DE102008006364A1 - Lighting and display device - Google Patents

Abstract

A ring light for the concentric illumination of an object or a surface has a semiconductor chip (1), on the surface of which at least one light-emitting diode region having a light emission region is formed, which can emit light perpendicular to the surface. At least one location from which no light can be emitted is present on the surface of the semiconductor chip, this location being concentrically surrounded by one or more of the light emission areas and having the shape of a recess (3) formed in the surface. Similarly, a display device for reproducing image information may be formed. This includes a semiconductor chip in the surface of which a light-emitting diode region is formed having a light emission region capable of emitting light perpendicular to the surface, the light emission region being delimited by one or more regions from which no light is emitted Light emission area has the shape of a Sentinel, icons, logos or a picture.

Description

The The present invention relates to a lighting and display device based on LED devices and in particular on a Ring light for the concentric illumination of an object or a surface and a method of manufacture the same.

at incident light illumination of any object by a point light source, or by a single, more or less circular Light source, resulting in a brightness range of the brightest Center ago against the edge increasingly in intensity loses. Is this brightness range only slightly larger as the illuminated object, so the intensity drop can against the edge disturbing. Will now be the center the light source through an optically opaque article darkened, so is a better uniformity speed the lighting achieved by the fact that the total light intensity is reduced.

at oblique or generally lateral illumination of a three-dimensional Object by a single light source arise on the illumination direction opposite side shadow. Depending on the object and its property to be considered can these shadows desired or disturbing. disturbing especially if certain structures of interest be under-lit thereby.

Around can also lighten these shaded structures a second light source from a different direction can be used. However, if all shadow regions are to be largely illuminated, so the object from all sides must be illuminated at the same time. Numerous light sources on a circular ring to arrange an object However, it is laborious and in practice barely with the necessary Uniformity feasible.

For the reasons mentioned above, compact annular light sources are built, so-called ring lights. A ring light is an annular light source that illuminates an object as evenly as possible from all sides. An exemplary embodiment of such a ringlight is in EP 0 194 229 A2 described.

A uniform, shadow and reflection-free lighting of objects is an important requirement for the reliable Working an image processing system. Therefore, there are many in the trade available ring lights, which are directly attached to a camera lens to be assembled. By choosing the size, the brightness, beam angle, color and many other features The ring light can do this optimally to the given task be adjusted. For example, focusing essays concentrate the light on a limited area in the center, especially at small objects and magnifying optics makes sense. A uniform, low-reflex illumination can be achieved again with diffuse glass panes.

In usually a ring light leads to a very uniform and centered on the image and reduced shadows. However, it does happen, especially with broad objects that are not be fully illuminated, even to different Brightness, and circular reflections may occur.

DE 10 2005 030 761 A1 describes for the illumination of larger objects, the annular arrangement of many LEDs on a support, wherein mounted in the center of the ring, a camera or any working tools can be attached or passed. On such rings of LEDs, for example, explosion-proof, maintenance-free or adapted to special dimensions, continuation of the light glass or plastic cylinder can be placed. If such rings are manufactured in SMD technology with miniaturized LEDs, the inner diameter is approximately 3 cm.

to Realization even smaller inside diameter, if a micro-optic used in the center of the ring light, a particularly small object Illuminated in a narrow room or a correspondingly thinner Be guided through the center of the ring light should, must be resorted to fiber optic technology. So when lighting small objects usually small glass fiber rings made, for example, to a conduit for Feeding or aspirating gases or liquids are arranged around. Furthermore, the glass fibers around an image-guiding fiber core, to GRIN lenses or smallest camera chips around, which depict the illuminated object, be arranged and / or to guide any instruments.

