EP2753863B1 - Lighting device - Google Patents

Description

A lighting device, for example for room lighting, is specified. 4th US2011 / 0175518 discloses a lighting device having an LED matrix and a wavelength conversion substance.

Further disclosed US2010 / 0123855 a lighting device with LEDs and a wavelength conversion substance.

For room lighting, a high light intensity is required, whereby even when using light-emitting diodes (LED) as light sources, a high waste heat can occur. Known LED-based light sources are therefore usually constructed with particular regard to the chip materials and the heat dissipation materials and often have an active cooling that cools a heat sink using a fan air flow.

In order to produce mixed-color and in particular white light, LED-based light sources usually have light-emitting diode chips that are individually provided with a phosphor. In order for a uniform color impression in a light source with a plurality of such LED-based light sources with individual phosphors can arise from the outset by a precise selection of the LED chips and the phosphor layers each emitted color must be set very accurately. This results in high demands on an accurate color measurement technology and accurate production control of the LED chips.

In addition, typical ballasts for LED-based light sources are usually designed as potential-free compact switching power supplies, which can usually have not inconsiderable power losses of up to 20%.

The publication US 2011/0175518 A1 describes a light source with a PCB on which a substrate with LEDs is arranged. The surface of the PCB is covered with a reflective layer adjacent to the substrate. Above the LEDs is a transparent cover with a spherical recess on the inside and a lenticular projection on the outside. On the inside, as seen from the LEDs, a wavelength conversion layer and above a filter layer are arranged.

The publication US 2010/0123855 A1 describes light-emitting modules having on a support, for example a PCB, which may be provided with a reflective coating, a plurality of LED chips, which are covered with a transparent resin and above a wavelength conversion layer. Furthermore, a display component is described with such a light-emitting module in a bottom housing, which is covered with an optical layer and a display panel, so that over the wavelength conversion layer, a cavity is formed.

The publication WO 2006/013800 A1 describes a light source comprising a substrate having a metal layer and insulating layers deposited thereon Has printed conductors for connecting LED chips. Above the LED chips, a lens plate is arranged.

The publication EP 2 058 584 A1 describes a street lighting with a plurality of LEDs on a printed circuit board in a housing with a base plate in which openings for lenses are present. In addition to exactly one LED and one lens per opening, a plurality of LEDs and associated therewith an optical element with a plurality of lens-like structures can also be present.

At least one object of certain embodiments is to provide a lighting device having a plurality of light-emitting semiconductor chips.

This object is achieved by an article according to the independent claim. Advantageous embodiments and further developments of the subject matter are characterized in the dependent claims and will become apparent from the following description and the drawings.

In accordance with at least one embodiment, a lighting device has a carrier plate, on which a plurality of light-emitting semiconductor chips spaced apart from each other is arranged. In particular, the lighting device may be suitable for room lighting.

According to a further embodiment, the carrier plate has a plastic material and can, for example, in particular comprise a plastic plate or plastic layer. Furthermore, the carrier plate can have conductor tracks or electrical contact paths on a surface or in the interior, by means of which the light-emitting Semiconductor chips can be contacted electrically. In addition, the support plate may for example comprise a metal layer and / or a metal plate. For example, the carrier plate can be a plastic layer have, which is glued to a metal plate or a metal foil. The metal plate or metal foil may be arranged, for example, on the rear side of the carrier plate facing away from the semiconductor chips.

According to a further embodiment, the carrier plate has a reflective mounting surface, on which the plurality of light-emitting semiconductor chips is arranged. The reflective mounting surface may in particular be formed by a metallically conductive layer, that is, for example, by an applied layer with a reflective metal. By way of example, the metallically conductive layer can also provide an electrical connection for the semiconductor chips and be formed at least partially in the form of conductor tracks, contact paths and / or connection surfaces. The metallically conductive layer can, for example, be vapor-deposited or patterned by phototechnical means and subsequently electrolytically reinforced. It is also possible to print the metallically conductive layer by other methods and then thermally and / or chemically produce the desired structure. Alternatively, it is also possible to apply a punched-out metal foil surface by gluing. In particular, the metallically conductive layer can be applied to a plastic film or plastic plate.

According to a further embodiment, the semiconductor chips are applied by gluing, for example by means of a conductive adhesive, or by soldering to the metallically conductive layer. It is also possible to electrically connect light-emitting semiconductor chips with contact terminals facing away from the carrier by bonding, that is to say by so-called bonding wires, to the metallically conductive layer.

According to a further embodiment, a translucent or transparent, ie a diffusely translucent or transparent, radiation plate with a light output semiconductor chip facing away from the light emitting semiconductor chips in the emission direction downstream of the light emitting semiconductor chips. The radiating plate may comprise or be made of a transparent or translucent material, for example a plastic material or a glass.

The radiating plate can be designed, for example, as a diffusing screen which, in particular in conjunction with the reflective mounting surface of the carrier plate, has a glare-free light output surface.

According to a further embodiment, the radiating plate has a recess above each of the plurality of light-emitting semiconductor chips, wherein each of the recesses has a diffuser material and / or a wavelength conversion substance on an inner surface facing the semiconductor chips. The recesses have such dimensions that the diffuser material or the wavelength conversion material is spaced from the semiconductor chips.

According to a further embodiment, the recesses are dome-shaped. In particular, the recesses may be formed in the form of spherical sections or elliptical sections, so that the respective inner surface has the shape of a spherical shell or an ellipse shell. The recesses can be incorporated into the radiating plate, for example by embossing be. It is also possible to make the recesses in the manufacture of the radiating plate simultaneously. If the radiating plate comprises or is made of a plastic or a glass, the recesses can be incorporated during the shaping of the radiating plate, for example by casting. It is also possible to incorporate the recesses in a rolling process.

According to a further embodiment, the recesses are formed the same, ie in particular with the same shape and the same size. It is alternatively also possible that the recesses are formed differently.

