WO2019175389A1 - Spotlights comprising led clusters - Google Patents

Abstract

The invention relates to spotlights for stationary mounting in an exterior or interior space, in particular stadium spotlights, comprising an array of a number of identical LED clusters, wherein each LED cluster comprises a plurality of LEDs, and the LED clusters in the array are arranged at a distance from one another which is greater than the distance between the LEDs inside the LED clusters, wherein at least some of the plurality of identical LED clusters in the array are arranged rotated with respect to one another about their central axis.

Description

 HEADLIGHTS WITH LED CLUSTER

DESCRIPTION

The present invention relates to a headlamp for stationary mounting in the exterior or interior, in particular a stadium headlamp, and in particular relates to the arrangement of the LED within the headlamp.

It is known in the prior art to arrange a plurality of LEDs in a headlight (which is understood here to mean any form of semiconductor light sources, including organic LEDs), in particular with an associated optical component in a cluster. However, if, for example, the cluster has a matrix arrangement of 3x3 LEDs, the result is a slightly quadratic distortion in the luminous intensity distribution measured in a plane perpendicular to the optical axis of the headlamp. This effect is exacerbated as the size of the cluster increases. However, as often as possible circular distributions of light are desired for headlights, optical components or faceted reflectors is trying to generate from the square or rectangular distorted light distribution curve again a rotationally symmetric light distribution. However, the use of scattering optical components or faceted reflectors always reduces the maximum of the light intensity due to the scattering. This is the case with headlamps which are intended to illuminate a certain area over a long distance, e.g. Headlights in a sports stadium, not desired.

Object of the present invention is to provide a headlamp with LEDs, which a possible rotationally symmetric light distribution curve at the same time lower half-beam angle, ie a sharp maximum of the light distribution curve along the optical axis of the headlight generated.

The problem is solved by a headlamp according to claim

1.

A special feature of the headlight according to the present invention is that several LED clusters are provided in an array in the headlight and the clusters are rotated against each other about their central axis. For example, the same matrix-shaped, cross-shaped or other arrangements of LEDs can be provided within each cluster and the clusters are each rotated by an angle to a nearest neighbor. As a result of this rotation of the individual LED clusters relative to one another, a superposition of the individual light distribution curves results in a rotationally symmetrical overall light distribution curve, without widening the overall light distribution, i. to generate a larger half-beam angle around the maximum of the light intensity along the optical axis. The angle of rotation of the individual LED clusters depends on the cluster size. Generally, for rectangular LED clusters, the larger the cluster, the smaller the angle of rotation must be to produce a rotationally symmetric light distribution.

According to one embodiment, each of the LED clusters each has a row of LEDs, in particular three LEDs. A single row of LEDs would produce an elliptically distorted light distribution. By rotating the individual clusters to each other, ie, the LED rows are rotated to each other, the individual elliptically distorted light distribution curves are superimposed to form a rotationally symmetric light distribution curve. According to another embodiment, the LED clusters comprise a rectangular or square matrix of LEDs. These LED clusters would also individually produce an elliptical or square-distorted LVK in a cone-shaped curve around the optical axis. The superimposition of the mutually rotated individual LVKs results in a rotationally symmetric LVK again.

According to another preferred embodiment, some of the LED clusters comprise a cross-shaped arrangement of two mutually perpendicular LED rows or rectangular LED arrays. The individual LVKs of these clusters would already be closer to a circular shape, but still distorted in relation to the circular shape. The combination of several such clusters, which are twisted according to the invention, leads to a homogenization of the LVK.

According to a preferred embodiment, the plurality of LED clusters are rotated by the angles ± a and ± 2a to each other, where a is an angle <45 °. In general, larger square LED clusters require a smaller twist angle compared to linearly extending clusters. For a 4x4 LED cluster, for example, it is preferable to rotate the clusters by 22.5 ° to each other. In order to obtain a fully rotationally symmetrical LVK, therefore, the LED clusters must be rotated by ± 22.5 ° and ± 45 ° to each other. For linear clusters, eg for Ix3 LED clusters, the angle of rotation must be greater. For such clusters, for example, the angle of a = 45 ° is preferred. This arrangement has further advantages in terms of possible thermal distortion of the LED array. At a = 45 °, the effects of thermal distortion occur in a symmetric array of at least nine or more clusters inside the LED clusters out. As a result, the rotationally symmetrical LVK is maintained even when the headlamp is heated.