In this case, the glass fibers are bundled at the proximal end of the respective instrument and light from any light source outside the axis of the instrument, which need not be a miniaturized light source, is coupled into the fiber bundle. The production of such ring lights, for example for medicine including dental medicine, is very complex and therefore expensive. The coupling of light into a small fiber bundle is usually associated with large losses, since most of the corresponding light sources have large angles of emission. Examples of such ring lights are in US 2004/0249424 A1 . WO 02/062262 A2 . EP 0 194 229 A1 and CH 673214 specified.

at the use of LEDs for lighting, for example In display devices, there are moreover general the limitation that masks to play back more complex mappings before the LEDs must be set, resulting in brightness loss leads.

in view of It is an object of the present invention to address the above problems Invention, a method for inexpensive production miniaturized ring lights and display devices ready for in which the brightness losses are reduced, as well as a ring light and a display device with corresponding properties.

The Problem is solved by a ring light according to claim 1, a method for producing a ring light according to claim 18, A display device according to claims 23 and 24 and a method for producing a display device according to claims 30 and 32.

further developments The invention are described in the subclaims.

Further Features and convenience of the present Invention will become apparent from the description of embodiments based on the drawings. From the figures show:

1 a plan view of a ring light according to the first embodiment,

2 a plan view of a ring light according to the second embodiment,

3 a plan view of an array of ring lights according to the first embodiment

4 a plan view of a ring light according to a modification of the second embodiment,

5 a plan view of a light element according to the fourth embodiment,

6 a view of a ring light with attached optical fiber according to the third embodiment,

7 a view of a ring light according to a modification of the third embodiment,

8th a side view of a ring light according to the first embodiment,

9a a view of a display device in which the LED area is so delimited from the surrounding non-luminous area that it has the shape of an arrow,

9b a view of a display device in which the LED area is delimited so that it surrounds a non-luminous inner area,

9c a view of another display device with a further design of the LED area and

9d a view of a display device in which the displayed character is composed of several sub-areas.

Embodiment 1

As in 1 As shown in the first embodiment, a ring light source consists of a semiconductor chip 1 in that a diode is designed so that when a voltage is applied to the diode, or when a current flows, light from a light emission region 2 on the surface of the semiconductor chip 1 is emitted. In the middle of the light emission area 2 is a hole 3 attached, which extends perpendicular to the surface of the semiconductor chip through the entire semiconductor chip. Since no light is emitted from the region of the bore when a voltage is applied to the diode, the entire component has the property of a miniature ring light. Since the ring light consists of a microstructure (a light-emitting diode), it is possible to obtain a ring light having a small inner diameter of about 0.01 mm to about 0.8 mm.

The above-mentioned semiconductor chip 1 may conveniently be a chip that is used in an LED. The term 'light emission region' is not intended to be limiting in that it denotes a region with photoluminescent material. The invention can be applied both to LEDs having a photoluminescent material on the surface of the semiconductor chip and to those which do not comprise such a material. If the photoluminescent material is missing, the area of the light emitting area is identical to the light emitting area of the diode. If the photoluminescent material is present, the light emitting region is that region of the photoluminescent material which emits light because it is excited by light from a diode formed in the semiconductor chip. Of course, there may also be hybrid forms in which the light emitting region includes both regions in which the light emission originates from the photoluminescent material, and regions in which the outwardly emitted light is emitted directly from a diode.

For example, the housing can be removed from a commercially available LED to Access to the semiconductor chip 1 to obtain. The opening 3 can then be from the top of the semiconductor chip 1 , or optionally the applied photoluminescent layer, to the underside of a carrier substrate 5 extend, on which the semiconductor chip is normally mounted. 8th Fig. 12 schematically shows a side view of such a structure. Since the photoluminescent layer and the support substrate are optional, they are not explicitly mentioned in the further embodiments.

3 shows a whole field of ring lights as they are in 1 are shown. Due to the small size of a single ring light, it is possible to realize such a field on a relatively small area. In this embodiment, a plurality of identical or different miniaturized ring lights can illuminate a field of objects. Likewise, this embodiment can be used to illuminate a plurality of glass fiber or tube ring lights with a single LED array. This would be conceivable, for example, on a microtiter plate, as used in molecular biology.