According to a further embodiment, precisely one light-emitting semiconductor chip is arranged in each case in a respective recess. Furthermore, each of the semiconductor chips can be arranged downstream of exactly one recess.

According to a further embodiment, the recesses have a diameter which is at least twice greater than side lengths of the light-emitting semiconductor chips. Furthermore, the recesses may have diameters less than or equal to twenty times the side lengths of the light-emitting semiconductor chips. In this case, adjacent recesses may preferably be spaced from each other. Alternatively, it is also possible that adjacent recesses merge into each other.

According to a further embodiment, the radiating plate is fixed to the carrier plate. For example, the radiating plate can be fixed to the carrier plate by means of a fixed but detachable connection possibility. For example, the radiating plate by means of clamping nails be connected to the carrier plate. The clamping nails, which may be formed, for example, as plastic nails or plastic rivets, may extend from the light emitting surface of the radiating plate through the radiating plate and the carrier plate to a rear side of the carrier plate, where they are connected with clamping nail caps in a clamping connection. The radiating plate and the carrier plate may have holes through which the clamping nails protrude. As an alternative to the clamping nails other connecting pins can be used, such as screws. Furthermore, the radiating plate can also be mounted laterally displaceably on the carrier plate, for example with connecting pins such as clamping nails or eccentric screws and holes or holes in the carrier plate and / or the radiating plate, which have a larger diameter than the connecting pins or which are embodied for example as elongated holes. In addition, other known fastening and adjustment possibilities and Justiereinstellhilfen can be provided by means of which two larger plates laterally displaceable precisely adjusted to each other and can be fixed.

According to a further embodiment, the light-emitting semiconductor chips are suitable for emitting light in a wavelength range from ultraviolet radiation to infrared radiation, particularly preferably visible light. In this case, one or more or all of the semiconductor chips can emit monochromatic or mixed-colored light, for example white light. For this purpose, a semiconductor chip can have a light-emitting semiconductor layer sequence which emits directly monochromatic light or additionally has a wavelength conversion element in the form of a light-emitting semiconductor layer sequence Phosphor layer, a phosphor plate or a phosphor-containing potting is applied, which can convert at least a portion of the radiation generated by the semiconductor layer sequence in light with a different wavelength. The semiconductor chips may in particular be designed as epitaxially grown semiconductor layer sequences or may each have an epitaxially grown semiconductor layer sequence. The semiconductor layer sequence may comprise an arsenide, phosphide and / or nitride compound semiconductor material, which is formed with respect to its composition and in terms of its layer structure according to the desired light. In particular, one or more or all of the semiconductor chips can be mounted directly on the carrier body, that is to say in particular on the reflective mounting surface, without a respective housing body.

According to a further embodiment, the semiconductor chips are equal to one another and emit at least substantially the same light. "Essentially the same light" and "identical semiconductor chips" here and in the following mean that the light emitted by the individual semiconductor chips as well as the compositions of the semiconductor chips can be differentiated within the scope of customary manufacturing variations. In particular, the semiconductor chips may preferably emit blue light. The light of the semiconductor chips, as explained further below, can be partially converted by means of the wavelength conversion substance into light of a different color, so that the illumination device can emit mixed-colored light.

According to a further embodiment, semiconductor chips emitting different colors are used, which enable a desired mixed-color, in particular white, illumination only at the illuminated location. As a result, the light-emitting plate can have differently colored points of light, while the illumination effect is produced by the superimposition and the mixture of the individual different colors of the semiconductor chips. This may also make it possible, for example, for information, for example traffic information, notes or logos, such as company logos, to be clearly color readable on the light emitting surface, while white light is perceived by the arrangement of differently colored semiconductor chips at a location to be illuminated. Such an unusual experience has hitherto been known, for example, only from polished glass prisms of chandeliers, in which colored areas of the lamp are artificially caused by white light.

In accordance with a further embodiment, the semiconductor chips are arranged on the carrier plate at a distance from each other in such a way that the spacing of two respective directly adjacent semiconductor chips is a multiple of the side lengths of the semiconductor chips. Typical side lengths for semiconductor chips may, for example, be less than or equal to a few millimeters, in particular less than or equal to 1 millimeter.

According to a further embodiment, the semiconductor chips are distributed on the carrier plate with a density of approximately 1 semiconductor chip per square centimeter.

The spaced arrangement of the semiconductor chips on the carrier plate allows a large beam area while low power dissipation, that is, the heat dissipated heat generated during operation of the light-emitting semiconductor chips in the carrier body is evenly distributed and thus no so-called "hot spots" arise.

In particular, the illumination device can have a large light emission area combined with a low power dissipation through the spaced-apart light-emitting semiconductor chips, whereby an effective heat transfer from the semiconductor chips to the surrounding air is possible in a simple manner via the carrier plate and via the light output surface of the radiation plate. In particular, it may be advantageous if the metallically conductive layer has a significantly larger area than the area occupied by the semiconductor chips, whereby an effective heat distribution on the carrier plate is achieved. At the same time, as described above, the semiconductor chips can be adhesively bonded or soldered onto the metallically conductive layer in an electrically conductive manner, so that the metallically conductive layer can also have contact connections and can serve to supply the current. If the carrier plate has an insulating layer, for example a plastic layer on which the metallically conductive layer is applied, and if the insulating layer has sufficiently high electrical insulation of contact possibilities, the entire interconnection of the light-emitting semiconductor chips, for example, can also be based on the power grid potential. It can be simple low-loss power supplies with voltages of several times the respective individual voltage of a semiconductor chip used become. Below, an embodiment of a suitable electrical circuit is described.

Although the heat flow from the individual semiconductor chips that has been widened by the metallically conductive layer must flow through the insulating layer as far as the rear side of the carrier plate, the thermal resistance thereof is usually significantly lower in relation to the transition between the carrier plate and the air. The maximum density of the semiconductor chips on the carrier plate, in particular on the metallically conductive layer, is essentially determined by the physically limited air-heat transmission rate with natural convection of a maximum of about 10 W / (K m ² ), wherein the natural convection still can be supplemented by a heat radiation in the best of the same order of magnitude.