According to a preferred embodiment, the clusters are rotated over the entire array by a total of 360 °. That is, there are multiple angles of rotation (e.g., a = 45 ° as previously stated) so that the clusters cover in stages all angles of rotation between 0 ° and 360 °, resulting in the desired rotationally symmetric light distribution. For larger matrix-shaped LED clusters, however, it has been shown that even smaller angles of rotation across the clusters in the entire array are sufficient to produce an almost rotationally symmetric LDC.

According to a preferred embodiment, the total light distribution produced by all LED clusters measured in a conical-section section of the lamp, in particular a cone-shaped section perpendicular to the main emission of the lamp, is constant. This results in a uniform illuminance on a flat surface, which is arranged at an angle to the optical axis of the headlamp. In the event that the headlamp is aligned exactly perpendicular to the surface to be illuminated, a constant light distribution curve in each conical section of the lamp perpendicular to the main emission of the lamp is desirable. However, when the optical axis of the headlamp is tilted with respect to the surface to be illuminated, constant light distribution curves in a cone-shaped section corresponding to the tilt angle of the surface to be illuminated relative to the optical axis of the headlamp are advantageous.

According to a preferred embodiment, each of the LED clusters has its own optical device. The optical Device can serve to bundle the light distribution of the respective cluster. However, it does not have to be designed to spread the light distribution. Accordingly, a faceted reflector or a lens having light-diffusing properties is not necessary. The scattering of the light to even out the LVK, as is common in the prior art, is not necessary due to the mutually rotated LED clusters. The optics can therefore be made more light bundling, if a strong focusing headlights is desired.

According to a preferred embodiment, the distance of adjacent LED clusters in the array, measured from respectively the center of the LED clusters, is greater than or equal to the optical device. As a result, the optical devices for each cluster can be arranged close to the array. The optical devices may also be connected together, each associated with one of the LED clusters, which is inexpensive to manufacture. Separate optical devices for each cluster have the advantage of being less sensitive to thermal distortion of the entire device.

According to a preferred embodiment, the LEDs within the LED cluster have different colors. For example, the LED colors in an LED cluster may include red, green and blue. By the light mixture, white light can be generated. A single cluster would still show color differences, because the mixture of light within a cluster with an optic, as far as it is not light scattering, not sufficient for complete mixing of the light of the LEDs. The inventive arrangement of several clusters, which are twisted to each other, however, this effect is compensated, so that the different LED colors in the entire headlamp are mixed so far that, for example, white light can be generated. Any other mixed color can also be generated, in which case the number of red, green and blue LED colors are selected accordingly. It is also possible to mix the light of different colored clusters, each having a uniform light color, by rotating the clusters. This may be predetermined as an alternative or in addition to the color mixing within the clusters.

According to a preferred embodiment, the headlight may also comprise at least two different groups of respective same LED clusters in an array. The groups of LED clusters in the array are each rotated as described above for the same LED clusters. The twist angles within the groups of clusters need not be the same. In particular, the smaller clusters may have a greater angle of rotation than the larger clusters.

According to a preferred embodiment, individual or multiple LED clusters in the array can be switched on and off separately and / or dimmable independently of the other clusters in the array. With this embodiment, different light distribution curves can be generated by a headlight. By switching on or off individual clusters, the light distribution can be switched, for example between oval and circular. By dimming, the light distribution can even be changed continuously. Furthermore, it is also possible for individual LEDs within the clusters to be switched separately from the remaining LEDs of the relevant cluster. Also in these embodiments can be different Create light distributions by turning on or off or dimming LEDs within the clusters.

Other features and advantages of the present invention will become apparent from the following description of preferred embodiments, taken in conjunction with the accompanying drawings. The figures show the following:

Figure 1 shows an array of nine 3x3 LED clusters.

