EP1854152A2

EP1854152A2 - Light source

Info

Publication number: EP1854152A2
Application number: EP06705360A
Authority: EP
Inventors: Gerhard Staufert
Original assignee: Lucea AG Wey & Spiess Treuhand- und Revisionsgesellschaft
Current assignee: Lucea AG
Priority date: 2005-02-28
Filing date: 2006-02-27
Publication date: 2007-11-14
Also published as: WO2006089450A3; WO2006089450A2

Abstract

The invention relates to a light source comprising a linear arrangement of a plurality of sub-groups of at least one unhoused LED chip (14). Said sub-groups are arranged along a line at defined, preferably regular distances from each other. The LED chips are applied to a carrier (13) for electrically contacting the same. According to the invention, a (single) body (11) of optically transparent material is provided, said body at least partially surrounding each LED chip such that light emitted from the LED chip is diffused through the body, the at least one carrier being mechanically fixed to the body.

Description

LIGHT SOURCE

The present invention relates to a light source with LED chips as light-emitting elements.

Linear light sources (i.e., light sources having an overall elongated light emitting body) are available in a variety of designs and for a variety of applications. They are, for example, well known for the external illumination of flat objects such as, for example, signs, posters or pictures in practice.

Often, they are carried out with at least one or more fluorescent tubes arranged in a row. For a reasonably efficient use of the light emitted by the fluorescent tubes around homogeneous light usually unilaterally elongated reflector elements are arranged, which should redirect the light to the largest possible proportion of the illuminated object to be illuminated. Such linear light sources have the following disadvantages:

Due to the relatively large, i. Also in the best case amounts to at least about 7 mm, diameter of the fluorescent tubes are for a reasonably efficient deflection of the light reflector elements with large

Reflector surfaces necessary, ie, the cross section of the linear light source extends over several centimeters, bringing such a light source in many Cases as the object to be lit disturbing appears. If the reflectors designed with the smallest possible cross-section, significantly larger light losses must be accepted.

It always occurs stray light in the order of some 10%. This not only reduces the efficiency of the linear light source in principle, but it also causes a glare of the viewer.

- With such arrangements, it is extremely difficult to achieve a homogeneous illumination of the sheet-like object without a large part of the light undesirably illuminates the environment of the sheet-like object.

Also known in practice are linear light sources for the external illumination of flat objects, which are designed with a linear arrangement of a multiplicity of packaged, light-bundling LED lamps.

Such embodiments have the great advantage that the stray light losses are reduced in comparison to the fluorescent tube solution and that it is tight by the use of light, i. For example, to ± 20 °, focusing LED easier to focus the light to a large extent as possible to focus on the flat object. But they also have the disadvantage that a homogeneous illumination of the flat object can be achieved only with great effort.

For reasons of efficiency, it is desirable for the linear light source to be close to an edge of the planar object, for example 10 cm above and 10 cm in front of this, can be arranged and exactly the object, and not its surroundings, illuminated in a grazing light.

If LED lamps which are packaged to generate the linear light source and emit their light rotationally symmetrically with respect to their optical axis are formed, then, when the linear light source is arranged near an edge of the planar object along this edge, unwanted cone-like light zones are produced. In addition, a larger part of the light will impinge on the object in the vicinity of the light source, whereby an uneven illumination is also produced in the direction away from the light source of the flat object.

Linear light sources for internal illumination from illuminating, flat objects such as light boxes in advertising are also known in practice. In addition to conventional solutions using, for example, fluorescent tubes, solutions are increasingly found in which the light of linearly arranged at intervals of, for example, 1 cm housed LED lamps is coupled into at least one of the edges of a transparent plate. The large surfaces of the transparent plate then act, by total reflection, as a light guide, and the light is distributed over the whole plate. Targeted structures on at least one of the large surfaces or in the interior of the plate specifically generated inhomogeneities ensure the desired light emission.

Such a linear light source constructed by means of LED lamps has the following disadvantages:

Not all light of the LED lamps is coupled into the plate, a not inconsiderable proportion is reflected (Fresnel's law). This reflected Proportion will be the greater in the wider range of angles the LED bulbs emit their light.

- In this sense, it would therefore be desirable that the LED lamps bundle the light very closely. However, unwanted conical light zones occur in the edge region of the plate. One way is to make this cone-shaped light

To obscure zones by a correspondingly wide opaque edge strip, which is perceived as ugly and what the usable zone of the

Plate restricts. The other possibility, a light output in further

Angle, for example, the use of oval LED lamps, brings not only as mentioned significant losses in efficiency by reflection with it, but the reflected light also occurs as disturbing stray light

Appearance.

For linear light sources for the external illumination of flat objects, such as panels, posters or pictures, which are to be arranged for reasons of efficiency in the vicinity and along an edge of the planar object to be illuminated, the following requirements must be met:

It should produce as little stray light and thus as little glare as possible from the viewer.

- It should be constructed for cost reasons with as few discrete light-generating elements.

The discrete light-generating elements must be as homogeneous as possible in the longitudinal direction of the light source in order to avoid cone-like bright zones a wide range of angles, that is, for example, in a range of greater than ± 50 °, leave.

The linear light source in the plane perpendicular to the planar object and to its longitudinal direction is intended to deliver its light asymmetrically in the sense of its optical axis, that it sends more light to the distant zones of the planar object than to the near and thus a homogeneous illumination generated.

The same requirements apply to linear light sources for internal illumination of flat objects, such as light boxes in advertising.

Also for other than linear light sources - for example, for the diffuse illumination of objects, etc. - similar requirements apply:

The light source should produce as little stray light and thus as little glare as possible from the viewer.

It should be constructed with as few discrete light-generating elements as possible.

To avoid cone-like bright zones, the discrete light-generating elements must emit their light as homogeneously as possible in a wide angular range. Finally, for technical applications - that is, for applications where the generated light (including IR or UV light) is used to effect a chemical or physical process - the requirements are often slightly different. It is also desirable that as few light-generating elements as possible must be used and that as little scattered light as possible be generated, but often the highest possible energy density is desired, ie the angular range is often as narrow as possible.

