WO2019219289A1 - Lighting element and illumination module having low height - Google Patents

Abstract

The invention relates to a lighting element, comprising a preferably linear light source (10), a mirror (20) and a reflector (30), preferably having a flat surface at least in some sections, wherein the light source (10) is designed to emit a majority of the light thereof directly onto the mirror (20), wherein the mirror (20) reflects the light received from the light source (10) toward the reflector (30), and wherein the reflector (30) preferably comprises a partially reflective surface (31) and reflects said light at least partially diffusely in a direction, the primary direction of which approximately corresponds to the direction in which the light source (10) emits the light thereof. The invention furthermore relates to an illumination module (1) for emitting a homogeneous light from a flat light emission window (101), comprising a light box (100) having an opening defining a light emission window (101) and at least one lighting element.

Description

Light element and lighting module with low height

description

The invention generally relates to a luminous element. In particular, the invention relates to an elongated

Luminous element, which is of low height and emits a homogeneous, surface light. The invention further relates to a lighting module, comprising the luminous element.

The market for luminaires and lighting equipment is subject to rapid technological development and is highly sensitive to the dimensions, the quality of the emitted light with regard to the respective uses and the manufacturing costs.

Luminaires with a comparatively large luminous

Surface, also referred to as surface light, are characterized by the fact that the light is emitted as uniformly as possible over a given area. In general, such lights have a housing, also referred to as a light box, wherein by means of a light source light is conducted into the interior of the housing and penetrates via at least one of the outer surfaces to the outside.

Such surface lights can, for example, as

Signboard or advertising medium. Other embodiments include a light guide plate in which light is coupled from at least one side. There are additional requirements for flat luminaires, which are to be used not only as a backlight, but directly as a lamp.

In addition, light sources (LEDs) are increasingly being used as the light source. This is particularly the case where, on the one hand, low energy consumption or, on the other hand, special design options are sought.

Thus, it is well known to accommodate a plurality of individual LEDs in a lamp together to either increase the light intensity or a flat or

generally represent an extended area of light. In the general lighting area are here, for example

Ceiling panels in open-plan offices, which were previously realized with fluorescent tubes, and are now being replaced more and more by LEDs.

Also in the automotive field or especially in the aviation sector, for example in the field of interior lighting of the cabins of commercial aircraft, such flat lights with LED light sources are of great interest.

The problem here is the one hand to achieve a high degree of homogeneity of the luminous area and the other

Dimensions of the lighting system, as for example in the cabin area of commercial aircraft space is very cramped. The lamps, also referred to as backlight systems, can comprise a large number of LEDs distributed over the surface. However, the height of such lighting systems and the number of light sources to be used per area are directly related to each other. A flat lighting can thus be achieved by a variety of checkerboard-like, punctiform light emitting LEDs.

Such a lighting system describes about the DE 10 2007 044 566 Al. A general disadvantage of such rear lighting is that the distance between the light sources, especially in a

Using LEDs as a light source, each other must be quite low in order to achieve good homogeneity.

The distance between the LEDs should not be greater than the distance to the diffuser. This means that a large number of LEDs must be provided for large areas.

A surface light is also described, for example, in the document DE 10 2011 013 206 A1. At this

Area light is provided a light box in which by means of a light source in operation light on a

Light mixing chamber is directed.

Another construction of an elongate illumination system is shown in DE 10 2010 001 204 A1. Here, light from a light-emitting diode is directed onto a reflector and leaves it collimated. Therefore, more complex ones

Light guide means required to allow the collimated light to emerge homogeneously from the illumination system. Therefore, it is desirable to have lighting systems which have a low overall height in comparison with a luminous area in order to be used as versatile as possible, for example also in the automotive sector or in the aviation sector, for example for cabin lighting.

On the other hand, it is also desirable if as few light sources and easy-to-manufacture reflectors are installed to the complexity and thus the

Reduce manufacturing costs and the

Reduce probability of default.

This task is surprisingly simple by a

Luminous element and a lighting module according to one of the independent claims. Preferred embodiments and further developments of the invention are to be taken from the respective subclaims.

The invention accordingly provides a luminous element comprising a punctiform light source, a mirror and a reflector.

The invention further relates to a lighting module for emitting a homogeneous light from a flat light exit window, comprising a light box with an opening defining a light exit window and at least one luminous element.

In the following, the term homogeneous light refers to a surface provided in the perception of a Observers understood the same brightness. This means, in particular, that there are no sudden changes in the brightness that are visible to the naked eye.

With the mirror and the reflector of the luminous element, the rays emitted by the light source can be directed in a desired direction. Accordingly, ask

Mirror and reflector is a cooperative system for radiation control. The light source serves to emit electromagnetic radiation, which is advantageous in the visible wavelength range. Therefore, instead of radiation or rays is also referred to below by light or light rays.

The light source is preferably arranged and arranged to radiate a predominant part of its light directly onto the mirror. The predominant part of the light of the radiation source means that the mirror is arranged in the direct beam path of the light source.

For this purpose, the mirror preferably comprises a reflective surface onto which this radiation of the light source can impinge and be mirrored.

For the purposes of the invention, the mirror is in this case

arranged so that it can reflect the light received from the light source in the direction of the reflector loss as possible. The reflector is therefore preferably arranged in the beam path of the mirror to the mirror

to receive reflected light from the light source. For this purpose, the reflector preferably comprises a partially reflecting, preferably at least partially planar surface. A flat surface for reflection of the light has the advantage that it can be simple in construction, for example by a surface coating on the flat, low-cost body to be manufactured.

As a result, the reflector can be formed very thin, which contributes to a very low height of the luminous element and the lighting module based thereon. This flat surface therefore also makes it possible

Lighting module with a large spatial extent in one direction with low height too

realize.

