for illuminating a longitudinally extending straight roadway, in particular in tunnels. The use of LEDs as light sources reduces the energy requirements for the luminaires and extends the maintenance intervals of the luminaire.

A preferred angle γ is greater than or equal to 45 °. In particular, an angle between 50 ° and 60 ° in a sectional plane which intersects the roadway in the longitudinal direction, i. the C180 ° -0 ° -plane of the luminaire, preferred.

According to one embodiment, each punctiform light source is assigned in each case a lens and / or a reflector. These optical means can produce the semi-spherical radiation characteristic of the point light sources as previously defined. According to one embodiment of the invention, the point-shaped light sources in the plane are arranged in a regular structure, in particular in a matrix. It is of particular advantage if the point-shaped light sources are all identical, if necessary including their associated lenses or reflectors. This lamp can not only be produced inexpensively.

According to a preferred embodiment, the point-shaped light sources are arranged at a distance of at least 20 mm, preferably between 25 mm and 50 mm, in the plane. In this planar arrangement, in addition to the previously mentioned advantages of glare, it is also ensured that the point-shaped light sources, in particular LEDs, can be sufficiently cooled. For example, the plane on which the LEDs are mounted may be defined by the surface of a lamp body, which may be formed of a thermally conductive material, such as aluminum.

According to one embodiment of the invention, only one plane is provided, which is occupied by the plurality of point light sources. According to an alternative embodiment, it is also possible to provide a plurality of planes, each with a multiplicity of punctiform light sources, which each have a spacing from the light-scattering plate. In particular, the distances between each one plane and the light-diffusing plate can change continuously in one direction. In this embodiment, an angle between the plane and the light-diffusing plate is included in each case, which may also be constant according to a preferred embodiment. This embodiment is suitable, for example, for a luminaire, which is arranged on the side of an object to be illuminated, such as a road or tunnel section. Due to the inclination of the planes, the main emission direction of the luminaire in the direction of the object to be illuminated can be determined. For example, a road surface can be illuminated by the lamp according to the invention, which is arranged next to the lamp. In this embodiment, the use of multiple levels is to dispose the plurality of point light sources particularly preferred, because thereby the height of the lamp, given a slope of the planes, compared to an embodiment with only one inclined plane can be reduced.

According to a preferred embodiment of the luminaire, it is designed as a street lamp, in particular for mounting on a tunnel ceiling or a tunnel side wall.

Further features and advantages of the invention will become apparent from the following description of a preferred embodiment with reference to the accompanying figures.

Figur 1

zeigt schematisch eine perspektivische Ansicht auf einer Leuchte gemäß der vorliegenden Erfindung von der Seite ohne Gehäuseeinfassung;

Figur 1a

zeigt einen Abschnitt der Leuchte nach Figur 1 im Bereich einer LED im Quer- schnitt;

Figur 2

zeigt ein Polardiagramm einer Lichtstärkeverteilungskurve der erfindungsge- mäßen Leuchte in drei verschiedenen C-Ebenen;

Figur 3

zeigt die Lichtstärkeverteilungskurve in einer kartesischen Darstellung mit und ohne Leuchtdichteintegrator;

Figur 4

zeigt ein Polardiagramm der Lichtstärke in Kegelmantelmantelkurven für vier verschiedene Öffnungswinkel des Kegels;

Figur 5

zeigt eine alternative Ausführungsform der Leuchte mit mehreren Ebenen in einer Schnittdarstellung; und

Figur 6

zeigt die Leuchte nach Figur 5 in perspektivischer Ansicht.

The figures show the following:

FIG. 1

shows schematically a perspective view of a lamp according to the present invention from the side without housing enclosure;

FIG. 1a

shows a section of the light FIG. 1 in the area of an LED in cross section;

FIG. 2

shows a polar diagram of a luminous intensity distribution curve of the inventive luminaire in three different C-planes;

FIG. 3

shows the luminous intensity distribution curve in a Cartesian representation with and without luminance integrator;

FIG. 4

shows a polar diagram of the light intensity in Kegelmantelmantelkurven for four different opening angle of the cone;

FIG. 5

shows an alternative embodiment of the luminaire with multiple levels in a sectional view; and

FIG. 6

shows the light after FIG. 5 in perspective view.

A side perspective view of an embodiment of a luminaire is shown schematically in FIG FIG. 1 shown, to illustrate the technical details, the side parts of the housing are not shown.

The luminaire comprises as a luminous means a plurality of LEDs 2, which are arranged in a plane 4 on the surface of a luminaire body 6. The LEDs 2 are arranged in a regular matrix, wherein the distances between the LEDs 2 along rows 8 arranged in parallel are constant. Furthermore, the distance between the rows 8 is constant. The distances of the LEDs within a row 8 and between the rows 8 have a value between 30 mm and 40 mm.