It is an object of the invention to provide a light source with light-generating elements - for example. In a linear arrangement - which overcomes the disadvantages of the prior art and which allows the greatest possible lighting efficiency with the simplest possible structure and is as cost effective as possible. Preferably, the light source should satisfy as many of the above requirements as possible.

The light source has a plurality of subgroups of at least one unhoused LED chip.

According to a first version, the subgroups are in a linear arrangement. For example, a "linear" arrangement means that the subgroups form a straight line, and a slightly curved line forming a circle, an ellipse, a circle or ellipse segment, etc. is also possible, with the average radius of curvature of the line being much larger than Also, a zigzag, meandering or similar course is conceivable as long as a line is defined and the average distance of each LED chip from a straight centerline is much smaller (eg at least a factor of 5, or at least one factor 10) is smaller than the length of the line. preferably arranged at regular intervals from each other along the line. Of course, also included are arrangements in which a plurality of lines is formed.

According to a second version, the subgroups are distributed in a different manner from a linear array, for example grid-like.

Each of the subgroups comprises at least one LED chip, but it can also consist of several different chips. For example, to produce any light color, it may be useful to put together a group of several chips which emit red, green or blue light.

The LED chips are applied to an electrically contacting carrier. According to a first. Variant all LED chips are applied to a common, for example. Platinen- or flexprintartigen carrier. According to a further variant, a carrier is present per subgroup or per unit of several subgroups, electrical connections existing between the carriers.

According to the invention, a (single), preferably full (ie no voids) body of optically transparent material is present, which at least partially surrounds the LED chips, so that the light-emitting surfaces of each LED chip are enveloped and in such a way that the LEDs Chips radiated light propagates in the optically transparent material, wherein the at least one carrier is mechanically fixed to the optically transparent body. The light generated by the LED chips and propagating in the optically transparent material is coupled out front optically transparent body over a desired area to the outside. The optically transparent body is preferably designed such that it deflects the light of the chips by means of at least partial reflection at at least one interface, as a rule by total reflection, so that the desired light distribution is produced. The at least partial reflection ensures that the light is directed to the desired light exit surface and at the same time prevents light from escaping in undesired locations as stray light. For this purpose, the LED chips are present on a formation or on formations which have light-deflecting boundary surfaces. The formations have a shape tapering towards the LED chips in an environment of the LED chips. This shape can be comb-like in the case of a linear arrangement of the chips, the LED chips being arranged in the vicinity of the ridgeline. Often the shape is flattened in the vicinity of the ridge line, wherein the flattening forms a support surface against which the often flat support. In the case of an arrangement in which the LED chips do not form a linear arrangement, the formations are hilly, with one or more LED chips, for example, also being flattened ("the hilltop"), being present Due to the tapered shape, light emitted sideways from the LED chips is reflected by the at least partial reflection in a direction corresponding to the main emission direction deflected - lateral leakage from the optically transparent body is prevented .. The side sections with respect to the LED chips thus act as a kind of Lichtumlenkflächen.

Also on the Lichtumlenkflächen subsequent side surface portions of the body can - except for any decoupling partial surfaces with corresponding coupling-out structures - act photoconductive. The light distribution can be direction-dependent and at most asymmetrical. Under certain circumstances, the light deflection surfaces or the entire side walls may also be mirrored at least in sections.

With these features, the invention offers a surprisingly simple approach with which the problem posed at the outset is achieved and which, in many cases, brings about improvements over the prior art. Due to the fact that the LED chips are not located outside the flat object, but emit their light directly inside the plate to be flooded with light, stray light losses are largely avoided. The light source is also inexpensive to produce and can be easily carried out so that it is robust against environmental influences. Because the LED chips are generally in contact only with the carrier and the optically transparent body enclosing it, and the surrounding medium does not reach the LED chips, they are naturally protected against environmental influences. Preferably, there are no gas inclusions between the LEDs and the optically transparent body.

The fact that a single, all LED chips together at least partially enclosing optically transparent body is present, does not mean that the optically transparent body must be in one piece or monolithic-homogeneous. It may also be composed of several components of possibly different materials that are transparent. Preferably, such different materials have a similar refractive index, which differs, for example, by at most 30%, more preferably by at most 20% or even at most 15% or 10%. On the optically transparent body additional, for example. Not transparent elements may be attached, for example. Verspiegelungen etc.

LED chips usually emit light into the half-space, more precisely into a certain solid angle, for example ± 70 °, ± 80 ° or ± 90 °. This has the meaning of Invention the advantage that no "backwards" emerging light deflected, but only the "forward" emerging light has to be bundled into the desired space area. This not only results in drastically reduced stray light losses, but also makes it possible in a simple manner to generate directional, possibly completely asymmetrical, light distributions. In particular, it is possible to produce in one direction a very wide light distribution of for example + 70 °, ± 80 ° or ± 90 ° and in a direction perpendicular to the first a much narrower light distribution of for example ± 10 ° to + 40 °.

The center of the solid angle is often referred to as the optical axis of the LED chip. According to one embodiment of the invention - in the version "linear

Arrangement "- the optical axes of a majority of the LED chips, usually all LED chips, run in a common plane

Light source of emitted light in this plane is different from that perpendicular to the plane. In general, it will be much wider in the said plane than perpendicular to this plane. But it is also possible that the

Light distribution perpendicular to the plane with respect to this is asymmetrical.

In the simplest case of a linear arrangement of the LED chips, said optically transparent body can be, for example, simply a cylindrical body with a cross-section which is, for example, a rectangle whose two corners are chamfered at the plane containing the LED chips. In this way, in the longitudinal direction (with respect to the linear array) of the long transparent body, a light distribution corresponding to that of the unpackaged LED chips is obtained, while the light is deflected transversely at said oblique surfaces by total reflection and in many cases sufficiently well is bundled (ie, said oblique surfaces act as the light redirecting surfaces). An improvement in the bundling behavior can be achieved by making the Lichtumlenkflächen approximately parabolic. Such a parabolic shape You can also by several, for example. Three, cones with different slopes replicate. This may be a preferred option for small series production. A further improvement of the bundling effect can be achieved by the surface opposite the LED chips is not flat, but designed in the sense of a cylindrical lens.