The direction in which the majority of the light is emitted after reflection at the reflector surface corresponds approximately to the direction in which the

Light source emits its light. Starting from the

Direction in which the light source emits the light is the radiation pattern through the system for

Radiation steering approximately z-shaped.

A preferably at least partially diffuse reflection at the reflector surface is of great advantage in order to achieve a homogeneous light distribution in the beam path to the reflector.

In order to avoid unwanted stray radiation, which could adversely affect the homogeneous radiation from the reflector surface, suitable means for absorbing such radiation may be provided, preferably in the form of a diaphragm or by a

absorbent element. These devices can already absorb the light from the light source, which does not hit directly on the mirror, and thus prevent unwanted stray radiation, which to

 Brightness differences can lead, which in turn can adversely affect the desired homogeneity.

For the purposes of the invention, it makes sense to use a light-emitting element, that is to say a light-emitting diode (LED), as the light source. Of course, other forms of light sources are conceivable, for example, light from a remote light source means

Optical fiber are introduced. However, light-emitting diodes are advantageous due to their low power consumption, their longevity, their small size and their easy mounting option.

Other arrangements of the light source are also possible, for example with one of several light sources, for example a plurality of light-emitting diodes. These light emitting diodes may be arranged substantially along a line, wherein the light emitting diodes on the line or in a

two-dimensional arrangement regularly or irregularly distributed along the line to be arranged. For example, the light source may intermittently have one or more

Light emitting diodes spaced discretely or continuously spaced apart, such as undulating, spaced apart, along or near the line. For the invention are advantageously bright or white

glowing light sources selected to a high

Luminosity and thus to achieve a sufficiently high brightness. Preferably, therefore, are white radiant

Light sources used. For white emitting LEDs, blue LEDs known to those skilled in the art can be used with a yellowish luminescent layer arranged in front of them, this layer acting as a wavelength converter. In general, such "white" LEDs

more energy efficient than LEDs that produce a white hue of the mix of red, green and blue LEDs.

Of course, it is also possible to obtain a different hue of the luminous element by an appropriate selection of light sources of different color, so for example a reddish hue by the use of a red LED.

In order to be able to use a large part of the light emitted by the light source, it is furthermore advantageous if the opening or emission angle of the light source is not too large in order to achieve a high efficiency of the luminous element and to reduce losses as far as possible. The term efficiency means according to the invention on the

Lichtaustrittsfenster incident luminous flux of the

Light source. The beam angle is the angle that is included by lateral points with half maximum light intensity.

In general, therefore, are light sources with a

Beam angle of not more than 120 °, preferably not more than 90 ° and more preferably not more than 60 °. Especially good experiences were

For example, made with an LED light source with a 90 ° beam angle. It is also possible to additionally provide an optical element for beam shaping,

for example, a converging lens to the rays

bundle up .

The mirror in the radiation steering system is the first element to which most of the light emitted by the light source falls. It is advantageous that it is concavely curved from the light source

educated. The curved, concave surface of the mirror is preferably mirrored and thus provides the

Mirror surface available. In this case, the mirror surface is preferably arranged so that incident beams of the light source are deflected in the direction of the reflector.

To a high homogeneity of the radiated light in the

To obtain light exit window, the mirror surface is preferably arranged so that no mirrored rays can fall directly on the light exit window.

The inventors have found that in particular a high homogeneity of the radiated from the reflector

Light can be achieved when the beams are already deflected by the reflector in the beam path upstream mirror at different angles in the direction of the reflector, so that the mirror in the direction Reflector mirrored radiation is preferably not predominantly collimated.

The mirror may be a tilted paraboloid. The light source is preferably in

Focus of the paraboloid. Of great importance is the ratio of the focal length of the paraboloid to the size of the light-emitting surface, so in the case of an LED as the light source of the chip area, as this results in the size of the mirror.

The distance of the focal point from the vertex, that is, the focal length, may be in a range of up to 10 mm, preferably up to 5 mm, and more preferably up to 3 mm. For example, a distance of 3 mm is very well suited when using an LED as a light source, which is arranged at the focal point of the parabola and has a chip width of 0.5 mm.

This ratio of focal length to width should be

at least be guaranteed to provide adequate

To achieve collimation of the radiation. With a much smaller ratio of focal length to the size of the light-emitting surface, in the example of the chip size, sufficient collimation can no longer be achieved. In addition, the optics are also prone to small errors in the

Positioning or contour. A larger focal length, however, brings no advantage, since the size of the mirror scales with the focal length and thus the lighting element more

Space depth would require. For the purposes of the invention, therefore, the beams preferably do not leave the mirror in a collimated state and are therefore preferably, at least predominantly, not parallel to one another. This has the consequence that they impinge on the reflector surface at different angles. This effect already leads to a very good homogeneity of the incident light on the reflector.

For the purposes of the invention, the term homogeneous light or homogeneity of the light is a homogeneous

Illuminance understood. The illuminance, also known as luminous flux density or luminance, describes a surface-related luminous flux which strikes an illuminated object. It can be specified in the size cd / m ² .

The required homogeneity within the meaning of the present

Invention can be achieved by the following two parameters

to be discribed. An overall homogeneity can thus be quotient of the lowest brightness by the largest one

Define brightness. Ideally, if the brightness is the same everywhere, then the total homogeneity is 1. In the worst case, when the brightest area is much brighter than the darkest one, the total converges

Total homogeneity to the value zero.

According to the invention could light elements with a

Total homogeneity of at least 0.7, preferably from

at least 0.75, and more preferably at least 0.8. These values can also be expressed as a percentage of the achievable homogeneity, so that the achievable overall homogeneity of the luminous element and of the illumination module can be 70%, preferably at least 75% and particularly preferably at least 80%. In certain embodiments, values could also be achieved about 83%.