The level 4 may be formed from one or more boards, wherein the LEDs 2 are each electrically contacted in several rows together. The electrical connections are housed in the lamp body 6 (not shown). According to the illustrated embodiment, the LEDs are mounted in a row 8 each on a common strip-shaped board, which can be replaced in one piece for maintenance purposes. The board 8, and preferably also the intermediate areas in the plane 4 are formed of a thermally conductive material, so that the heat generated during operation of the LEDs can be dissipated through the lamp body 6. The above-mentioned distances of the LEDs 2 are advantageous because the available area is sufficient to dissipate the heat to the ambient air.

The LEDs 2 form punctiform light sources, because the luminous area of the chip, on which the LED is located, is very small compared to the dimensions of the total luminaire. When looking directly at the LEDs, the viewer perceives the light source as punctiform because the eye is unable to resolve the luminous surface.

At the lateral edges of the lamp body 6 spacers 10 are arranged on the plane 4, on which a light-scattering plate 12 is held at a constant distance D to the plane 4. The light-scattering plate 12 is, for example, a glass plate which has a transmittance of 89.1%, preferably 91.7%, and more (measured according to DIN 5036 Part 3 or ISO 5740-1982 or CIE Publication No. 38 ). The proportion of scattered transmission is between 87.1% to 90.7%, which corresponds to 98% to 99% of the total transmittance. To achieve the light scattering, a surface of the plate 12 (preferably the side facing the light sources) may be provided with regular or irregular elevations or depressions. The feature size, i. the mean dimension of the protrusions or depressions is preferably less than 3 mm. Alternatively or additionally, the material of the plate 12 or the surface of the plate 12 may have a haze.

The light-diffusing plate 12 acts in the described lamp as a luminance integrator, as shown in FIG. 1a becomes clear, which schematically shows a cross section through the lamp in the region of a single LED 2. The distances in the FIG. 1 are not shown to scale. In particular, the distance D between the LED 2 and the light-diffusing plate 12 is larger.

wobei LVF der Leuchtdichteverminderungsfaktor ist, ID der Lichtstärkewert in abgestrahlter Richtung des Beobachters von der Abstrahlfläche der als Leuchtdichteintegrator wirkenden lichtstreuenden Platte ist, I der Lichtstärkewert in abgestrahlter Richtung des Beobachters von der Lichtaustrittsfläche der der LED zugeordneten Optik ist, d der Abstand zwischen der leuchtenden Quelle (von dem Chip) der LED zu der Lichtaustrittsfläche der LED-Optik ist, D der Abstand zwischen der LED 2 bzw. der Ebene 4 und der lichtstreuenden Platte 12 ist und α der halbe Halbstreuwinkel der Lichtstärkeverteilung ohne die Anwendung der lichtstreuenden Platte ist und αD der halbe Halbstreuwinkel der Lichtstärkeverteilungsanwendung mit der lichtstreuenden Platte ist.The LED 2 is associated with a reflector 14 and a lens 16 which define the semispherical radiation characteristic of the LED 2. In the illustrated embodiment, the Abstrahlcharakteristik is shown as a cone sheath with dashed lines. Without the light scattering plate 12, a viewer would see the light source as a single small luminous surface perceive which is effectively determined by the size of the lens diameter 16 and the light exit opening of the reflector 14. By arranging the light-diffusing plate 12 at the distance D in front of the light-emitting surface of the LED 2, the luminous area of the LED 2 perceived by the viewer is increased, thereby reducing the luminance of the radiating surface on the light-diffusing plate generated by a single light source. In the luminaire according to the invention, the distance D determines the reduction of the luminance which an observer perceives on the plate 12 for each individual LED. The luminance reduction factor LVF can be determined from the following formula: $$\mathit{LVF}=\frac{\mathit{ID}}{I}\cdot \frac{d^2}{{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="imgf0001.png,imgf0005.png"\; state="\{\{state\}\}">D</figure-callout>}}^2}\cdot \frac{{\tan }^2\alpha }{{\tan }^2\mathit{aD}}.$$

where LVF is the luminance reduction factor, ID is the luminous intensity value in the irradiated direction of the observer from the radiating surface of the light diffusing plate acting as luminance integrator, I is the luminous intensity value in the irradiated direction of the observer from the light exit surface of the optics associated with the LED, d is the distance between the luminous source (from the chip) of the LED to the light emitting surface of the LED optic, D is the distance between the LED 2 and the plane 4 and the light diffusing plate 12 and α is the half half angle of the light intensity distribution without the application of the light diffusing plate and αD is half the half-beam angle of the light intensity distribution application with the light-diffusing plate.