In the above or other cases, the long transparent body may have any repeating additional shapes in its longitudinal direction, such as transversely to the longitudinal direction V-shaped grooves or dome-like shapes. With such additional shapes, it is also possible in a simple manner to concentrate the light emerging from the LED chips in the longitudinal direction of the long transparent body to a desired solid angle.

The two end faces (or faces) of the long transparent body may also be designed as planes which are not simply perpendicular, but may form the light exit at the ends of the linear light source in a desired manner by tilting and / or by an approximately parabolic shape.

In various embodiments, the light source is designed such that the light emitted by the LED chips is mostly coupled out by a light exit surface of the optically transparent body, which lies opposite the carrier surface. In this configuration, the above directivity is utilized. The directional effect can be further enhanced by the light exit surface having a cylindrical lens-like or domed-lens-like or otherwise refractive and / or diffractive collimating structure. A further directivity can be achieved in that the carrier is mirrored and has a hollow-mirror-like shape. According to a further embodiment, the light source is a planar object, which emits light through at least one of the large side surfaces, that is, for example, a panel illuminated from the inside. This embodiment can be considered as a combination of a linear light source with a large-area transparent body. In this embodiment, the side surfaces thus have comparatively large sections, which are preferably parallel to the carrier surface and parallel to the optical axes of the LED chips. At least one of the side wall sections may be provided with coupling-out structures.

According to further embodiments, the optically transparent body may have the shape of a torus, in which the LED chips are arranged along the inner circumferential line and radiate outwards. This results in a virtually isotropic emission characteristic along the plane of the torus. In the case of a torus-like, optically transparent body, the LED chips-and with them the shaping with the light deflection surfaces-can also be arranged along the outer circumferential line, which enables the generation of high light densities in the interior of the torus. This is of particular interest for technical applications. Instead of a torus, the optically transparent body can also be formed by a plurality of quasi stacked tori with identical radii or with different radii.

According to still other embodiments, the light source is flat in the sense that the optically transparent body is formed flat and defines a plane and the LED chips are distributed over this plane. Along the plane, the LED chips can form multiple linear arrays.

The light source can be designed such that it has structures which, in addition to a possible isotropic radiation characteristic, are still called "spots" - ie directed emitters - act. Such spots can be formed by formations in the form of, for example, rotation parabola-type collimation structures.

Often, in the various embodiments, all LED chips of the light source are electrically connected together. This means, i.a., that all LED chips of the light source can be lit simultaneously by applying a voltage between two electrodes. The LED chips can be connected in groups in series, the groups being connected in parallel. If there are several carriers, these are, for example, connected to one another by wires or strands.

The electrical paths of the carrier can be designed so that a contact can take place from the outside in each case between, for example, any two LED chip subgroups. For example, the carrier may have two separate connection paths, possibly each with an extension between the subgroups. Contacting can be achieved by drilling a thin hole at the points to be contacted and pressing in contact pins which are slightly larger in diameter than the drilled holes, thereby establishing contact. This works even if the carrier and conductor tracks are completely enclosed by the transparent material of the main body (or of the silicone in the groove).

The invention also relates to a pixel wall, ie a planar arrangement of two-dimensionally juxtaposed, individually controllable light sources. The light sources of the pixel wall are designed according to the invention. According to a preferred embodiment, at least some of the light sources of the pixel wall have LED chips with different emission wavelengths, for example red, green and blue LEDs. The LEDs of themselves different wavelengths are then independently controllable (and therefore not electrically connected), so that the pixel can shine in a desired color. According to a first alternative, the light sources are monochrome, with more or less identical emission wavelengths, so that only a light-dark image can be displayed. According to another alternative, each light source is monochrome, but there are light sources with (for example three) different emission wavelengths, with groups each having a light source of each emission wavelength, similar to the principle of certain color television sets.

The light sources of the pixel wall are preferably formed as flat objects, of which light is emitted through one of the large side surfaces. The optical axes of the LED chips thus form an angle to the pixel wall plane and are preferably perpendicular or approximately perpendicular (angle between 80 ° and 90 °) to her.

Also, the carrier can be transparent, which is particularly advantageous in the pixel wall. If the carrier then bears tightly against the neighboring element (and, for example, is still connected to it by a transparent permanently elastic layer), light from the neighboring element couples into the carrier and makes it appear bright towards the outside. The carrier may additionally be mirrored on its upper side, so that the coupled-in light of the neighboring element reflects back and thus the brightness of the neighboring element is optimized. The refractive index of the carrier material may be selected so that it does not deviate very little, for example at most by 30% or even at most 20% or 10% from that of the optically transparent body, then the coupling-in of the light from the neighboring element will be particularly effective Good. Of course, in addition to the transparent main body and the possible mirroring, the carrier also has conductor structures for contacting the LED chips; Of course these do not have to be transparent. The long, substantially optically transparent body should, as mentioned, enclose the LED chips in such a way that coupling losses are minimized.

This can be achieved in a simple manner by the carrier with the LED chip and the long transparent body are produced independently of each other and subsequently combined. For this purpose, the long transparent body must have on one of its sides a groove whose shape and roughness has no significant influence and which is therefore very inexpensive to produce. For the purpose of combining the two components mentioned above, this groove is initially filled with a low-viscosity, at least partially curable, transparent material, such as a suitable silicone. After curing, this filler material should have an optical refractive index which comes as close as possible to that of the long transparent body, a difference of, for example, 0.1 to 0.2 not playing a decisive role according to Fresnel's law.

The initially thin liquid filler compensates for all irregularities of said groove so that they no longer play a role visually. In the still highly fluid filling material, the carrier carrying the LED chips is inserted in a second step so that the filling material completely surrounds at least the chips, but possibly also the carrier. Thereafter, the filler material is cured, wherein a material with permanently elastic properties after curing is preferable to avoid for the LED chips unfavorable mechanical stresses.