According to a further embodiment, the carrier plate has a plurality of webs on the mounting surface and / or on the rear side opposite the mounting surface. The webs may be formed, for example, in the form of profile knobs or web-shaped elevations. By the webs, for example, an increase in the stability of the carrier plate can be achieved. For example, the support plate between the webs may have a thickness of about 0.5 mm to about 2 mm, while the webs may have a web height in the order of 0.3 mm to 2 mm, the boundaries are respectively included, whereby the material the support plate mechanical strength and thus security against bending and twisting can be given. Bends or twisting of the support plate are to be avoided, since these could lead to solder or adhesive tears of the semiconductor chips on the mounting surface.

The radiating plate may have grooves on the side facing the carrier plate, in which webs present on the mounting side of the carrier plate are arranged. As a result, an increase in the stability of the connection between the carrier plate and the radiating plate can be achieved.

Furthermore, in particular webs which are arranged on the opposite side of the mounting surface, for example, also serve for cooling. For cooling, it is particularly advantageous if the webs arranged on the back run in such a way that they are parallel to the main cooling air flow, in the case of natural convection, therefore, perpendicular to the later operating orientation of the lighting device. In other words, the back webs can particularly preferably run along the direction of gravity in an operating device arranged for operation.

By the webs, especially back webs, for example in the form of profile studs in the vertical direction of air flow to achieve a chimney effect, thus a mechanical stiffening and at the same time a surface enlargement to improve the heat transfer to passing air, ie convection, as well as to improve the heat dissipation can be achieved ,

According to a further embodiment, the radiating plate has a web-shaped structure on the light outcoupling surface. With this, a similar effect can be achieved as through the webs of the carrier plate. Furthermore, by the web-shaped structure on the light output surface and the Abstrahlcharakteristik the lighting device can be influenced.

In accordance with a further embodiment, the carrier plate or at least the rear side of the carrier plate facing away from the mounting surface has a material or a coating which has good heat radiation. In particular, a good heat radiation is understood to mean a heat emission level which is as close as possible to 1 in a temperature range from about 50.degree. C. to about 100.degree. Such a thermal emissivity can be achieved, for example, by means of glass as the material of the carrier plate. In the case of a back-side coating of the carrier plate, the coating may in particular be rough, for example formed by a radiator paint or a suitable lacquer or a glaze.

According to a further embodiment, the rear surface of the carrier plate opposite the mounting surface is formed by a metal plate or metal foil. The metal plate or metal foil may have, for example, webs described above and / or a heat-radiating surface coating described above. In the case of a metal plate or metal foil forming the rear side of the carrier plate, the heat-radiating surface coating may also be formed, for example, as an anodized layer. Furthermore, it is also possible to provide the rear metal plate or metal foil for connection of a protective conductor for the lighting device.

According to a further embodiment, a wavelength conversion substance is arranged downstream of the light-emitting semiconductor chips. It can, how described above, the wavelength conversion substance can be arranged in the form of a phosphor directly on the semiconductor chips. However, the wavelength conversion substance is particularly preferably arranged in the recesses of the radiation plate. It is also possible that in each case a wavelength conversion substance is formed both directly on a semiconductor chip and on the inner surface of the recess downstream of the semiconductor chip, wherein the wavelength conversion substances may be identical or different in order to achieve a desired emission characteristic.

According to a further embodiment, the respective wavelength conversion substance in the recesses is suitable for converting the primary light emitted by the respectively assigned light-emitting semiconductor chips into a secondary light different therefrom. The primary light and the secondary light may comprise one or more wavelengths and / or wavelength ranges in an infrared to ultraviolet wavelength range, in particular in a visible wavelength range. For example, the primary light may have a wavelength range from an ultraviolet to green wavelength range, while the secondary light may have a wavelength range from a blue to infrared wavelength range. Particularly preferably, the primary light and the secondary light superimposed can create a white-colored luminous impression. For this purpose, the primary light can preferably give rise to a blue-colored luminous impression and the secondary light can produce a yellow-colored luminous impression, which can result from spectral components of the secondary radiation in the yellow wavelength range and / or spectral components in the green and red wavelength ranges.

The wavelength conversion substance may comprise one or more of rare earth and alkaline earth metal garnets such as YAG: Ce ³⁺ , nitrides, nitridosilicates, sions, sialons, aluminates, oxides, halophosphates, orthosilicates, sulfides, vanadates and chlorosilicates. Furthermore, the wavelength conversion substance may additionally or alternatively comprise an organic material which may be selected from a group comprising perylenes, benzopyrene, coumarins, rhodamines and azo dyes. The wavelength conversion substance in the recesses may in each case comprise suitable mixtures and / or combinations of the stated materials.

The material or materials for the wavelength conversion substance may be in the form of particles, which may have a size of 2 to 10 μm.

According to a further embodiment, a diffuser material is arranged on the inner surfaces of the recess, in particular having scattering particles or may be formed thereby, for example comprising or may be a metal oxide, such as titanium oxide or alumina such as corundum, and / or glass particles. The scattering particles may have diameters or grain sizes of less than one micrometer up to an order of magnitude of 10 micrometers or even up to 100 micrometers.

Furthermore, the diffuser material and / or the wavelength conversion substance can be embedded in a transparent matrix material and / or chemically be bound. The transparent matrix material may comprise, for example, siloxanes, epoxides, acrylates, methyl methacrylates, imides, carbonates, olefins, styrenes, urethanes or derivatives thereof in the form of monomers, oligomers or polymers and furthermore also mixtures, copolymers or compounds therewith. For example, the matrix material may comprise or be an epoxy resin, polymethylmethacrylate (PMMA), polystyrene, polycarbonate, polyacrylate, polyurethane or a silicone resin such as polysiloxane or mixtures thereof.