In FIG. 3 is to illustrate the half-beam angle of the light intensity distribution with and without light scattering plate (integrator) a luminous intensity distribution curve of the luminaire in a vertical sectional plane perpendicular through the plane 4 of the light represented. The dashed line shows the light intensity distribution, which results without light-diffusing plate 12, while the solid line represents the light intensity distribution with light-diffusing plate 12. The Height of the maxima of the two curves in the diagram of FIG. 3 is normalized to a better overview to the same value.

Due to the LED optics j each individual light source (lenses 16 and reflectors 14) results in a deviating from the Lambert Verieilung light intensity distribution of the luminaire, as shown as a dashed line in FIG. 3 is shown. There are two maxima at about ± 60 ° and a minimum at 0 °. The direction of 0 ° corresponds to the mid-perpendicular on the plane 4. Due to the light-scattering plate, the half-width of the maxima is increased from 2α to 2αD. Furthermore, the position of the maxima shifts from about ± 58 ° to ± 55 °, respectively on both sides of the mid-perpendicular within the indicated C-plane. By this measure, the glare can be reduced to the observer. In particular, by varying the distance D, the maximum luminance can be set to an acceptable value for a specified angle.

A luminous intensity measurement of the light distribution curve for three different C-planes is in FIG. 2 shown. The C-levels of the luminaire correspond to vertical planes of intersection through the level 4. The representation for the C180 ° -0 ° -square corresponds to the representation after FIG. 3 , In the C270 ° -90 ° plane, the light intensity distribution is much narrower, as indicated by the dot-dash line in FIG. 2 is shown. If the luminaire with the C180 ° -0 ° plane is arranged along the carriageway, the carriageway can therefore be uniformly illuminated over a length section.

FIG. 4 shows the corresponding cone envelope curves of the light intensity distribution for four different cone angles in a polar representation. The light intensity measurement is carried out in a circle around the perpendicular bisector, for different radii, each corresponding to an opening angle of a cone sheath. From this representation, it is also clear that the light in an advantageous manner for illuminating a road surface in the longitudinal direction (0 ° -180 ° axis of FIG. 4 ) is suitable.

According to other embodiments of the luminaire, the optics of the LEDs may also produce an asymmetrical light distribution of each individual LED. These can also be arranged rotated to each other. As a result, it is possible, for example, to generate a light band buckling, which occurs in the cone envelope curve according to FIG FIG. 4 as an asymmetric curve with respect to the 0 ° -180 ° axis. Such lights are suitable for example for illuminating a curved section of a roadway or for illuminating the roadway from a position laterally of the roadway edge. In an alternative embodiment, the light band buckling is generated in that the light-scattering plate 12 is wedge-shaped with respect to the planes 4 of the point-shaped light sources. The punctiform light sources may have a symmetrical light beam characteristic with respect to the 0 ° -180 ° axis. The inclination of the plane 4 with respect to the plate 12 may, for example, between 5 ° and 25 ° are preferably about 15 °.

In the FIGS. 5 and 6 an alternative embodiment of the lamp is shown. Compared to the previously described embodiment, this lamp has a plurality of levels 4 ', 4 "and 4"', which are each inclined at an angle between 5 ° and 25 °, preferably between 15 ° to 20 °, with respect to the light-scattering plate 12 , Each of the levels 4 ', 4 ", 4"' has a plurality of LEDs 2, as described in the previous embodiments with only one level 4. The lamp is designed as a street lamp, which can be arranged at the lateral edge of the road, wherein the LED levels 4 ', 4 "and 4'" are aligned inclined towards the road. With this inclination, the light in the direction of the road to illuminate a road surface outside the vertical direction, in which the lamp is mounted, for example, on a mast, align.

The multiple LED levels 4 ', 4 "and 4"' each have the same angle of inclination relative to the light-scattering plate 12. This has the advantage that the height of the lamp, compared to a luminaire with only one level 4, which has the same angle of inclination, does not need to grow unnecessarily. Preferably, the lights between two and five planes, each with the same inclination angle or different inclination angles between 0 ° and 25 ° relative to the light-diffusing plate 12, on.

In addition to the LED levels 4 ', 4 "and 4"' are reflector elements, in particular mirror elements 18, mounted, the light, because of the inclination of the LED levels 4 ', 4 ", 4"' partially laterally of the levels within the Luminaire housing is radiated, are directed back to the object to be illuminated. These mirror elements can be arranged at an angle between 90 ° to 120 ° (corresponding to a light incidence angle between 0 ° to 30 °) to the main emission direction of the LEDs.