Inventive light sources can be produced with this very simple method, which is economical even for small numbers. The method is also the subject of the invention. The method includes the steps as set forth above: Inserting a groove-like depression into an oblong depression of an optically transparent body,

Filling the groove-like depression with liquid or plastically or elastically deformable transparent material,

Attaching at least one support having electrically contacted unhoused LED chips mounted thereon, such that the LED chips protrude into and are at least partially enclosed by the liquid or deformable material,

at least partial curing of the liquid or deformable material.

Steps 2 and 3 can also be carried out in reverse order, i. First, the carrier is inserted or inserted with the LED chips in the groove-like depression and then allowed to flow from one end of the liquid transparent material into the recess. For this purpose, it may be advantageous if the cross section of the groove-like depression has a step on which the carrier is placed so that the LED chips float freely in the lower part of the groove. The deeper part of the groove can then be made as deep as possible, so that the inflow of the liquid, transparent material is facilitated.

The light source can be produced in, for example, very long pieces and subsequently cut into sections, each comprising at least one LED group. This also does not impair the possibility of a flat shape of the end surfaces which is not perpendicular to the base surface (corresponding to the support surface after the attachment of the support). The separation can be effected in such a way that a desired shape (inclined plane or parabolic shape, etc.) results. It goes without saying that light sources according to the invention can also be produced by a method other than that described here.

It goes without saying that "light" in this text generally refers to electromagnetic radiation and, where useful in addition to visible light, includes, in particular, infrared and ultraviolet radiation.

In the following, the inventive linear light source with asymmetrical light emission will be explained with reference to exemplary embodiments.

Figure 1 shows a schematic oblique view of a simple linear light source for the external illumination of flat objects.

FIGS. 2a to 2d schematically show differently optically effective cross sections of the simple linear light source of FIG. 1.

FIGS. 3a and 3b show schematic oblique views of linear light sources with optical elements for influencing the light distribution in the plane extending along the linear light source.

FIG. 4 shows a schematic oblique view of a simple linear light source for internal illumination of a planar object. FIG. 5 shows a schematic oblique view of a simple linear light source for internal illumination of a planar object with a variant for producing white light.

FIG. 6 shows schematically the cross section through a pixel wall which is constructed with the aid of elements according to FIG.

FIGS. 7a to 7c show principle sketches with different cross-sectional shapes of formations which have the LED chips and whose side faces have a light-deflecting effect,

FIG. 8 shows the view of a torus-shaped light source according to the invention with light emission direction to the outside,

FIG. 9 shows the view of a torus-shaped light source according to the invention with light emission direction inwards,

FIGS. 10 and 11 each show a light source radiating against an inner side with a plurality of lines formed by LED chips;

FIGS. 12 and 13 each show a planar light source with a plurality of lines formed by LED chips;

FIGS. 14 to 16 embodiments of flat light sources with additional collimation structures. Figure 1 shows the schematic oblique view of a simple linear light source 10 for external illumination, for example, of flat objects.

The linear light source consists of a long transparent base body 11 with a light exit surface Hd and a groove-like depression 12 on the opposite side of the light exit surface Hd. The two side surfaces have flat bevels IIb and Hc at the transitions to the opposite side of the light exit surface Hd Material of which the base body 11 consists may be glass or a suitable plastic such as acrylic glass (PMMA) or polycarbonate.

A plurality of LED chips 14 is mounted at defined intervals on a suitable support 13 and electrically contacted by means of this support 13 and electrically connected to each other (parallel and / or series connection). Instead of a respective LED chip 14, groups of several, i. For example, 2 to 9, LED chips at defined intervals on the carrier 13 may be arranged. The LED chips 14 may be surrounded on the carrier 13 before the union with the transparent main body 11 with a - not shown - transparent protective material. A suitable transparent protective material may be, for example, a permanently elastic silicone. Furthermore, the LED chips 14 can be surrounded by a light conversion dye (phosphor), which is possibly mixed into the protective material mentioned, and has, for example, the task of converting blue light emitted by the LED chip 14 into white.

The groove-like recess 12 is filled with a first relatively thin liquid transparent material which hardens after the union of the base body 11 and the carrier 13 with the LED chips 14 at least partially. It is preferable to have a transparent filling material which becomes permanently elastic after curing remains. A suitable transparent filling material may be, for example, a permanently elastic silicone.

The main body forms, together with the filling material, an optically transparent body, on which an extension is formed at the end by the flat bevels IIb, 11c, which tapers towards a ridgeline (namely the line along which the LED chips are arranged).

This function has the function that with respect to an optical axis of the LED chip laterally emitted light is deflected by at least partial reflection so that it temporarily remains in the optically trans-parent body and can be used together with the light emitted in the forward direction (the LED chips) light , The inclination of the flat bevels IIb and 11c is chosen for this purpose so that the light emitted by the LED chip light is deflected at the surfaces IIb and 11c by total reflection and emerges in the desired light distribution to the surface Hd. The chamfers IIb, 11c thus act as Lichtumlenkflächen

The end faces I Ia are formed here perpendicular to the linear LED arrangement (to the cylinder axis of the substantially cylindrical transparent body 11), but they may also have chamfers or the like.

With a total width of the linear light source 10 of about 2.5 mm, a total height thereof of about 2 mm, a width of the flat lower surface of the base body 11 of 1 mm and a height of the chamfers IIb and 11c of 0.8 mm can be with Such a structure, a light distribution in the common center plane of all LED chips 14 of, for example, + 80 ° and in the plane perpendicular to this centering, for example, reach ± 35 °. In FIG. 1, as in the following figures, only one LED chip is drawn per subgroup, but it is just as possible for there to be a plurality of LED chips per subgroup; the subgroups may each have the same or a different number of LED chips. Not all chips must be strictly in a straight line, as in the illustrated embodiments. Configurations are also conceivable in which a zigzag or comparable arrangement is present, wherein the ensemble of the LED chips has an extent which is greater in one dimension than in the other two dimensions and thus defines a line.

Of course, also superstructures with much larger dimensions can be easily realized.

FIGS. 2 a to 2 d schematically show examples of different cross sections with different light distributions of a linear light source 20.

