WO2009095225A1

WO2009095225A1 - Device for illumination and display

Info

Publication number: WO2009095225A1
Application number: PCT/EP2009/000545
Authority: WO
Inventors: Philipp Zeller
Original assignee: Vidensis Gmbh
Priority date: 2008-01-28
Filing date: 2009-01-28
Publication date: 2009-08-06
Also published as: DE102008006364A1

Abstract

An annular light for concentrical illumination of an object or a surface features a semiconductor chip (1) that has on its surface at least one light emitting diode with an associated light emitting area (2) that is able to emit light perpendicular to the surface. On the surface of the semiconductor chip there is at least one region that emits no light and that is concentrically surrounded by one or more light emitting areas and that has the appearance of a recess or opening (3) that has been made in the surface. In a similar way it is possible to get a displaying device to display image information. This displaying device consists of a semiconductor chip with a light emitting diode on its surface with an associated light emitting area that is able to emit light perpendicular to the surface and where the light emitting area is delimited towards one or multiple regions that emit no light such that the light emitting area has the shape of a sign, a symbol, an icon, a logo or an image.

Description

Device for Illumination and Display

The present invention relates to an illumination and a display- ing device based on LED elements and further it mainly relates to an annular light intended for concentrical illumination of an object or a surface as well as it relates to a manufacturing technique for said devices.

A top-down illumination of any object by a single circular shaped light source results in a brightness distribution where the center is the brightest area and the intensity is increasingly reduced towards the edges . This drop of intensity towards the edges can be irritating if that area of brightness distribution is only slightly larger than the illuminated object itself. If however the center of the bright spot of the light source is being optically blocked by a dark object, a better homogeneity can be achieved by the effect that the overall intensity is being reduced.

When a three dimensional object is illuminated transversely or in general laterally by one single light source, shades will always appear on the side opposite of the illumination. These shades can be welcomed or distracting, depending on the object itself and its properties that shall be looked at. The shades are most distracting if specific structures of interest are not illuminated brightly enough leading to a lack of contrast.

In order to shed light onto those structures hidden in the shade, a second light source positioned at a different angle may be used. If however all areas of shade shall be largely illuminated, the object needs to be illuminated from any direction simultaneously. It is however very intricate to place a large num- ber of light sources onto a ring shape around an object and in practice it probably is not feasible with the uniformity needed.

For all the reasons mentioned above compact light sources in the shape of rings are being produced in many different versions. They are called ring or annular lights. An annular light is a light source in form of a ring that shall illuminate objects as homogeneously as possible from every direction simultaneously. An exemplary version of such an annular light is described in EP 0 194 229 A2.

A uniform illumination of objects without shadows or reflections is an important requirement for the reliable work of an image processing system. Therefore a variety of annular lights that can be mounted directly on a camera objective are available commercially. By choosing the size, the brightness, the radiation angle, the color and many more characteristics of an annular light it can be adjusted perfectly to almost every assignment of illumination and visualization. For instance, focusing objectives concentrate the light onto a limited area in the center of the plane of interest, which is an advantage especially for small objects or when using magnification optics. A uniform illumination causing few or even no reflections can also be achieved by the use of diffuse glass filters.

In general an annular light provides a very uniform illumination having reduced shadows, which is further centered on the image of interest. However, it is still possible that areas of differ- ent brightness or even circular reflections appear, mostly by illuminating broad objects that are not fully covered by the illumination. DE 10 2005 030 761 Al describes a multi-LED ring with many LEDs placed on a ring shaped carrier for the illumination of larger objects. In the middle of the ring shaped carrier a camera or any working instruments can be mounted or alternatively fed through. Glass or plastic fibers or cylinders can be attached to such multi-LED rings in order to guide the light to specific dimensions or into rooms that need a service-free or explosion- proof illumination.

If such rings are being produced using SMD technology and minia- turized LEDs, they can get as small as to inner diameters of about 3 cm .

In order to get a smaller inner diameter of an endoscope that features micro optics in the center of the annular light or to illuminate microscopic objects in very narrow spaces or if a very thin object needs to be forwarded through the center or a so called working channel of an endoscope, optical fibers are needed.

In order to illuminate small objects tiny rings of parallel optical fibers are produced that are i.e. placed around a tube or a capillary. These central tubes are used to deliver or aspirate gases or liquids or as a guide for any kind of instruments and in most cases they are needed for the stability of the ring of optical fibers. Instead, these optical fibers may be placed around a core of image guiding fibers, around a GRIN rod lens or around tiny camera chips that are all able to image the illuminated object.