The respective diffuser material and / or the respective wavelength conversion substance in the recesses can be distributed homogeneously in the matrix material. Furthermore, a combination of a plurality of said materials for the diffuser material and / or the wavelength conversion substance can be arranged in one or more or all the recesses, which can be mixed or present in different layers.

According to a further embodiment, the diffuser material and / or the wavelength conversion substance are layered on the inner surface. As a result, the diffuser material and / or the wavelength conversion substance can be arranged, in particular, at a distance from the respectively assigned light-emitting semiconductor chips in the recess. The diffuser material and / or the wavelength conversion substance may be evenly distributed over the inner surface of a recess. Alternatively, it is also possible. that a wavelength conversion substance, for example, by a sedimentation process or another suitable process unevenly in terms of its composition and / or is applied in a recess in terms of its thickness, for example, to achieve a desired color luminance and color effect.

According to a further embodiment, the radiation plate in at least some or all recesses on the semiconductor chip facing inner surface on a wavelength conversion substance on the side facing the semiconductor chips each side has a reflector layer, which is reflective for the converted from the wavelength conversion material secondary light and that of the semiconductor chips radiated primary light is permeable. The reflector layer can be applied for example in the form of a so-called Bragg reflector in the multi-layer method.

In the case of a wavelength conversion substance arranged at a distance from a semiconductor chip on the inner surface of a recess, the wavelength conversion substance may be thermally separated from the semiconductor chip. As a result, it is possible to prevent the so-called Stokes conversion loss heat arising in the wavelength conversion substance, which arises during the conversion of the primary light of the semiconductor chip into the secondary light, from heating the semiconductor chip. Rather, the loss of conversion heat can be released via the radiating plate to the ambient air at the light outcoupling surface, whereby the wavelength conversion substance and also the semiconductor chip can be kept cooler than in the case of a wavelength conversion substance arranged directly on a semiconductor chip. Furthermore, the wavelength conversion substance on the inner surface of the Recess over the semiconductor chip with respect to a direct chip coating larger converter layer surface, whereby the power density of the primary light in the wavelength conversion material is lower. As a result, a significantly lower aging degradation of the wavelength conversion substance is to be expected.

Furthermore, due to the diffuser material and / or the wavelength conversion substance on the inner surface of the recesses in the case of a direct view of the light outcoupling surface without additional scattering measures, the glare effect by the light-emitting semiconductor chips can be so small that no unpleasant consequences occur for a viewer.

According to a further embodiment, the carrier plate is equipped with the light-emitting semiconductor chips. For example, during operation, the semiconductor chips can all emit the same light, in particular blue light. Manufacturing tolerances with regard to the individual semiconductor chips, which result in slightly different color locations and / or wavelength ranges of the respectively emitted light, can be determined by means of a short operation of the semiconductor chips and a preferably fast, spectral measurement. From this, the respective compositions and thicknesses of the wavelength conversion substances as well as their respective distributions on the inner surfaces of the recesses of the radiating plate can be calculated, which may require that as uniform as possible light and the same color, for example white, light be radiated over the entire radiating plate. For example, slightly different blue radiated from the semiconductor chips Wavelengths corresponding different materials and / or compositions of the wavelength conversion materials and / or different thicknesses of the wavelength conversion materials can be calculated. In particular, by the data of the spectral measurements, for example, automatically running, individually controlled coating processes for the wavelength conversion substances in the recesses of the radiating plate can be controlled such that the color variations of the semiconductor chips can be compensated for by adapted wavelength conversion materials.

This makes it possible to select and install semiconductor chips from a larger color and brightness tolerance range, since no complex individual color compensation has to be performed chip by chip. Rather, a spectral measurement of all, for example, over one hundred, light emitting semiconductor chips on the carrier, which can be followed by an individual coating of the recesses of the radiating plate in an automatic process, after which the radiating plate is joined to the carrier.

According to a further embodiment, the radiating plate has scattered particles distributed for diffuse scattering in the radiating plate. The scattering particles, which can be melted in, for example, in the production of the radiating plate, may, for example, have a previously described diffuser material. Furthermore, it is also possible that the radiating plate has a translucent, light-scattering coating on the light output surface. With particular advantage, the scattering body and / or the coating have the highest possible degree of absorption or spreading in the temperature range from 30 ° C to 80 ° C on.

Furthermore, it is also possible that the radiation plate on the light output surface scattering structures, for example in the form of depressions or elevations, which may be evenly or randomly distributed on the light output surface. Additionally or alternatively, it is also possible that the radiating plate has a scattering coating or scattering structures on the side facing the light-outcoupling surface and facing the carrier plate.

According to a particularly preferred embodiment, the illumination device particularly preferably spatially separated, so spaced light emitting semiconductor chips on the mounting surface, where the radiating plate is arranged downstream of the recesses, wherein in the recesses a wavelength conversion substance is arranged. In comparison with conventionally used expensive aluminum or copper carriers or corresponding metal core boards, good heat dissipation can preferably be formed by a metallically conductive layer on a plastic layer or plate on which the semiconductor chips are connected electrically and at the same time thermally. Due to the arrangement of the semiconductor chips on the carrier plate and the radiating plate arranged downstream of the semiconductor chips, the individual semiconductor chips can satisfy limited requirements with respect to their size and power as well as with respect to their respective radiated color loci. In addition to the wavelength conversion substance in the recesses, the radiation plate preferably has scattering structures on the light emission surface and / or the surface opposite the light-emitting surface and / or in the form of volume-embedded scattering particles. In addition, the combination with the webs described above, particularly on the back of the support plate is particularly advantageous in order to achieve a simple, yet sufficient cooling effect with simultaneous mechanical strength and stiffening.