For comparison, the total homogeneity can be used in a monitor, which is approximately 90% in white. A value of from about 70%, especially from about 80% is considered homogeneous.

The second parameter concerns the relative local

Homogeneity deviation and is defined as the relative change in brightness per unit length, e.g. in

Percent per millimeter. A little local

Homogeneity deviation is important because the eye

especially sensitive to changes in brightness that take place over a short distance. This

 Homogeneity deviation can be determined according to the following rule: (Brightness (p) - Brightness (p + d)) / ((Brightness (p)

+ Brightness (p + d) * d),

where "p" indicates a first measuring point and "d" denotes the distance to a second measuring point. In the context of the present invention d = 1 mm is assumed. The maximum relative local change is therefore the

Maximum of the absolute values of the relative local change.

The underlying measured values can either be measured or determined by means of suitable simulation models. The local homogeneity deviation of the luminous element and the illumination module is at most 0.75% / mm, preferably at most 0.70% / mm and especially at most 0.65% / mm. This value can for example be compared with a luminaire comprising LED light sources, in which the homogeneity is achieved by a distance of the LEDs of 20 mm. If this luminaire also has an overall homogeneity of 83%, but the brightness changes every 20 mm with the period of the LED arrangement, a significantly less favorable local homogeneity deviation of 2.5% / mm results.

An advantage is the arrangement of the system for

Radiation steering, so the arrangement of the mirror surface relative to the reflector surface, therefore chosen so that the mirrored rays impinge on the reflector surface at a predetermined, rather shallow angle. The angle between the impinging rays to

Surface normal of the reflector is therefore rather large.

It is advantageous if this angle between the

Direction of incident, mirrored rays and the

Surface normal of the reflector between 89.5 ° and 20 °, preferably between 89 ° and 30 ° and especially

preferably between 89 ° and 35 °.

For this purpose, the mirror surface preferably has a multiplicity of planar mirror elements set against one another, which are placed against each other as densely as possible and without gaps. In a preferred embodiment, the individual mirror elements are even, so that the mirror surface is formed as a discontinuous mirror surface, comprising a plurality of juxtaposed planar mirror elements. The number of mirror elements can vary, and in the case of planar mirror elements, the accuracy of the contour simulation with the number of mirror elements

Mirror elements is rising. For example, at least five or more planar mirror elements can be provided.

Embodiments with, for example, 20 to 30

Mirror elements, however, are able to reproduce the desired contour even more finely.

The individual mirror elements of the mirror are arranged so that they deflect the beams differently depending on the emission direction of the light source.

The size of the mirror elements is preferably determined as a function of the position relative to the light source so that approximately the same amount of light of the light source falls on each mirror element. Thus, the size of the mirror elements depends on their respective angle with respect to the light source and may be of one

Mirror element to an adjacent mirror element

vary .

It is also possible to change the contour of the mirror surface

continuously image, wherein the intended contour is generated by suitable shaping process. It is not necessary that the light source lies directly in the area of the focal point.

By way of example, the mirror may comprise a base, the surface of which, pointing towards the light source, may be formed with the corresponding mirror elements or the reflecting surface contour. This surface can then, for example, with a mirror

Be provided surface coating.

Likewise, the surface of the reflector can also be equipped with a surface layer or comprise a layer system which has a predetermined emission characteristic. Advantageously, the surface of the reflector has a partly diffuse and partly specularly reflective

Radiation characteristic on. Preferably, the diffuse portion is higher than the specularly reflective

Proportion, which leads to a better homogeneity of the radiated light.

In one embodiment, the proportion is more diffuse

Radiation of the reflector between 70% and 90%, preferably between 75% and 85% and most preferably about 80%, wherein the respective remaining portion of the radiation then specular reflected, that is mirrored, can be.

In general, a high proportion of diffuse radiation, even over 80% or even over 90%, is favorable for achieving a high homogeneity of the luminous element. The illumination module according to the invention for emitting a homogeneous light from a flat light exit window can be a receptacle or holder for holding the

Include lighting element. For this purpose, it may further comprise the facilities required for the operation of the luminous element, that is, for example, a heat sink or

Heat conductor for heat dissipation of the heat generated during operation of the light source, or else corresponding

electrical connections or control units.

To open a broad field of application, the

Light box of the lighting module advantageous from low height. The height is the extent of the

Lighting module in one direction parallel to the

Surface normals of the opening defined by the light exit window. Preferably, the light box has a height of less than 100 mm, preferably less than 60 mm, more preferably less than 40 mm and most preferably 20 mm or less.

Despite the low height of the lighting module allows surprisingly a large extension of the

Light emission window in one direction, the

Beam guidance corresponds. This expansion in the direction of the beam guidance is also referred to below as width.

Accordingly, there is a particularly favorable ratio of this width of the light exit window of the light box to the height of the light box. This ratio is at least 5: 1, preferably at least 10: 1 and particularly preferably at least 20: 1. This means, that at a height of the light box, for example, 20 mm, a width of the light exit window of 400 mm or more is possible.

This makes it possible to compare one to the other

provide a particularly wide illumination module with a particularly wide light exit window. The width of the side next to the light source

Light exit window can be 200 mm up to 2,000 mm. Lower widths are technically possible, but require very small light sources. With even greater widths over 2,000 mm, it may be more difficult to maintain a sufficient luminance.

The opening of the light emission window forming the

Light box is in an advantageous manner with a

closed by a translucent element. This can

prevent dirt or moisture in the

Lightbox penetrate. The translucent element may be made of glass or plastic.

In a further development of the invention that is

translucent element equipped with additional decorative elements. For this purpose, the translucent element may for example be colored and / or include additional decorative elements to produce a predetermined visual impression.