Therefore, the optical fibers are being combined into a bundle towards the proximal end of the corresponding instrument and light is being coupled into this bundle of fibers from a not necessarily miniaturized light source that is placed off the instrument's axis. Fabrication of these annular lights, e.g. for medical and dental applications, is very intricate and therefore costly. Coupling of light into a small bundle of light guiding optical fibers is in general very lossy, because most light sources have large angles of radiation. Examples for this kind of annular lights are described in US 2004/0249424 Al, WO 02/062262 A2 , EP 0 194 229 Al and in CH 673214.

If LEDs are being used for illumination of e.g. display devices, there is actually a restriction, that for the display of complex structures optical masks need to be put in front of the LEDs. These masks lead to a loss of brightness. This loss of brightness coincides with the original amount of electrical power consumed, therefore leading to higher temperature in the device and a bad efficiency of the illumination.

With respect to the problems described above the object of the present invention is to describe a procedure for the fabrication of miniaturised annular lights and display devices which have a reduced loss of brightness or intensity, as well as an annular light and a display device with said properties.

This object is achieved by an annular light according to claim 1, a procedure for the fabrication of an annular light according to claim 18, a display device according to claims 23 and 24 and a procedure for the fabrication of a display device according to claims 30 and 32.

Further developments of the invention are described in the dependent claims .

Further properties and advantages of the present invention arise from the description of embodiments making reference to the figures. The figures show: Fig. 1 A top view of an annular light source according to the first embodiment,

Fig. 2 a top view of an annular light source according to the second embodiment ,

Fig. 3 a top view of a field of annular light sources according to the first embodiment,

Fig. 4 a top view of an annular light source according to a modification of the second embodiment,

Fig. 5 a top view of a light source element according to the fourth embodiment,

Fig. 6 a general view of an annular light with a light guide attached according to the third embodiment,

Fig. 7 a general view of an annular light according to a modification of the third embodiment,

Fig. 8 a side view of an annular light according to the first embodiment,

Fig. 9 a a general view of a display device that features an LED area that is shaped by delimiting it from the surrounding non-glaring area such that an arrow is displayed,

Fig. 9 b a general view of a display device that features an LED area with a delimited inner area that is non-glaring, wherein the LED area is shaped to surround that inner area, Fig. 9 c a general view of another display device that features another shape of the LED area and

Fig. 9 d a general view of a display device that shows a shape or sign that is being composed from multiple

LED areas .

Embodiment 1

As shown in Fig. 1 an annular light source consists of a semiconductor chip 1 featuring a diode that way that a light emitting area 2 emits light from the surface of the semiconductor chip if a voltage or a current, respectively, is fed to the diode. In the center of the light emitting area 2 a borehole 3 is formed, which borehole 3 is perpendicular to the surface of the semiconductor chip and goes completely through the whole semiconductor chip. As therefore no light is emitted from the area of the borehole when a voltage is fed to the diode, the whole device gets the specification of a miniaturized annular light. As this annular light consists of a micro structure (a light emitting diode) , it is possible to get an annular light with a small inner diameter of about 0.01mm up to about 0.8mm.

The semiconductor chip 1 as mentioned above may ideally be a chip that is used in an LED. The term 'light emitting area¹ is not meant to be limiting such that the area necessarily consists of photoluminescent material. The present invention can be applied to both, LEDs that feature a photoluminescent material on the surface of the semiconductor chip as well as LEDs that are built without such a material. If no photoluminescent material is present the light emitting area is identical to the regions of the electrodes of the LED that emit light. If photoluminescent material is present, the light emitting area is the surface of said photoluminescent material, which emits light because it is activated to emit light by the radiation from a diode that has been formed in the semiconductor chip. Also, mixed versions of the above examples are of course possible, in which the light emitting area contains both, regions where the light is emitted from the photoluminescent material as well as regions where the light is emitted directly from a diode or a part thereof.

So it is e.g. possible to remove the housing of a commercially available LED in order to get access to the semiconductor chip 1. The borehole 3 may then go from the upper surface of the semiconductor chip 1 or the possibly present layer of photoluminescent material down to the lower surface of a carrier substrate 5 as it is generally used to mount this kind of semiconductor chips. Fig. 8 shows a side view of such a structure sche- matically.

As the layer of photoluminescent material as well as the carrier substrate are both optional they are not being explicitly mentioned in the further embodiments.