According to a further embodiment, the radiation plate has a lens-shaped surface structure over at least some recesses. The surface structure may in particular be formed as a bulge, ie convex, on the light output surface. It is also possible that the lenticular surface structure protrudes in the form of a recess, that is concave, as a recess in the light output surface. Due to the lenticular surface structures, it may be possible to optimize the radiation behavior, in particular for the far field of the lighting device as desired. It does not have to be present over all recesses and thus over all light-emitting semiconductor chips, a lenticular surface structure. But it may also be possible that a lenticular surface structure is arranged over each of the recesses, so that there is exactly one recess or indentation per recess. The lenticular surface structures may be simultaneously incorporated as described above for the recesses in producing the radiating plate, for example by a stamping or rolling process or by a casting process by which the radiating plate, for example made of a plastic material or glass, is produced. It is also possible, the lenticular surface structures in particular in the case of convex bulges of a transparent or translucent material in a rolling process subsequently applied to the light output surface of the radiating plate. The material of the lenticular surface structures may be the same as for the radiating plate or another.

According to a further embodiment, the lighting device has an electrical circuit for operating the semiconductor chips of the lighting device. The electrical circuit, which may allow, for example, the operation of the lighting device with mains voltage, for example, have a non Netzpotentialfreies ballast with bridge rectifier, current limiting series capacitor and the inrush current limiting small series resistance in an electrical supply line of the lighting device. As a result, the carrier plate with the semiconductor chips and the radiating plate can be made particularly filigree. Alternatively, it is also possible to integrate parts of the electrical circuit, such as the ballast, in the lighting device.

The lighting device described here may, for example, be glare-free in accordance with the listed features and embodiments. Furthermore, the heat, for example, directly to the environment, so the room air, are delivered without additional fans and the associated noise development must be taken into account. Furthermore, the mechanical assembly can be done easily, at the same time the electrical contact and the heat dissipation and the high voltage insulation, for example, up to 4 kV, can be made possible.

Further advantages, advantageous embodiments and developments emerge from the embodiments described below in conjunction with the figures.

• Figur 1 eine schematische Darstellung einer Beleuchtungsvorrichtung gemäß einem Ausführungsbeispiel,
• Figuren 2A bis 7C schematische Darstellungen von Beleuchtungsvorrichtungen gemäß weiteren Ausführungsbeispielen,
• Figur 8 schematische Darstellungen von Anordnungen von Beleuchtungsvorrichtungen in einem Raum gemäß weiteren Ausführungsbeispielen und
• Figur 9 eine schematische Darstellung einer elektrischen Schaltung zum Betrieb einer Beleuchtungsvorrichtung gemäß einem weiteren Ausführungsbeispiel.

Show it:

• FIG. 1 a schematic representation of a lighting device according to an embodiment,
• FIGS. 2A to 7C schematic representations of lighting devices according to further embodiments,
• FIG. 8 schematic representations of arrangements of lighting devices in a room according to further embodiments and
• FIG. 9 a schematic representation of an electrical circuit for operating a lighting device according to another embodiment.

In the exemplary embodiments and figures, identical, identical or identically acting elements can each be provided with the same reference numerals. The illustrated elements and their proportions with each other are not to be regarded as true to scale, but individual elements, such as layers, components, components and areas, for better presentation and / or better understanding may be exaggerated.

In FIG. 1 a section of a lighting device 100 according to a first embodiment is shown. The lighting device 100 has a plurality of light-emitting semiconductor chips 1, which are arranged on a carrier plate 8. The support plate has in 1, a plastic plate or plastic layer is shown, on which a metallically conductive layer is arranged as a reflective mounting surface 89, which can additionally serve for the electrical connection of the semiconductor chips 1 in addition to the reflection of the primary light emitted by the light-emitting semiconductor chip 1.

A translucent or transparent radiating plate 20, which has a light output surface 29 facing away from the semiconductor chips 1 and via which the light emitted by the semiconductor chips 1 can be emitted by the lighting device 100, is arranged downstream of the light-emitting semiconductor chips 1. The radiation plate 20 has recesses 22 over the light-emitting semiconductor chips 1, each of the recesses 22 having an inner surface 28 on which a wavelength conversion substance 21 is arranged. Alternatively or additionally, a diffuser material can also be arranged on the inner surfaces 28 of the recesses 22 for the wavelength conversion substance 21.

The semiconductor chips 1 can, for example, emit blue light, which is partially converted by the wavelength conversion substance 22 into yellow and / or green and red secondary light, so that the illumination device 100 emits white light during operation.

The light-emitting semiconductor chips 1 emit in the embodiment shown all an equal light. This may mean, in particular, that the semiconductor chips 1 emit blue light, which is not exactly the same in the context of manufacturing variations, but rather of semiconductor chip too Semiconductor chip may be different. In order to achieve a homogeneous color distribution via the light output surface 29, the semiconductor chips 1 can be measured spectrally one after the other after the mounting of the reflective mounting surface 89 of the carrier plate 8. Corresponding to the respective color locus of the semiconductor chips 1, the wavelength conversion substance 21 in each associated recess 22 can be fitted correspondingly with regard to its composition and / or its thickness in order to achieve the highest possible homogeneity over the light-emitting surface 29, both with regard to the radiated brightness and the emitted color locus.

In the exemplary embodiment shown, exactly one semiconductor chip 1 is followed by a recess 22 in each case. Alternatively, it is also possible that a plurality of semiconductor chips 1 are arranged within a recess 22. The semiconductor chips 1 are distributed as relatively small units over a large area a on the mounting surface 89 of the carrier 8. Particularly preferably, the carrier 8 has approximately one semiconductor chip 1 per square centimeter. As a result, a large radiator surface and a low power dissipation can be achieved.

The radiating plate 20 is made of a plastic material or a glass, which may be transparent, that is to say transparent, or translucent, that is, diffusely translucent. A translucent effect can be achieved, for example, by scattering elements within the radiation plate 20 or by scattering surface structures or coatings on the light emission surface 29 or the side of the emission plate 20 opposite the light emission surface 29.