Figure 2a shows the schematic cross section of a linear light source 20, in which the non-perpendicular to the support surface extending portions 21b and 21c of the two side walls (the side walls here consist of these sections, ie do not parallel to each other and perpendicular to the support surface extending portions) of the transparent body 21 are symmetrical to the center plane of the linear light source and have parabolic-like shape. With such a construction, the light distribution perpendicular to the center plane of the linear light source can be made substantially narrower than with the configuration shown in FIG. With parabola-like side walls or side wall sections, light distributions of less than ± 15 ° are easily achievable in the size ratios described for FIG. FIG. 2b shows the schematic cross section of a linear light source 20, with a largely corresponding structure as in FIG. 2a. In addition to the parabolic side walls 21b and 21c, here the light exit surface 21d is not flat but designed in the sense of a cylindrical lens. With such a construction, the light distribution perpendicular to the center plane of the linear light source can be made even narrower than with the configuration shown in FIG. 2a. In the size ratios described for Figure 1 light distributions of less than ± 10 ° can be achieved here easily.

Figure 2c shows the schematic cross-section of a linear light source 20, in which the two side walls 21b and 21c of the transparent base body 21 are asymmetrical to the center plane of the linear light source and a parabolic

Have shape and in which the light-emitting surface 21 d flat here to d

Center plane of the linear light source 20 is. With such a structure, a clearly asymmetrical light distribution perpendicular to the center plane of the linear light source can be achieved.

Figure 2d shows the schematic cross section of a linear light source 20, in which the two side walls 21b and 21c of the transparent base body 21 are asymmetrical to the center plane of the linear light source and parabolic-like shape and in which the carrier 23 with the LED chips 24 obliquely to the median plane of linear light source 20 stands. Even with such a construction, a clearly asymmetrical light distribution perpendicular to the center plane of the linear light source can be achieved.

It can be worked with any combination of the sketched in Figure 1 and Figure 2 elements to produce configurations with different optical properties. FIGS. 3a and 3b show schematic oblique views of linear light sources with optical elements for influencing the light distribution in the center plane extending along the linear light source.

FIG. 3a corresponds in all points to the configuration described in FIG. In addition, however, the LED chips 34 carrying carrier 33 is mirrored and reshaped so that between the LED chips, or between any LED chip groups, inclined planes are present, the light emitted in the direction of the median plane of the linear light source in a desired light distribution to the exit surface 3 Id of the transparent body 31 can escape.

The deformation of the carrier 33 can also be done so that arbitrarily shaped generatrices, ie in particular in an environment of the LED chip subgroups in cross section parabolic similar, arise.

FIG. 3 b illustrates two further possibilities for influencing the light distribution in the direction of the center plane of all LED chips 34.

On the one hand, the light exit surface 31d of the transparent main body 31 is designed per LED chip or per possible LED chip group in the sense of a cylindrical lens. This allows a shaping of the light distribution in the direction of said center plane. In combination with the structure of FIG. 2b, dome-lens-like structures result, by means of which the light distribution is influenced both in the direction of the plane and perpendicularly thereto.

Second, the end surfaces 31a - which were previously perpendicular planes in all configurations - are designed as parabola-like surfaces. This causes a Narrowing of the light distribution in the direction of said center plane at the ends of the linear light source 30th

The features shown in Figures 3a and 3b can be combined with those of Figures 1 and / or 2, whereby almost any desired light distributions in the center plane of all LED chips 34 and perpendicular to this center plane can be generated.

FIG. 4 shows a schematic oblique view of a simple linear light source for internal illumination of a planar object.

The linear light source is integrated in a flat transparent base body 41, which has a groove-like depression 42. The two side surfaces have flat bevels 41b and 41c, respectively, at the transitions to the plane containing this groove-like depression 42. The transparent material constituting the main body 41 may be glass or a suitable plastic such as acrylic glass (PMMA) or polycarbonate.

As with the embodiments described above and below, a plurality of LED chips 44 are mounted at defined intervals on a suitable carrier 43 and electrically contacted by means of this carrier 43 and electrically connected to each other. Instead of in each case one LED chip 44, groups of several, ie, for example, 3 to 9, LED chips can also be arranged on carrier 43 at defined intervals. The LED chip 44 can be surrounded on the carrier 43 even before the union with the transparent main body 41 with a transparent protective material (not shown). A suitable transparent protective material may be, for example, a permanently elastic silicone. Furthermore, the LED chip 44 may be surrounded by a light conversion dye (fluorescent dye, phosphorus), which may be mixed in said protective material, which, for example, has the task of converting blue light emitted by the LED chip 44 into white.

The groove-like recess 42 is filled with a first relatively thin liquid transparent material which hardens after the union of the main body 41 and the carrier 43 with the LED chips 44 at least partially. It is preferable to use a transparent filling material which remains permanently elastic after curing. A suitable transparent filling material may be, for example, a permanently elastic silicone.

The LEDs can also be incorporated into the transparent block as a whole - for example, cast or molded. Then the groove-like, filled with transparent filling material wells can be omitted.

The inclination of the flat bevels 41b and 41c is selected such that the light emitted by the LED chip is deflected at the surfaces 41b and 41c by total reflection and remains within the planar base body 41 by total reflection. At least one of the large side surfaces of the main body 41 is structured so that light incident on it partially decouples to the outside, wherein

Under certain circumstances, light escapes partially through the opposite surface and remains partially within the main body 41. The design of such

Structuring is well known and need not be described here.

At a total thickness of the flat base body 41 of about 2.5 mm and a width of the flat lower surface of the base body 41 of 1 mm and a height of the Chamfers 41b and 41c of 0.8 mm can be achieved with such a structure, a light distribution in the common center plane of all LED chips 44, for example, ± 80 ° and in the plane perpendicular to this centering, for example, ± 35 °. In this case, far more than 90% of the light emitted by the LED chips remain within the flat main body 41.

This means that thanks to the wide distribution of light in the direction of said central plane only a few LED chips are necessary to ensure a completely homogeneous light emission from the flat body already at a distance of mm from the LED chips 44. It also means, thanks to the relatively narrow distribution of light in the perpendicular to said center plane and the mentioned very high coupling ratio of over 90%, that the light emitted by the LED chip light and a flat body with dimensions up to 2 m in height completely and homogeneously can shine through.