Fig. 3 shows a complete field or array of annular lights similar to the one as shown in Fig. 1. As a single annular light of this type is essentially small it is possible to build up such a field on a relatively small surface. With this embodiment multi- pie identical or different individual miniaturized annular lights can be used to illuminate a field of objects. Further, this embodiment can also be used to couple light into multiple annular lights made out of optical fibers or light guiding tubes. An application of the latter could possibly be an advan- tage on a microtiter plate which is commonly used in molecular biology applications.

Above, the borehole 3 was denoted to go through an active part of the LED. However, it is also possible to produce an LED from scratch in such a way that its active, light emitting part is built in the shape of a ring. Such a design leads to a higher efficiency of the radiation as well as a higher yield of the production of annular lights, as the opening is no more a miss- ing part of the active light emitting area of the diode. Further, the risk of damages such as short circuits or broken contacts near the diode junction, which may be produced by forming the borehole, and, as a consequence, a deficiency of that light element is prevented. Finally, with said method, another problem can be prevented: The absence of any protective layer after building the borehole, which is close to the delicate diode junction, leading to the fact that this region of the semiconductor is being exposed directly to influences of the surrounding such as dust, dirt (e.g. drilling debris), humidity or air, is avoided. This kind of exposition may possibly degrade the layer of photoluminescent material, or a short circuit might be caused.

Embodiment 2

The borehole 3 does not necessarily need to be in the middle of a single light emitting area. It is also possible to build a structure where a borehole 3 is placed somewhere between several light emitting areas 2. In the second embodiment shown in Fig. 2 there is a field of four light emitting areas where a borehole 3 is placed in the middle between these four areas .

As the four light emitting areas 2 are symmetrically placed around the borehole 3, this device shows the properties of an annular light.

Fig. 4 shows an embodiment similar to Fig. 2, however, in Fig. 4 the inner diameter of the opening 3 has been chosen such that the light emitting areas 2 are immediately adjacent to the edge of the opening 3.

If the opening 3 has a circular shape then the form of the light emitting area overall is close to a ring.

The embodiment of the present invention according to the second embodiment is not limited to four light emitting areas. Principally, this embodiment can be chosen for any other number of light emitting areas within a field. However, the approach to an ideal ring is the better, the higher the number of light emitting areas that surround opening 3 is. Further, the light emitting areas do not need to be all identical concerning their form, shape or size.

Manufacturing method for annular lights according to the embodiments 1 and 2

Practical tests have shown that many different methods can be applied to build the boreholes 3 or, alternatively, openings 3. Each of these methods has its specific advantages and disadvantages. If the position and the initial shape of a light emitting area are not known in the beginning, they can be found by feeding a low voltage or a low current respectively to the LED. The light emitting area can then be easily determined with the naked eye without the danger of damaging the sight of the eye.

Mechanical Drilling

In the process of mechanical drilling it is crucial to consider the different hardness of all materials out of which the LED has been assembled, such as the semiconductor crystal, its support substrate, the fluorophore and the protective lacquer. This is necessary in order to avoid the LED from breaking apart. Therefore, the LED (without its housing, meaning the semiconductor crystal together with all possibly attached layers, with or without a support substrate) must be positioned and fixed as flat and as stable as possible on a stable basis of the drilling machine .

Additionally, the choice of revolutions per minute of the drill must be done such that the LED is not overheated, as that could lead to damage. Further, the drilling process needs to be done carefully paying attention for any drilling dust not to get underneath the protective gel or lacquer layer. Dust reduces the optical power of the LED by its presence alone, but it possibly also damages or degrades the photoluminescent material. The protective gel often used in LEDs is some kind of an optically transparent protective lacquer that protects the photoluminescent layer from any influences of the surrounding, mostly humidity and oxygen. Depending on the manufacturer of the LED there are different lacquer materials that are commonly used. Some are firm or hard after completion of the LED manufacturing, some others remain elastic at different but material specific grades of durameters . Therefore it is recommended to use hollow drilling tools, yet it is not possible for all dimensions. For the drilling of very small boreholes through small LED areas the drill and the LED mounted to it must both be free of mechanical backlash and any kind of vibrations, and the adjustment of the drill must be performed as precisely as possible. The best results can be obtained by using a camera system attached to the drilling machine or to the turning lathe, respectively.