The illumination device 100 can be designed in any desired size and can have, for example, more than 100 light-emitting semiconductor chips 1. A suitable electrical circuit for operating the lighting device 100 is in connection with FIG. 9 shown.

The embodiments of lighting devices shown in the following figures represent modifications and advancements of the in FIG. 1 shown lighting device 100 is.

The lighting device 101 according to the embodiment in the FIGS. 2A and 2B , which show in each case a schematic sectional view and a plan view of the light output surface 29 of the lighting device 101, has in addition to the lighting device 100 of the embodiment in FIG FIG. 1 on the semiconductor chips 1 facing away from back side 88 of the support plate 8, a plurality of webs 33. These serve for a stiffening of the support plate 8 and thus the entire lighting device 101, but are also suitable to increase the surface of the back 88 of the support plate 8 in order to achieve better heat transfer between the support plate 8 and the surrounding air. For example, the webs 33 may be designed in the form of profile nubs, which, with respect to the arrangement of the lighting device 101 during operation, are preferably arranged along the air flow direction to achieve a chimney effect. Due to the convection achieved in this way, an improvement of the heat release to the passing air can be achieved.

In the illustrated embodiment, the support plate 8 and the radiating plate 20 are connected to each other by means of clamping nails 31. These are formed as plastic nails, protrude through the radiating plate 20 and the support plate 8 and are clamped with arranged on the back 88 of the support plate 8 Klemmnagelkappen 32. By the clamping nails 31, which may also be designed as plastic rivets, and the Klemmnagelkappen 32, which may also be referred to as counter-clamping caps, the radiating plate 20 and the support plate 8 can be firmly but also releasably stapled together.

In FIG. 3 another embodiment of a lighting device 102 is shown. This has as so-called flip-chip semiconductor chips 1, which are arranged on a metallically conductive layer 4 of the carrier 8 and connected to this electrically conductive. For this purpose, a connection layer 6, for example in the form of a conductive adhesive or a solder layer, is arranged between rear chip metal contact layers 2 of the semiconductor chips 1 and connection regions of the metallically conductive layer 4. The semiconductor chips 1 are further encapsulated by means of a transparent encapsulation 18 on the metallically conductive layer 4, so that by the encapsulation 18, a contact protection against the metallically conductive layer 4 can be achieved.

The carrier 8 further comprises a plastic plate on which the metallically conductive layer 4 is applied, and whose rear side 88 has webs 33. The plastic plate of the support plate 8 has in the illustrated embodiment, a thickness d1 of about 0.5 mm to about 2 mm, while the above arranged radiating plate 20 has a thickness d2 of about 1 mm to about 2 mm, wherein the boundaries are each included. The webs 33 on the back 88 of the support plate 8 have a height of about 0.3 mm to about 2 mm, so that by the webs 33, the lighting device 102 can be significantly stiffened and so mechanical resistance to bending and twisting can be achieved which could otherwise lead to cracks in the connection layer 6 semiconductor chips 1 and the metallically conductive layer 4.

In addition to the power supply, the metallically conductive layer 4 as described in the general part also serves the heat distribution of the heat generated in the semiconductor chips 1 in operation loss heat, which can be transmitted over the metallically conductive layer 4 effectively and over a large area on the support plate 8. For improved radiation of the heat over the back side 88 of the carrier plate 8 to the environment, a surface coating 34 is applied thereon, for example in the form of a heart body color which has a high heat emissivity of as close as possible to 1 in a temperature range from 50 ° C. to 100 ° C., for example, preferably at about 80 ° C having. Such a temperature may correspond to the typical operating temperature of the lighting device 102.

The radiating plate 20 has, as in FIG. 3 can be clearly seen, dome-shaped recesses 22 which are spherical or elliptical and which are preferably embossed or cast. The recesses 22 furthermore have a diameter which corresponds at least to twice the side length of the respective semiconductor chip 1 arranged in a recess 22. The on the inner surface 28 The layer 22 of the wavelength conversion substance 21 arranged in the recess 22 can thereby be arranged thermally separated from the respective semiconductor chip 1, whereby the advantages described above in the general part can be achieved.

As an alternative to the exemplary embodiment shown with the wavelength conversion substance 21 on the inner surface 28 of the recesses 22, it may also be possible to apply a wavelength conversion substance directly to the semiconductor chips 1 and to provide the inner surfaces 28 of the recesses 22 with a further wavelength conversion substance 21 and / or a diffuser material.

Furthermore, the radiation plate 20 has scattering particles 25 as well as scattering structures 23 and 24 on the light emission surface 29 and the surface remote from the light emission surface 29, by means of which the emission plate 20 has a diffusely translucent and thus translucent effect. Furthermore, the radiation plate 20 has embedded scattering particles. By the scattering structures 23, 24 and the scattering particles 25, an improvement in the homogeneity of the radiated brightness and the emitted color impression can be achieved. Furthermore, the illumination device 102 can be perceived by a viewer from the side of the light emitting surface 29 without disturbing glare effects. The scattering structures 23 and 24 may be formed by embossing or by casting. As an alternative to the exemplary embodiment shown, only scattering particles 25 or only scattering structures 23 and / or 24 can also be present.

In FIG. 4 a further embodiment of a lighting device 103 is shown, which compared to Lighting device 102 of the previous embodiment, a support plate 8 having an insulating plastic layer 41, on which the metal-conductive layer 4 as a reflective mounting surface 89 and this facing away from a metal plate or metal foil 22 are arranged. The metal plate or metal foil 42 and the insulating plastic layer 41 may be glued together, for example. The metal plate or metal foil 42 is connected to a protective conductor 43, for example in accordance with the applicable electrical installation regulations. This can also be achieved in addition to a shield against any existing alternating electric fields of the power grid.

The metal plate or metal layer 42 further comprises on the rear side 88 of the support plate 8 forming side of a paint or anodized or other coating 34, which has a particularly high Wärmeleistungsabstrahlkoeffizienten in a wavelength range of about 10 microns, especially at slightly elevated room temperature. This can be achieved by glazing or anodization or by a radiator color, which can be designed, for example, also colored and not black.