Furthermore, it is advantageous if the lighting module comprises further devices which prevent the light from the light source directly onto the light exit window falls. The devices can be designed to direct this light into non-critical areas of the lighting module. Preferably, however, it is possible to work with a diaphragm and / or an absorbent element. Aperture and / or absorbing element are preferably arranged so that they prevent a direct beam path from the light source to the light exit window, so that no light from the light source directly through the

Light emission window of the light box can penetrate to the outside.

Furthermore, it is also advantageous to arrange the diaphragm and / or the absorbing element in such a way that no light is reflected in such a way that it impinges on the mirror at a different angle than light originating directly from the light source. This can be uneven

Brightness field on the mirror surface, which in turn is unfavorable for the desired high homogeneity of the emitted light.

Conversely, it can also be useful to add extra

Provide reflectors, which are adapted to increase the brightness in the edge region of the reflector surface, where tend to impinge rather small amounts of light, and thus the homogeneity of the emitted light

improve .

The lighting module according to the invention may have more than one single light source, for example also a plurality of preferably arranged in series

Light sources. This is advantageous if not only a large width of the light exit window is desired, but also a large length, ie an extension in a direction perpendicular to the beam guide.

In such an embodiment, the plurality of light sources are preferably arranged along a longitudinal line. Also advantageous are arranged along this line light sources arranged uniformly over the length. Conveniently, the distance between two adjacent light sources is the same. For a homogeneous light, it is advantageous if the distance between two adjacent light sources is not greater than the shortest distance of the light exit surface of the light source to a straight line which extends along the surface of the light source

 Light emission window runs. This ensures homogeneous light distribution even in the longitudinal direction.

It is obvious to the person skilled in the art that the designations width and length of the light exit window are merely selected in order to respectively increase the different extents of the light exit window in relation to the further components of the illumination module

describe. This means that the width of the

Light emission window also larger than the length of the

Light emission window can be.

An illumination module according to the invention can comprise, for example, a light exit window with a width of 400 mm and a length of 500 mm with a height of 20 mm. In this lighting module can be about 50 Light sources laterally offset from the

 Light exit window to be arranged in the longitudinal direction.

In one embodiment of the invention are two

Lighting modules provided, wherein the one

is arranged mirror-inverted to the other and wherein both lighting modules on the front sides of the

Light box _Z collisions. Preferably, these end faces each comprise the light exit window, so that the two light exit windows _{Z can} collide and virtually a common, then twice as wide

Form light exit window. This way you can

Particularly simple, the width of the light emission window can be doubled, so that widths in a range of more than 500 mm up to 1,000 mm or even beyond are possible. To cover the

Light emission window can be a common

be provided translucent element, so that no seam is visible to the viewer. In this embodiment, the light sources can then each be arranged along the outside of the light boxes.

The invention makes it possible to build very flat

To provide lighting modules which

at the same time over comparatively large

Have light exit window.

This makes it possible, for example, to provide the lighting module for cabin interior lighting in commercial aircraft. Of course many more

 Lighting options conceivable, for example, a use as a backlight for advertising, information or display panels.

The invention will be described below with reference to preferred

Embodiments and with reference to the accompanying figures described in more detail.

The drawings show:

Fig. 1 shows schematically a section of a

 Illumination module with a luminous element in cross section,

 Fig. 2 schematically shows a section of a

 Illuminating module according to FIG. 1 in cross-section with a large number of marked light beams,

Fig. 3 shows schematically the radiation course

 exemplary for a light beam in one

 Overall consideration,

 FIG. 4 schematically shows a lighting module according to FIG. 1 in FIG

 Cross section with a variety of

 marked light rays,

 Fig. FIG. 5 shows a schematic cross-section of a view with two illumination modules of FIG. 1 arranged in mirror image relative to one another, FIG.

Fig. 6 the result of a measurement of the luminance along the width of the light exit window of a lighting module according to the invention with a parabolic mirror, 7 shows the result of a measurement of the luminance along the width of the light emission window of a further illumination module according to the invention with a non-parabolic mirror,

 8 shows schematically a lighting module in cross-section with a non-parabolic mirror according to the measurement from FIG. 7, FIG.

 9 shows the result of a comparison simulation of

 Luminance along the width of a

 Light emission window when using a number of 25 LED light sources as direct

 Lighting,

 Fig. 10 purely schematically of the comparison simulation

 Fig. 9 underlying arrangement of the LED light sources

 Fig. 11 is a comparison of different geometric

 Formations of the mirrors in relation to the

 Light source, and

 Fig. 12 shows a further comparison of different

 Mirror shapes.

Detailed description of preferred embodiments

In the following detailed description

For the sake of clarity, preferred embodiments denote substantially identical parts in or on these embodiments. For better

Clarification of the invention, however, the preferred embodiments shown in the figures are not always drawn to scale. Fig. 1 shows schematically a section of a

Illumination module with a luminous element in cross section. In this schematic representation is alone the

For the sake of clarity, the presentation of

Holding means for attaching and holding the components as well as other devices of the marked as a whole in the illustration by the reference numeral 1

Lighting module has been omitted. So are

For example, no electrical contacts or heat sink located.

The luminous element is in this representation in the

Lighting module 1 integrated. Of course, it can also be manufactured as a separate component and in the

Lighting module to be installed. The luminous element comprises a punctiform light source 10, a mirror 20 and a reflector 30.

To illustrate the dimensions of the

 Illumination module 1 is given a coordinate system. Here, the direction indicated by "x" denotes the width, the direction indicated by "y" denotes the length, and the direction designated by "z" denotes the height of the

Lighting module.