Laser drilling

If a laser is used to form (or drill) the opening the accurate positioning is much easier to do. However, a laser beam of high energy may destroy surrounding material and almost always traces of burnt material remain. These reduce the optical power of the remaining active regions of the LED. Further, it is difficult to get a circular hole in very small dimensions. Water jet drilling/cutting

There are hardly any traces of debris remaining if an opening is made by the use of a water jet. However, this technique may cause the silicon to break or, just as the mechanical drilling, may cause the different layers that form the complete LED to fall apart. Nevertheless, it is recommended to keep an eye on the remains of dust of the material that was cut off .

Micro erosion technique Micro erosion technique with or without prior mechanical micro drilling, leads to the best results. It is, however, very intricate to perform and only economical if large numbers can be produced.

Embodiment 3

According to the third embodiment annular lights that are built according to embodiments 1 or 2 are attached to tubes or capillaries made out of glass or plastics as light guides 4. The at- tachment is done directly on the light emitting areas using a special optically transparent glue. The final product is shown in Fig. 6. In this device the coupling of light into the light guide is optimized and therefore compared to the state of the art annular lights not only the overall size has been reduced, but also the energetical efficiency has been improved. It is of course also possible to attach a light guide 4 by the means of a small ring made out of glass fibers, quartz fibers or plastic fibers .

As all capillaries are, generally spoken, tubes with very small inner diameters, the expression capillary or capillary tube will be omitted for the rest of this document and only the word tube is being used. It shall however be noted that these tubes can be extremely fine (thin) , which means that their inner diameter may be as small as 0.01 mm or more.

The light guiding tube can have different optical properties. Depending on the application and the light intensity needed, it may even be sufficient to use a normal glass tube or plastic tube. They also act as lightguides known from the geometrical optical theory of internal total reflections. It is further possible to apply metallic mirror layers on the inner and the outer surface of these tubes in order to improve the light guiding properties. Otherwise it is always possible to use as light guiding tubes specific hollow light guides that feature over their cross section one or more steps in their diffractive index or a gradient of the diffractive index. According to these pos- sibilities a variety of light guiding properties at any wavelengths can be chosen.

Light guiding tubes are available in different dimensions and with a variety of properties for different wavelengths and they can be adjusted to the specific use of the instrument.

A tube that is attached that way may e.g. also be a cone, where the inner or the outer or both diameters are not remaining constant over the length of the tube or a part thereof . The diameter and the thickness of the tube's wall may therefore be smaller or larger at the end through which the illumination takes place than the corresponding diameter and wall thickness on the other side where the light is coupled in by means of the annular light LED.

The cladding of the light guiding tube may further on hold recesses or gaps or be foraminated in longitudinal direction.

Further it is possible for the tube's wall to have openings, cracks or splits. So it is even possible that the tube is built from two halves of tube like shells that may not be together as a closed unit at the end through which the illumination takes place and that may even have different lengths.

It is as well possible that the tube is built from light guiding segments in the longitudinal direction which need not necessarily be in direct contact and which further not even need to be made out of the same light guiding material, as it is shown in Fig. 7. Further it is sufficient if the tube is only attached in direct contact to the LED only at those positions where a light emitting area is present on the semiconductor chip.

When attaching tubes to the annular LED according to the present invention it must be ensured that the corresponding inner diameters be well centered and not tilted in longitudinal direction. A specific optical glue needs to be used in order to optimize the coupling of the light.

Due to the small area of fixation and, in relation to that, the large lever effect of the long tube, the glue needs to guarantee an adequate stability. Certain applications need an additional reinforcement by means of an outer construction around the LED and the initial part of the tube. Also an inner reinforcement by means of a middle tube may be attached if it is possible for the dimensions needed.

Further, the inner part of the tube as well as the borehole 3 or opening 3 through the LED need to remain free of any glue possibly flowing in, which needs to be actively prevented, in particular when working with very small inner diameters due to the capillary forces. Under certain circumstances it may make sense to place and mount the future central channel or optics or in- strument in the same manufacturing step, if it does not need to be turned, displaced longitudinally or replaced later on.

Accuracy of mounting, straightness and stability when applying the glue may be achieved by the help of certain auxiliary ob- jects. Typically such an object may be a wire with the according diameter or, even better, a fitting rod made out of Teflon. The latter is not being fixed by glue flowing into the inner side of the tube thanks to the specification of Teflon. Otherwise it may be possible, depending on the dimensions, to put in an intermediate tube that is both, a reinforcement and an insulator against glue in one.