If the semiconductor chips 1 are fixed by soldering on the metallic conductive layer 4 and connected thereto, for example by means of a tin-indium solder, the insulating plastic layer 41 is designed to be correspondingly resistant to short-term heating during soldering for a few seconds. Alternatively, a bond by means of a heat and current conductive adhesive is possible, which can also be bonded with heat support.

In FIG. 5 Another embodiment of a lighting device 104 is shown, in which compared to the previous embodiment, the metal plate 42, which forms the back of the support plate 8, webs 33 for improving the mechanical strength and rigidity and also to improve the heat dissipation.

The radiation plate 20 of the illumination device 104 furthermore has lenticular surface structures 26 over the recesses 20. In the embodiment shown, the lenticular surface structure 26 is formed as a convex elevation. Alternatively, with a corresponding thickness of the radiation plate 20, the lenticular surface structure 26 may be formed, for example, as a concave indentation. Preferably, the bulges 22 and respectively arranged above lenticular surface structure 26 are arranged centered to each other. Furthermore, the semiconductor chips 1 are preferably arranged in the recesses 22 centered to these.

The lenticular surface structures 26 can be formed, for example, in the production of the radiation plate 20 by appropriate casting or embossing. Furthermore, it is also possible to subsequently form the lenticular surface structure 26 by a corresponding method, for example a rolling method, with a material that is the same as or different from the radiating plate 20. Even if the recesses 22 and the lenticular surface structures 26 are shown spherically in the embodiment shown, they can also be aspherically shaped, for example, to optimize the same color emission in all emission directions.

In FIG. 6 a further embodiment of a lighting device 105 is shown, which has on the light emitting surface 29 lens-shaped surface structures 26. By means of the dashed lines are in FIG. 6 the beam paths of the primary light emitted directly by the semiconductor chip 1 and of the secondary light generated by the wavelength conversion substance 21 in the recess 22 are shown.

The primary light is focused by the lenticular surface structure, while the secondary light, which is radiated by the wavelength conversion substance 21 with almost a Lambertian radiation distribution, although also bundled, but with a different radiation characteristic than the directly emitted primary light. By a suitable arrangement of the semiconductor chips on the support plate 8 and by, for example, additional scattering measures such as scattering particles, a scattering coating or scattering structures, it can be achieved that the light emitting surface 29 can detect individual points of light with the primary light, while at a location to be illuminated, a homogeneous superposition of Primary light and the secondary light is perceived.

To improve the radiation of the secondary light emitted by the wavelength conversion substance 21, a reflector layer 27 is arranged on the side facing the semiconductor chip 1 side of the wavelength conversion material 21, which is permeable to the primary light generated by the semiconductor chip 1 and the secondary light generated by the wavelength conversion material 21 is reflective. The reflector layer 27 may be formed for example in the form of a Bragg filter.

In the FIGS. 7A to 7C another embodiment of a lighting device 106 is shown. The schematic sectional views of FIGS. 7A and 7B thereby run along the webs 36 and 33 according to the supervision in FIG. 7C , By means of the dashed lines are each of the respective image plane not shown elements in the FIGS. 7A and 7B indicated.

The lighting device 106 shown has both on the reflective mounting surface 89 and on the opposite rear side 88 webs 33 and 36 which are perpendicular to each other. Thereby, a further improvement and an increase in the rigidity or mechanical strength of the lighting device 106 can be achieved as compared with the previous embodiments. The radiation plate 20 has grooves 30 in which the webs 36 formed on the reflective mounting surface 89 are arranged.

In FIG. 8 For example, embodiments of the arrangement of lighting devices in a room are shown. In the FIG. 8 illustrated lighting devices 107 to 112 may be performed, for example, according to one or more of the aforementioned embodiments.

The lighting devices 107 and 108 are arranged horizontally and vertically on or in the wall of the room shown by way of example. In an arrangement on the wall, the lighting devices are preferably mounted in front of the wall, that a rear ventilation is possible while at an arrangement in the wall heat dissipation can take place through the wall.

The lighting devices 109 and 110 are arranged horizontally and vertically in room surface corners, while the lighting devices 111 is arranged symmetrically tilted against each other on the ceiling. The lighting device 112 is, for example, horizontal or tilted to the horizontal, arranged hanging from the ceiling and may for example be formed in a flow vane shape.

Corresponding to the horizontal or vertical arrangement of the lighting devices 107 to 112, the webs 33 of the carrier body 8 shown in the previous embodiments can be aligned along the direction of gravity in order to achieve a convection flow for cooling.

In FIG. 9 an electronic circuit 200 is shown which is suitable for operating the lighting devices of the preceding embodiments. By the electronic circuit 200, the lighting devices described can be easily operated and controlled on a 230V Wechsellesromnetz with a phase conductor L, a neutral conductor N and a protective conductor SL, with parts of the electronic circuit 200 as a ballast cost, reliable and simple and good Active power factor and high efficiency may have.

The electronic circuit 200 has circuit parts 91, 92 and 93, wherein the circuit part 93 by one of the vorab shown lighting devices 100 to 112 can be formed.

The circuit part 91, which is designed as a so-called Einschaltbox, is used to adjust the electrical power with which is designed to be operated as a ballast circuit part 92, the circuit part 93 designated lighting device to be operated.

The switches S1 and S2 of the circuit part 91, which can also be part of a room installation or also integrated in the circuit part 92, each serve to adjust half the power of the lighting device by each half of the in FIG. 9 D-emitting semiconductor chips of the lighting device can be switched by the switches S1 and S2. By dividing the maximum power in the two switchable by means of the switches S1 and S2 circuits can be secured against total failure in case of a defect in one of the circuits can be achieved. The switch S3 is used to set a small power, for example, for a night light function.