The illumination module 1 shown in the example comprises a light box 100 with an opening 101 defining a light exit window. Only a small section of the illumination module 1 is shown, which shows the illumination module 1

Light source includes. The lighting module 1 is in the Capable of producing a homogeneous light from the plane

Output light emission window. The brightness of the emitted light of the light source 10 is homogeneous over the area defined by the opening 101, which means in particular that it does not jump

Changes in brightness are. A viewer is therefore unable to discern differences in brightness with the naked eye.

With the mirror 20 and the reflector 30 of the luminous element, the rays emitted by the light source 10 can be directed in a desired direction. Accordingly, mirror 20 and reflector 30 constitute a cooperative system for radiation control. Light source 10 emits light during operation.

In the example, the light source 10 is set up so that it radiates a predominant part of its light directly onto the mirror 20. In the example, the reference numeral 11 indicates that direction of the radiation in which the intensity is highest. In the example, the radiation of the light source 10 is further emitted in accordance with Lambert's law, which is advantageous in order to produce the most homogeneous possible illumination, as a function of the

Beam angle a precisely determinable amount of light per

Angular segment is emitted.

In this embodiment, the predominant part of the light of the light source 10 falls on the mirror 20 arranged directly in the beam path. The mirror 20 is in this case relative to the light source 10 and to the reflector 30 arranged that a large part of the light received by the light source is deflected after reflection in the direction of the reflector 30.

The reflector 30 is therefore arranged relative to the mirror 20 such that a majority of the mirror 20

Radiation hits him. The reflector 30 comprises for this purpose a planar, partially reflecting surface 31. In the example, this surface 31 comprises at least one layer, which is particularly simple and with predetermined optical

Properties can be applied to a flat body. The reflector 30 is therefore very thin

formed, which advantageously contributes to a very low height of the lighting module 1.

The surface 31 of the reflector 30 reflects the incident light of the light source 10 in operation at least partially diffusely in the direction of the light exit window 101.

The main direction, in which the majority of the light of the light source 10 radiates after reflection on the reflector surface 31, approximately corresponds to the direction in which the light source 10 emits its light. Starting from the direction in which the light source 10 radiates the light, the radiation path through the system for radiation deflection is approximately z-shaped. By way of example only, a light beam 13a, 13b, 13c is illustrated, which illustrates the approximately z-shaped radiation steering in the direction of the width of the illumination element 1. The reference numeral 13a is a light beam

denotes, which is discharged directly from the light source 10. 13b marks this ray of light after the

Reflection on the mirror 20 and with 13c is finally reflected at the reflector 30 light beam

which points in the direction of the light exit window 101.

The light source 10 is formed in the example as white-emitting light emitting diode (LED). Of course, it is also possible to use different colored LEDs or other light sources, such as optical fibers.

The light source 10 further has an example in the example

Beam angle of 120 °. Larger radiation angles are rather unfavorable, since then larger portions of the emitted light no longer impinge directly on the mirror 20. However, it is possible to additionally provide an optical element for focusing the beams (not shown), for example a converging lens.

The mirror 20 includes a curved, concave surface 21, which faces the light source 10. This surface is mirrored and thus provides the mirror surface. To get a high homogeneity of the radiated

Obtaining light in the light exit window is the

Mirror surface arranged so that no reflected rays can fall directly on the light emission window. This can be ensured by virtue of the fact that each light beam incident on the mirror surface of the

Light source 10 undergoes a deflection, which in the direction of the reflector 30 and thus away from the

Light exit window 101 leads.

The mirror surface is designed so that

incident light at different angles in

Direction is deflected to the reflector 30. As a result, the deflected by the mirror beams 13b are not

collimated.

The mirror 20 is a 2 ° tilted paraboloid, so a kind of parabolic mirror, which does not collimate the light in the direction of the axis, but tilted by 1 ° thereto. As a result, the light is not mirrored parallel to the reflector 30, but runs from the mirror at 2 ° towards him. The light source 10 is in this example in the focal point B of the non-tilted paraboloid, so the mirror 320. In the illustrated embodiment, the focal point B of the parabola is about 3 mm away from the apex of the paraboloid. In the example, the light source 10 has a chip width of 0.5 mm, which dimension relates to the extent in the direction "x".

The mirror surface has, at least approximately, a shape as a paraboloid. The mirror surface is still like that

designed that the mirrored rays in

different, rather flat angles impinge on the reflector surface. The angle between the

impinging rays to the surface normals of the

Reflektors is therefore rather large. From the mirror 20 mirrored rays have a

Divergence on, i. a loss of directional control in reflection. Too large a divergence is unfavorable, since in this case not all beams can be directed directed at the reflector. In the exemplary embodiment, this divergence is indicated by the angle d. This

Divergence is mainly due to chip width of the LED and is in the 0 ° direction in the current example +/- 2.4 ° when using an LED as a light source with 0.5 mm chip width. For a LED with a chip width of 1.0 mm, the divergence is +/- 4.8 °. In the 30 ° direction, the divergence reduces to about +/- 1 ° for a 0.5 mm LED or +/- 2 ° for a 1 mm wide LED. The size of the mirror is selected depending on the chip width and the divergence such that the divergence is not too large.

The impact at different angles on the

Reflector surface 31 causes a very good homogeneity of the light is given on the reflector surface 31. The impact angle, indicated in the illustration as an angle, is between 89.5 ° and 20 °, preferably between 89 ° and 30 ° and particularly preferably between 89 ° and 35 °. The imaged light beam 13b strikes, for example, at an angle of about 30 °

Reflector surface 31 on.

Radiation reflected by the reflector surface 31 is radiated in a direction at least approximately corresponding to the emission direction of the light source 10. In the case of an LED as the light source, therefore, the chip area of the LED and the reflector surface 31 are particularly favorable at least approximately parallel to each other. That of the

Reflector 30 radiated light is homogeneous in the context of the invention.