Embodiment 4

Instead of one or multiple circular openings through the whole LED device as it was described in the first three embodiments it is also possible to form openings or structures of any shape in the semiconductor chip by the means of drilling, machining, Ia- ser drilling, cutting or erosion. These can be holes of different diameters that partly cover each other, oval, angular or whatsoever combined shapes. The LED device itself may initially feature one single or multiple light emitting areas the shape of which is being varied as shown in Fig. 5. The expression "light emitting area" is used exactly in the same way as it was done for the prior embodiments. That means a light emitting area does not necessarily need to be identical to an LED region or an electrode of the LED.

That way, light emitting areas in the shape of any thinkable combination of annular lights, shapes, forms, figures, symbols or logos can be produced that get self-glowing if the LED is activated. This unlimited variety of shapes of LEDs may be used for complicated illumination situations but also as a display of symbols on machines and instruments.

As an example, the light emitting area of an LED can be designed in a way that an arrow is displayed, as it is shown in Figs. 9a to 9d. When a single light emitting area is present such as shown in Fig. 9a through 9c, the border or the edge of the light emitting area by which the light emitting region is delimited from the region, which is not emitting light, is identical to the shape of the sign or symbol that is intended to be displayed. In this example this is an arrow, so any observer looking at the LED will immediately recognize an arrow.

For the design of the shape of the light emitting area there are no limits. It is possible to have islands that are not emitting light within the light emitting area according to Fig. 9c. That way it is optionally possible to display the letter ¹A¹ or, as a general symbol of poison, a glowing skull of which the eyes and the nose are dark.

Another application are control LEDs placed on all kinds of electrical devices, that show e.g. the glowing word ,,ON" without the need of placing an according diapositive on top of the LED. But even complicated direction tables with many details or company logos can be produced.

Especially, the different specifically shaped light emitting areas do not need to be all placed on a single semiconductor chip.

By combining light emitting areas of different LEDs that emit light of different colors using SMD technology it is even possible to generate multicolored shapes and forms as they are often used in consumer electronics or in toys. That way, many small LEDs can be placed in a field onto a single support substrate as it is known from LED arrays. The individual light emitting areas may vary in their wavelengths or also in their intensities. Thereby, the individual light emitting areas do not need to be of the same size or shape. They may feature splits, cracks, openings, holes, penninsulas and edges in order to build by their assembly specific glowing shapes as shown in Fig. 9d.

Manufacturers of LEDs can shape or design LEDs directly during their production process. This may be possible i.e. by the use of specially designed lithography masks. Hereby, the forms and shapes do not necessarily need to be built by etching but also by growth processes or adding, spraying or sputtering of layers.

Even though all the embodiments mentioned above describe very small annular lights or light sources, the invention is not limited thereto. Using powerful LEDs makes applications in the macroscopic range possible (Diameter of the annular light larger than 1 cm, preferentially larger than 3 cm) .

Even though a broad variety of applications of the annular lights and display devices according to the present invention is possible, this invention is particularly useful for annular lights and displaying devices in combination with medical and dental devices and endoscopes or with boroscopes for industrial and investigational use and also with illumination sources for automatic camera systems, known as machine vision.

Claims

1. Annular light for the concentrical illumination of an object or a surface where the annular light features a semiconductor chip (1) while on the surface of said semiconductor chip (1) there is at least one light emitting diode that is able to emit light perpendicular to the surface and on the surface of the semiconductor chip (1) next to at least one light emitting area (2) that belongs to an area of the light emitting diode there is at least one region of which no light is emitted, while this region is surrounded concentrically by one or multiple of the light emitting areas (2) and this region has the appearance of a recess or opening that has been formed in the surface.

2. Annular light according to claim 1, in which said opening (3) goes through the overall thickness of the semiconductor chip

(D ■

3. Annular light according to claim 1 or 2, in which said at least one region of which no light is emitted is placed inside of a single light emitting area (2) .

4. Annular light according to claim 1 or 2 , in which said at least one region of which no light is emitted is placed in the interspace between a field of multiple light emitting areas (2) .

5. Annular light according to claim 1, 2 or 4 , in which said at least one region of which no light is emitted covers a part of at least one light emitting area (2) .

6. Annular light according to one of the claims 1 to 5, in which said light emitting area (2) features a layer of photolumines- cent material that is placed on the surface of the semiconductor chip (1) .