All of the configurations shown in FIGS. 2 a to 2 d can also be used in the case of a flat light source according to FIG. 4.

FIG. 5 shows in principle the same structure as FIG. 4. In contrast to FIG. 4, however, any color conversion dye present is not arranged in the immediate vicinity of the LED chips 54, but the color conversion dye 51 e covers at least one of the large side surfaces of the flat main body 51 the advantage that no additional structure for decoupling the light is needed, and that light that is radiated from the color conversion layer 51e "back ,, ,, is not lost, but to the opposite large surface of the flat body 51 exits. FIG. 6 schematically shows the cross section through a translucent pixel wall which is constructed with the aid of elements 60 according to FIG. 4 and which, for example, can produce an arbitrary image in the sense of a screen on house facades or on floors, ceilings and walls of rooms.

The planar elements 60 are arranged close to each other in the two directions lying in the same area. The LED chips 64 are arranged in subgroups each consisting of a mixture of red, green and blue light emitting LED. They are contacted by means of the carrier 63 so that red, green and blue within an element 60 can each be controlled independently of each other.

The close-fitting elements 60 are mounted by means of spacers 66 on a large-area support member 65. The distance ensured by the spacers 66 is a fraction of a mm to a few mm. The large-area support element may be a window glass or a house wall or a ceiling or any large flat surface.

Each element 60 acts as a pixel of a digital image. To achieve high resolutions of the image, the pixels, i. the elements 60, be relatively small, which means, for example, for the facade of a high-rise s element size of about 20 x 20 cm and for floor ceiling or walls of an inner space element size of a few centimeters. However, this also means that non-illuminated edges between the pixels or the elements 60 must be minimal.

To achieve this, the carrier 63 consists for example of the same transparent material as the flat base body 61 and has at its the LEDs facing surface conductors for contacting them. The close-to-close arrangement of the elements 60 takes place by means of a transparent material with a similar refractive index, that is, for example, with a silicone. In this way, light from the neighboring element couples into the carrier 63 and makes it appear bright to the outside. The carrier 63 is additionally mirrored on its upper side 63 a (ie on its surface facing the LEDs), so that the coupled-in light of the neighboring element is reflected back and the brightness of the neighboring element is thus optimized.

The oblique surface 61c necessary for the light bundling results in a gap 61f between mutually following elements 60, which can appear as a dark edge. By a suitable design of the surface 61c this is avoided.

The area Ic is inclined so that a well-defined, small proportion of the

LED chips 64 incident on them light is not deflected by total reflection, but decoupled directly. In this way it is achieved that also the gap 6 If appears in the same brightness as the rest of the element 60.

In sum, a pixel wall is designed that has no dark edges between the individual pixels and therefore allows very small pixels.

If such a pixel wall is installed on the outer facade of a (high) house, an additional transparent protective element 67 is necessary, which consists for example of a thin glass pane or a suitable transparent plastic film.

In addition, in this case, it is often desirable that the entire structure is not transparent, but translucent. If the large-area support element 65 translucent, so for example glass, such a light transmission is guaranteed by the described structure.

With the exception of FIGS. 2 a to 2 d, in the embodiments shown, the comb-like formations with the light-deflecting side wall sections are always drawn as bevelled side surfaces. FIGS. 7 a to 7 c show, in addition to FIGS. 2 a to 2 d, principle sketches with variations of cross sections through formations which may be present on optically transparent bodies of embodiments of the invention and which have LED chips 74. The formations of the type shown in FIGS. 7a to 7c, as well as those of FIGS. 2a to 2d, or modifications to optically transparent bodies of various shapes may be present, for example as shown in the preceding or following figures.

The principle of the simplest embodiment with flat bevels 71b is outlined again in FIG. 7a. The arrows illustrate how light radiated laterally from the LED chips with respect to an optical axis 74a

Total reflection is deflected so that it remains in the optically transparent body.

Instead of a single bevel, the comb-shaped formation may also have a plurality of bevelled sidewall portions 71b, 71c, which form different angles to the optical axis and, for example, imitate a parabolic-like course, as shown in Figure 7b. This increases the bundling effect, i. the scattering of the light directions becomes smaller.

Another possible variation is also sketched in FIG. 7b: The position of the LED chip can be varied. Here is the LED chip along its optical Axis slightly displaced against a heart of light source; a spacer 78 is shown symbolically in the figure.

Finally, FIG. 7c, like FIGS. 2a-2d, shows a curved course of the side wall sections 71h. In contrast to the parabolic-like progressions in FIGS. 2a to 2d, however, the carrier surface 71i is significantly wider. The ridge line in the sense of the invention is here in the middle of the support surface 71 i. Many other embodiments are conceivable, for example. Even with sections concave progressions; the shaping can also be selected specifically for the specific application and, for example, bring about certain desired bundling characteristics.

The light source according to FIG. 8 is designed as a torus radiator emitting from inside to outside. A linear array of LED chips 84 is located on the inside of a toroidal optically transparent body 81, namely along its inner peripheral line. The light-emitting surfaces of the LED chips are aligned against the outside of the toms. The sidewall sections 81b, which are formed by a configuration of the type outlined in FIGS. 2a-2d and 7a to 7c, deflect light generated by the LED chips to the outside by reflection. The light is emitted by a light exit surface 81d running along the outer circumferential line of the torus. This results in a radiation characteristic, as sketched in the small picture on the left in the figure. The light source according to FIG. 8 can be advantageous, in particular, for room lighting since, given a suitable arrangement, it does not fade even at high light output and can illuminate the room walls uniformly.

The light source according to FIG. 9 also has a toroidal optically transparent body. The LED chips 94 are arranged along the outer peripheral line of the optically transparent body so that the light-emitting surfaces are oriented towards the inside. The formations with the light-deflecting side walls 91b correspondingly connect to the outer peripheral line and deflect light emitted laterally from the LED chips inward. The light exit surface 91d is located on the inside. The light source according to FIG. 9 can bring about a high light intensity in the torus center. This can be advantageous in industrial applications, for example for the curing of plastics, the exposure of photosensitive materials, the sterilization (in particular with UV light), etc. The development of LED chips, which radiate at the wavelengths required for the sterilization of water , is in progress.