While protruding the hole 3 Of course, an LED may be designed from the outset so that its active light-emitting region has a ring shape. Such a design leads to an increased yield in the production of the ring lights, since the opening is not in the active, light-emitting diode region. This avoids the problem that the formation of an opening in the region of the diode junction can lead to short-circuits or contact interruptions in this area and thus to a failure of the luminous element. Furthermore, one avoids the problem that by forming the opening in the region of the sensitive diode junction, this area is exposed more strongly to environmental influences, as a result of which impurities (for example, drill cuttings), moisture and air can reach this point. This could degrade a photoluminescent layer by oxidation or reduction, or a short circuit could be induced.

Embodiment 2

The hole 3 does not necessarily have to be present in the midst of a single light emission area. Also conceivable is a structure in which the bore 3 in the middle of a field of light emission areas 2 is available. At the in 2 In the second embodiment shown, the panel includes four light emitting areas, with the opening 3 located in the middle between these areas. Because the four light emission areas 2 symmetrically the hole 3 surrounded, the device has the property of a ring light.

4 shows a similar embodiment as 2 , however, is in 4 the diameter of the opening 3 such that the light emission areas 2 directly to the edge of the opening 3 adjoin. For a circular shape of the opening 3 is thereby more closely approximating the shape of the entire light emitting area to an annular shape.

The embodiment of the invention according to the second embodiment is not limited to four light emission regions. In principle, the embodiment is applicable to any other number of light emitting regions within a field. However, the greater the number of light emission areas that the opening, the better the approach to an ideal ring 3 surround. Incidentally, the light-emitting regions need not all be identical in shape to each other.

Method for producing the ring lights according to embodiment 1 and 2

Experiments have shown that many techniques for making the holes or openings 3 each technique has specific advantages and disadvantages. If the position and initially present shape of a light emission area is not known in advance, these can be determined by applying a low voltage to the light emitting diode. The light emission area can then be detected with the naked eye without damaging the eye.

Mechanical drilling

In mechanical drilling, attention must be paid to the different hardnesses of the materials constituting the LED, such as the carrier substrate of the semiconductor chip, the semiconductor crystal, the fluorophore and the protection gel, in order to prevent break-up. Therefore, the LED (without housing, ie the semiconductor crystal together with possibly applied layers, optionally with and without carrier substrate) must be fixed as flat as possible and stable on a base. In addition, when selecting the speed, make sure that the LED is not overheated, so that the diode is not damaged. Care must also be taken that the drilling dust does not penetrate into or under the protective gel. This affects the radiation of the LED by its mere presence, but can additionally damage the phosphor. The protective gel is a kind of optically transparent protective lacquer which protects the phosphor layer of an LED against environmental influences, in particular moisture and oxygen protects. Depending on the LED manufacturer, hardening or even elastic substances are used. Therefore, it is recommended, but not possible on all dimensions, to use hollow drills. For small LED surfaces and correspondingly very small holes, the drill must be mounted without vibration and backlash and the centering of the drill must be made extremely precise. Here we recommend a camera system on the drill stand, respectively on the lathe.

laser drilling

At the Laser drilling, the centering is naturally easier. A high-energy laser beam can be surrounding material destroy and leaves almost always traces of combustion. These affect the luminosity the remaining active regions of the LED. It is also difficult to drill a circular hole at very small dimensions.

Waterjet drilling

The Drilling with a water jet leaves the fewest traces on the remaining material, but can lead to the breakage of the silicon or how the mechanical drilling to disintegrate the individual Layers. Likewise is on the dust of the removed material too respect, think highly of.

Micro Erosionstechnik

Micro Erosionstechnik with or without previous micro-drilling leads to the most beautiful Results, but is very complex and only in large numbers profitable.