FIG. 2 shows an array of nine LED clusters with LEDs arranged in a cruciform manner.

FIG. 3 shows two LED clusters, each with 21 LEDs, which are rotated relative to one another around the angle a.

Figures 4a and 4b show LED boards with linear 3x3 LED

Clusters rotated at 45 ° and 90 ° to each other in an array of new clusters, where gur 4b involves thermal distortion.

FIG. 5 shows mutually rotated 4x4 LED clusters in one

 Array, where the LEDs have different colors.

Figures 6a and 6b show LVKs in a vertical

 Section plane through the luminaire without rotated clusters (a) and with clusters rotated by 30 ° (b).

FIG. 7 shows an array with two mixed cluster sizes.

Referring to Figure 1, there is shown a first embodiment of a headlamp, wherein the headlamp only the top view of the LED array in the headlight is shown. The arrangement comprises nine LED clusters 2, each comprising a 3x3 matrix of LEDs 1. The clusters are offset by a distance a from each other, wherein the distance a is substantially greater than the distance of the LEDs 1 within the cluster. Each cluster is associated with an optical component 3, for example a lens. As shown in FIG. 1, the clusters 2 are twisted relative to one another, the relative angle between clusters a and 2a being. For example, a can be an acute angle <45 °, in particular 22.5 °. In another embodiment, the angle a may also be 30 °. Each of the clusters 2 with associated optics 3 generates its own light distribution, which differ in a cone-shaped section from an ideal circular light distribution. However, as a result of the superimposition of the light distribution curves of the nine clusters 2, the overall result is an approximately circularly symmetrical light distribution.

FIG. 2 shows an alternative embodiment in which the clusters 2 each comprise five LEDs 1, the LEDs being arranged in two mutually perpendicular rows to three LEDs. This type of cross-shaped cluster also, taken together with the optics, produces an asymmetrically distorted light distribution. Due to the rotation angle, however, this effect is canceled out in the LVK of the entire headlamp by the rotation of the LED cluster 2 relative to one another.

FIG. 3 shows an arrangement with two LED clusters 2, each having 21 LEDs 1. The LEDs within the clusters are aligned in the form of two rectangular LED matrices (3x5 matrix) arranged perpendicular to each other. This type of cluster is already approximated to a circular shape, making these clusters especially for circular optical Facilities 3 are suitable. The rotation about the angle a releases the asymmetry of the light distributions in the total light distribution. In such clusters with relatively many LEDs, relatively small twist angles a are sufficient. For example, in the embodiment shown, the use of only two clusters, which are rotated at an angle of less than 30 ° to each other, is sufficient to compensate for the effect in the light distribution.

Figures 4a and 4b show a special arrangement of 3x1 LED cluster 2, which are not only set up to produce a circular distribution as possible, but also to compensate for the effect of thermal expansion of the board on which the clusters are arranged. In this case, all LED rows of the clusters are aligned in the center of the LED board 5 in a square array of a total of nine 3 × 1 clusters 2. For each optical system in which the lowest possible half-beam angle is to be achieved, the center 8 of the optical system 3 should be as central as possible above the middle LED. By a thermal expansion of the board, as shown in Figure 4, but shifts the center of the optics relative to the respective middle LEDs of the 3xl LED cluster. However, the rotation of the clusters aligned with the center of the LED board minimizes the effect of thermal expansion on the light distribution.

FIG. 5 shows an embodiment with six LED clusters 12, each having a 4x4 matrix of LEDs. In this embodiment, however, differently colored LEDs 9, 10 and 11 in the colors red, green and blue are combined in each cluster. Also in this embodiment, the clusters are rotated at the angle a against each other, as in the previous embodiments described. The light of the cluster 12 is already mixed within the clusters, so that the color red, green and blue produces approximately white light. However, the light mixture within the clusters 12 is still insufficient. By using multiple clusters 12 that are rotated to each other, this effect of the light mixture is also improved, so that the total light of the headlight appears almost uniformly white.