The overall homogeneity of the illustrated illumination module 1, that is to say the quotient of the lowest brightness and the greatest brightness, stated in percent, is 83% in the exemplary embodiment shown and thus corresponds to the requirements for homogeneity.

The local homogeneity deviation, ie the relative

Change in the brightness per unit length, is in the illustrated embodiment at most 0.75% / mm.

The mirror surface in the embodiment has for this purpose a number of 25 juxtaposed, planar

Mirror elements. The individual mirror elements of the

Mirror 20 are arranged so that they deflect the radiation differently depending on the emission direction of the light source 10.

The size of the mirror elements is selected so that approximately the same amount of light of the light source 10 falls on each mirror element. This leads to a

Most of the mirror elements are approximately the same

Receives light amount. Thus, the brightness distribution of the incident light on the mirror surface is already very homogeneous. Of course it is also possible to

Mirror with a different number of mirror elements or the concave, preferably at least approximately parabolic mirror surface continuously To design, for example, by editing the surface with appropriate finishing tools.

In the illustrated embodiment, the light source 10 is located near the focal point B of the mirror 20, as long as the concave mirror surface 20 constructed from the mirror elements would be compared to a paraboloid.

However, the light source 10 can also, if it is structurally useful, be positioned elsewhere, for example offset upwards. The light source 10 can for example sit on a base connected to the light box, which also serves as a heat sink.

The only schematically drawn in the illustration

Mirror 20 may also include a socket in which the mirror elements are facing the light source

Surface 21 are formed. To the reflecting

To obtain surface 21, this is provided with a reflective surface coating, in the example a

metallic, aluminum-based coating. Likewise, metallic mirror elements can be provided, which allow a high reflection. The reflectance of

Mirror surface is at least 80 °, preferably at least 90%, more preferably at least 95% to keep losses low and high efficiency of

To achieve lighting element.

Likewise, the surface 31 of the reflector 30 is also provided with a surface layer. In the example, it is a metallic layer system with a

predetermined emission characteristic, in which a diffuse reflective and a specular reflective portion are present. In the example, the proportion of the diffusely reflected radiation of the reflector is between 70% and 90%, preferably between 75% and 85% and most preferably 80%. The remaining portion of the radiation is reflected speculatively. The surface of the reflector

appears rather white. It may be e.g. to act on a painted or foiled surface. It can also be a white plastic with a corresponding surface roughness.

The light box 100 of the lighting module 1 is of low overall height. A low height is of great

Advantage in terms of the possible uses of

Lighting module, for example, to cramped under

Space to realize a flat, homogeneous lighting. The lower the overall height, the more diverse the possible applications.

On the other hand, the achievable height is limited by the requirements of the radiation steering in order to obtain a homogeneous luminous surface.

The system according to the invention for radiation control was particularly in view of a low height at

at the same time designed comparatively large light emission window, while still paying attention to a small number of light sources and a homogeneous radiation.

The section shown in FIG. 1 comprises only a very small proportion in relation to the width of the light box, so that the actual size ratios of the Illumination module 1 of FIG. 1 can not be completely removed.

The light exit window which is only indicated in FIG. 1 has, for example, an extension in the direction "x", that is to say a width of approximately 400 mm

Light box is only 20 mm. This results in a ratio of the width of the light exit window 101 to the height of the light box of 20: 1. According to the invention, this ratio can be at least 5: 1, preferably at least 10: 1.

Accordingly, embodiments are conceivable that significantly wider at a greater height of the light box

Allow expansions of the light exit window. So it is conceivable to realize a width of the light emission window of more than 400 mm up to 800 mm with a height of only 40 mm.

The opening of the light box forming the light exit window 101 is closed by a light-transmitting element 102, which likewise is shown only schematically in a section in the illustration. The opening of the light box is thereby closed, so that no dirt or moisture can penetrate into the light box. In the example, the translucent element is a glass. In addition to glass, plastic materials are also possible.

In a development of the invention is therefore the

Light box 100 with the translucent element 102 protected on all sides against the ingress of dripping water, so that uses in the outdoor area are possible, for example, for backlighting Hinweisafein or advertising media.

In a further development of the invention, the translucent element is equipped with additional decorative elements. For this purpose, the translucent element may for example be colored and / or comprise additional decorative elements. Direct imprints are also possible.

Light source 10, mirror 20 and light exit window 101 of the lighting module 1 are so to each other

arranged that no light from the light source 10 impinges directly on the light exit window 101. In the example, therefore, an absorbing element 40 is provided, which prevents laterally emitted light of the

Light source 10 can escape. Such a light beam is in the illustration with the reference numeral 14a

characterized. This light beam 14a is prevented from leaking directly through the light emission window 101 by the absorbing member 40. Directly

Exiting light would lead to much brighter areas, so that a homogeneity is no longer present. Likewise, it is also possible to provide an aperture.

In the example, a further absorbing element 41 is also provided, which absorbs part of the light radiation reflected by the mirror 20. In this way it is possible to produce a broad, homogeneous light field already on the reflector surface 31. It is conceivable to provide the absorbing elements 40, 41 with a reflective surface to there

In addition, direct incident light on the mirror and thus the efficiency of the lighting module 1 to

increase. According to the invention, however, it is rather disregarded that this additional light on the

Mirror surface 21 leads to lighter areas, which then also transferred to the reflector surface 31 and ultimately lead to a poorer homogeneity.

The invention shown in cross section

Lighting module 1 can also have a larger in

elongated extent, in the representation with "y"

marked have. Therefore, only a single light source 10 is located.

In a preferred embodiment, the

Illumination module 1, a plurality of light sources 10, which are arranged along a longitudinal line. The light sources 10 are arranged uniformly along the line over the length, wherein the distance between two adjacent light sources 10 is the same.