Embodiment 3

According to the third embodiment, ring lights designed according to Embodiments 1 or 2 are glass or plastic tubes or capillaries as optical fibers 4 applied. The application takes place z. B. with optical adhesive directly to the light emission areas. The final product is in 6 shown. In the apparatus obtained, the coupling of light is optimized in the light guide and thus, in addition to the size compared to the prior art also reduces the energy consumption gieverbrauch. Of course, the applied optical fiber 4 also a (quartz) glass fiber ring or a plastic fiber ring.

There all capillaries in general tubes with very small ones Inside diameters are, from now on this term is omitted and only the term tube is used. It should be noted, that these tubes can be very thin, ie inner diameter from about 0.01 mm upwards.

The Light conducting pipe can visually have different properties. Depending on the purpose and required light intensity a normal glass or plastic tube can be used, whose Light conducting properties solely by total reflection at the Inner and outer walls are created. It is conceivable that inner or the outer or both surfaces to mirror metallically to improve the light conductivity. Furthermore, the light-conducting tubes can also be specific hollow optical fibers act whose cross-section one or two jumps or a refractive index gradient. Accordingly can offer various light-guiding properties at arbitrary wavelengths to get voted.

light Conductive pipes are available in different dimensions and variants for various wavelengths available and can adapted to the particular use of the instrument. Such a mounted tube can represent a cone in the broadest sense, by the inner or the outer diameter or also both diameters over the tube length or a part of it does not stay constant. The diameter and the Width of the pipe wall at the exit point of the light can so be smaller or larger than the corresponding ones Values for the wall on the side in which the light passes through the annular LED is coupled.

Furthermore, the wall of the light-conducting tube may have recesses or gaps in the longitudinal direction. Thus, the tube can be composed of two half-shells, which can diverge at the end at which the light emerges, and can have different lengths. Likewise, it is conceivable that the tube consists of longitudinally extending segments that do not touch each other and do not even have to be made of the same light-conducting material, as in 7 is indicated. Further, it is sufficient if the tube is seated only at the locations on an LED where there is a light emission area on the surface of the semiconductor chip.

When applying pipes to the ring light LED, it must be ensured that the respective inside diameters are well centered and not tilted against one another. An optical adhesive must be used so that the light coupling can take place as unhindered as possible. Due to the small fixation support and the relatively large leverage effect of the long tube, the adhesive must also provide sufficient stability. In certain applications, an additional external reinforcement in the form of, for example, a protective cap must be applied. An internal reinforcement in the form of an intermediate tube is also thinking bar, if the dimensions allow it. Furthermore, the inside of the tube and also the hole through the LED should remain free of penetrating adhesive, which must be actively prevented especially for very small inner diameters due to the capillarity. Under certain circumstances, it makes sense to use the center to be placed later in the same work step, unless it has to be replaced, rotated or moved longitudinally later.

Fit, Straightness and stability when gluing can also can be achieved with a matching sub-item, typically a wire with a corresponding diameter or even better with a Teflon rod with the required dimensions. The latter will not fixed by inward adhesive, as Teflon can only be firmly glued with very few adhesives. Otherwise can, if the dimensions allow, an inner intermediate tube inserted as a stabilizer and adhesive insulator in one become

Embodiment 4

Instead of a single or a plurality of circular holes through the entire LED component, as described in the first to fourth embodiments, also structures of any shape can be drilled, milled, laser cut, cut or eroded into the component. These can be overlapping holes of different diameters, angular, oval or combined shapes. The LED component may have a single or a plurality of light emission regions, the shape of which is varied, as shown in FIG 5 is shown. The term "light emission region" is used here in the same way as was the case in the preceding embodiments, ie a light emission region does not necessarily have to be identical to a light emitting diode region.

In order to become light-emitting areas in the form of arbitrary ring light combinations, Shapes, figures or symbols created during operation of the LED become self-luminous. Such arbitrarily designed forms of LEDs can for complicated lighting or too Used to display symbols on machines or devices become.

For example, the light emitting area of an LED may be configured to display an arrow, as in FIG 9a to 9d shown.