FIGS. 6a and 6b show the effect of the rotation of the clusters relative to one another. The figures show a LVK in a vertical plane through the light exit surface of the headlamp, wherein in the x-axis, the polar angle is plotted against the mid-perpendicular in the sectional plane. The dashed and solid lines indicate the values for two mutually perpendicular planes (C0 / 180 plane and C90 / 270 plane of the luminaire). Figure 6a shows a comparative example in which 3x3 LED clusters in an array of six clusters are all arranged in parallel. The LVK in the plane parallel to the rows of LEDs indicates distinct spikes (in Figure 6a the solid line). In contrast, Figure 6b shows an embodiment in which the 3x3 LED clusters are rotated in 30 ° increments to each other. The LVK is much more rotationally symmetric, which can be seen from the fact that the dashed and the solid line of the two different cutting planes are congruent to each other.

FIG. 7 shows a circuit board 5 with three 3x3 LED clusters 2 and two 2x2 clusters. The two different clusters are positioned in an array of 2x3 clusters. The 3x3 LED clusters are rotated around and 2a to each other. The three 2x2 LED clusters are rotated by ± 45 ° to each other. Generally, a larger one is for the smaller cluster sizes Angle of rotation necessary than for the larger cluster sizes to achieve the desired effect of a rotationally symmetric light distribution as possible.

LIST OF REFERENCE NUMBERS

1 LEDs

 2 LED clusters

 3 optical component, e.g. Lens or reflector

5 LED board

 8 Center point of the optical component

 9 red LED

 10 green LEDs

 11 blue LEDs

 12 LED clusters with LEDs of different colors a Distance of the LED clusters in the array

Claims

1. Spotlight for stationary mounting in the outside or Interior area, in particular stadium spotlight, comprising an array of a plurality of identical LED clusters (2, 12), each LED cluster having a plurality of LEDs (1, 9, 10, 11), and the LED clusters (2, 12) is disposed in the array at a distance (a) from one another which is greater than the spacing of the LEDs within the LED clusters, characterized in that at least some of the plurality of like LED clusters (2, 12) in the array are mutually contiguous Center axis are arranged twisted to each other. 2. Headlight according to claim 1, wherein at least some of the LED cluster (2) each comprise a series of LEDs (1), in particular three LEDs. 3. Headlight according to one of the preceding claims, wherein at least some of the LED clusters (2) comprise a rectangular or square matrix of LEDs (1). 4. Headlight according to one of the preceding claims, wherein at least some of the LED clusters (2) comprise a cross-shaped arrangement of two mutually perpendicular LED rows or rectangular LED matrices. 5. Headlight according to one of the preceding claims, wherein the plurality of LED clusters (2) are rotated by the angle ± a and ± 2a to each other, where a is an angle <45 °. 6. Headlight according to claim 5, wherein a = 45 °. 7. Headlight according to claim 5, wherein a = 22.5 °. 8. Headlight according to one of the preceding claims, wherein the LED clusters (2) over the entire array are rotated away by a total of 360 °. 9. Headlight according to one of the preceding claims, wherein the generated by all LED clusters (2) Total light distribution curve measured in one Cone-shaped section of the lamp, in particular a cone-shaped section perpendicular to the main emission of the lamp, is constant. 10. Headlight according to one of the preceding claims, wherein each of the LED cluster (2) has its own optical Device (3). 11. Headlight according to claim 10, wherein the optical Device (3) comprises a reflector and / or a lens. 12. Headlight according to claim 10 or 11, wherein the distance of adjacent LED clusters (2) in the array measured from each of the center of the LED cluster from greater than or equal to the diameter of the optical device (3). 13. Headlight according to one of the preceding claims, wherein the LEDs (9, 10, 11) within the LED cluster (12) have different colors. 14. A headlight according to claim 13, wherein the LED colors in an LED cluster (12) comprise red, green and blue. 15. Headlight according to one of the preceding claims, wherein at least some of the plurality of LED clusters have different light colors. 16. Headlight according to one of the preceding claims, wherein the headlamp has at least two different groups of each same LED clusters (2) in the array. 17. Headlight according to one of the preceding claims, wherein each of the plurality of LED clusters (2) in the array independently of the other LED clusters (2) in the array separately on and off and / or dimmbar.