The length, that is to say the extent in the direction "y", may be chosen differently The light exit window 101 indicated in the example in FIG. 1 has a length of 500 mm the

Illumination module 1 comprises a light source 10 per cm length of the light exit window 101. This ratio has proved to be favorable to produce a homogeneous light in the longitudinal direction. Of course, larger and smaller dimensions in the longitudinal direction are possible.

In order to be able to emit a homogeneous light from the light exit window, the distance between two adjacent light sources 10 is not greater than the shortest distance of the light exit surface of the light source 10 to a straight line which extends along the surface of the light exit window 101. This also ensures a longitudinal direction

homogeneous light distribution.

Fig. 2 shows schematically a section of a

Illumination module 1 according to Fig. 1 in cross section with a plurality of drawn light beams, wherein the

For clarity, only a light beam 13a of

Light source 10 is indicated and the associated mirrored light beam 13b. It can be clearly seen in the illustration that the mirrored light beams are not collimated, but run at different angles. The reference numeral 13d denotes a light beam which impinges on the diaphragm 40.

FIG. 3 schematically shows the course of the radiation by way of example for a light beam 13a, which is mirrored on the mirror 20, in an overall view.

4 shows schematically a lighting module 1 according to FIG.

1 in cross section with a plurality of marked light beams. In the illustrated embodiment, the Reflector 30 and the light exit window 101 arranged plane-parallel to each other, wherein the reflector 30 has approximately the same extent as the light exit window 101st

Fig. 5 shows schematically a view of a

Lighting device according to the invention, comprising two mirror-image mutually arranged lighting modules 1, in cross section. The two lighting modules 1 collide at the end faces of the light box 100 together.

In this arrangement, the two are the

Light emission window 101 defining openings of the two light boxes 100 to each other, so that the two

Light emission window 101 along a common edge _Z collide and provide a common light emission window of double the width.

It may also be in a development of the invention, a common translucent element, such as a

Cover glass, be provided, which the respective

Closes openings of both light boxes together. In this way, the structural separation for a viewer is barely perceptible.

6 shows the result of a measurement of the luminance along the width of the light exit window using the example of a lighting module 1 with a 400 mm wide

Light emission window and a parabolic mirror 20. Shown are the luminance and the

Homogeneity deviation as a function of the position along the width of the light emission window. The in the graphic The luminance given here corresponds to the luminance and, in the context of this invention, describes the surface-related luminous flux which strikes an illuminated object. The luminance is given in the size cd / m ² . The local homogeneity deviation is given in the size% / mm and represents the relative change in the brightness per

Length unit is.

It shows a very good homogeneity of the luminance both in the central region of the light emission window and towards the two-sided adjoining

Border areas.

Accordingly, there is also a good homogeneity in those

Given areas that are close to the light source 10, as well as in those areas which are located far from the light source 10. The measured total homogeneity is about 90%. The local

Homogeneity deviation is about 0.6% / mm. A

Homogeneity deviation in the dimension mm ^-1 corresponds to a homogeneity deviation in the dimension (% / mm) after multiplication by 100. The efficiency of the

Lighting module 1 is about 38%.

 Thus, according to the invention is shown in the

Embodiment to call the measured brightness as homogeneous. The most slight fluctuations of the

Luminance are not considered to the human eye

Brightness fluctuation perceptible.

The embodiment shown makes it possible in a particularly simple manner, the width of the light emission window significantly increase without the same time

geometrically related height of the light box 100 increases. In this way, widths of the light-emitting window of 800 mm and more up to 2,000 mm are possible, the height of the light box can still be kept very low, in the example at about 20 mm.

FIG. 7 shows the result of a measurement of the luminance along the width of the light emission window using the example of a further illumination module 1 according to the invention with a 400 mm wide light exit window and a non-parabolic mirror 20.

It also shows a very good homogeneity of the luminance in both the middle range of the

 Light exit window as well as to the adjoining on both sides edge areas. The measured

 Total homogeneity is also about 90%. The local homogeneity deviation is about 0.75% / mm and is thus slightly less favorable than in the parabolic mirror embodiment. The efficiency of

Lighting module 1, however, is slightly higher at about 44%. This is also in this embodiment, the

to call the measured brightness homogenous. In this embodiment, which is shown purely schematically in Fig. 8, a planar reflector was used without additional apertures.

Fig. 8 shows schematically a lighting module 1 in

Cross-section with a non-parabolic mirror 120 and a plurality of drawn light beams, wherein the For clarity, only a light beam 13a from the light source 10 and one of the non-parabolic

Mirror 120 mirrored light beam 13b is marked.

Fig. 9 shows the result of a comparison simulation of the luminance along the width of a light emission window when using a number of 25 LED light sources as direct illumination. The brightness, ie the luminance, is therefore significantly higher than in the preceding

discussed lighting devices according to the invention.

The measured total homogeneity of this arrangement is about 90%. The local homogeneity deviation is

however, only at about 1.2% / mm and is thus by a factor of 2 worse than in the embodiments according to the invention shown above. In addition, these local homogeneity deviations occur as periodic

Strip pattern regularly. Clearly visible in the illustration are the significant fluctuations in the luminance, which correspond directly to the LED light sources arranged above. Thus, a higher overall brightness can be achieved, a comparably good

Homogeneity is no longer present. The

Brightness differences of this arrangement are visible to the naked eye, in particular due to the stripe pattern.

Another disadvantage of a direct LED lighting results in that insufficient scattering effect of

translucent element the individual LED points are visible in the review. To this effect too Avoid is a very strong element of scattering

required, which in turn significantly reduces the efficiency of such a device.

Fig. 10 also shows purely schematically the

Comparative measurement of Fig. 9 underlying arrangement of the LED light sources. In the example, LED light sources 210 are shown whose spacing is selected such that a

Total homogeneity of 90%. Shown is a line-shaped arrangement of the LED light sources 210, which have a distance of 18 mm from each other.