For driving the lighting device in the circuit part 93 by means of the switches S1 and S2 of the circuit part 1, the lighting device has two separate circuits with a plurality of semiconductor chips connected in series. For a high power factor (cos φ), the sum-flow voltage of the semiconductor chip rows should be on the order of magnitude of the AC effective voltage or slightly below. As for example in the embodiment of FIG. 4 is shown, the lighting device in Circuit part 93 connected to the protective conductor SL by means of the protective contact Sch.

The circuit part 92 designed as a ballast can be implemented separately from the circuit part 93, that is to say the lighting device, in the supply line of the lighting device or, alternatively, also integrated in the lighting device. The circuit part 92 has in the illustrated embodiment current limiting series capacitors C1 and C2, which have a high voltage and current pulse strength in the order C = Im / (π · f · (Us-Uc)), where Im is the average current, the is applied to the semiconductor chips, f the mains frequency, Us the mains peak voltage and Uc the sum of a semiconductor chip series circuit. For example, for a 50 Hz AC 230V power system and a 20W electrical power device with a semiconductor chip series voltage of about 200V, the current Im is calculated to be 20W / 200V = 0.1A and the series capacitance about 5 μF.

The capacitor C3 in the small power circuit has a corresponding fraction of the capacitance of the capacitors C1 and C2 for limiting the operating current of the semiconductor chips to a desired fraction of the current in the switching over the switches S1 and S2 current branches. For a limitation of the operating current Im in the circuit for small power to 1/100 of the operating current Im, the capacitance of the capacitor C3 in the illustrated embodiment is then about 50 nF.

The circuit part 92 further has Einschaltbegrenzungswiderstände R, which in the Magnitude of about 0.03 · Ueff ² / P with the effective voltage Ueff and the power loss P are, which corresponds to a resistance of about 80 ohms with a power loss of less than 1.5 W in the illustrated embodiment. The capacitors C4 and C5 are in the illustrated embodiment in the order of about 2 nF, while the capacitors C6 and C7 are designed as electrolytic capacitors with a capacity of about 1 uF to about 5 uF. Furthermore, the circuit part 92 rectifier units B1 and B2, which are designed as a bridge rectifier for a current of up to 2 A, to be load-resistant to turn-on.

As an alternative to the exemplary embodiment shown, the electrical circuit 200 may also have only one current branch, for example the current branch which can be switched via the switch S1.

The features and modifications contained in the individual embodiments shown may also be present individually or in other combinations in lighting devices, even if they are not explicitly shown. Furthermore, features according to the embodiments described in the general part may alternatively or additionally be provided in the exemplary embodiments.

The invention is not limited by the description based on the embodiments of these. Rather, the invention encompasses any novel feature as well as any combination of features, including in particular any combination of features in the claims.

Claims (13)

1. Lighting device for room lighting, having

   - a carrier plate (8) having a reflective installation surface (89), on which a plurality of light-emitting semiconductor chips (1) spaced apart from one another is arranged,

   - a translucent or transparent emission plate (20), which is arranged downstream from the light-emitting semiconductor chips (1) in the emission direction, having a light decoupling surface (29) facing away from the light-emitting semiconductor chips (1),

   - wherein the emission plate (20) has a plurality of recesses (22), which are each arranged downstream from at least one semiconductor chip (1),

   - wherein each of the recesses (22) has, on an inner surface (28) facing toward the semiconductor chips (1), a diffuser material and/or a wavelength conversion material (21) spaced apart from the light-emitting semiconductor chips (1),

   characterized in that
   the emission plate (20) has, for diffuse scattering, scattering particles (25) distributed in the emission plate (20) and/or scattering structures (23) on a rear side opposite to the light decoupling surface (29) and/or a translucent coating and/or scattering structures (24) on the light decoupling surface (29).
2. Lighting device according to Claim 1, wherein the recesses (20) are in the form of spherical caps.
3. Lighting device according to Claim 1 or 2, wherein the recesses (20) each have a diameter which is larger than side lengths of the semiconductor chips (1) by a factor greater than or equal to 2 and less than or equal to 20.
4. Lighting device according to any one of the preceding claims, wherein the emission plate (20) has a lens-shaped surface structure (26) over at least some recesses (22) on the light decoupling surface (29).
5. Lighting device according to any one of the preceding claims, wherein respectively one light-emitting semiconductor chip (1) is arranged in one recess (22) in each case.
6. Lighting device according to any one of the preceding claims, wherein the reflective installation surface (89) is formed by a metallically conductive layer (4).
7. Lighting device according to Claim 6, wherein the light-emitting semiconductor chips (1) are electrically connected by the metallically conductive layer (4).
8. Lighting device according to any one of the preceding claims, wherein the carrier plate (8) has a plurality of webs (33, 36) on the installation surface (89) and/or a rear side (88) opposite to the installation surface (89).
9. Lighting device according to Claim 8, wherein the emission plate (20) has grooves (30), in which webs (36) of the carrier plate (8) provided on the installation side (89) are arranged.
10. Lighting device according to any one of the preceding claims, wherein a rear side (88), which is opposite to the installation surface (89), of the carrier plate (8) is formed by a metal plate or metal foil (42).
11. Lighting device according to any one of the preceding claims, wherein a rear side (88), which is opposite to the installation surface (89), of the carrier plate (8) has a heat-emitting coating (34).
12. Lighting device according to any one of the preceding claims, wherein the emission plate (20) has, in each of the recesses (22) on the inner surface (28) facing toward the semiconductor chips (1), a wavelength conversion material (21), which converts light emitted from the semiconductor chips (1) into converted light, and wherein, on the respective side of the wavelength conversion material (21) facing toward the semiconductor chips (1), a reflector layer (27) is arranged, which is reflective for the converted light and is transmissive for the light emitted from the semiconductor chips (1).
13. Lighting device according to any one of the preceding claims, wherein the emission plate (20) is connected by means of clamping nails (31) to the carrier plate (8).

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