Instead of the toroidal light source according to FIG. 9, according to the same principle a disc-shaped light source can also be made available, in which the LED chips and the formations with the light-deflecting side walls are arranged along the outer circumferential line. At least one of the large areas of the disk-shaped light source then preferably has light-coupling structures, so that the light source acts as a uniformly illuminated disk.

The light sources of Figures 10 and 11 also have the topology of a torus (the surfaces are "topologically equivalent" to the torus), ie, they are formed as a continuous-through body, consisting of a plurality of stacked tori of the type of light source Figure 9. The optically transparent body 101 of the light source of Figure 10 is in the form of a hollow cylinder having a plurality of flattened combs on the outside of the molds Each of the molds carries outwardly inwardly radiating LED chips 104 and acts through the Side surfaces 101b light-deflecting for laterally radiated electromagnetic radiation Inside the cylinder, material to be illuminated (for example water to be sterilized, etc.) can be transported in the direction of the cylinder axis Light source also serve to illuminate an elongated object. Instead of the drawn course with ring-like lines, the LED chips can also run in a spiral along the cylinder jacket.

The light source of Figure 11 differs from that of Figure 10 in that the emission direction - it is by the arrangement of the LED chips

114 and the orientation of the formations determined - in function of the axial

Position varies so that the light density inside the cavity formed by the optically transparent body 111 increases toward the center of the body. This configuration is particularly favorable for cases where a high light density is desired at a certain point. The formations and LED chip lines of the embodiment of FIG. 11 can also run in a spiral.

The embodiments according to FIGS. 12 and 13 are examples of planar light sources in which, in contrast to the likewise planar light source according to FIG. 4, linear arrangements of the LED chips span a plane which runs parallel to the light exit surface. In the arrangement according to FIG. 12, the LED chips 124 and the formations with the light-deflecting sidewalls 121b form a plurality of concentric circles, which together form the substantially disk-shaped light source. The light exit surface is not visible in the figure lower surface of the optically transparent body 121. Instead of the arrangement with several concentric circles, the LED chips and the formations could also form a spiral-like structure or meander. The light source as a whole can also be oval, ie have an elliptical peripheral line, or have a different peripheral shape. The at least one - as in all figures 8 to 13 not shown - - carrier of the LED chips can be linear and, for example, be bendable and follow the arrangement of the LED chips. Alternatively, it may also be formed as a plate which in Essentially the entire back of the light source - in the figure, this corresponds to the top - spanned and has a LED chip arrangement mirrors reflective strip structure.

With regard to the nature of the carrier analogously, the light source according to FIG. 13 can be constructed, which, for example, is rectangular in its basic form and in which the linear arrangements of light sources form straight lines which run essentially parallel to one another here.

Both in the embodiment according to FIG. 12 and in that according to FIG. 13, it is not mandatory that all LED chips 124 and 134 are arranged in a common plane; Rather, the distance to the light exit surface from linear arrangement to linear arrangement, may also be different from LED to LED within the linear arrays.

As an alternative to the illustrated embodiments with a plurality of comb-like formations, each carrying linear arrays of LEDs, an embodiment with a plurality of hill-like formations is conceivable, each carrying an LED chip or a group of LED chips. The hill-like formations may have an approximately conical shape and be distributed rasteratig. The LED chips or groups of LED chips are preferably arranged at the vertices of the formations.

The light source according to FIG. 14 corresponds, for example, in geometry and basic structure (arrangement of a plurality of LED chips 144 on a carrier 143 and light-deflecting sidewall sections 141b) to that of FIG. 4 or that of FIG. 5. According to a first variant, in contrast to FIG figure 4 all surfaces of the optically transparent body 141 smooth and transparent. Then, light exits through the narrow surfaces 141a, 141d. According to a second variant, the upper surface 141e in the image is structured and, for example, additionally mirrored. The narrow surfaces 141a, 141d are, for example, mirrored. Then, light exits diffusely through the lower large area 141f. According to further variants (complementary or alternative) serving as a light exit surface lower large surface roughened or otherwise provided with auskoppelnden structures.

In addition, the optically transparent body has rotation-parabolic collimating structures 141g on its upper side, to the vertex of which an LED chip or a plurality of LED chips 145 are attached. A separate carrier 146 serves to contact these LED chips 145. These LED chips 146 with rotation-parabolic collimating structures 141g generate concentrated light, which also exits on the opposite side 141f.

The light source of Figure 14 can be used anywhere where a diffuse basic lighting is to be combined with a source bundled light, eg. As an automotive rail vehicle or aircraft interior lighting with reading light. Only one or more than two collimation structures can be used.

FIG. 15 shows a variant of the light source of FIG. 14, which allows the LED chips 154 arranged in a linear manner and LED chips associated with the collimation structures 151g to be mounted on a common circuit board serving as a support

153 are attached. This is made possible by a deflection surface 151h of the optically transparent body 151. The shape with the light-deflecting

Side walls 151b are arranged so that the optical axis of the linearly arranged LED chips 154 are approximately perpendicular to the large areas 151e, 151f. The Deflection surface 151h has an angle of approximately 45 ° to the large surfaces and causes the light to deflect a plane parallel to the large surfaces, guided in this plane and, for example, coupled out as in the embodiment according to FIG.

Finally, the embodiment according to FIG. 16 finally combines the approaches of FIGS. 12 and 13 (planar light source with arrangement of LED chips which span a surface) on the one hand and FIGS. 14 and 15 ("spots" with rotationally parabolic structures 161g and associated LED chips) 166) on the other hand.

In each of the embodiments of FIGS. 14 to 16, instead of rotation-parabolic collimation structures, other light-bundling structures may also be used for the spots, for example approximately rotational-parabolic structures; these can be conical in sections.