Fig. 11 shows a comparison of different

geometrical formations of the mirrors. The picture shows a tilted parabolic mirror, a parabolic mirror and a tilted parabolic mirror with non-parabolic outlet.

A tilted parabolic mirror with one not

parabolic outlet has the advantage that a greater distance to the light source 10, so for example to the LED, is given. Therefore, this arrangement is less sensitive to tolerances. In the juxtaposition is the

Light source at position (0, 0) arranged.

Finally, FIG. 12 shows a further comparison of different mirror shapes in a reference system in which the light source is again arranged in position (0, 0). Shown are a parabolic mirror 320, a 2 ° tilted parabolic mirror 20 and mirror 220 with higher focal length and additional bend at the outlet. This embodiment is characterized by a lower tolerance sensitivity as well as a higher efficiency. Furthermore, it can cause a better illumination of the reflector very close to the mirror.

The present invention thus makes it possible to provide particularly flat-mounted lighting modules, which simultaneously over comparatively large

Have light exit window. Due to the

Radiation control according to the invention, the light occurs very homogeneous from the light exit window.

This makes it possible, for example, to provide the lighting module for interior lighting, for example as cabin interior lighting in commercial aircraft.

Of course many more

 Lighting options conceivable, for example, a use as a backlight for advertising, information or display panels.

Claims

claims 1. luminous element comprising a preferably  linear light source (10), a mirror (20) and a reflector (30), preferably at least in sections with a flat surface, wherein the light source (10) is arranged to radiate a major part of its light directly onto the mirror (20) the mirror (20) reflects the light received by the light source (10) towards the reflector (30), and wherein the reflector (30) is preferably a  partially reflective surface (31) and reflects this light at least partially diffuse in a direction whose main direction corresponds approximately to the direction in which the light source (10) emits their light. 2. Luminous element according to one of the preceding  Claims, characterized in that the light source (10) comprises at least one light emitting diode (LED). 3. luminous element according to one of the preceding  Claims, characterized in that the emission angle of the light source (10) is not more than 120 °, preferably not more than 90 ° and more preferably not more than 60 °. 4. luminous element according to one of the preceding Claims, characterized in that the Light source (10) an optical element for  Beam forming comprises, preferably a  Collecting a lens. 5. luminous element according to one of the preceding  Claims, characterized in that the mirror (20) comprises a curved concave mirror surface (21), seen from the light source (10), preferably in the form of a paraboloid or similar paraboloid, and / or with an additional bend at the outlet. 6. luminous element according to one of the preceding  Claims, characterized in that incident on the mirror surface (21) rays of the  Light source (10) are deflected to the reflector (30). 7. Luminous element according to one of the preceding  Claims, characterized in that the  Radiation at different angles in the direction of the reflector (30) are deflected so that the radiation leaving the mirror (20) is not collimated. 8. luminous element according to one of the preceding Claims, characterized in that the mirror (20) is formed so that the mirrored rays at an angle to the surface normal of the reflector (30) between 89.5 ° and 20 °, preferably between 89 ° and 30 ° and especially preferably impinge between 89 ° and 35 ° on the surface of the reflector (30). 9. luminous element according to one of the preceding  Claims, characterized in that the mirror (20) comprises a plurality of juxtaposed, planar mirror elements which deflect each beam differently depending on the emission direction of the light source (10). 10. Luminous element according to one of the preceding  Claims, characterized in that the  Reflector (30) comprises a layer system on the surface, which has a partially diffuse and partly specularly reflective radiation pattern, wherein preferably the radiation at the surface of the reflector (30) between 70% and 90%, preferably between 75% and 85% and especially preferably 80% is emitted diffusely, and wherein the remainder of the radiation is reflected speculatively. 11. Luminous element according to one of the preceding  Claims, characterized in that the  Reflector emits light homogeneously, with the  Total homogeneity is at least 70%, preferably at least 75% and more preferably at least 80% and / or wherein the local homogeneity deviation is at most 0.75% / mm, preferably at most 0.70% / mm and especially is not more than 0.65% / mm 12. Illumination module (1) for emitting a homogeneous light from a flat light exit window (101), comprising a light box (100) with a light exit window (101) defining  Opening and at least one luminous element,  preferably according to one of the claims. 13. lighting module (1) according to the preceding claim, characterized in that the light box (100) has a height of less than 100 mm, preferably less than 60 mm, more preferably less than 40 mm and most preferably 20 mm or less. 14. Lighting module (1) after one of the two  preceding claims, characterized in that the ratio of the extension of the light box (100) in the direction of the beam guide to the overall height of the light box (100) is at least 5: 1, preferably at least 10: 1 and more preferably at least 20: 1. 15. lighting module (1) after one of the three  preceding claims, characterized in that the width of the light exit window (101) is between 200 mm and 2,000 mm. 16. Illumination module (1) according to one of the preceding claims 12 to 15, characterized in that the light exit window (101) a translucent element comprises, preferably of glass or plastic. 17. Lighting module (1) according to the above  Claim, characterized in that the  translucent element is colored and / or decorative elements. 18. Illumination module (1) according to one of the preceding claims 12 to 17, characterized in that a diaphragm and / or an absorbing element is provided to prevent direct radiation from the light source (10) to the light exit window (101). 19. Lighting module (1) according to any one of the preceding claims 12 to 18, characterized in that a plurality of light sources (10) is provided which are arranged along a longitudinal direction along a longitudinal line. 20. Lighting module (1) according to the above  Claim, characterized in that the distance between two adjacent light sources (10) is equal, and wherein this distance between two adjacent  Light sources (10) is not greater than the shortest distance of the light exit surface of the light source (10) to a straight line which extends along the surface of the light exit window (101).