The lamp according to the FIGS. 5 and 6 is designed as a lamp for attachment to a lamppost, especially for outdoor use. For this purpose, a light carrier 20, which is designed in particular for mounting on a lamp post, provided on a lamp housing 22. The inclination of the LED levels 4 ', 4 "and 4"' with respect to the plate 12 is for all levels 4 ', 4 ", 4"' in a common sectional plane (image plane of FIG. 5 ), which runs vertically through the lamp and the light carrier 20 intersects. According to an alternative embodiment, which is intended to arrange two luminaires on a common mast, the inclination of the LED levels 4 ', 4 "and 4'" lies in a common sectional plane, which is 90 ° with respect to the vertical sectional plane of the luminaire , which cuts the light carrier 20, is rotated. In this embodiment, two lights can be mounted on opposite sides of a common light pole. Said embodiment with two lights on a lamppost has the advantage that on the object to be illuminated, such as the road surface, a higher luminance can be achieved.

Numerous modifications of the illustrated embodiments of the luminaires may be made without departing from the scope of the invention as defined by the following claims. For example, different symmetric or asymmetric reflectors and / or lenses for the LEDs 2 may be provided to produce different light distributions. In particular, a symmetrical light intensity distribution along an axis of symmetry, a symmetrical light intensity distribution in two axes of symmetry, as in FIGS. 2 to 5 represented, and a rotationally symmetrical light intensity distribution preferred.

LIST OF REFERENCE NUMBERS

2

punctiform light source

4, 4 ', 4 ", 4"'

level

6

luminaire body

8th

Circuit board of a LED series

10

spacer

12

Light-scattering plate

14

reflector

16

lens

18

mirror surfaces

20

Light carrier

22

luminaire housing

Claims (14)

Luminaire having a multiplicity of punctiform light sources (2), in particular LEDs each having an optic, which are arranged in a plane (4),
wherein the light sources (2) each have a semispherical radiation characteristic, which in a sectional plane perpendicular to said plane at least one maximum having light intensity along a direction inclined from the mid-perpendicular on the plane (4) by a non-zero angle γ,
and a light scattering plate (12) arranged at a distance (D) from the plane (4). Luminaire according to claim 1, wherein the distance (D) between the plane (4) of the punctiform light sources (2) and the light-diffusing plate (12) is at least 10 mm, preferably between 30 mm and 50 mm. Luminaire according to one of the preceding claims, wherein the distance (D) between the light-scattering plate (12) and the plane (4) over the entire plane (4) is constant or the light-scattering plate with respect to the plane (4) is wedge-shaped, so in that the distance (D) between the plane (4) and the light-diffusing plate (12) changes continuously along one direction. Luminaire according to one of the preceding claims, wherein the angle γ is greater than or equal to 45 ° for each light source (2). Luminaire according to one of the preceding claims, wherein the luminous intensity value of each punctiform light source (2) in the at least one maximum is at least twice as large as the luminous intensity value along the perpendicular bisector. Luminaire according to one of the preceding claims, wherein the punctiform light sources (2) each have two maxima in the sectional plane, preferably two identical maxima, at an angle of ± γ with respect to the perpendicular bisector. Luminaire according to one of the preceding claims, wherein a plurality or all of the point-shaped light sources (2) are identical to each other. Luminaire according to one of the preceding claims, wherein the light sources (2) each comprise a lens (12) associated therewith and / or a reflector (14) associated therewith. Luminaire according to one of the preceding claims, wherein the punk-shaped light sources (2) are arranged in a regular structure, in particular in a matrix, in the plane (4). Luminaire according to one of the preceding claims, wherein the punctiform light sources (2) are arranged at a distance of at least 20 mm, preferably between 25 mm and 50 mm, in the plane (4). Luminaire according to one of the preceding claims, which is designed as a luminaire for lighting purposes indoors or outdoors, in particular as a street lamp. A luminaire according to any one of the preceding claims, wherein a plurality of planes (4 ', 4 ", 4"') are provided, each having a plurality of said punctiform light sources (2). A luminaire according to claim 12, wherein the plurality of planes (4 ', 4 ", 4"') are each arranged at a distance from the light-diffusing plate extending along one direction for each of the planes (4 ', 4 ", 4"'). ) changes constantly. Luminaire according to claim 12 or 13, wherein the planes (4 ', 4 ", 4"') are in each case inclined at an angle of between 5 ° and 25 ° with respect to the light-diffusing plate (12), wherein the angles of inclination in one for all planes ( 4 ', 4 ", 4"') is located in the common cutting plane perpendicular to the light-diffusing plate (12) and in particular for all levels (4 ', 4 ", 4"') are the same.

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