In the presence of a single light emission area, as in 9a to 9c That is, the outline of the light-emitting area along which the boundary to the non-light-emitting area passes is identical to the contour of the shape to be displayed, here, an arrow symbol, and a viewer looking at the LED immediately sees the arrow symbol ,

There are no limits to the shape of the light-emitting region. Thus, there may be islands in the light emission area that do not emit light, as in US Pat 9c is shown. In this way, for example, one could also represent the letter 'A' or, as a general symbol of toxicity, a skull whose eyes and nose are not lit.

A further possible applications are control LEDs on electrical appliances, for example, the word "ON" radiate without a corresponding slide must be mounted above it. Further could also detailed, fixed, information panels or self-luminous company logos are created. Especially the specially designed light emission areas have to not all on a single semiconductor chip.

By combining different colored LED lighting panels in SMD technology colorful shapes can be generated, as they are used in entertainment media or toys like. Many small LEDs can be applied next to each other on a single carrier substrate, as is known from LED arrays. The individual light emission regions can deviate from one another in the emitted light wavelengths or intensities. The individual light emission regions need not all be the same size and not all have the same shape. They can have interruptions, holes, bulges, and debauchery, creating special luminescent forms, as in 9d is shown.

LED manufacturers The individual LEDs could be targeted during production make in the appropriate forms. this could for example, by a corresponding embodiment of lithography masks happen. The figures can not only by Ätzvorgänge, but z. B. also by Aufwachsvorgänge or layer application be generated.

Even though in the above embodiments in many places on the Applicability of the invention for very small ring lights or light sources has been pointed out, the invention is not on this limited. When using correspondingly strong LEDs is of course also a macroscopic applicability Range (ring light diameter greater than 1 cm, preferably greater than 3 cm).

Although a variety of applications of the ring lights and display devices according to the invention is conceivable, the before underlying invention especially for ring lights and display devices in combination with dental equipment and general medical devices and endoscopes or with industrial or forensic boroscopes or lighting for automated camera systems, such as those used in large-scale production facilities.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• EP 0194229 A2 [0005]
• DE 102005030761 A1 [0008]
• US 2004/0249424 A1 [0010]
• WO 02/062262 A2 [0010]
• EP 0194229 A1 [0010]
• - CH 673214 [0010]

Claims (32)