Claims

1. Light source with a plurality of subgroups of at least one unhoused LED chip (14, 24, 34, 44, 54, 64, 74, 84, 94, 104, 114, 124, 134, 144, 154, 164) a light-emitting surface, and a body (11, 21, 31, 41, 51, 61, 81, 91 ^" , 101, 111, 121, 131, 141, 151, 161) made of optically transparent material, the light-emitting surface of each Wrapped LED chips, so that light emitted by the LED chips light propagates in the optically transparent material, and that at least a portion of the side of the LED chip with respect to an optical axis emitted light by at least partial reflection at least one interface

Body is deflected, wherein the LED chips on at least one electrically contacting carrier (13, 23, 33, 43, 53, 63, 143, 153, 163) are applied, wherein the at least one carrier is mechanically fixed to the optically transparent body ,

2. Light source according to claim 1, characterized in that the optically transparent body has at least one formation, which tapers against a ridge line or a vertex, wherein at least some of the LED chips are arranged on the molding or the formations, and wherein these LED chips are arranged so that at least a portion of the light emitted by the LED chip light by reflection at a

Boundary surface of the formation is deflected.

3. Light source according to one of claims 1 to 3, characterized in that the subgroups are present in at least one linear, a line defining arrangement.

4. The light source of claim 3 based on claim 2, characterized in that the formation or formations is or are comb-like and that the LED chips are arranged along the ridge line.

5. Light source according to claim 3 or 4, characterized in that the or the carrier is or are present on a support surface of the body, to which connect laterally side walls with respect to the line.

6. Light source according to claim 5, characterized in that the side walls have a section with chamfers (IIb, 11c, 21b, 21c, 31b, 31c, 41b, 41c, 51b, 51c, 71b, 71c, 81b, 91b, 101b, 121b, 141b, 151b), which section does not form a right angle with respect to the carrier surface, but forms an oblique plane adjoining the carrier surface or has a curved course, the curve preferably being parabolic.

7. Light source according to one of claims 5 or 6, characterized in that light emitted by the LED chips is mostly coupled out of the body by means of a surface opposite the carrier surface (Hd, 21d, 31d, 81d, 9Id).

8. Light source according to claim 7, characterized in that the light exit surface (21 d, 3 Id) has a cylindrical lens-like or domed lens-like structure.

9. Light source according to one of claims 3 to 8, characterized in that the light distribution in a median plane of the optical axes differs from that perpendicular to the median plane

10. Light source according to one of claims 3 to 9, characterized in that the boundary surfaces of the body are formed so that laterally and perpendicular to the line light emitted by the LED chips is deflected by at least partial reflection.

11. Light source according to one of claims 3 to 10, characterized in that the body has on both sides with respect to the line side walls which act as lichtumlenkende surfaces through which preferably up to any partial surfaces with Auskoppelstrukturen no light or a maximum of 20% of the LED Chips generated light escapes.

12. Light source according to claim 11, characterized in that a side surface of the body has coupling-out structures.

13. Light source according to one of the preceding claims, characterized in that the optical axes of a plurality of LED chips, preferably all LED chips, run in a plane ..

14. Light source according to claim 13, characterized in that the plane is parallel to sections of side surfaces of the body.

15. Light source according to one of the preceding claims, characterized in that the position of the interfaces and the refractive index of the body are selected so that laterally emitted by the LED chips light is deflected by total reflection.

16. Light source according to one of the preceding claims, characterized in that electrically conductive connections between the LED ^■ contacts contacting contacts of the carrier or the carrier exist, so that all the LED chips are electrically connected to each other.

17. Light source according to claim 16, characterized in that a plurality of carriers is present and that the carriers are interconnected by wires or strands.

18. Light source according to one of the preceding claims, characterized by a conversion dye (5Ie) which is present either in a surrounding at least some of the LED chips layer or on a surface through which decouples light from the body.

19. Light source according to one of the preceding claims, characterized in that the optically transparent body is a continuous

Opening, and that the LED chips along an inner side of the optically transparent body are mounted so that light emitted by them exits on an outside of the body

20. Light source according to one of claims 1 to 18, characterized in that the optically transparent body has a through opening, and that the LED chips along an outer side of the optically transparent body are mounted so that light emitted by them in the continuous

Opening exit ..

21. Light source according to one of the preceding claims, characterized in that the LED chips are present in an arrangement in which they span a plane, wherein the optical axis of the LED chips is perpendicular to this plane or forms an angle to it.

22. Light source according to one of the preceding claims, characterized in that it comprises additional collimating structures forming formations (141g, 151g, 161g), which are associated with additional LED chips (146, 156, 166)

23. pixel wall, comprising a plurality of light sources (60) according to one of the preceding claims, wherein the light sources are individually controllable.

24. The pixel wall of claim 23, wherein at least some of the light sources comprise LED chips having different emission wavelengths, and wherein the LED chips having differing wavelengths can be independently driven.

Pixel wall according to claim 23 or 24, characterized in that it defines a pixel wall plane in which the elements forming each pixel are arranged side by side, and in that the optical axes of the LED chips form an angle to the pixel wall plane, and preferably stand perpendicular to her.

Pixel wall according to one of Claims 23 to 25, characterized in that the carrier is transparent and in that a material forming a main body of the carrier preferably has an optical refractive index, which deviates by at most 30% from that of the body of optically transparent material.

27. A method for producing a light source, comprising the method steps

a) providing a body of optically transparent material having an elongated base and adjoining portions of

Side surfaces, which sections are not perpendicular to the base,

b) attaching a groove-like depression in the base area,

c) filling the groove-like depression with liquid or plastically or elastically deformable transparent material,

d) attaching at least one support with electrically-connected unhoused LED chips mounted thereon,

such that the LED chips protrude into the liquid or deformable material and are at least partially enclosed by the latter,

e) curing the liquid or deformable material,

wherein the method steps c) and d) in any order feasible.

28. The method according to claim 27, characterized in that the optical refractive index of the liquid or deformable material after curing differs by at most 30%, preferably at most 20% from that of the body.

29. The method of claim 27 or 28, characterized in that the body is divided into sections after curing, so that each section is functional as a stand-alone light source.