7. Annular light according to one of the claims 1 to 6, on which a light guiding tube (4) is attached to the edge of said at least one region of which no light is emitted in a way that it totally covers the shape of said at least one region of which no light is emitted.

8. Annular light according to claim 7, in which the light guiding tube (4) is a glass tube or a plastic tube.

9. Annular light according to claim 7 or 8 , in which the light guiding tube (4) is flexible.

10. Annular light according to one of the claims 7-9, in which the light guiding tube (4) is a capillary.

11. Annular light according to claim 7, in which the light guiding tube (4) is a ring of glass fibers or a ring of plastic fibers .

12. Annular light according to claim 7, in which the light guiding tube (4) is a ring of quartz fibers.

13. Annular light according to one of the claims 7-12, in which the inner diameter and/or the outer diameter of the light guiding tube (4) is not constant.

14. Annular light according to claim 13, in which the inner diameter and/or the outer diameter of the light guiding tube (4) is smaller or larger on the end that is attached to the semiconductor chip (1) than on the opposite end.

15. Annular light according to claim 7, in which the light guid- ing tube (4) is built from two half shells that need no necessarily to be in contact to each other.

16. Annular light according to claim 7, in which the light guiding tube (4) is built from more than two segments that need no necessarily to be in contact to each other.

17. Annular light according to claim 7, in which the wall of the light guiding tube (4) is only present at the areas of the edge of the at least one region of which no light is emitted where outside of this edge there is a light emitting area (2) on the semiconductor chip (1) .

18. Method for manufacturing an annular light that contains the following step: Forming a region that emits no light on the surface of a semiconductor chip (1), which semiconductor chip (1) features at least one area of a light emitting diode, while the region that emits no light is surrounded concentrically by one or multiple light emitting areas (2) that belong to at least one light emitting diode and said region that emits no light is formed by fabricating a recess or opening (3) in the surface of the semiconductor chip (1) .^•

19. Method according to claim 18, in which said recess or opening (3) is at least partially made by drilling.

20. Method according to claim 18 or 19, in which said recess or opening (3) is at least partially made by etching.

21. Method according to one of the claims 18 to 20, in which said recess or opening (3) is at least partially made by erosion.

22. Method according to claim 19, in which said drilling is per- formed by mechanical drilling or by machining or with a turning lathe or with a cutting water jet or by cutting with a laser.

23. Displaying device for the display of image information that contains a semiconductor chip (1) wherein on the surface of said semiconductor chip (1) there is at least one light emitting diode that features a light emitting area (2) that is able to emit light perpendicular to the surface wherein the light emitting area (2) is delimited from one or more regions that emit no light such that the borderline has the shape of a sign, a symbol, an icon, a logo or an image.

24. Displaying device for the display of image information that features one or more semiconductor chips (1) wherein on the surface of said semiconductor chip (1) there is at least one light emitting diode that features at least one light emitting area (2) that are able to emit light perpendicular to the surface, wherein a plurality of light emitting areas (2) is present that is arranged such that the ensemble has the shape of a sign, a symbol, an icon, a logo or an image.

25. Displaying device according to claim 23 or 24, in which said light emitting area (2) features a layer of photoluminescent material that is placed on the surface of the semiconductor chip (1) .

26. Displaying device according to one of the claims 23 to 25, in which at least one area that emits no light has been at least partly built by taking away layers that are built originally in order to set up the light emitting diode.

27. Displaying device according to one of the claims 23 to 26, in which the shape of the semiconductor chip (1) is identical to the shape of the light emitting area (2) .

28. Displaying device according to claim 23 or 24, in which said area that emits no light has been at least partly built by at- taching an optically dense layer to the surface of the semiconductor chip.

29. Displaying device according to one of the claims 23 to 28, in which the shape of the light emitting area (2) features at least one letter or one cipher or a company logo or a combination thereof .

30. Method for manufacturing a displaying device according to one of the claims 23 to 29, in which the shape of a light emitting area (2) is formed by removing parts of the light emitting diode or the photoluminescent layer of an LED by way of etching, drilling, machining, lathe turning or erosion.

31. Method for manufacturing a displaying device according to claim 30, in which the shape of a light emitting area (2) is formed by the additional removal of parts of the semiconductor chip (1) that are not a part of the LED itself by way of etching, drilling, machining, lathe turning or erosion.

32. Method to manufacture a displaying device according to one of the claims 23 to 31, in which the shape of a light emitting area (2) is formed by the use of specifically designed lithography masks in the production process of the LED.