Ring light for the concentric illumination of an object or a surface, wherein the ring light is a semiconductor chip ( 1 ), in the surface of the semiconductor chip ( 1 ) at least one light-emitting diode region is formed, which can emit light perpendicular to the surface and on the surface of the semiconductor chip in addition to at least one light emitting diode region associated with the light emitting region ( 2 ) at least one point from which no light can be emitted, this point being concentric with one or more of the light emission areas ( 2 ) is surrounded and the shape of a recess ( 3 ) formed in the surface. Ring light according to claim 1, in which the recess ( 3 ) extends through the entire thickness of the semiconductor chip. A ring light according to claim 1 or 2, wherein the at least one non-light emitting point is located in the midst of a single light emitting region ( 2 ) is located. Ring light according to claim 1 or 2, wherein the at least one light-emitting point is located in one of the interspaces of a field of light-emitting regions ( 2 ) is located. A ring light according to claim 1, 2 or 4, wherein the at least one non-light emitting point forms part of an edge region of at least one light emitting region ( 2 ) covers. Ring light according to one of Claims 1 to 5, in which the light emission region ( 2 ) has a layer of photoluminescent material, which on the surface of the semiconductor chip ( 1 ) is applied. Ring light according to one of claims 1 to 6, wherein on the edge of the at least one light-emitting point, a light-conducting tube ( 4 ) is placed so that it covers the peripheral region of the at least one non-light-emitting point. Ring light according to Claim 7, in which the light-conducting tube ( 4 ) is a glass tube or a plastic tube. Ring light according to claim 7 or 8, wherein the light-conducting tube ( 4 ) is flexible. Ring light according to one of claims 7 to 9, wherein the light-conducting tube ( 4 ) is a capillary tube. Ring light according to Claim 7, in which the light-conducting tube ( 4 ) is a fiberglass ring or a plastic fiber ring. Ring light according to Claim 7, in which the light-conducting tube ( 4 ) is a quartz glass fiber ring. Ring light according to one of claims 7 to 12, wherein the inner diameter of the light-conducting tube and / or its outer diameter is not constant. Ring light according to claim 13, wherein the inner diameter and / or the outer diameter of the light-conducting tube at the end, which on the semiconductor chip ( 1 ), is smaller or larger than at the opposite end. Ring light according to Claim 7, in which the light-conducting tube ( 4 ) is composed of two half-shells that do not need to touch each other. Ring light according to claim 7, wherein the light is conductive Tube is composed of more than two segments that are not have to touch. Ring light according to Claim 7, in which the wall of the light-conducting tube ( 4 ) is present only at the locations of the edge of the non-light-emitting point at which outside of the edge on the semiconductor chip ( 1 ) a light emission area ( 2 ) is located. A method of producing a ring light, comprising the step of: forming a non-light emitting site on the surface of a semiconductor chip ( 1 ), which has at least one light emitting diode region, wherein the non-light emitting point concentrically of one or more of the light emitting regions ( 2 ), which are associated with the at least one light-emitting diode region, is surrounded and formed by forming a recess (FIG. 3 ) in the surface of the semiconductor chip ( 1 ). Method according to Claim 18, in which the recess ( 3 ) is formed at least partially by a drilling operation. Method according to claim 18 or 19, in which the recess ( 3 ) is formed at least partially by an etching process. Method according to one of claims 18 to 20, wherein the recess ( 3 ) is formed at least partially by an erosion process. The method of claim 19, wherein the drilling operation by means of mechanical drilling, turning or milling, or water jet drilling or Cutting is done with a laser. Display device for displaying image information, comprising a semiconductor chip ( 1 ), in the surface of which a light-emitting diode region is formed, to which a light emission region ( 2 ), which can emit light perpendicular to the surface, the light emission region ( 2 ) is delimited from one or more areas from which no light is emitted, that the borderline has the shape of a hint symbol, icons, logos or an image. Display device for reproducing image information containing one or more semiconductor chips ( 1 ), in which in the surface in each case a light-emitting diode region is formed, the at least one light emitting region ( 2 ), which can emit light perpendicular to the surface, wherein a plurality of the light emission regions ( 2 ) arranged so as to be in the form of a hint symbol, icon, logo or picture in their entirety. A display device according to claim 23 or 24, wherein a light emitting area (Fig. 2 ) has a layer of photoluminescent material deposited on the surface of the semiconductor chip. Display device according to one of the claims 23 to 25, wherein a non-light-emitting region by at least partial removal of the layers is formed, which in the light-emitting diode region serve the formation of the LED. Display device according to one of the claims 23 to 26, in which the shape of the semiconductor chip with the shape of the light emission area is identical. A display device according to claim 23 or 24, wherein the non-light emitting area by applying an opaque Layer formed on the surface of the semiconductor chip is. Display device according to one of the claims 23 to 28, wherein the shape of the light emission area is at least a character or a number or a company logo or a Combination has the same. A method of manufacturing a display device according to any one of claims 23 to 29, wherein the shape of a light emitting region (Fig. 2 ) is formed by removing parts of the light-emitting diode region or the photoluminescent layer of an LED by means of etching, milling, milling, turning or erosion. Method for producing a display device according to claim 30, wherein the shape of a light emitting region is formed by additional removal of parts of the semiconductor chip, which are not part of the diode, by means of etching, tube, Turning, sawing, milling or eroding. Method for producing a display device according to any one of claims 23 to 31, wherein the shape of a light-emitting diode region is formed by using appropriately designed lithography masks in the production the diode.